Answer: The molar mass of unknown molecule is 157.07 g/mol
Explanation:
The equation used to calculate relative lowering of vapor pressure follows:
[tex]\frac{p^o-p_s}{p^o}=i\times \chi_{solute}[/tex]
where,
[tex]\frac{p^o-p_s}{p^o}[/tex] = relative lowering in vapor pressure
i = Van't Hoff factor = 1 (for non electrolytes)
[tex]\chi_{solute}[/tex] = mole fraction of solute = ?
[tex]p^o[/tex] = vapor pressure of pure acetone = 400 torr
[tex]p_s[/tex] = vapor pressure of solution = 361.8 torr
Putting values in above equation, we get:
[tex]\frac{400-361.8}{400}=1\times\chi_{A}\\\\\chi_{A}=0.0955[/tex]
This means that 0.0955 moles of unknown molecule is present in the solution
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 unknown molecule = 0.0955 moles
Mass of unknown molecule = 15.0 grams
Putting values in above equation, we get:
[tex]0.0955mol=\frac{15.0g}{\text{Molar mass of unknown molecule}}\\\\\text{Molar mass of unknown molecule}=\frac{15.0g}{0.0955mol}=157.07g/mol[/tex]
Hence, the molar mass of unknown molecule is 157.07 g/mol
Calculate the concentration of OH-in a solution that has a concentration of H+ = 8.1 x 10^−6 M at 25°C. Multiply the answer you get by 1010 and enter that into the field to 2 decimal places.
Answer:
The answer is 12.35
Explanation:
From the question we are given that the concentration of [tex]H^{+}[/tex] is [tex]8.1 * 18^{-6}M[/tex]
Generally The rate equation is given as
[tex]K_{w} = [H^{+} ][OH^{-} ][/tex]
and [tex]K_{w}[/tex] the rate constant has a value [tex]1 * 10^{-14}[/tex]
Substituting and making [[tex]OH^{-}[/tex]] the subject we have
[tex][OH^{-} ] = \frac{1 * 10^{-14}}{[H^{+}]} = \frac{1 * 10^{-14}}{8.1 *10^{-6}} =1.235 * 10^{-9}[/tex]
[tex][OH ^ {-}] = 1.235 * 10^{-9}M[/tex]
Multiply the value by [tex]10^{10}[/tex] as instructed from the question we have
Answer = [tex]1.235 * 10 ^{-9} * 10^{10} = 12.35[/tex]
Hence the answer in 2 decimal places is 12.35
The concentration of OH¯ in the solution multiplied by 10¹⁰ is 12.35
Data obtained from the question:Concentration of Hydrogen ion [H⁺] = 8.1×10¯⁶ MConcentration of Hydroxide ion [OH¯] =? How to determine [OH¯]The concentration of hydroxide ion [OH¯] can be obtained as follow:
K = [H⁺][OH¯]
Equilibrium constant (K) = 1×10¯¹⁴
1×10¯¹⁴ = 8.1×10¯⁶ × [OH¯]
Divide both side by 8.1×10¯⁶
[OH¯] = 1×10¯¹⁴ / 8.1×10¯⁶
[OH¯] = 1.235×10¯⁹
Multiply by 10¹⁰
[OH¯] = 1.235×10¯⁹ × 10¹⁰
[OH¯] = 12.35
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Suppose that a certain drug company manufactured a compound that had nearly the same structure as a substrate for a certain enzyme but that could not be acted upon chemically by the enzyme. What type of interaction would the compound have with the enzyme
Answer: Reversible competitive inhibition
Explanation:
In the case of reversible competitive inhibition, an inhibitor molecule competes with the substrate for binding to the active site of the enzyme. The inhibitor blocks the active site of the enzyme. Thus the enzyme substrate complex do not form. The structure of the inhibitor is similar to the substrate thus also have the binding affinity with the enzyme. The process is reversible because the inhibitor will leave the enzyme it exerts no permanent effect on the enzyme.
The given situation is the example of reversible competitive inhibition as substrate remain unchanged and the enzyme was not able to act on the substrate chemically may be due to inhibition of the function of the enzyme.
Identify each element below, and give the symbols of the other elements in its group:
(a) [He] 2s²2p¹
(b) [Ne] 3s²3p⁴
(c) [Xe] 6s²5d¹
Answer:
Answer in explanation
Explanation:
a. Boron , element 5
Helium has 2 electrons, add to the other 3 to give 5.
Other group members are : Aluminum Al, Gallium Ga, Indium In , Thallium Tl and Nihonium Nh
b. Sulphur, element 16
Neon is 10 , add other 6 electrons to make 16
Other group members are: Oxygen O, selenium Se , Tellurium Te and Polonium Po
c. Lanthanum, element 57
Xenon is 54, add the other 3 electrons to give 57.
Other elements in group : Scandium Sc , Yttrium Y , Actinium Ac, Lutetium Lu and/or Lawrencium Lr
A radio wave has a frequency of 3.8 x 10¹⁰ Hz. What is the energy (in J) of one photon of this radiation?
The energy of a photon can be calculated using Planck's equation (E = hf). Given the radio wave frequency of 3.8 x 10^10 Hz and using Planck's constant (6.626 x 10^-34 J·s), the energy of one photon of this radiation is 2.52 x 10^-23 Joules.
Explanation:To find the energy of one photon of radiation, we need to use Planck's formula: E = hf. Here, 'E' represents energy, 'h' is Planck’s constant (6.626 x 10^-34 J·s), and 'f' is frequency. Given that the frequency (f) of the wave is 3.8 x 10^10 Hz, we substitute these values into Planck's equation:
E = hf = (6.626 x 10^-34 J·s) (3.8 x 10^10 Hz) = 2.52 x 10^-23 J
So, the energy of one photon of this radiation is 2.52 x 10^-23 Joules.
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Rank the elements in each of the following sets in order of increasing IE₁:
(a) Sb, Sn, I
(b) Sr, Ca, Ba
Explanation:
Ionization energy is defined as the energy required to remove the most loosely bound electron from a neutral gaseous atom.
When we move across a period from left to right then there occurs a decrease in atomic size of the atoms. Therefore, ionization energy increases along a period.
But when we move from top to bottom in a group then there occurs an increase in size of the atoms. Hence, ionization energy decreases along a group.
(a) As Sb, Sn and I are all period 5 elements. Hence, these elements are arranged in order of increasing [tex]IE_{1}[/tex] as follows.
Sn < Sb < I
(b) As Sr, Ca, and Ba are all elements of group 2a. Hence, these elements are arranged in order of increasing [tex]IE_{1}[/tex] as follows.
Ba < Sr < Ca
A 279.6 mL sample of an aqueous solution at 25°C contains 91.6 mg of an unknown nonelectrolyte compound. If the solution has an osmotic pressure of 8.44 torr, what is the molar mass (in g/mol) of the unknown compound?
Answer:
The molar mass of the compound is 720.8 g/mol
Explanation:
Let's apply the colligative property of Osmotic pressure to solve this.
Formula is π = M . R . T
where π is pressure (atm)
M is molarity (mol/L)
R, Universal Constant Gases
T, Absolute T° ( T° in K = T° in C + 273)
Let's replace the data:
8.44 Torr = M . 0.082 L.atm/mol.K . 298K
As we have the pressure in Torr, we must convert to atm, to work properly.
8.44 Torr . 1 atm/ 760 Torr = 0.0111 atm
0.0111 atm = M . 0.082 L.atm/mol.K . 298K
0.0111 atm / (0.082 L.atm/mol.K . 298K) = M → 4.54×10⁻⁴ mol/L
So molarity is the moles of solute (mass (g) / molar mass) / volume (L)
Let's convert the volume to L → 279.6 mL . 1L / 1000 mL = 0.2796 L
4.54×10⁻⁴ mol/L . 02796 L = 1.27×10⁻⁴ moles
This moles are represented by the 91.6 mg, so let's convert the mass of solute from mg to g
91.6 mg . 1 g / 1000 mg = 0.0916 g
Molar mass → g/mol → 0.0916 g / 1.27×10⁻⁴ moles → 720.8 g/mol
Write the expected ground-state electron configuration for the following. (Express your answers as a series of orbitals using noble gas notation, in order of increasing orbital energy. For example, the electron configuration of Li would be entered as [He]2s1.) a The element with one unpaired electron that forms a covalent compound with fluorine. Configuration: b The (as yet undiscovered) alkaline earth metal after radium.
Answer:
For a: The element forming covalent compound with fluorine is Hydrogen.
For b: The electronic configuration of the element X is [tex][Uuo]8s^2[/tex]
Explanation:
Electronic configuration is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom is determined by the atomic number of that atom.
To write the electronic configuration of the elements in the noble gas notation, we first count the total number of electrons and then write the noble gas which lies before the same element.
For the given options:
For a:Covalent compound is defined as the compound which is formed by the sharing of electrons between the atoms forming a compound. These are usually formed when two non-metals react.
Hydrogen is the 1st element of the periodic table and is considered as a non-metal. It has 1 unpaired electron.
Its electronic configuration is [tex]1s^1[/tex]
Fluorine is the 9th element of the periodic table. It is also a non-metal.
Its electronic configuration is [tex][He]2s^22p^5[/tex]
The two elements will share 1 electron to attain stable configuration and form HF compound.
For b:Radium is the 88th element of the periodic table having electronic configuration of [tex][Rn]7s^2[/tex]
Let the alkaline earth metal that is not yet discovered be X
The electronic configuration of the element X is [tex][Uuo]8s^2[/tex]
The expected ground-state electron configuration for the element that forms a covalent compound with fluorine is [He]2s2p4. The electron configuration of the undiscovered alkaline earth metal after radium cannot be determined.
Explanation:a) The element with one unpaired electron that forms a covalent compound with fluorine has the electron configuration of [He]2s22p4.
b) The alkaline earth metal after radium has not been discovered, so its electron configuration cannot be determined at this time.
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In the mid-17th century, Isaac Newton proposed that light existed as a stream of particles, and the wave-particle debate continued for over 250 years until Planck and Einstein presented their revolutionary ideas. Give two pieces of evidence for the wave model and two for the particle model.
Answer:
Light as a wave
1. Young's Double Slit Experiment
2. Davisson-Germer Experiment
Light as a particle
1. Einsteins Photoelectric Effect Phenomenon
2. Diffraction Phenomenon of Particles
Evidence for light as a wave includes diffraction and interference patterns, while evidence for the particle model includes the photoelectric effect and emission spectra.
The mid-17th century debate on whether light is a wave or a particle extended well into the 20th century until revolutionary concepts by Planck and Einstein. There is evidence for both the wave model and the particle model of light. Two pieces of evidence for the wave nature of light are diffraction and interference patterns, as seen in Thomas Young's double-slit experiment.
Diffraction occurs when light encounters an obstacle, spreading out as a result, and interference patterns occur when waves overlap and combine in constructive or destructive ways. Conversely, evidence for the particle nature includes phenomena like the photoelectric effect, as explained by Einstein, where light knocks electrons from a material, and the behavior of emission spectra, where individual energy quanta or "photons" are emitted from atoms.
The temperature of a 10.0 L sample of nitrogen in a sealed container is increased from 22°C to 202°C, while its pressure is increased from 1.00 atm to 3.00 atm. What is the new volume (in liters) of the nitrogen sample?
Answer:
The new volume is 5.37 L
Explanation:
Step 1: Data given
Initial volume = 10.0 L
Initial temperature = 22.0 °C
Initial pressure = 1.00 atm
Final temperature = 202 °C
Final pressure = 3.00 atm
Step 2: Calculate final volume
(P1*V1)/T1 = (P2*V2)/T2
⇒ with P1 = The initial pressure = 1.00 atm
⇒ with V1 = The initial volume = 10.0 L
⇒ with T1 = The initial temperature = 22 °C = 295 Kelvin
⇒ with P2 = The final pressure = 3.00 atm
⇒ with V2 = The final volume = TO BE DETERMINED
⇒ with T2 = The final temperature = 202 °C = 475 Kelvin
(1.00 * 10.0) / 295 = (3.00 * V2) / 475
10 / 295 = 3V2/ 475
3V2 = 4750/295
V2 = 5.37 L
The new volume is 5.37 L
If you are using 3.00% (mass/mass) hydrogen peroxide solution and you determine that the mass of solution required to reach the equivalence point is 5.125 g, how many moles of hydrogen peroxide molecules are present?
Answer:
0.004522 moles of hydrogen peroxide molecules are present.
Explanation:
Mass by mass percentage of hydrogen peroxide solution = w/w% = 3%
Mass of the solution , m= 5.125 g
Mass of the hydrogen peroxide = x
[tex]w/w\% = \frac{x}{m}\times 100[/tex]
[tex]3\%=\frac{x}{5.125 g}\times 100[/tex]
[tex]x=\frac{3\times 5.125 g}{100}=0.15375 g[/tex]
Mass of hydregn pervade in the solution = 0.15375 g
Moles of hydregn pervade in the solution :
[tex]=\fraC{ 0.15375 g}{34 g/mol}=0.004522 mol[/tex]
0.004522 moles of hydrogen peroxide molecules are present.
To determine the number of moles of hydrogen peroxide molecules present in the solution, multiply the mass of the solution by the mass percent of hydrogen peroxide. Then, convert the mass of hydrogen peroxide to moles using its molar mass. The number of moles of hydrogen peroxide molecules is approximately 0.00452.
Explanation:To determine the number of moles of hydrogen peroxide molecules present, we first need to calculate the mass of hydrogen peroxide in the solution. We can do this by multiplying the mass of the solution (5.125 g) by the mass percent of hydrogen peroxide (3.00% or 0.03).
Mass of hydrogen peroxide = 5.125 g × 0.03 = 0.15375 g
Next, we need to convert the mass of hydrogen peroxide to moles using its molar mass. The molar mass of hydrogen peroxide (H2O2) is 34.0146 g/mol.
Moles of hydrogen peroxide = 0.15375 g ÷ 34.0146 g/mol ≈ 0.00452 mol
Therefore, there are approximately 0.00452 moles of hydrogen peroxide molecules present.
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A solution contains 0.25 M Ni(NO3)2 and 0.25 M Cu(NO3)2. Can the metal ions be separated by slowly adding Na2CO3? Assume that for successful separation 99% of the metal ion must be precipitated before the other metal ion begins to precipitate, and assume no volume change on addition of Na2CO3.
Explanation:
Ksp of NiCO3 = 1.4 x 10^-7
Ksp of CuCO3 = 2.5 x 10^-10
Ionic equations:
NiCO3 --> Ni2+ + CO3^2-
CuCO3 --> Cu2+ + CO3^2-
[Cu2+][CO3^2-]/[Ni2+][CO3^2-]
= (2.5* 10^-10)/(1.4* 10^-7)
= 0.00179.
[Cu2+]/[Ni2+]
= 0.00179
= 0.00179*[Ni2+]
If all of Cu2+ is precipitated before Na2CO3 is added.
= 0.00179 * (0.25)
The amount of Cu2+ not precipitated = 0.000448 M
The percent of Cu2+ precipitated before the NiCO3 precipitates = concentration of Cu2+ unprecipitated/initial concentration of Cu2+ * 100
= 0.000448/0.25 * 100
= 0.18%
Therefore, percentage precipitated = 100 - 0.18
= 99.8%
The two metal ions can be separated by slowly adding Na2CO3. Thus that is the unpptd Cu2+.
The metal ions can be separated by slowly adding Na2CO3 based on the relative solubilities of their carbonates. Nickel carbonate (NiCO3) is less soluble than copper carbonate (CuCO3), allowing the selective precipitation of nickel ions before copper ions.
Explanation:To determine if the metal ions can be separated by slowly adding Na2CO3, we need to consider the solubility of the metal carbonates. Nickel carbonate (NiCO3) and copper carbonate (CuCO3) both have low solubilities, but it is crucial to examine their relative solubilities. If one carbonate is significantly less soluble than the other, it can be selectively precipitated first.
In this case, NiCO3 is less soluble than CuCO3. Therefore, by slowly adding Na2CO3 to the solution, we can precipitate the majority of the Ni2+ ions as NiCO3 before CuCO3 begins to precipitate. This satisfies the condition that 99% of the metal ion must be precipitated before the other metal ion begins to precipitate.
Therefore, it is possible to separate the nickel and copper ions in the solution by slowly adding Na2CO3.
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name each ionic compound. In each of these compounds, the metal forms only one type of ion. a)CeCl b)SrBr2 c) K2O d)LiF
Explanation:
A. CeCl
Cerium chloride.
Metal: Ce+
B. SrBr2
Strontium chloride.
Metal: Sr2+
C. K2O
Potassium oxide.
Metal: K+
D. LiF
Lithuim fluoride.
Metal: Li+
Chlorine (Cl) creates an anion with a -1 charge, but the metal cerium (Ce) only forms one type of ion with a +3 charge. As a result, the substance is known as cerium(III) chloride.
a) CeCl: Cerium(III) chloride
Whereas bromine (Br) generates an anion with a -1 charge, the metal strontium (Sr) only forms one sort of ion with a +2 charge in this combination. As a result, the substance is known as strontium bromide.
b) SrBr2: Strontium bromide
In this molecule, oxygen (O) generates an anion with a -2 charge whereas the metal potassium (K) only produces one sort of ion with a +1 charge. The substance is referred to as potassium oxide as a result.
c) K2O: Potassium oxide
Lithium is the only element present in this combination (Li). As lithium only ever produces an ion with a positive charge, it is known simply as lithium.
d) Li: Lithium
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Theistic religion is centered in a belief in Select one: a. spirits or animals that control our lives. b. such totems as a rabbit's foot or four-leaf clover. c. gods who are thought to be powerful, who have an interest in human affairs, and who merit worship. d. abstract ideals only.
Answer: C. gods who are thought to be powerful, who have an interest in human affairs, and who merit worship.
Explanation: Theistic religion is a religious belief in the existence of a supreme being in the form of God or gods who control the affairs of men. Theism is classified into different categories from Monotheism ( the belief in the existence of only one God), Polytheism ( the belief in the presence of different supreme beings), Pantheism (where it is believed that the universe in itself is a God),Autotheism( a believe that each person has a divine nature,it means that divinity exists in us), etc.
Theism is derived from the Greek word known as "Theo" which means God.
Why does the malachite green dye elute first? What physical properties does it have that affect it’s interaction with alumina and how are those different from crystal violet?
Answer:
MG is less polar
Explanation:
The structures of crystal violet (CV) and malachite green (MG) are shown in Figures 1 and 2, respectively.
The obvious difference is that CV has an extra dimethylamino group (polar).
Alumina is a polar adsorbent, so it retains the more polar substances more strongly and they are eluted last.
MG is less polar than CV, so it is retained less strongly and is eluted first.
Arrange the following H atom electron transitions in order of increasing frequency of the photon absorbed or emitted:
(a) n = 2 to n = 4
(b) n = 2 to n = 1
(c) n = 2 to n = 5
(d) n = 2 to n = 1
The question is incomplete , complete question is:
Arrange the following H atom electron transitions in order of increasing frequency of the photon absorbed or emitted:
(a) n = 2 to n = 4
(b) n = 2 to n = 1
(c) n = 2 to n = 5
(d) n = 4 to n = 3
Answer:
Hence the order of the transition will be : d < a < c < b
Explanation:
[tex]E_n=-13.6\times \frac{Z^2}{n^2}ev[/tex]
where,
[tex]E_n[/tex] = energy of [tex]n^{th}[/tex] orbit
n = number of orbit
Z = atomic number
Energy of n = 1 in an hydrogen atom:
[tex]E_1=-13.6\times \frac{1^2}{1^2}eV=-13.6 eV[/tex]
Energy of n = 2 in an hydrogen atom:
[tex]E_2=-13.6\times \frac{1^2}{2^2}eV=-3.40eV[/tex]
Energy of n = 3 in an hydrogen atom:
[tex]E_3=-13.6\times \frac{1^2}{3^2}eV=-1.51eV[/tex]
Energy of n = 4 in an hydrogen atom:
[tex]E_4=-13.6\times \frac{1^2}{4^2}eV=-0.85 eV[/tex]
Energy of n = 5 in an hydrogen atom:
[tex]E_5=-13.6\times \frac{1^2}{5^2}eV=-0.544 eV[/tex]
a) n = 2 to n = 4 (absorption)
[tex]\Delta E_1= E_4-E_2=-0.85eV-(-3.40eV)=2.55 eV[/tex]
b) n = 2 to n = 1 (emission)
[tex]\Delta E_2= E_1-E_2=-13.6 eV-(-3.40eV)=-10.2 eV[/tex]
Negative sign indicates that emission will take place.
c) n = 2 to n = 5 (absorption)
[tex]\Delta E_3= E_5-E_2=-0.544 eV-(-3.40eV)=2.856 eV[/tex]
d) n = 4 to n = 3 (emission)
[tex]\Delta E_4= E_3-E_4=-1.51 eV-(-0.85 eV)=-0.66 eV[/tex]
Negative sign indicates that emission will take place.
According to Planck's equation, higher the frequency of the wave higher will be the energy:
[tex]E=h\nu [/tex]
h = Planck's constant
[tex]\nu [/tex] frequency of the wave
So, the increasing order of magnitude of the energy difference :
[tex]E_4<E_1<E_3<E_2[/tex]
And so will be the increasing order of the frequency of the of the photon absorbed or emitted. Hence the order of the transition will be :
: d < a < c < b
Final answer:
The order of increasing frequency of photon absorbed or emitted for the H atom electron transitions is (a) n = 2 to n = 4, (c) n = 2 to n = 5, (b) n = 2 to n = 1, and (d) n = 2 to n = 1.
Explanation:
The frequency of a photon absorbed or emitted by a hydrogen atom is related to the energy difference between the initial and final energy levels. The energy difference decreases as the value of n increases, so (a) n = 2 to n = 4 has the lowest frequency, followed by (c) n = 2 to n = 5, (b) n = 2 to n = 1, and finally, (d) n = 2 to n = 1 has the highest frequency.
Why is the water solubility of benzoic acid significantly less than the water solubility of the benzoate ion?
Answer:
It is because of difference in polarization
Explanation: Benzoic acid is a non-polar strong acid with low solubility and no internal stabilizing structures to favor the carboxylic acid . Benzoate ion is polar which has high solubility due to being polar.
The water solubility of benzoic acid is much lower than that of the benzoate ion because of the difference in polarization.
PolarizationThe water solubility of benzoic acid is much lower than that of the benzoate ion because of the difference in polarization.Polarization is a feature of certain electromagnetic radiations that describes how the direction and magnitude of the vibrating electric field are associated in a specific way.Benzoic acid is a non-polar strong acid with low solubility and no internal stabilizing structures that favor carboxylic acid. Because benzoate ion is polar, it has a high solubility.Find out more information about the polarization here:
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A sodium hydroxide solution that contains 24.8 grams of NaOH per L of solution has a density of 1.15 g/mL. Calculate the molality of the NaOH in this solution.
Final answer:
The molality of the sodium hydroxide (NaOH) solution is 0.54 mol/kg.
Explanation:
The molality of a solution is defined as the number of moles of solute per kilogram of solvent. In this case, the solute is sodium hydroxide (NaOH) and the solvent is water.
To calculate the molality, we need to first convert the given mass of NaOH to moles using its molar mass, which is 40.0 g/mol. Then, we need to convert the mass of the solution to kilograms using the density of the solution, which is 1.15 g/mL.
Using the given information:
Mass of NaOH = 24.8 g/L
Density of solution = 1.15 g/mL
Molar mass of NaOH = 40.0 g/mol
The molality can be calculated as follows:
Convert mass of NaOH to moles: 24.8 g/L x (1 mol NaOH / 40.0 g NaOH) = 0.62 mol/LConvert density of solution to mass of solution: 1.15 g/mL x 1000 mL/L = 1150 g/LConvert mass of solution to kilograms: 1150 g/L ÷ 1000 = 1.15 kg/LCalculate molality: 0.62 mol/L ÷ 1.15 kg/L = 0.54 mol/kg2. Assume that a sample of 10.00 g of a solid unknown is dissolved in 25.0 g of water. Assuming that pure water freezes at 0.0 oC and the solution freezes at -5.58 oC, what is the molal concentration of the solution
Answer:
m = 3 moles/kg
Explanation:
This is a problem of freezing point depression, and the formula or expression to use is the following:
ΔT = i*Kf¨*m (1)
Where:
ΔT: Change of temperature of the solution
i: Van't Hoff factor
m: molality of solution
Kf: molal freezing point depression of water (Kf = 1.86 °C kg/mol)
Now, the value of i is the number of moles of particles obtained when 1 mol of a solute dissolves. In this case, we do not know what kind of solution is, so, we can assume this is a non electrolyte solute, and the value of i = 1.
Let's calculate the value m, which is the molality solving for (1):
m = ΔT/Kf (2)
Finally, let's calculate ΔT:
ΔT = T2 - T1
ΔT = 0 - (-5.58)
ΔT = 5.58 °C
Now, let's replace in (2):
m = 5.58/1.86
m = 3 moles/kg
This is the molality of solution.
The other data of mass, can be used to calculate the molecular mass of this unknown solid, but it's not asked in the question.
Write two different resonance forms for triphenylmethyl cation. Write the structure showing the positive charge at an ortho position.
Final answer:
Two resonance forms of the triphenylmethyl cation were provided, with the positive charge located at the central carbon atom and one of the ortho positions.
Explanation:
The triphenylmethyl cation is a carbocation formed by removing an electron from the triphenylmethyl radical. It has the formula C19H16+. To write two resonance forms, we need to show the positive charge at different positions in the structure. One possible resonance form is where the positive charge is at the central carbon atom, and the other form is where the positive charge is at one of the ortho positions. The resonance structures can be represented as follows:
C6H5--C+--C6H5
: :
C6H4--C6H5 C6H6--C6H4
How many electrons in an atom can have each of the following quantum number or sublevel designations?
(a) 2s
(b) n = 3, l = 2
(c) 6d
Answer :
(a) Number of electrons in an atoms is, 2
(b) Number of electrons in an atoms is, 10
(c) Number of electrons in an atoms is, 10
Explanation :
There are 4 quantum numbers :
Principle Quantum Numbers : It describes the size of the orbital. It is represented by n. n = 1,2,3,4....
Azimuthal Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
Magnetic Quantum Number : It describes the orientation of the orbitals. It is represented as . The value of this quantum number ranges from . When l = 2, the value of
Spin Quantum number : It describes the direction of electron spin. This is represented as . The value of this is for upward spin and for downward spin.
Number of electrons in a sublevel = 2(2l+1)
(a) 2s
n = 2
Value of 'l' for 's' orbital : l = 0
Number of electrons in an atoms = 2(2l+1) = 2(2×0+1) = 2
(b) n = 3, l = 2
Number of electrons in an atoms = 2(2l+1) = 2(2×2+1) = 10
(c) 6d
n = 2
Value of 'l' for 'd' orbital : l = 2
Number of electrons in an atoms = 2(2l+1) = 2(2×2+1) = 10
In quantum chemistry, the 2s sublevel can hold 2 electrons, the n = 3, l = 2 sublevel (3d) can hold 10 electrons, and the 6d sublevel can also hold 10 electrons.
Explanation:In quantum chemistry, specific sublevels or orbitals within an atom can hold certain numbers of electrons.
(a) The 2s sublevel can hold a maximum of 2 electrons. This is because 's' orbitals can contain up to 2 electrons.
(b) For n = 3, l = 2, this refers to the 3d orbital. 'd' orbitals can hold a maximum of 10 electrons, so 10 electrons can exist in this energy level.
(c) For the 6d orbital, it can also hold up to 10 electrons, as it is also a 'd' orbital.
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During the GFP purification experiment, the instructor will have to make breaking buffer for the students to use. This buffer contains 150mM NaCl. Given a bottle of crystalline NaCl (M.W. = 40g/mol), describe how you would make 500ml of 150mM NaCl. Include the type and sizes of any measuring vessels that you use to make the solution.
Answer:
Explanation:
150 mM NaCl = 0.15 M NaCl
500 ml of 0.15 M NaCl = 500 x 0.15 ml of M NaCl
= 75 ml of M NaCl
M.W = 40 g
1000 ml of M NaCl requires 40 g
75 ml of M NaCl requires (40/1000) x75
= 3 g
We shall take 500 ml of water in a graduated cylinder . Then we weigh 3 g of salt and add it to 500 ml of water and mix it . We shall get 500 ml of 150mM NaCl.
Final answer:
To make 500mL of 150mM NaCl solution, calculate the required mass of NaCl (4.383 grams), dissolve it in less than 500mL of DI water, and then adjust the volume to 500mL using a graduated cylinder for precise measurement.
Explanation:
To make 500 mL of 150mM NaCl solution, you first need to calculate the amount of NaCl required using the molarity formula, which is Molarity (M) = moles of solute / liters of solution. Given that the molar mass of NaCl is 58.44g/mol (not 40g/mol as incorrectly stated in the question), to prepare a 150mM (0.150M) NaCl solution, the calculation is as follows:
Calculate the moles of NaCl needed: moles = 0.150M * 0.500L = 0.075 moles.Convert moles to grams: grams = moles * molar mass = 0.075 mol * 58.44 g/mol = 4.383 grams.Measure out 4.383 grams of NaCl using an electronic scale.Dissolve the measured NaCl in less than 500 mL of di-ionized water (DI water) in a beaker.Transfer the solution to a 500 mL graduated cylinder and add DI water until the volume reaches 500 mL to ensure the correct concentration.
It is important to dissolve the NaCl in less than the final volume before adjusting up to the final desired volume. This approach ensures accuracy in the concentration of the resulting solution.
An unsaturated hydrocarbon is A. a hydrocarbon that contains oxygen. B. a compound in which all carbon atoms have four single bonds. C. a compound in which one or more carbon atoms have double or triple bonds. D. a hydrocarbon that is dissolved in water. E. a cycloalkane with five or more carbons.
Answer:
. C. a compound in which one or more carbon atoms have double or triple bonds.
Explanation:
An unsaturated hydrocarbon -
It refers to the organic compound , where the carbon atom remains unsaturated with the number of hydrogen atoms , i.e. , maximum number of hydrogen atom a carbon atom can hold is four , and less than four number of hydrogen atom attached to the carbon atom , makes the hydrocarbon unsaturated in nature .
Hence ,
It the carbon atom have one or more number of double or triple bond , then the compound is said to be unsaturated in nature .
Hence , from the question,
The correct option is c.
The addition of a ____________ group to butane increases the solubility of the resulting molecule in water.
methyl
ethyl
double bond
hydroxyl group
propyl
Answer: hydroxyl group
Explanation:
The H atom and the Be3³⁺ ion each have one electron. Does the Bohr model predict their spectra accurately? Would you expect their line spectra to be identical? Explain.
Explanation:
a) Bohr model is perfect for atoms that have single electron and fortunately both Be3+ ion and H atom have one electron so, Bohr model can easily and accurately applied to predict the spectrum of Be3+ and H atom.
b) The energy of an atom in Bohr model is given by
[tex]E= \frac{-13.6z^2}{n^2}[/tex]
the values of z for H atom and Be3+ ion are 1 and 4 respectively. Hence, energy of atoms would be different for both atoms. Hence, line spectra to be identical is not possible.
To make the five standard solutions you will need for the Beer's Law Plot, you will first create a stock solution from ( NH 4 ) 3 Fe ( ox ) 3 ⋅ 3 H 2 O . The stock solution is made using 125 mg of ( NH 4 ) 3 Fe ( ox ) 3 ⋅ 3 H 2 O dissolved in deionized (DI) water in volumetric glassware for a total volume of 25 mL. Calculate the concentration of the stock solution.
Answer:
Concentration of stock solution in g/L = 5.0g/L
Concentration of stock solution in mol/L = 0.00117 mol/L or 0.00117 M
Explanation:
Concentration in mol/L = (Concentration in g/L)/(Molar mass)
Mass of (NH₄)₃Fe(ox)₃.3H₂O stock = 125mg = 0.125g
Volume of stock solution required = 25mL = 0.025 L
Concentration in g/L = 0.125/0.025 = 5.0 g/L
Molar Mass of (NH₄)₃Fe(ox)₃.3H₂O = (NH₄)₃Fe(C₂O₄)₃.3H₂O = 428.0632 g/mol
Concentration in mol/L = 5/428.0632 = 0.00117 mol/L = 0.00117 M
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At what temperature (in degrees Celsius) will xenon atoms have the same average speed that Cl2Cl2 molecules have at 41 ∘C∘C?
Answer:
Xenon atoms will have a temperature of 308.25 °C
Explanation:
Step 1: Data given
Molar mass of Cl2 = 70.9 g/mol
Molar mass of Xenon = 131.29 g/mol
Temperatue of Cl2 molecules = 41 °C = 314 K
Step 2: Calculate temperature
The average speed of a gas particle is given by v = √(8RT/πM).
We can simplify this to:
T1/M1 = T2/M2
⇒ with T1 = The temperature of Cl2 molecules = 314 K
⇒ with M1 = the molar mass of Cl2 = 70.9 g/mol
⇒ with T2= The temperature of Xenon = TO BE DETERMINED
⇒ with M2 = The molar mass of Xenon = 131.29 g/mol
314/70.9 = T2/131.29
T2 = 581.4 Kelvin
581.4 Kelvin = 308.25 °C
Xenon atoms will have a temperature of 308.25 °C
Final answer:
To find the temperature at which xenon atoms have the same average speed as Cl2 molecules at 41 degrees Celsius, use the equation for the average speed of gas molecules. Substitute the molar masses of Cl2 and xenon into the equation and solve for temperature. The temperature is approximately 191.89 degrees Celsius.
Explanation:
To determine the temperature at which xenon atoms have the same average speed as Cl2 molecules at 41 °C, we need to use the equation for the average speed of gas molecules:
average speed = sqrt((3 * kB * T) / (molar mass))
where kB is the Boltzmann constant and T is the temperature in Kelvin.
Since the gas molecules we are comparing are different, we need to find the molar mass of Cl2 molecules and xenon atoms. The molar mass of Cl2 is 70.90 g/mol and the molar mass of xenon is 131.29 g/mol.
Substituting the values into the equation, we have:
sqrt((3 * (1.380649 × 10-23) * T) / (70.90)) = sqrt((3 * (1.380649 × 10-23) * (41 + 273.15)) / (131.29))
Simplifying and solving for T, we find that the temperature at which xenon atoms have the same average speed as Cl2 molecules at 41 °C is approximately 191.89 °Celsius.
What determines the types of chemical reactions that an atom participates in? A. the number of electrons in the outermost electron shell B. the number of electrons in the innermost electron shell C. its atomic mass the number of protons D. it contains its atomic number
Answer:
The answer would be A. the number of electrons in the outermost electron shell.
Explanation:
These are called valence electrons which are transferred, shared, and rearranged by creating covalent bonds producing new substances.
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The type of chemical reaction an atom chooses is determined by the number of the outermost electrons in the outermost shell of an atom.
The reactivity of an atom is determined by the number of electrons in the outermost shell of the particular atom.The number of electrons is used to determine the type of bond formed by that atom in a chemical reaction.The outermost shell of the atom is called the valence shell and the number of outermost electrons is thus called the valence electrons.About the importance of electrons the below points should be noted;
The electron is the major constituent of an atom which determines the reactivity of an atom.The outermost electron is more used for any reaction to occur than the innermost electronsTherefore the answer is the number of electrons in the outermost electron shell.
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What is the concentration of K+K+ in 0.15 MM of K2SK2S? Express your answer to one decimal place and include the appropriate units.
Answer : The concentration of [tex]K^+[/tex] ion in 0.15 M [tex]K_2S[/tex] is, 0.3 M
Explanation :
The given compound is, [tex]K_2S[/tex]
When [tex]K_2S[/tex] dissociates then it gives potassium ion and sulfide ion.
The balanced dissociation reaction is:
[tex]K_2S\rightarrow 2K^++S^{2-}[/tex]
By the stoichiometry we can say that, 1 mole of [tex]K_2S[/tex] dissociates to give 2 moles of [tex]K^+[/tex] ion and 1 mole of [tex]S^{2-}[/tex] ion.
Or, in terms of concentration we can say that:
0.15 M of [tex]K_2S[/tex] dissociates to give [tex]2\times 0.15M=0.3M[/tex] of [tex]K^+[/tex] ion and 0.15 M of [tex]S^{2-}[/tex] ion.
Thus, the concentration of [tex]K^+[/tex] ion in 0.15 M [tex]K_2S[/tex] is, 0.3 M
The concentration of K+ in a 0.15 M solution of K2S is 0.3 M, calculated by multiplying the concentration of K2S by two, since each unit of K2S produces two K+ ions.
Explanation:The concentration of K+ in a solution of 0.15 M K2S can be determined by recognizing that each formula unit of K2S produces two K+ ions.
Therefore, to find the concentration of K+, you multiply the concentration of K2S by two:
Concentration of K2S = 0.15 MConcentration of K+ = 2 × (Concentration of K2S)Concentration of K+ = 2 × 0.15 M = 0.30 MThe concentration of K+ in the solution is 0.3 M, where M stands for molarity, representing moles of solute per liter of solution.
What is the wavelength (in nm) of the least energetic spectral line in the infrared series of the H atom?
Answer:
The least energetic spectral line in the infrared series of the H atom is 656.1 nm
Explanation:
Photon wavelength is inversely proportional to energy. To obtain the least energetic spectral line of the hydrogen atom (H), we determine the longest wavelength possible.
[tex]\frac{1}{\lambda} = R_H[\frac{1}{n_f^2} -\frac{1}{n^2}][/tex]
Where;
nf = 2
n = 3
RH is Rydberg constant = 1.09737 × 10⁷m⁻¹
λ is the wavelength of the least energetic spectral line
Substituting the above values into the equation, we will have
[tex]\frac{1}{\lambda} = 1.09737 X 10^7[\frac{1}{2^2} -\frac{1}{3^2}][/tex]
[tex]\frac{1}{\lambda} = 1.09737 X 10^7[\frac{1}{4} -\frac{1}{9}][/tex]
[tex]\frac{1}{\lambda} = 1.09737 X 10^7[0.25 -0.1111][/tex]
[tex]\frac{1}{\lambda} = 1.09737 X 10^7[0.1389][/tex]
[tex]\frac{1}{\lambda} = 1524246.93[/tex]
[tex]\lambda} = \frac{1}{1524246.93}[/tex]
[tex]\lambda} = 6.561 X10^{-7} m[/tex]
λ = 656.1 X10⁻⁹ m
In (nm): λ = 656.1 nm
Therefore, the least energetic spectral line in the infrared series of the H atom is 656.1 nm
The wavelength of the least energetic spectral line in the infrared series of the hydrogen atom is approximately 18,400 nanometers (nm).
To find the wavelength of the least energetic spectral line in the infrared series of the hydrogen atom, we can use the Rydberg formula for the hydrogen atom:
1 / λ = R_H * (1/n₁² - 1/n₂²)
Where:
λ is the wavelength of the spectral line.
R_H is the Rydberg constant for hydrogen, approximately 1.097 x 10^7 m⁻¹.
n₁ is the principal quantum number of the initial energy level.
n₂ is the principal quantum number of the final energy level.
For the least energetic line in the infrared series, we need to consider the transition where the electron moves from a higher energy level (n₂) to a lower energy level (n₁). In this case, n₂ > n₁.
Since we are interested in the infrared series, we'll consider transitions ending in the n₁ = 3 energy level. We want the least energetic line, so we'll choose the smallest value for n₂.
Let's take n₂ = 4 and calculate:
1 / λ = 1.097 x 10^7 m⁻¹ * (1/3² - 1/4²)
1 / λ = 1.097 x 10^7 m⁻¹ * (1/9 - 1/16)
1 / λ = 1.097 x 10^7 m⁻¹ * (7/144)
Now, solve for λ:
λ = 144 / (1.097 x 10^7 m⁻¹ * 7)
λ ≈ 0.0184 meters or 18.4 millimeters
To express the wavelength in nanometers (nm), we can convert millimeters to nanometers:
λ ≈ 18.4 mm * 1,000,000 nm/mm = 18,400 nm
So, the wavelength of the least energetic spectral line in the infrared series of the hydrogen atom is approximately 18,400 nm.
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For the Bradford assay, the instructor will make a Bradford reagent dye by mixing 50 ml of 95% v/v ethanol with 100 mg of Coomassie Blue followed by the addition of 100 ml of 85% v/v phosphoric acid. This entire mixture is then diluted to 1 liter with water. What is the final concentration of phosphoric acid?
Answer:
4.25% is the final concentration of phosphoric acid.
Explanation:
Initial concentration of phosphoric acid = [tex]C_1=85\%=0.85[/tex]
Initial volume of phosphoric acid = [tex]V_1=50 mL[/tex]
Final concentration of phosphoric acid = [tex]C_2=?[/tex]
Final volume of phosphoric acid = [tex]V_2=1 L=1000 mL[/tex]
( 1L = 1000 mL)
[tex]C_1V_1=C_2V_2[/tex]
[tex]C_2=\frac{C_1times V_1}{V_2}[/tex]
[tex]=\frac{0.85\times 50 mL}{1000 mL}=0.0425=4.25%[/tex]
4.25% is the final concentration of phosphoric acid.