Calculate the number of grams of sodium chloride in the solution. (Hint: Remember that sodium chloride is a strong electrolyte.)

Final answer:

The rate law for the reaction of iodide ions with hypochlorite ions is determined to be rate = k[OCl-][I-]. The rate constant k is calculated to be 6.044×109 M-1s-1. The rate of the reaction when [OCl-]= 1.8×10-3 M and [I-]= 6.0×10-4 M is 6.532×103 M/s.

Explanation:

When the iodide ion reacts with the hypochlorite ion, we can determine the rate law by analyzing the given rate data. To write the rate law, we need to compare how the rate changes with changes in concentrations of the reactants. Looking at the provided data:

When [OCl-] doubles while [I-] is constant, the rate doubles, implying first-order dependence on [OCl-].

When [I-] doubles while [OCl-] is constant, the rate also doubles, suggesting first-order dependence on [I-].

Thus, the rate law is rate = k[OCl-][I-].

To calculate the rate constant (k), we can use any set of data. Using the first set:

1.36×104 M/s = k(1.5×10-3 M)(1.5×10-3 M)

k = 1.36×104 M/s / (2.25×10-6 M2)

k = 6.044×109 M-1s-1

To calculate the rate when [OCl-]= 1.8×10-3 M and [I-]= 6.0×10-4 M:

rate = (6.044×109 M-1s-1)(1.8×10-3 M)(6.0×10-4 M)

rate = 6.532×103 M/s

Answer:

a and b are correct

Explanation:

This because both are aqueous solutions,therefore, identity of solvent is same that is water.

And because both solutions are non electrolyte they would not ionize in solution, and for the same concentration, the freezing point of both solution would also be  same. Since depression in freezing point is a colligative property this means that it depends on number of solute particles not nature of particles .

Hence answer is that  their freezing points and  Identity of the solvent shall remain the same.

Explanation:

Explanation:

1 Cal of energy is equivalent to 4.184 Joules.

A.

770Cal of energy = 3221.680 joules

Therefore, 780kCal of energy = 3221680 Joules.

B.

3200000 Joules (in 2 s.f).

C.

I000 joules = 1 kJoule

3221680 joules = 3221.689 kJoules.

D.

3200 kJ (in 2 s.f).

1) The energy in joules is equal to 3221680 Joules.

2) The energy in joules to two significant figures is 3200000.

3) The energy in kilojoules is 3221.689 KJ.

4) The energy in kilojoules to two significant figures is 3200 KJ.

Significant figures can be used to generate numbers that can be written in the form of digits. We can find the number of significant digits by counting the values beginning from the first non-zero digit placed on the left.

The significant figures of a given number can be described as those significant digits, which deliver the meaning with respect to its accuracy.

Given the energy used for the bike = 770 kcal.

We know that 1 cal = 4.184 J

The energy in Joules = 770 × 1000 × 4.184 = 3221680 J

The energy in joules to two significant figures is equal to 3200000.

The energy in kilojoules =  3221689/1000 = 3221.689 KJ

The energy in kilojoules to two significant figures is equal to 3200 KJ.

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Answer : The number of mmol of bromobenzene is, 20.6 mmol

Explanation :

The balanced chemical reaction will be:

[tex]C_6H_5Br+HNO_3\rightarrow C_6H_4NO_2Br[/tex]

First we have to calculate the moles of p-bromonitrobenzene.

Moles of p-bromonitrobenzene =[tex]\frac{\text{ given mass of p-bromonitrobenzene}}{\text{ molar mass of p-bromonitrobenzene}}[/tex]

Molar mass of p-bromonitrobenzene = 202 g/mol

Moles of p-bromonitrobenzene = [tex]\frac{4.17g}{23g/mole}=0.0206moles[/tex]

Now we have to calculate the mmol of bromobenzene.

From the balanced chemical reaction we conclude that,

As, 1 mole of p-bromonitrobenzene produced from 1 mole of bromobenzene

So, 0.0206 mole of p-bromonitrobenzene produced from 0.0206 mole of bromobenzene

Moles of bromobenzene = 0.0206 moles = 20.6 mmol

Conversion used : 1 moles = 1000 mmol

Thus, the number of mmol of bromobenzene is, 20.6 mmol

To find out how many millimoles of bromobenzene were used to synthesize 4.17 grams of p-bromonitrobenzene, divide the mass of p-bromonitrobenzene by its molecular weight (202 g/mol) and convert the result to millimoles, yielding 20.6 mmoles.

If you synthesized 4.17 grams of p-bromonitrobenzene, the number of millimoles (mmoles) of bromobenzene you started with can be calculated using the molecular weight of p-bromonitrobenzene. The molecular weight of p-bromonitrobenzene (C6H4BrNO2) is approximately 202 g/mol. Assuming 100% conversion, the moles of p-bromonitrobenzene synthesized would be the mass of the final compound divided by its molecular weight.

Number of moles =  rac{4.17 g}{202 g/mol} = 0.0206 moles

Since 1 mole equals 1000 mmoles, the amount in mmoles would be:

Number of mmoles = 0.0206 moles  imes 1000 = 20.6 mmoles

Therefore, you would have started with 20.6 mmoles of bromobenzene to synthesize 4.17 grams of p-bromonitrobenzene assuming 100% conversion in the reaction.

Answer:

Experimental concentration is 0.04M

Number density is 2.4092×10^25 molecules/m^3

Explanation:

Experimental concentration = 0.001773g/cm^3 × 1mole/44g × 1000cm^3/1L = 0.04mole/L = 0.04M

Number density = 0.04mole/L × 6.023×10^23molecules/1mol × 1000L/1m^3 = 2.4092×10^25molecules/m^3

Final answer:

The condensed ground-state electron configurations of transition metal ions are given, and it is stated which ions are paramagnetic.

Explanation:

The condensed ground-state electron configurations of the transition metal ions are as follows:

(a) Mo³⁺: [Kr]4d³

(b) Au⁺: [Xe]5d¹⁰

(c) Mn²⁺: [Ar]3d⁵

(d) Hf²⁺: [Xe]4f¹⁴5d²×

Out of these, Mo³⁺ and Mn²⁺ are paramagnetic because they have unpaired electrons in their d orbitals, which allows them to be attracted to a magnetic field.

Answer:

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Explanation:

Answer:

Marble 1 and 2 will repel each other, but no interaction occurs with marble 3.

Explanation:

Rubbing the marbles 1 and 2 with silk makes them lose the electrons and they become slightly positively charged. However the marble 3 is neutral as it's not rubbed with silk. So upon briging them all close together, the positively charged marbles repel each other as the same charges repel.  However there will be no interaction with marble 3.

Final answer:

Charged glass marbles 1 and 2, when brought close together, will repel each other, and if brought near uncharged marble 3, an initial attraction may occur followed by repulsion if charges are transferred.

Explanation:

When two glass marbles (marbles 1 and 2) are rubbed against silk, they become positively charged due to the transfer of electrons from the marbles to the silk, leaving the marbles with an excess of positive charges. This is because, according to the principles of electrostatics, rubbing materials together can transfer electrons from one material to another, resulting in one becoming positively charged and the other negatively charged. As a result, if marbles 1 and 2 are brought close together, they will repel each other, as indicated in Figure 18.4 (b), which shows that two similarly charged glass rods repel. When either of these charged marbles is brought near an uncharged marble (marble 3), an initial attraction may occur due to induced charges in the uncharged marble. However, if any charge is transferred upon contact, the like charges will cause marble 3 to then also be repelled by the charged marbles 1 and 2.

Answer:The average energy of the particles is dependent on the molecular mass of the particle is not part of Kinetic Molecular Theory.

Explanation:

The kinetic theory of gases was postulate by Clausius in 1857. Clausius speculated on how heat energy, temperature, and molecule motion could explain gas behavior. The kinetic theory of gases includes the following:

- A gas consists of molecules in constant random motion.

-Gas molecules influence each other only by collision; they exert no other forces on each other.

-All collisions between gas molecules are perfectly elastic; all kinetic energy is conserved.

- The volume actually occupied by the molecules of a gas is negligibly small; the vast majority of the volume of the gas is empty space through which the gas molecules are moving.

The Kinetic Molecular Theory includes assumptions about gas particles' size, motion, lack of forces of attraction or repulsion, and the dependence of average kinetic energy on temperature. The statement 'Gas particles do not repel each other' is actually part of the theory.

The Kinetic Molecular Theory makes several general assumptions about gases. These include :

Looking at the options provided, the statement which is NOT part of the Kinetic Molecular Theory is option A) Gas particles do not repel each other. This is because the theory does indeed state there are no forces of attraction or repulsion between gas particles.

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Answer:

m = 341.22 g

Explanation:

∴ V = 242 mL

∴ m = (δ)×(V)

⇒ m = (1.41 g/mL)×(242 mL)

⇒ m = 341.22 g

The mass of 242 mL of sulfuric acid with a density of 1.41 g/mL is 341.22 g.

To calculate the mass of 242 mL of sulfuric acid, we can use the density of the acid, which is 1.41 g/mL. The formula for calculating mass is:

Mass = Volume x Density

Substituting the given values into the formula:

Mass = 242 mL x 1.41 g/mL

Calculating the multiplication:

Mass = 341.22 g

Therefore, the mass of 242 mL of sulfuric acid is 341.22 g.

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Answer:

6.25 μg/mL

Explanation:

When a dilution is made, the mass of the solute is conserved (Lavoiser's law), so the mass pipetted will be the mass in the assay. The mass is the concentration (C) multiplied by the volume (V). If the pipet solution is called 1, and the assay 2:

m1 = m2

C1*V1 = C2*V2

C1 = 250 μg/mL

V1 = 25 μL

V2 = 975 μL + 25 μL = 1000 μL (is the final volume of the assay after the addition of LDH)

250*25 = C2*1000

C2 = 6.25 μg/mL

The final concentration of LDH in the assay is 6.25 ug/ml.

To determine the final concentration of LDH in the assay, you need to consider the volumes of LDH and assay buffer used. In this case, you pipet 25 ul of 250 ug/ml LDH into 975 ul of assay buffer. To calculate the final concentration, you can use the formula:

Final Concentration = (Volume of LDH x Concentration of LDH) / Total Volume of Assay

Substituting the values, the final concentration of LDH in the assay is:

Final Concentration = (25 ul x 250 ug/ml) / (25 ul + 975 ul) = 6.25 ug/ml

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The magnitude of ΔHsolute is often larger than the magnitude of ΔHhydration in general.

The magnitudes of ΔHsolute and ΔHhydration can vary depending on the solute and the solvent being used. However, in general, the magnitude of ΔHsolute is often larger than the magnitude of ΔHhydration.

ΔHsolute represents the energy required to separate the solute particles, which typically involves breaking intermolecular forces. This process is usually endothermic and requires more energy compared to the process of dissolving the solute in water. On the other hand, ΔHhydration represents the energy released when solute particles are surrounded by water molecules during dissolution, which is often exothermic but smaller in magnitude compared to ΔHsolute.

For example, when table salt (NaCl) dissolves in water, the magnitude of ΔHsolute required to break the ionic bonds between Na+ and Cl- ions is significantly larger than the magnitude of ΔHhydration as water molecules surround the separated ions.

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Answer:

5.00 µM

Explanation:

Given data

We can find the final concentration using the dilution rule.

C₁ × V₁ = C₂ × V₂

C₂ = C₁ × V₁ / V₂

C₂ = 250.0 µM × 1.00 mL / 50.0 mL

C₂ = 5.00 µM

The concentration of the diluted solution is 5.00 µM.

Answer:

As explained

Explanation:

My reaction will be positive and I will feel elated that a new elements has been discovered as this will be a modification of the earlier claim by berzelius and the likes that there are over 106 known elements ; Metal, Non Metals and Metalloids.

However, fitting the new discovered element in between Tin and antimony may be an issue, as the physical properties of the new elements has to be known, its melting point, metals or non metals as this is paramount to be able to classify the elements. if the elements fits in between tin and antimony, it is an indication that the elements is mot likely a metal or non-mental and may belong to group IVB or VB. Another issue is, the discoverer will have to create his own periodic table to be able to stand in with the discovery of Dimitriy Mendelev.

Final answer:

Skepticism would be the initial reaction to a claim of a new element discovered between tin and antimony, as it contradicts the known ordered structure of the periodic table, where all elements are arranged based on their atomic numbers.

Explanation:

If a claim was made that a new element had been discovered that fits between tin (Sn) and antimony (Sb) in the periodic table, my reaction would be skeptical. Based on the well-established structure of the periodic table, it is unlikely that such a discovery would go unnoticed as the elements are arranged in sequential order of atomic number, and any gaps within this order have been filled by either known elements or placeholders for elements that have yet to be observed in nature or synthesized in a lab. Additionally, Mendeleev's predictions of eka-aluminum and eka-silicon were fulfilled by gallium and germanium, respectively, because their properties matched the predictions so well that they were accepted as the elements Mendeleev had predicted to exist.

Scientifically, it would be extraordinary to find an element that has been missed in such a well-studied part of the periodic table. Chemistry professionals would expect substantial evidence, including reproducible experimental results and peer-reviewed research, to support such an extraordinary claim. The element's discovery would also need to be in accordance with the properties of other elements around it, considering trends across periods and groups within the periodic table.

Answer : The balanced chemical reaction will be:

[tex]H_2O(l)\rightleftharpoons H^+(aq)+OH^-(aq)[/tex]

Or,

[tex]H_2O(l)+H_2O(l)\rightleftharpoons H_3O^+(aq)+OH^-(aq)[/tex]

Explanation :

Autoionization of water  : The autoionization of water means that the reaction water with water means self ionization.

In the autoionization of water, one water molecule loses an hydrogen ion and another one gains it.

The balanced chemical reaction will be:

[tex]H_2O(l)\rightleftharpoons H^+(aq)+OH^-(aq)[/tex]

Or,

[tex]H_2O(l)+H_2O(l)\rightleftharpoons H_3O^+(aq)+OH^-(aq)[/tex]

The autoionization of water is a chemical reaction where two water molecules react to form hydronium and hydroxide ions. This is represented as H₂O(l) + H₂O(l) = H3O+(aq) + OH¯(aq). The ion-product constant for water (Kw) is a measure of this process.

The autoionization of water is a process in which water molecules, acting as both an acid and a base, react with each other to form ions. This can be represented by the chemical reaction: H₂O(l) + H₂O(l) = H3O+(aq) + OH¯(aq). In this equation, the (l) denotes the liquid state of water and (aq) designates aqueous, or water-dissolved, ions.

The ion-product constant for water, Kw, is equal to the product of the concentrations of the hydronium and hydroxide ions: Kw = [H3O+][OH¯]. At 25 °C, the value of Kw is approximately 1.0 × 10-14, indicating very slight ionization. This value increases with temperature, indicating an endothermic reaction.

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Answer:A, C, D, E, F

Explanation:

A. True: Oxidizing agents are electron acceptors. They accept electrons and the get reduced. This means their oxidation number reduces

B. False: Reducing agents do not accept H+ ions. Reducing agents remove oxygen from another substance or give hydrogen to it.

C. True: oxidizing agents oxidizes other molecules but they accept electrons and get reduced themselves. If a molecule accepts electrons it has been reduced.

D True: Redox reactions MAY and may not involve the transfer of hydrogen ions depending on the reactants (H+). But redox in terms of acid and base means the donating and receiving of protons(H+)

E. True: A molecule that has gained H atoms is said to be reduced. Oxidizing agents are always the proton acceptor.

F. True: Oxidizing agents May and may not accept H+. In terms of acid and base oxidizing agents accept protons(H+)

Regarding redox reactions, statements C, D, and E are generally true. Statement B and F can be true in specific scenarios but not universally, while statement A is incorrect because oxidizing agents actually donate electrons.

In redox reactions, oxidation and reduction occur simultaneously. We look at the given statements:

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Answer:

The order of the reaction is 4.

The rate law of the reaction will be :

[tex]R=k[NO]3[H_2]^1[/tex]

Rate constant of the reaction: k =[tex] 6\times 10^5 M^{-3}s^{-1}[/tex]

Explanation:

[tex]2NO(g) +2H_2 (g)\rightarrow N_2(g) + 2H_2O(g)[/tex]

Let the stoichiometric coefficient of the NO and [tex]H_2[/tex] in rate law be x and y .

Rate of the reaction is given  by :

[tex]R=k[NO]^[H_2]^y[/tex]

1) When , [tex][NO]=0.0100 M, [H_2]=0.0100 M[/tex]

R =  0.00600 M/s

[tex]0.00600 M/s=k[0.0100 M]^x[0.0100 M]^y[/tex]..[1]

2) When , [tex][NO]=0.0200 M, [H_2]=0.0300 M[/tex]

R =  0.144 M/s

[tex]0.144 M/s=k[0.0200 M]^x[0.0300 M]^y[/tex]..[2]

3) When , [tex][NO]=0.0100 M, [H_2]=0.0200 M[/tex]

R =  0.0120 M/s

[tex]0.0120 M/s=k[0.0100 M]^x[0.0200 M]^y[/tex]..[3]

Dividing [1] and [3]

[tex]\frac{0.00600 M/s}{0.0120 M/s}=\frac{k[0.0100 M]^x\times [0.0100 M]^y}{k[0.0100 M]^x\times [0.0200 M]^y}[/tex]

y = 1

Dividing [1] and [2]

[tex]\frac{0.00600 M/s}{0.144 M/s}=\frac{k[0.0100 M]^x\times [0.0100 M]^1}{k[0.0200 M]^x\times [0.0300 M]^1}[/tex]

x = 3

The order of the reaction = x + y = 3 + 1 = 4

The rate law of the reaction will be :

[tex]R=k[NO]3[H_2]^1[/tex]

Rate constant of the reaction: k

When , [tex][NO]=0.0100 M, [H_2]=0.0100 M[/tex]

R =  0.00600 M/s

[tex]0.00600 M/s=k[0.0100 M]^3[0.0100 M]^1[/tex]..[1]

[tex]k=\frac{0.00600 M/s}{[0.0100 M]^3[0.0100 M]^1}=6\times 10^5 M^{-3}s^{-1}[/tex]

Final answer:

The reaction between nitrogen monoxide and hydrogen is second-order with respect to NO, first-order with respect to H2, and third-order overall. The rate law is rate = k[NO]²[H₂], where k is the rate constant specific to the reaction conditions.

Explanation:

The rate law expression for the reaction between hydrogen and nitrogen monoxide to form dinitrogen monoxide and water vapor can be determined using the given rate equation. By analyzing the equation rate = k[NO]²[H₂], we can deduce the orders of reaction with respect to each reactant and the overall order.

The rate law shows that the reaction rate is directly proportional to the square of the concentration of nitric oxide (NO) and linearly proportional to the concentration of hydrogen (H₂). Therefore, the order of reaction with respect to NO is 2 (second order), and with respect to H₂, it is 1 (first order). The overall order of the reaction is the sum of these individual orders, which is 2 + 1 = 3 (third order).

The rate constant (k) would be determined experimentally by measuring the reaction rates at known concentrations of reactants. It is specific to the reaction's conditions, such as temperature and pressure, and would be stated in units that correspond to a third-order reaction.

Answer: methanol and acetone are not suitable solvents for extracting organic compounds because they are miscible with water virtually in all proportions

Explanation:

Methane and acetone both are polar solvents, which means they are soluble in water. Hence, not suitable for the extraction from aqueous solutions.

Methanol is the simplest alcohol which is volatile, colorless, and inflammable.

Acetone is an organic compound whose chemical formula is CH3CH3CO.

Acetone and methanol both contain polar ends and are miscible in water.

Polar solvents are not suitable for the extraction of any compound.

Thus, Methanol and acetone are not suitable for extracting organic compounds from aqueous solutions.

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Answer:

a) Mg

b) Cl

c) Mn

d) Ne

Explanation:

This electron configuration for the atom in its excited state violates the Aufbau principle or rule like we have above.

Aufbau principle states "that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels."

We however can know and identify which element is in the excited state by knowing the sum of the electron that spread across the orbital and matching it up with the atomic number of the element in the periodic table.

The electron configurations given represent atoms in excited states. By identifying the element and writing its condensed ground-state configuration, we can gain information about the energies of unoccupied orbitals in the atom's ground state.

(a) The electron configuration 1s²2s²2p⁶3s¹3p¹ represents an atom in an excited state. By looking at the electron configuration, we can identify the element as silicon (Si). The condensed ground-state configuration for silicon is 1s²2s²2p⁶3s²3p².

(b) The electron configuration 1s²2s²2p⁶3s²3p⁴4s¹ represents an atom in an excited state. The element can be identified as sulfur (S). The condensed ground-state configuration for sulfur is 1s²2s²2p⁶3s²3p⁴.

(c) The electron configuration 1s²2s²2p⁶3s²3p⁶4s²3d⁴4p¹ represents an atom in an excited state. This electron configuration belongs to the element zinc (Zn). The condensed ground-state configuration for zinc is 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰.

(d) The electron configuration 1s²2s²2p⁵3s¹ represents an atom in an excited state. From this configuration, we can identify the element as nitrogen (N). The condensed ground-state configuration for nitrogen is 1s²2s²2p³.

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Answer:

2.165 x 10^3 nm.

Explanation:

Using Rybergs equation,

1/lambda = R * (1/n1^2 - 1/n2^2)

Where,

R = rybergs constant = 109737.32 cm^-1

n1 = 7

n2 = 4

= 109737.32 * (1/7^2 - 1/4^2)

= 4619.05

Lambda = 2.165 x 10^-4 cm

Since 100 cm = 1m, 1 nm = 10^-9 m

= 2.165 x 10^-4 cm * 1 m/100 cm * 1 nm/10^-9 m

= 2.165 x 10^3 nm.

Answer:

Vapor pressure of solution = 111.98 Torr

Explanation:

Colligative property to apply: Lowering vapor pressure

P° - P' = P° . Xm . i

P°, vapor pressure of pure solvent

P', vapor pressure of solution

Xm, mole fraction of solute

i, Van't Hoff factor.

Let's determine the Xm.

Moles of solute = mass / molar mass → 34.2 g / 58.45 g/mol = 0.585 moles

Moles of solvent = 375 g / 18 g/mol = 20.83 moles

Mole fraction = 0.585 mol / 0.585 mol + 20.83 mol → 0.0273

Let's replace the data in the formula:

118.1 Torr - P' = 118.1 Torr . 0.0273 . 1.9

118.1  Torr - 6.12 Torr = P'

Vapor pressure of solution = 111.98 Torr

Answer: False

Explanation: Electrolyte are good conductors of electricity because they contain ions which are able to move about

Explanation:

Reaction is first order.

Rate Constant (k) = 5.11x10-5s-1

Temperature = 472k

Initial Concentration = 3.00×10-2M

(A) What is the half-life (in hours) of this reaction?

Formular for half life of a first order reaction is;

t1/2 = 0.693 / k

t1/2 = 0.693 / (5.11x10-5)

t1/2 = 0.1386 x 10 ^ 5 s

Upon converting to hours by dividing the value by 3600;

t1/2 = (0.1386 x 10 ^ 5) / 3600 = 3.85 hours

(B) How many hours will it take for the concentration of methyl isonitrile to drop to 6.25% of its initial value?

6.25% of initial concentration;

(6.25 / 100) * 3.00×10-2 = 0.1875 x 10 ^ -2M

ln[A] = ln[A]o − kt

[A] = Final Concentration

[A]o = Initial Concentration

upon making t subject of interest;

t = (ln[A]o - ln[A] ) / k

Inserting the values;

t = [  In(3.00×10-2) - In(0.1875 x 10 ^ -2) ] / 3.85

t = 2.7726 / 3.85

t = 0.72 hours

Answer:

Specific gravity of the sample = 8.947

Explanation:

Specific gravity of a substance is defined as the density of that substance divided by the density of water.

Density of water = 1000g/l

Density of substance = mass/volume

= 85/9.5 x 10^-3

= 8947.37 g/l

SG = 8947.37/1000

= 8.947

Final answer:

To calculate the specific gravity of a sample, divide its density by the density of water. With a given mass of 85 grams and a volume of 9.5 mL, the sample's density is 8.9474 g/mL. Consequently, the specific gravity is 8.9474, as it's a dimensionless ratio.

Explanation:

The specific gravity of a sample is the ratio of the density of that sample to the density of a reference material, usually water. To determine the specific gravity of the sample given, you need to first calculate its density using the mass and volume. The mass of the sample is given as 85 grams and the volume is given as 9.5 mL.

First, calculate the density of the sample using the formula density = mass/volume. Density = 85 g / 9.5 mL = 8.9474 g/mL. Since the density of water at 4 degrees Celsius (which is typically used as the reference density) is 1 g/mL, the specific gravity of the sample is the ratio of the sample's density to that of water. Therefore, specific gravity = sample density / water density = 8.9474 g/mL / 1 g/mL = 8.9474. This means that the specific gravity of the sample is 8.9474, which is a dimensionless number.

Final answer:

To calculate the mass of NaCl needed to lower the water's freezing point to -14.4°C, we use the freezing point depression formula with the known freezing point depression constant for water. After finding the molality, we can calculate the required mass of NaCl using its molar mass.

Explanation:

The student has asked about calculating the mass of salt (NaCl) needed to add to a specific volume of water to achieve a desired freezing point depression for making ice cream. This involves a concept called freezing point depression, which is a colligative property and is part of the solution chemistry topics in high school.

To calculate the mass of NaCl required to lower the freezing point of water to -14.4°C, we can use the freezing point depression equation ΔT = Kf × m × i, where ΔT is the freezing point depression, Kf is the freezing point depression constant of the solvent (water in this case, which is 1.86°C/m), m is the molality of the solution, and i is the van 't Hoff factor, which is 2 for NaCl due to its complete dissociation into Na+ and Cl- ions.

To find the molality (m), we rearrange the equation to m = ΔT / (Kf × i). With ΔT being 14.4°C (since water normally freezes at 0°C and we want -14.4°C), Kf is 1.86°C/m, and i is 2, we get m = 14.4°C / (1.86°C/m × 2) = 3.87 mol/kg. The mass of NaCl needed can then be calculated by converting molality to moles and then to grams using the molar mass of NaCl (58.44 g/mol).

Final answer:

Calculate the molality using the freezing point depression formula, convert to moles, and then to mass, resulting in 330 grams of NaCl needed to lower the freezing point of 1.46L of water to -14.4°C.

Explanation:

To find the mass of salt (NaCl) to be added to water in an ice-cream maker to achieve a freezing point depression to -14.4° C, we will use the freezing point depression formula ΔTf = i * Kf * m, where ΔTf is the freezing point depression, i is the van't Hoff factor (number of particles the solute breaks into), Kf is the cryoscopic constant of the solvent (water), and m is the molality of the solution.

For NaCl, which dissociates into Na+ and Cl-, the van't Hoff factor (i) is 2. Since 1L of water is approximately 1000g and the density of water is 1.00 g/mL, we have 1.46 kg of water. The freezing point depression (freezing point change) ΔTf is 14.4° C because pure water freezes at 0° C and we're freezing at -14.4° C. Kf for water is given as 1.86°C/m.

Solving the equation for m (molality), we have m = ΔTf / (i * Kf) = 14.4° C / (2 * 1.86°C/m) = 3.87 m (molality). To convert molality to moles of salt, we multiply by the mass of the solvent in kg: 3.87 m * 1.46 kg = 5.65 moles of NaCl. The molar mass of NaCl is approximately 58.44 g/mol, so the mass of NaCl needed is 5.65 moles * 58.44 g/mol = 330 grams.

Answer:

We need 7.01 grams of KOH (option 5)

Explanation:

Step 1: Data given

Volume aqueous KOH solution = 250 mL = 0.250 L

Molarity = 0.500 M

Molar mass of KOH = 56.10 g/mol

Step 2: Calculate moles KOH

Moles KOH = molarity * volume

Moles KOH = 0.500 M * 0.250 L

Moles KOH = 0.125 moles

Step 3: Calculate mass of KOH

Mass KOH = moles KOH * molar mass KOH

Mass KOH = 0.125 moles * 56.10 g/mol

Mass KOH = 7.01 grams

We need 7.01 grams of KOH

Answer:

The density of solution is 1.283 g/mL.

Explanation:

Molarity of the KOH before dilution = [tex]M_1[/tex]

Volume of the solution before dilution = [tex]V_1=30.2 mL[/tex]

Molarity of the KOH after dilution = [tex]M_2=0.173 M[/tex]

Volume of the solution after dilution = [tex]V_2=1.20 L=1200 mL[/tex]

[tex]M_1V_1=M_2V_2[/tex]

[tex]M_1=\frac{M_2V_2}{V_1}=\frac{0.173 M\times 1200 mL}{30.2 mL}[/tex]

[tex]M_1=6.8742 M[/tex]

[tex]Molarity=\frac{moles}{Volume (L)}[/tex]

[tex]V_1=30.2 mL=0.0302 L [/tex] (1 mL = 0.001 L)

[tex]M_1=\frac{n}{V_1}[/tex]

[tex]n=M_1\times V_1=6.8742 M\times 0.0302 L=0.2076 mol[/tex]

Mass of 0.2076 moles of KOH:

0.2076 mol × 56 g/mol = 11.6256 g

Mass of KOH is solution = 11.6265 g

Mass of the solution = M

Mass percentage of solution = 30.0% of KOH

[tex]30.0\%=\frac{11.6265 g}{M}\times 100[/tex]

M = 38.755 g

Density of the solution , d= [tex]\frac{M}{V_1}[/tex]

[tex]d=\frac{38.755 g}{30.2 mL}=1.283 g/mL[/tex]

The density of solution is 1.283 g/mL.

Answer :

(a) Number of orbitals in an atom = 1

(b) Number of orbitals in an atom = 5

(c) Number of orbitals in an atom = 3

(d) Number of orbitals in an atom = 9

Explanation :

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 [tex]m_l[/tex]. The value of this quantum number ranges from [tex](-l\text{ to }+l)[/tex]. When l = 2, the value of

Spin Quantum number : It describes the direction of electron spin. This is represented as [tex]m_s[/tex]. The value of this is [tex]+\frac{1}{2}[/tex] for upward spin and [tex]-\frac{1}{2}[/tex] for downward spin.

Number of orbitals in an atom = (2l+1)

(a) 1s

n = 1

The value of 'l' for 's' orbital is, l = 0

Number of orbitals in an atom = (2l+1) = (2×0+1) = 1

(b) 4d

n = 4

The value of 'l' for 'd' orbital is, l = 2

Number of orbitals in an atom = (2l+1) = (2×2+1) = 5

(c) 3p

n = 1

The value of 'l' for 'p' orbital is, l = 1

Number of orbitals in an atom = (2l+1) = (2×1+1) = 3

(a) n = 3

l = 0, 1, 2

Number of orbitals for (l = 0) = (2l+1) = (2×0+1) = 1

Number of orbitals for (l = 1) = (2l+1) = (2×1+1) = 3

Number of orbitals for (l = 2) = (2l+1) = (2×2+1) = 5

Number of orbitals in an atom = 1 + 3 + 5 = 9

For the designations (a) 1s, there is one orbital; (b) 4d, there are five orbitals; (c) 3p, there are three orbitals; (d) n = 3, there are nine orbitals in total including s, p, and d subshells.

The number of orbitals in an atom that can have specific designations depends on the quantum numbers, particularly the principal quantum number (n) and the angular momentum quantum number (l). Here is the breakdown for each given designation:

Final answer:

Henry Moseley discovered that the periodic table should be arranged by atomic number, not atomic mass, by observing the frequencies of x-ray emissions. This corrected previous discrepancies and properly sequenced elements like argon and potassium.

Explanation:

Henry Moseley's study of atomic x-ray spectra led to a significant change in how elements are ordered in the periodic table. Previously, the elements were arranged by atomic mass, but Moseley discovered that the atomic number, which is the number of protons in an atom's nucleus, was a more accurate way to organize them. This realization occurred when he noticed that the frequencies of x-rays emitted by elements, when bombarded with electrons, formed a consistent pattern in relation to their atomic number instead of their mass.

An example sequence that was confirmed by Moseley's finding is the correct placement of argon before potassium in the periodic table. Despite argon having a higher atomic mass, its atomic number is 18, while potassium's is 19, following Moseley's rule of increasing atomic numbers. This corrected discrepancies in Mendeleev's periodic table, such as the sequence of cobalt (atomic number 27) being placed before nickel (atomic number 28), despite their atomic masses suggesting the opposite order.