Answer:
A and D are true , while B and F statements are false.
Explanation:
A) True. Since the standard gibbs free energy is
ΔG = ΔG⁰ + RT*ln Q
where Q= [P1]ᵃ.../([R1]ᵇ...) , representing the ratio of the product of concentration of chemical reaction products P and the product of concentration of chemical reaction reactants R
when the system reaches equilibrium ΔG=0 and Q=Keq
0 = ΔG⁰ + RT*ln Q → ΔG⁰ = (-RT*ln Keq)
therefore the first equation also can be expressed as
ΔG = RT*ln (Q/Keq)
thus the standard gibbs free energy can be determined using Keq
B) False. ΔG⁰ represents the change of free energy under standard conditions . Nevertheless , it will give us a clue about the ΔG around the standard conditions .For example if ΔG⁰>>0 then is likely that ΔG>0 ( from the first equation) if the temperature or concentration changes are not very distant from the standard conditions
C) False. From the equation presented
ΔG⁰ = (-RT*ln Keq)
ΔG⁰>0 if Keq<1 and ΔG⁰<0 if Keq>1
for example, for a reversible reaction ΔG⁰ will be <0 for forward or reverse reaction and the ΔG⁰ will be >0 for the other one ( reverse or forward reaction)
D) True. Standard conditions refer to
T= 298 K
pH= 7
P= 1 atm
C= 1 M for all reactants
Water = 55.6 M
To what does the term 'drying a liquid' refer?
a. Removing all traces of water to form a solid.
b. The technique of removing all traces of an organic solvent from water.
c. Removing all traces of water from an organic solvent.
d. The extraction of a solid from a polar solvent.
Answer: a. Removing all traces of water to form a solid
Explanation:
If the caffeine concentration in a particular brand of soda is 2.85 mg/oz, drinking how many cans of soda would be lethal? Assume that 10.0 g of caffeine is a lethal dose, and there are 12 oz in a can.
Final answer:
To calculate the number of cans of soda that would be lethal, we need to determine the amount of caffeine in a lethal dose and the amount of caffeine in one can of soda. Given that the lethal dose of caffeine is 10.0 g and there are 12 oz in a can, drinking approximately 10 cans of soda would be lethal.
Explanation:
To calculate the number of cans of soda that would be lethal, we need to determine the amount of caffeine in a lethal dose and the amount of caffeine in one can of soda. Given that the lethal dose of caffeine is 10.0 g and there are 12 oz in a can, we can use the caffeine concentration of the soda (2.85 mg/oz) to calculate the amount of caffeine in one can.
First, convert the caffeine concentration to mg/mL: 2.85 mg/oz = 2.85 mg/mL. Then, multiply the concentration by the volume of one can (12 oz = 354.88 mL): 2.85 mg/mL * 354.88 mL = 1011.84 mg.
To determine the number of cans that would be lethal, divide the lethal dose by the amount of caffeine in one can: 10.0 g / 1011.84 mg = 9.87 cans (rounded to the nearest whole number). Therefore, drinking approximately 10 cans of soda would be lethal.
102.1 g of Aluminum nitrite and 174.3 g of ammonium chloride react to form aluminum chloride, nitrogen, and water.
How many grams of the excess reagent remains after the reaction?
Answer:
57.39 g excess Aluminum nitrite
Explanation:
When performing stoichiometric calculations, the first thing we need is the balanced chemical reaction.
In this case we will have:
Al(NO₂)₃ + 3 NH₄Cl ⇒ AlCl₃ + 3 N₂ + 6 H₂O
( nitrite ion is NO₂⁻ )
Now that we have the balanced reaction, we need to calculate the number of moles, n, of Al(NO₂)₃ and NH₄Cl , and perform the calculations necessary to determine the excess reagent and its amount.
The number of moles is :
n = mass / MW where MW is the molecular weight and m the mass.
MW Al(NO₂)₃ = 40.99 g/mol
MW NH₄Cl = 53.49 g/mol
n Al(NO₂)₃ = 102.1 g / 40.99 g/mol = 2.49 mol Al(NO₂)₃
n NH₄Cl = 174.3 g / 53.49 g/mol = 3.26 mol NH₄Cl
Now lets calculate how many moles of NH₄Cl will react with 2.49 mol Al(NO₂)₃ :
( 3 mol NH₄Cl / 1 mol Al(NO₂)₃ ) x 2.49 mol Al(NO₂)₃ = 7.5 mol NH₄Cl
We only have 3.26 mol NH₄Cl . Therefore our limiting reagent is NH₄Cl , and the excess reagent is Al(NO₂)₃
Now lets calculate the number of moles Al(NO₂)₃ used to react with 3.26 mol NH₄Cl :
( 1 mol Al(NO₂)₃ / 3 mol NH₄Cl ) x 3.26 mol NH₄Cl =1.09 mol Al(NO₂)₃
The excess number of moles is:
= 2.49 mol - 1.09 mol = 1.40 mol Al(NO₂)₃
grams of Al(NO₂)₃ in excess
1.40 mol Al(NO₂)₃ x 40.99 g/mol = 57.39 g
The synthesis of dipropyl ether can be accomplished using 1-propanol. What reactants and conditions are necessary for this to occur
Answer: Reactants==>2 molecules of propanol.
Condition for Reaction to occur==> Strong acid,e.g HCl and high temperature (140°C).
Explanation:
Dipropyl ether can be sythesized commonly in two ways;
(1). Williamson ether synthesis of dipropyl ether: this chemical reaction involves the reaction of alkyl halide(propyl halide) with conjugate base of propanol.
(2). Acid catalyzed ether synthesis of dipropyl ether: this is the reaction this question is talking about. A strong acid is used in the Chemical Reaction, and , it is reaction between two(2) molecules of propanol. This is done in the presence of strong acid such as HCl and high temperature (up to 140°C).
The Reactants are the two molecules of propanol. The condition necessary for the reaction to occur is that the temperature must be high(140-143°C) and it must be in the presence of a strong acid.
In a dehydration reaction, 2 molecules lose one water molecule to combine. In presence of strong acid ([tex]\bold{H_2SO4}[/tex]) and high temperature at [tex]\bold{145^oC}[/tex] propanol can be accomplished to synthesize dipropyl ether.
Dehydration of Alcohol:
In high acidic and high-temperature conditions, alcohol dehydrates to form ether.
[tex]\bold{2R-OH \rightarrow R-O-R +H_2O}[/tex]
2 molecules of propanol will combine to form dipropyl ether in the presence of strong acid ([tex]\bold{H_2SO4}[/tex]) at [tex]\bold{145^oC}[/tex].
[tex]\bold{2CH_3 CH_2CH_2OH \rightarrow CH_3 CH_2CH_2-O-CH_2CH_2CH_3 + H_2O }[/tex]
Therefore, In presence of strong acid ([tex]\bold{H_2SO4}[/tex]) and high temperature at [tex]\bold{145^oC}[/tex]
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Which one of the following statements is notapplicable to molecularsolids?
a. The units that occupy the lattice points are molecules.
b. The binding forces in molecular solids are dispersion forces or dispersion forces and dipole-dipole interactions.
c. Molecular solids have relatively low melting points.
d. Molecular solids are usually excellent conductors of electric current. e. Molecular solids are soft compared to covalent solids.
Answer: The answer is D. Molecular solids are usually excellent conductors of electric current
Explanation: Molecular solids are solids that have separate individual molecules held together by intermolecular forces (Van der Waal's force) rather than bonds.
Van der Waal's forces are the weak forces that contribute to intermolecular bonding between molecules.
Examples of a molecular solid are water ice, solid carbon dioxide and white phosphorus.
Molecular solids cannot conduct electricity because they have localized electrons (election localized within the bonds in each molecule).
Final answer:
The statement that is not applicable to molecular solids is 'd. Molecular solids are usually excellent conductors of electric current' because molecular solids are poor conductors due to the lack of ions or free electrons.
Explanation:
To answer which statement is not applicable to molecular solids, let us examine each option given:
a. The units that occupy the lattice points are molecules - This is true for molecular solids.
b. The binding forces in molecular solids are dispersion forces or dispersion forces and dipole-dipole interactions - This is also true. Dispersion forces are present in nonpolar molecular solids, while polar molecular solids exhibit dipole-dipole interactions and sometimes hydrogen bonds as well.
c. Molecular solids have relatively low melting points - This statement is correct since the intermolecular forces in molecular solids are weaker than ionic or covalent bonds, resulting in lower melting points.
d. Molecular solids are usually excellent conductors of electric current - This statement is not true. Molecular solids lack ions or free electrons, which makes them poor conductors of electricity.
e. Molecular solids are soft compared to covalent solids - This is generally true because the intermolecular bonds in molecular solids are weaker than the covalent bonds in covalent solids.
Therefore, the statement that is not applicable to molecular solids is d. Molecular solids are usually excellent conductors of electric current.
What is the mass % of ammonium chloride in a 1.73 M ammonium chloride aqueous solution at 20 °C?
The question is incomplete, here is the complete question:
What is the mass % of ammonium chloride in a 1.73 M ammonium chloride aqueous solution at 20 °C? The density of the solution is 1.0257 g/mL
Answer: The mass percent of ammonium chloride in solution is 9.03 %
Explanation:
We are given:
Molarity of ammonium chloride solution = 1.73 M
This means that 1.73 moles of ammonium chloride is present in 1 L or 1000 mL of solution.
To calculate the mass of solution, we use the equation:[tex]\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}[/tex]
Density of solution = 1.0257 g/mL
Volume of solution = 1000 mL
Putting values in above equation, we get:
[tex]1.0257g/mL=\frac{\text{Mass of solution}}{1000mL}\\\\\text{Mass of solution}=(1.0257g/mL\times 1000mL)=1025.7g[/tex]
To calculate the number of moles, we use the equation:[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Moles of ammonium chloride = 1.73 moles
Molar mass of ammonium chloride = 53.5 g/mol
Putting values in above equation, we get:
[tex]1.73mol=\frac{\text{Mass of ammonium chloride}}{53.5g/mol}\\\\\text{Mass of ammonium chloride}=(1.73mol\times 53.5g/mol)=92.6g[/tex]
To calculate the mass percentage of ammonium chloride in solution, we use the equation:[tex]\text{Mass percent of ammonium chloride}=\frac{\text{Mass of ammonium chloride}}{\text{Mass of solution}}\times 100[/tex]
Mass of solution = 1025.7 g
Mass of ammonium chloride = 92.6 g
Putting values in above equation, we get:
[tex]\text{Mass percent of ammonium chloride}=\frac{92.6g}{1025.7g}\times 100=9.03\%[/tex]
Hence, the mass percent of ammonium chloride in solution is 9.03 %
When a hydrogen atom covalently bonds to another atom, how many electrons associated with this hydrogen atom become involved in such a bond?
Explanation:
A covalent bond is defined as the occurrence of a bond due to the sharing of electrons between the combining atoms.
Atomic number of hydrogen atom is 1 and its electronic configuration is [tex]1s^{2}[/tex]. So, in order to complete its octet it needs to gain or mutually shares one electron.
A covalent bond is generally formed between non-metal atoms.
Thus, we can conclude that hydrogen has only one electron that will be involved in the formation of a covalent bond.
In a covalent bond, a hydrogen atom contributes its single electron, which pairs with the electron from the other atom, forming a single covalent bond.
Explanation:When a hydrogen atom forms a covalent bond with another atom, it shares its single electron, resulting in a paired bonding configuration. As hydrogen has one electron in its valence shell, this one electron becomes involved in bonding. When two hydrogen atoms bond, each contributes their one electron to form a molecular orbital, resulting in a single covalent bond. This is represented in the formation of a hydrogen molecule (H₂), where the bond order is calculated as (2-0)/2=1, signifying one stable covalent bond. The electron configuration for each hydrogen atom in the molecule then resembles that of helium, with two electrons completing the 1s subshell.
Oxygen has an atomic number of 8 and an atomic mass of 16. How many valence electrons does it have?
2
4
6
8
16
Answer: 6 valence electrons
Explanation: the valence electron is the number of electron in the outermost shell of an atom.
Oxygen has an atomic number of 8. The electronic configuration will be 1s2 2s2 2p4 or 2, 6. Meaning the last shell is having 6 electrons and this is equivalent to the valence electron
Oxygen has 6 valence electrons.
Explanation:Oxygen has an atomic number of 8, which tells us that it has 8 protons in its nucleus. The atomic mass of oxygen is 16, which is the weighted average mass of all the isotopes of oxygen. Since the atomic number represents the number of protons and the number of electrons in an element, oxygen also has 8 electrons.
In the electron configuration of oxygen, the electrons are arranged in energy levels or shells. The valence electrons are the electrons in the outermost energy level, also known as the valence shell. Oxygen's electron configuration is 1s2 2s2 2p4. From this configuration, we can determine that oxygen has 6 valence electrons.
Valence electrons are responsible for the chemical behavior of an atom. In the case of oxygen, its 6 valence electrons allow it to form two covalent bonds. This enables oxygen to react with other elements to form compounds such as water and carbon dioxide.
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Write the rate law for the following elementary reaction:
2N2O5(g) - 2N204 Use k1 to stand for the rate constant.
Answer:
Rate law = k1 [N2O5]^2
Explanation:
Rate law only cares about reactants and rate law can only be determined experimentally or by using the coefficients of reactants in elementary reactions
If 2A---->B is an elementary reaction... rate law for this is rate=k[A]^2
So if we look at your question...2N2O5---->2N2O4 + 02 (I think you are missing O2 in question because otherwise equation is unbalanced)
Rate law = k1 [N2O5]^2
The rate law for the reaction 2N2O5(g) → 2N2O4(g) is rate = k1[N2O5]^2, indicating a second-order dependence on [N2O5]. For the reaction H2(g) + 2NO(g) → N2O(g) + H2O(g), the rate law is rate = k[NO]^2[H2], with the reaction being second order in NO and first order in H2.
Explanation:The rate law for an elementary reaction can be written directly from the stoichiometry of the reaction. Considering the provided elementary reaction 2N2O5(g) → 2N2O4(g), the rate law would be rate = k1[N2O5]^2, which indicates that the reaction is second order with respect to N2O5.
In general, for an elementary reaction like H2(g) + 2NO(g) → N2O(g) + H2O(g), the rate law given is rate = k[NO]^2[H2], which means that the reaction is second order with respect to NO (order of 2) and first order with respect to H2 (order of 1), making the overall order of the reaction three.
An alpha particle is the same as a helium-4 nucleus: it contains two protons and two neutrons in the nucleus. Given that the radius of an alpha particle is approximately 2.6 fm, calculate the density of an alpha particle in units of grams per cubic centimeter.
Answer:
1.31x10¹¹ g/cm³
Explanation:
The mass of the proton is equal to the mass of the neutron, which is 1.67x10⁻²⁴ g, so the mass of the alpha particle is 4*1.67x10⁻²⁴ = 6.68x10⁻²⁴ g.
1 fm = 1.0x10⁻²³ cm, thus the radius of the alpha particle is 2.3x10⁻¹² cm. If the particle is a sphere, the volume of it is:
V = (4/3)*π*r³, where r is the radius, so:
V = (4/3)*π*(2.3x10⁻¹²)³
V = 5.1x10⁻³⁵ cm³
The density of the particle is the how mass exists per unit of volume, so, it's the mass divided by the volume:
d = 6.68x10⁻²⁴/5.1x10⁻³⁵
d = 1.31x10¹¹ g/cm³
An alpha particle is a helium-4 nucleus consisting of two protons and two neutrons. The density of an alpha particle can be calculated by dividing its mass by its volume. For an alpha particle with a mass of approximately 4 atomic mass units and a radius of 2.6 femtometers, the density is approximately 4.90 x 10⁶ grams per cubic centimeter.
Explanation:An alpha particle is a helium-4 nucleus, consisting of two protons and two neutrons. The density of an alpha particle can be calculated by dividing its mass by its volume. Since the mass of an alpha particle is approximately 4 atomic mass units (amu) and its radius is given as 2.6 fm (femtometers), we can use the formula for the volume of a sphere to find the volume of the alpha particle.
V = (4/3)πr³ = (4/3)π(2.6 fm)³ = (4/3)π(2.6 x 10⁻¹⁵ m)³ = (4/3)π(2.6 x 10⁻¹⁵ x 10⁻¹⁵ x 10⁻¹⁵) m³ = (4/3)π(1.94 x 10⁻⁴) m³ ≈ 8.15 x 10⁻¹³ m³
To convert this volume from cubic meters to cubic centimeters, we can multiply by the conversion factor 1 m³ = 1 x 10⁶ cm³.
Volume in cm³ = (8.15 x 10⁻¹³ m³) x (1 x 10⁶ cm³/m³) ≈ 8.15 x 10⁻⁷ cm³
To find the density, we divide the mass of the alpha particle (4 amu) by its volume (8.15 x 10⁻⁷ cm³).
Density = mass/volume = (4 amu) / (8.15 x 10⁻⁷ cm³) ≈ 4.90 x 10⁶ g/cm³
A chemist adds of a M zinc nitrate solution to a reaction flask. Calculate the mass in grams of zinc nitrate the chemist has added to the flask. Round your answer to significant digits.
corrected question: A chemist adds 135mL of a 0.21M zinc nitrate solution to a reaction flask. Calculate the mass in grams of zinc nitrate the chemist has added to the flask. Round your answer to significant digits.
Answer:
5.37g
Explanation:
0.21M means ; 0.21mol/dm³
1dm³=1L , so we can say 0.21mol/L
if 0.21mol of Zinc nitrate is contained in 1L of water
x will be contained in 135mL of water
x= 0.21*135*10³/1
=0.02835moles
number of moles= mass/ molar mass
mass= number of moles *molar mas
molar mass of Zn(NO₃)₂=189.36 g/mol
mass= 0.02835 *189.36
mass=5.37g
Estimate ΔH for the reaction: C2H6(g) + Cl2(g)--> C2H5Cl(g) + HCl(g) given the following average bond energies (in kJ/mol): C-C, 348 C-H, 414 CI-CI, 242 C-CI, 327 H-CI, 431 68 kJ/mol 344 kJ/mol +276 kJ/mol -102 kJ/mo 113 kJ/mol
To estimate the reaction enthalpy (ΔH) for the given reaction, the energies required to break the reactant bonds are added, and the energies released from forming product bonds are subtracted. The estimated ΔH is found to be 1902 kJ/mol, which is the energy absorbed by the reaction.
The student was asked to estimate a balanced reaction using average bond energies. To solve for the reaction enthalpy (ΔH), the energy required to break the bonds in the reactants must be calculated and then the energy released in forming the bonds of the products has to be subtracted from it.
For the given reaction:
One C-C bond is broken: 348 kJ/molFive C-H bonds are broken: 5 x 414 kJ/molOne Cl-Cl bond is broken: 242 kJ/molOne C-Cl bond is formed: -327 kJ/molOne H-Cl bond is formed: -431 kJ/molTo calculate ΔH:
ΔH = Energy required to break bonds - Energy released in forming bonds
ΔH = (348 + (5 x 414) + 242) - (327 + 431)
ΔH = (348 + 2070 + 242) - 758
ΔH = 2660 - 758
ΔH = 1902 kJ/mol
Thus, the estimated ΔH for the reaction is 1902 kJ/mol, which indicates that it would absorb this amount of energy.
You have identified your product to be butylnapthyl ether and recrystallize it. The initial mass of the the crude ether was 141 mg. The mass after recrystallization was 121 mg. Calculate the percent recovery from recrystallization.
Answer:
85.82%
Explanation:
Mass before recovery = 141 mg
Mass after recrystallization = 121 mg
Percent recovery of recrystallization = actual mass / mass of crude extract * 100 = 121 / 141 * 100 = 85.82%
127 grams of copper metal react with 32 grams of oxygen gas to form a new compound, with no copper or oxygen left over. What is the mass of the new compound in grams?
Answer: The mass of the new compound formed will be 159 grams.
Explanation:
Synthesis reaction is defined as the reaction in which smaller substances combine in their elemental state to form a larger substance.
[tex]A+B\rightarrow AB[/tex]
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The chemical equation for the synthesis of copper oxide follows:
[tex]2Cu+O_2\rightarrow 2CuO[/tex]
Let the mass of new compound (copper oxide) formed be 'x' grams
We are given:
Mass of copper metal = 127 grams
Mass of oxygen gas = 32 grams
Total mass on reactant side = 127 + 32 = 159 g
Total mass on product side = x
So, by applying law of conservation of mass, we get:
x = 159 g
Hence, the mass of the new compound formed will be 159 grams.
Endospore structures are resistant to heat and chemicals because of ____ in their protective covering.
Answer:
The spore coat (proteinous coat)
Explanation:
Endospore is usually a position taken by a gram positive bacteria when it lacks nutrient. Endo- means within and the-spore means offspring. This is a complex stage which is a dormant and highly resistive cell wall that allows the bacteria preserve its genetic materials in times of deprivation within this protective cell.
They are also resistant to UV radiation, heat and chemicals. Once the environment become favourable, they reactivate from this vegetative state and absorb nutrients. This vegetative state consists of the following layers:
1. The outer coating called the exosporium which surrounds the spore is the thin layer responsible for covering the spore coat.
2. The proteinous coating which is the spore coat is the next layer which as a sieve. It is resistant to chemical and other toxins.
3. After this proteinous coating is a thick peptidoglycan called the cortex.
3. A cell/core wall which resides under the cortex. This layer will become the cell wall of the bacterium after the endospore germinates.
5. The center/core of the endospore js the next. The core has the spore chromosomal DNA and some cell structures, such as ribosomes and enzymes but is inactive.
The gas in a 250. mL piston experiences a change in pressure from 1.00 atm to 4.45 atm. What is the new volume (in mL) assuming the moles of gas and temperature are held constant
Answer:
56.2 mL
Explanation:
Given data
Initial volume (V₁): 250 mLInitial pressure (P₁): 1.00 atmFinal volume (V₂): ?Final pressure (P₂): 4.45 atmAssuming the gas has an ideal behavior, we can find the final volume using Boyle's law.
P₁ × V₁ = P₂ × V₂
V₂ = P₁ × V₁/P₂
V₂ = 1.00 atm × 250 mL/ 4.45 atm
V₂ = 56.2 mL
According to the question,
Volume,
[tex]V_1 = 250 \ mL[/tex][tex]V_2 = \ ?[/tex]Pressure,
[tex]P_1 = 1.00 \ atm[/tex][tex]P_2 = 4.45 \ atm[/tex]By using the Boyle's Law, we get
→ [tex]P_1 V_1 = P_2 V_2[/tex]
or,
→ [tex]V_2 = \frac{P_1V_1}{P_2}[/tex]
By putting the values, we get
[tex]= \frac{1.00\times 250}{4.45}[/tex]
[tex]= \frac{250}{4.45}[/tex]
[tex]= 56.2 \ mL[/tex]
Thus the above answer is right.
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Which of the following gases is expected to be most soluble in water? Explain your reasoning. (a) CH4 (b) CCl4 (c) CHCl3
Answer: (c) CHCl3
Explanation:
From the rule : a polar solvent will dissolve a polar compound and a non polar solvent will also dissolves a non polar compound.
(a) CH4 is non- polar and water is a polar solvent. Therefore CH4 is not soluble in water
(b) CCl4 is non polar and water is a polar solvent. Therefore CCl4 is not soluble in wtaer
(c) CHCl3 is polar molecule and water is also a polar solvent.
Therefore CHCl3 is expected to be most soluble in water
Among CH4, CCl4, and CHCl3, CHCl3 (chloroform) is expected to be the most soluble in water due to its somewhat polar nature which corresponds with the polarity of water.
Explanation:The gas expected to be most soluble in water among CH4, CCl4, and CHCl3 is CHCl3. This is based on the principle of 'like dissolves like'. In terms of polarity, water is polar and CHCl3 (chloroform) is also somewhat polar due to the presence of chlorine atoms, which have higher electronegativity. Since polar molecules are more likely to dissolve in another polar substance, CHCl3 would be the most soluble of the given gases in water.
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13.3 g of benzene (C6H6) is dissolved in 282 g of carbon tetrachloride. What is the molal concentration of benzene in this solution?
Answer:
0.605 molal
Explanation:
molality is the amount of solute in a particular mass of solvent.
lets calculate the amount of benzene solute.
mass of benzene= 13.3g
molar mass of C6H6= 12*6 +1*6 =72+7=78g/mol
amount of benzene= mass/molar mass
=13.3/78
=0.1705mol
molality= amount of solute/mass of solvent in kg
mass of solvent=282g=0.282kg
molality = 0.1705/0.282
=0.605 molal
To calculate the molal concentration of benzene in the solution, divide the number of moles of benzene (0.1703 moles) by the mass of carbon tetrachloride in kilograms (0.282 kg), resulting in a concentration of 0.604 molal.
To calculate the molal concentration of benzene in the solution, first, we need to determine the number of moles of benzene. The molar mass of benzene (C6H6) is approximately 78.11 g/mol. Using the mass of benzene given (13.3 g), we can calculate the moles of benzene as follows:
Number of moles of benzene = mass of benzene / molar mass of benzene
Number of moles of benzene = 13.3 g / 78.11 g/mol = 0.1703 moles
The molal concentration is then calculated by the number of moles of solute per kilogram of solvent. Since the mass of the solvent (carbon tetrachloride) is given in grams, we convert it to kilograms:
Mass of solvent in kg = 282 g / 1000 = 0.282 kg
Now, the molal concentration (m) can be calculated as:
Molal concentration (m) = moles of solute / mass of solvent in kg
Molal concentration (m) = 0.1703 moles / 0.282 kg = 0.604 Molal
Based on your knowledge of molecular geometry, which hypothesized structure of Benzene has bond angles strained well beyond known tolerances?
It seems that the question is lacking hypothesized structures, which are provided in Figure A
Answer:
Option A has bond angles that have the highest strain beyond known tolerance
Explanation:
Note: Please find the complete question in the attachment
The hypothesized structures in the options were the proposed structures of benzene in the mid 19th century by Ladenburg (1869), Thiele (1899), Armstrong (1887), and Kekule (1865) respectively
Option A suggests sp3 hybridization of the carbon atom. sp3 hybridized atoms are oriented at 109.5° to be stable. The structure suggests that bond angles between C-C bonds are 60° and 90°, these bond angles are well beyond the known tolerable angle strain.
Options B and D (currently accepted structures of benzene) are sp2 hybridized and their bonds angle is 120°, which is the optimal angle for sp2 hybridized atom. Option C also suggests sp2 hybridized carbon, so their will also be no ring strain in it. But it is not an accepted structure as it was suggested to contain radical like properties by Armstrong.
The strain in molecular geometries such as 1-cyclohexyne arises from abnormal bond angles that deviate from ideal sp³ hybridization. Benzene, however, remains stable due to electron delocalization and a regular planar hexagonal structure maintaining equal bond lengths and angles.
Explanation:Understanding Molecular Geometry and Strain in Hypothesized Structures
The concept of strained bond angles beyond known tolerances relates to proposed molecular structures that do not conform to normal, observed geometries. For instance, the 1,3,5-cyclohexatriene structure proposed for benzene in 1866 by Kekule features alternating single and double bonds. This would predict different bond lengths of 1.48 Å for single and 1.34 Å for double bonds. However, due to aromaticity, benzene is actually a regular planar hexagon with equal C-C bond lengths of 1.39 Å and bond angles of 120°, indicating the presence of resonance and delocalized p-orbital electrons.
In contrast, a structure like 1-cyclohexyne would suffer from severe angle strain since it attempts to maintain a planar structure with sp² hybridization that imposes 120° bond angles, which deviates from the tetrahedral angle of 109.5° expected for sp³ hybridized carbons as in cyclohexane. Additionally, cyclooctatetraene, if forced into a planar structure to achieve delocalization, would also experience prohibitive angle strain, as it can not attain a structure with equivalent π bonds between adjacent carbons without distorting natural bond angles.
The concept of electron delocalization is fundamental in understanding why certain hypothesized structures impose a strain on bond angles. For benzene, the planar structure and delocalization lead to stability, while for other cyclic compounds, the need to maintain ideal hybridization geometry can lead to significant strain if forced into non-tetrahedral geometries.
How many grams of Al were reacted with excess HCl if 2.34 L of hydrogen gas were collected at STP in the following reaction2Al + 6HCl --> 2AlCl3 + 3H2
Answer:
1.87 g of Al were reacted
Explanation:
We must apply the Ideal Gases law to solve the amount of moles of H₂ produced at STP
T = 273 K
P = 1 atm
P. V = n . R . T
1 atm . 2.34 L = n . 0.082 . 273 K
( 1 atm . 2.34 L ) / ( 0.082 . 273 K) = n
0.104 moles = n
Now we can find the moles of Al with the reaction. As ratio is 3:2 we have to make a rule of three to determine the moles we used.
3 moles of H₂ came from 2 moles of Al
0.104 moles of H₂ would come from ( 0.104 . 2 ) /3 = 0.0693 moles of Al
Finally we can know the mass of Al we used ( moles . molar mass)
0.0693 mol . 26.98 g/mol = 1.87 g
To determine the grams of Al reacted with excess HCl, we need to calculate the number of moles of H2 gas produced at STP, then use stoichiometry to convert the moles of H2 to moles of Al, and finally convert the moles of Al to grams using its molar mass.
Explanation:To determine how many grams of Al were reacted with excess HCl, we need to first calculate the number of moles of H2 gas produced at STP. From the balanced chemical equation, we can see that for every 2 moles of Al, 3 moles of H2 gas are produced. Since 1 mole of any ideal gas occupies 22.4 L at STP, we can convert the given volume of H2 gas to moles by dividing 2.34 L by 22.4 L/mol. This gives us approximately 0.1045 moles of H2 gas.
Using the stoichiometry of the reaction, we can then determine the number of moles of Al, which is the same as the number of moles of H2 gas produced. Finally, we can convert the moles of Al to grams using the molar mass of Al, which is 26.98 g/mol. Therefore, the number of grams of Al reacted would be approximately 0.1045 moles multiplied by 26.98 g/mol, resulting in approximately 2.82 grams of Al.
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An electron is confi ned to a linear region with a length of the same order as the diameter of an atom (about 100 pm). Calculate the minimum uncertainties in its position and speed.
Explanation:
The minimum uncertainty position is 100 nm.
Therefore, by Heisenberg Uncertainty principal
ΔxΔp≥h/2
Δp≥h/(2Δx)
we know that
h= [tex]1.0546\times10^{-34}[/tex] Js
Δx= [tex]100\times10^{-12} m[/tex]
therefore,
[tex]\Delta p =\frac{1.0546\times10^{-34}}{2\times12\times10^{-12}} = 5.3\times10^{-25} kgms^{-1}[/tex]
therefore,
[tex]\Delta v= \frac{\Delta p}{m} =\frac{5.3\times10^{-25}}{9.11\times10^{-31}}= 5.8\times10^{5} ms^{-1}[/tex]
In an ionic compound, the size of the ions affects the internuclear distance (the distance between the centers of adjacent ions), which affects lattice energy (a measure of the attractive force holding those ions together).
1. Based on ion sizes, arrange these compounds by their expected lattice energy. Note that many sources define lattice energies as negative values. Please arrange by magnitude and ignore the sign. Great Lateral Energy to least (weakest) lattice energy.
O Nal
O NaCl
O NaBr
O NaF
While ethanol is produced naturally by fermentation, e.g. in beer- and wine-making, industrially it is synthesized by reacting ethylene with water vapor at elevated temperatures. A chemical engineer studying this reaction fills a flask with of ethylene gas and of water vapor. When the mixture has come to equilibrium she determines that it contains of ethylene gas and of water vapor. The engineer then adds another of water, and allows the mixture to come to equilibrium again. Calculate the pressure of ethanol after equilibrium is reached the second time. Round your answer to significant digits.
Answer:
Pressure of alcohol after reaching equilibrium the second time = 2.62atm
Explanation:
Detailed step by step with explanation is as shown in the attachment.
Given: A(g) + B(g) ⇋ C(g) + D(g)
At equilibrium a 2.00 liter container was found to contain 1.60 moles of C, 1.60 moles of D, 0.50 moles of A and 0.50 moles of B. Calculate Kc. enter a number to 2 decimal places
If 0.10 mole of B and 0.10 mole of C are added to this system, what is the value of Q? enter a number to 2 decimal places
What will the new equilibrium concentration of A be? enter a number to 3 decimal places
Answer:
For 1: The value of [tex]K_c[/tex] is 10.24
For 2: The value of [tex]Q_c[/tex] is 9.07
For 3: The new equilibrium concentration of A is 0.220 M
Explanation:
We are given:
Volume of the container = 2.00 L
Equilibrium moles of A = 0.50 moles
Equilibrium moles of B = 0.50 moles
Equilibrium moles of C = 1.60 moles
Equilibrium moles of D = 1.60 moles
We know that:
[tex]\text{Molarity}=\frac{\text{Moles of solute}}{\text{Volume of solution}}[/tex]
For the given chemical reaction:
[tex]A(g)+B(g)\rightleftharpoons C(g)+D(g)[/tex]
For 1:The expression of [tex]K_c[/tex] for above equation follows:
[tex]K_c=\frac{[C][D]}{[A][B]}[/tex]
We are given:
[tex][A]_{eq}=\frac{0.50}{2.00}=0.25[/tex]
[tex][B]_{eq}=\frac{0.50}{2.00}=0.25[/tex]
[tex][C]_{eq}=\frac{1.60}{2.00}=0.8[/tex]
[tex][D]_{eq}=\frac{1.60}{2.00}=0.8[/tex]
Putting values in above equation, we get:
[tex]K_c=\frac{0.8\times 0.8}{0.25\times 0.25}\\\\K_c=10.24[/tex]
Hence, the value of [tex]K_c[/tex] is 10.24
For 2:Added moles of B = 0.10 moles
Added moles of C = 0.10 moles
[tex]Q_c[/tex] is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.
[tex]Q_c=\frac{[C][D]}{[A][B]}[/tex]
Now,
[tex][A]=\frac{0.50}{2.00}=0.25[/tex]
[tex][B]=\frac{0.60}{2.00}=0.3[/tex]
[tex][C]=\frac{1.70}{2.00}=0.85[/tex]
[tex][D]=\frac{1.60}{2.00}=0.8[/tex]
Putting values in above equation, we get:
[tex]Q_c=\frac{0.85\times 0.8}{0.25\times 0.3}\\\\Q_c=9.07[/tex]
Hence, the value of [tex]Q_c[/tex] is 9.07
For 3:Taking equilibrium constant as 10.24 for calculating the equilibrium concentration of A.
[tex]K_c=10.24[/tex]
[tex][B]_{eq}=\frac{0.60}{2.00}=0.3[/tex]
[tex][C]_{eq}=\frac{1.70}{2.00}=0.85[/tex]
[tex][D]_{eq}=\frac{1.60}{2.00}=0.8[/tex]
Putting values in expression 1, we get:
[tex]10.24=\frac{0.85\times 0.8}{[A]\times 0.3}[/tex]
[tex][A]_{eq}=\frac{0.85\times 0.8}{0.3\times 10.24}=0.220[/tex]
Hence, the new equilibrium concentration of A is 0.220 M
A chemistry student needs of -bromobutane for an experiment. He has available of a w/w solution of -bromobutane in ethanol. Calculate the mass of solution the student should use. If there's not enough solution, press the "No solution" button. Round your answer to significant digits.
The question is incomplete, here is the complete question:
A chemistry student needs 15.00 g of 2-bromobutane for an experiment. He has available 220. g of a 30.0 % w/w solution of 2-bromobutane in ethanol. Calculate the mass of solution the student should use. If there's not enough solution, press the "No solution" button. Round your answer to 3 significant digits.
Answer: The mass of solution, the student should use is 50.0 grams
Explanation:
We are given:
30.0 % (w/w) of 2-bromobutane
This means that 30 grams of 2-bromobutane is present in 100 g of solution
Mass of solution given = 220. g
Mass of 2-bromobutane, the student needs = 15.00 g
Calculating the mass of 2-bromobutane in given amount of solution:
[tex]\Rightarrow 220\times \frac{30}{100}=66g[/tex]
To calculate the mass of solution, we use unitary method:
If 66 grams of 2-bromobutane is present in 220 grams of solution
So, 15 grams of 2-bromonutane will be present in [tex]\frac{220}{66}\times 15=50.0g[/tex] of solution
Hence, the mass of solution, the student should use is 50.0 grams
Final answer:
To calculate the mass of solution, convert the mass of -bromobutane into moles and then use the concentration of the solution to determine the amount of solution needed.
Explanation:
To calculate the mass of solution the student should use, we need to first convert the mass of -bromobutane needed into moles. Then, we can determine the amount of solution needed by using the concentration of the w/w solution of -bromobutane in ethanol. Let's go step by step:
Convert the grams of -bromobutane into liters of solution using the concentration: liters of solution = moles / concentration.
Remember to round your answer to the appropriate number of significant digits.
Calculate the heat of reaction, ΔH°rxn, for overall reaction for the production of methane, CH4.
The heat of reaction, ΔH°rxn, for the production of methane, CH4, can be calculated using the enthalpy change of the reaction and the stoichiometric coefficients of the reactants and products.
Explanation:The heat of reaction, ΔH°rxn, for the production of methane, CH4, can be calculated using the enthalpy change of the reaction and the stoichiometric coefficients of the reactants and products. In this case, the reaction is:
C(s) + O₂(g) → CO₂(g) ΔH° = -393.5 kJ
To calculate the heat of reaction, we can multiply the enthalpy change by the stoichiometric coefficient of methane in the balanced equation:
ΔH°rxn = -393.5 kJ/mol × 1 mol = -393.5 kJ
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The heat of reaction for the production of methane (CH₄) from CO₂ and H₂O is calculated to be -890.4 kJ. Using Hess's Law and the standard enthalpies of formation, the standard enthalpy of formation for CH4 is found to be -74.7 kJ/mol.
To calculate the heat of reaction for the production of methane (CH4), we will use the given thermochemical equation:
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) ΔΗ = -890.4 kJStep-by-Step Calculation:
The equation states that 1 mole of CH₄ reacts with 2 moles of O₂ to produce 1 mole of CO₂ and 2 moles of H₂O, releasing 890.4 kJ of energy. This reaction is exothermic, so ΔΗ is negative.
The standard enthalpy of formation [tex](\Delta H^\circ _f)[/tex] of a compound is the change in enthalpy when one mole of a substance is formed from its elements in their standard states.
We know the standard enthalpies of formation at 298 K for CO₂(g) and H₂O(l), which are:
[tex]\Delta H_f^\circ(\text{CO}_2(\text{g})) = -393.5 \, \text{kJ/mol}[/tex]
[tex]\Delta H_f^\circ(\text{H}_2\text{O}(\text{l})) = -285.8 \, \text{kJ/mol}[/tex]
Using Hess's Law: [tex]\Delta H^\circ_{\text{rxn}} = \left[ \sum \Delta H_f^\circ (\text{products}) \right] - \left[ \sum \Delta H_f^\circ (\text{reactants}) \right][/tex]
Insert values into the equation:
[tex]\Delta H^\circ_{\text{rxn}} = \left[ (-393.5 \, \text{kJ/mol}) + 2(-285.8 \, \text{kJ/mol}) \right] - \left[ \Delta H_f^\circ(\text{CH}_4(\text{g})) + 2(0 \, \text{kJ/mol for O}_2) \right][/tex]
[tex]\Delta H^\circ_{\text{rxn}} = [-393.5 - 571.6] - [\Delta H_f^\circ(\text{CH}_4(\text{g})) + 0][/tex]
[tex]\Delta H^\circ_{\text{rxn}} = -965.1 \, \text{kJ} - \Delta H_f^\circ(\text{CH}_4(\text{g}))[/tex]
Given [tex]\Delta H^\circ_{\text{rxn}}[/tex] = -890.4 kJ, solve for [tex]\Delta H_f^\circ(\text{CH}_4(\text{g})): -965.1 \, \text{kJ} - \Delta H_f^\circ(\text{CH}_4(\text{g})) = -890.4 \, \text{kJ}[/tex]
ΔHf°(CH₄(g)) = -965.1 kJ + 890.4 kJ
ΔHf°CH₄(g)) = -74.7 kJ/mol
Therefore, the standard enthalpy of formation for methane, CH₄, is -74.7 kJ/mol.
Each Excedrin tablet contains 250 mg aspirin (ACE), 250 mg of acetaminophen (ACE), and 65 mg of caffeine (CAF). Calculate the theoretical percent (%) recovery of each component using the mass of one tablet (675 mg). (a) ASP (b) ACE (c) CAF (250 mg / xx mg tablet) x 100% a)ASP: 37.04%b)ACE: 37.04%c)CAF: 9.63%
Answer:
a) 37.04% b) 37.04% c) 9.63%
Explanation:
The theoretical percent recovery (Tr), is the total percentage of each compound in the sample. Depending on the technique used to recovery the compounds, the percent recovery will be less than the theoretical, because no technique is 100% efficient.
So, to calculate the theoretical, it will be the mass of the compound divided by the mass of the sample multiplied by 100%.
a) Tr = (250 mg)/(675 mg) * 100%
Tr = 37.04%
b) Tr = (250 mg)/(675 mg) * 100%
Tr = 37.04%
c) Tr = (65 mg)/(675 mg) * 100%
Tr = 9.63%
In each of the Excedrin table which consist of 250 mg of aspirin about 250 mg of acetaminophen and about 65mg of caffeine. The percentage of the theoretical components
will be 37.04% for the ASP and 37.04% for the ACE and about 9.63% for the CAF of 250 gm / xx mg tablets.Learn more about the 250 mg aspirin (ACE), 250 mg of.
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A mixture of xenon and oxygen gas is compressed from a volume of 99.0 L to a volume of 98.0 L, while the pressure is held constant at 69.0 atm. Calculate the work done on the gas mixture. Be sure your answer has the correct sign (positive or negative) and the correct number of significant digits
The work done on the gas mixture when it is compressed from 99.0 L to 98.0 L at a constant pressure of 69.0 atm is -69.0 atm L.
Explanation:In order to calculate the work done on a gas, we can use the equation:
Work = Pressure * Change in Volume
In this case, the pressure is held constant at 69.0 atm, and the change in volume is from 99.0 L to 98.0 L.
Using the formula, we can calculate the work as follows:
Change in Volume = Final Volume - Initial Volume = 98.0 L - 99.0 L = -1.0 LWork = Pressure * Change in Volume = 69.0 atm * -1.0 L = -69.0 atm LThe work done on the gas mixture is -69.0 atm L. The negative sign indicates that work is done on the system rather than by the system.
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Ethylene (CH2CH2) is the starting point for a wide array of industrial chemical syntheses. For example, worldwide about 8.0 x 1010kg of polyethylene are made from ethylene each year, for use in everything from household plumbing to artificial joints. Natural sources of ethylene are entirely inadequate to meet world demand, so ethane (CH3CH3) from natural gas is "cracked" in refineries at high temperature in a kineticallycomplex reaction that produces ethylene gas and hydrogen gas. Suppose an engineer studying ethane cracking fills a 30.0L reaction tank with 24.0atm of ethane gas and raises the temperature to 800.°C. He believes Kp= 0.040 at this temperature. Calculate the percent by mass of ethylene the engineer expects to find in the equilibrium gas mixture. Round your answer to 2 significant digits.
Answer: The percent by mass of ethylene in the equilibrium gas mixture is 3.76 %
Explanation:
We are given:
Initial partial pressure or ethane = 24.0 atm
The chemical equation for the dehydration of ethane follows:
[tex]C_2H_6(g)\rightleftharpoons C_2H_4(g)+H_2(g)[/tex]
Initial: 24.0
At eqllm: 24-x x x
The expression of [tex]K_p[/tex] for above equation follows:
[tex]K_p=\frac{p_{C_2H_4}\times p_{H_2}}{p_{C_2H_6}}[/tex]
We are given:
[tex]K_p=0.040[/tex]
Putting values in above expression, we get:
[tex]0.040=\frac{x\times x}{24-x}\\\\x^2+0.04x-0.96=0\\\\x=0.96,-1[/tex]
Neglecting the value of x = -1 because partial pressure cannot be negative.
So, partial pressure of hydrogen gas at equilibrium = x = 0.96 atm
Partial pressure of ethylene gas at equilibrium = x = 0.96 atm
Partial pressure of ethane gas at equilibrium = (24-x) = (24 - 0.96) atm = 23.04 atm
To calculate the number of moles, we use the equation given by ideal gas, which follows:
[tex]PV=nRT[/tex] .........(1)
To calculate the mass of a substance, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ..........(2)
For ethane gas:We are given:
[tex]P=23.04atm\\V=30.0L\\T=800^oC=[800+273]K=1073K\\R=0.0821\text{ L. atm }mol^{-1}K^{-1}[/tex]
Putting values in equation 1, we get:
[tex]23.04atm\times 30.0L=n\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 1073K\\\\n=\frac{23.04\times 30.0}{0.0821\times 1073}=7.85mol[/tex]
We know that:
Molar mass of ethane gas = 30 g/mol
Putting values in equation 2, we get:
[tex]7.85mol=\frac{\text{Mass of ethane gas}}{30g/mol}\\\\\text{Mass of ethane gas}=(7.85mol\times 30g/mol)=235.5g[/tex]
For ethylene gas:We are given:
[tex]P=0.96atm\\V=30.0L\\T=800^oC=[800+273]K=1073K\\R=0.0821\text{ L. atm }mol^{-1}K^{-1}[/tex]
Putting values in equation 1, we get:
[tex]0.96atm\times 30.0L=n\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 1073K\\\\n=\frac{0.96\times 30.0}{0.0821\times 1073}=0.33mol[/tex]
We know that:
Molar mass of ethylene gas = 28 g/mol
Putting values in equation 2, we get:
[tex]0.33mol=\frac{\text{Mass of ethylene gas}}{28g/mol}\\\\\text{Mass of ethylene gas}=(0.33mol\times 28g/mol)=9.24g[/tex]
For hydrogen gas:We are given:
[tex]P=0.96atm\\V=30.0L\\T=800^oC=[800+273]K=1073K\\R=0.0821\text{ L. atm }mol^{-1}K^{-1}[/tex]
Putting values in equation 1, we get:
[tex]0.96atm\times 30.0L=n\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 1073K\\\\n=\frac{0.96\times 30.0}{0.0821\times 1073}=0.33mol[/tex]
We know that:
Molar mass of hydrogen gas = 2 g/mol
Putting values in equation 2, we get:
[tex]0.33mol=\frac{\text{Mass of hydrogen gas}}{2g/mol}\\\\\text{Mass of hydrogen gas}=(0.33mol\times 2g/mol)=0.66g[/tex]
To calculate the mass percentage of ethylene in equilibrium gas mixture, we use the equation:
[tex]\text{Mass percent of ethylene gas}=\frac{\text{Mass of ethylene gas}}{\text{Mass of equilibrium gas mixture}}\times 100[/tex]
Mass of equilibrium gas mixture = [235.5 + 9.24 + 0.66] = 245.4 g
Mass of ethylene gas = 9.24 g
Putting values in above equation, we get:
[tex]\text{Mass percent of ethylene gas}=\frac{9.24g}{245.5g}\times 100=3.76\%[/tex]
Hence, the percent by mass of ethylene in the equilibrium gas mixture is 3.76 %
You have a 275 mg sample of a compound that contains aluminum and a group 7A element (F, Cl, Br, I or At). This compound reacts with excess silver nitrate as follows ("X" represents the unknown element):
Complete Question:
You have a 275 mg sample of a compound that contains aluminum and a group 7A element (F, Cl, Br, I or At). This compound reacts with excess silver nitrate as follows (“X” represents the unknown element): AlX3 + 3 AgNO3 → 3 AgX + Al(NO3)3. This reaction forms 581 mg of AgX. Identify element X.
Answer:
Br
Explanation:
By the stoichiometry of the reaction, 1 mol of AlX3 will form 3 moles of AgX. If we call the molar mass of X as m, and by the periodic table the molar masses of Al is 26.982 g/mol, and of Ag is 107.87, thus the molar masses of the compounds will be:
AlX3 = 26.982 + 3m
AgX = 107.87 + m
And the mass relationship will be the number of moles multiplied by the molar mass. So, by a simple direct rule of three:
26.982 + 3m g of AlX3 ------------- 3*(107.87 + m) g of AgX
275 mg of AlX3 ----------- 581 mg
825*(107.87 + m) = 15676.542 + 1743m
88992.75 + 825m = 15676.542 + 1743m
-918m = -73316.208
m = 79.86 g/mol
So, comparing with the values of the masses of the group 7 elements, X must be Br (79.904 g/mol).