Biology – Chemistry – Flashcards

What is the definition of molality?

If 27.9 g LiCl is dissolved in 175 g H2O, what is the weight percent of LiCl in the solution?

If 11.2 g of naphthalene, C10H8, is dissolved in 105.4 g of chloroform, CHCl3, what is the molality of the solution?

What is the mole fraction of urea, CO(NH2)2, in a solution prepared by dissolving 6.8 g of urea in 33.5 g of methanol, CH3OH?

What is the mass percent of an aqueous sodium hydroxide solution in which the molality of NaOH is 10.7 m?

What is the mole fraction of calcium chloride in 3.35 m CaCl2(aq)? The molar mass of CaCl2 is 111.0 g/mol and the molar mass of water is 18.02 g/mol.

What is the molality of ethanol, C2H5OH, in an aqueous solution that is 37.4% ethanol by mass?

What is the mole fraction of urea, CH4N2O, in an aqueous solution that is 54% urea by mass?

A concentrated hydrochloric acid solution has a density of 1.19 g/mL at 25°C and is 12.1 M. What is the percent by mass of HCl in the solution?

A concentrated sodium hydroxide solution is 50.5% NaOH by mass and has a density of 1.53 g/mL at 25°C. What is the molarity of NaOH?

How many milliliters of 15.7 M H2SO4 are needed to prepare 600.0 mL of 0.10 M H2SO4?

What volume of a 0.771 M solution of CaCl2 contains 1.28 g of solute?

What is the mass percent of an aqueous sodium hydroxide solution in which the mole fraction of NaOH is 0.101?

What mass of an aqueous 22.9% sodium chloride solution contains 99.5 g of water?

What is the mass of H2SO4 in a 46.4-mL sample of concentrated sulfuric acid that has a density of 1.84 g/mL and consists of 98.3% H2SO4?

The volume of a 15.8% (by mass) solution is 146.4 mL. The density of the solution is 1.084 g/mL. What is the mass of solute in this solution?

A 12.0% sucrose solution by mass has a density of 1.05 g/cm3. What mass of sucrose is present in a 63.0-mL sample of this solution?

Calculate the molarity of a solution of magnesium chloride with a concentration of 30.3 mg/mL.

Concentrated sodium hydroxide is 19.4 M and has a density of 1.54 g/mL. What is the molality of concentrated NaOH?

If the concentration of sodium carbonate in water is 12.8 ppm, what is the molarity of Na2CO3(aq)? The molar mass of Na2CO3 is 106.0 g/mol. Assume the density of the solution is 1.00 g/mL.

A 15 meter by 12 meter pool of water has a depth of 2.2 meters. What mass of silver ion is present in the reservoir if the concentration of silver ion is 0.14 ppm? (1 m3 = 1000 L; assume the density of the solution is 1.00 g/mL)

What concentration of silver nitrate (in ppm) is present in 7.1 × 10-7 M AgNO3(aq)? For very dilute aqueous solutions, you can assume the solution’s density is 1.0 g/mL. The molar mass of AgNO3 is 169.9 g/mol.

What mass of Zn(NO3)2 must be diluted to a mass of 1.00 kg with H2O to prepare 97 ppm Zn2+(aq)?

Which of the following statements is/are CORRECT?

The solubility of 1-hexanol in water is 0.60 g per 100 g of water at 25°C. What is the maximum amount of 1-hexanol that will dissolve in 5.3 g of water at 25°C?

Which of the following liquids will be miscible with water in any proportion: ethanol (CH3CH2OH), carbon tetrachloride (CCl4), hexane (C6H14), and/or formic acid (HCO2H)?

Which of the following compounds is not miscible with water?

Two nonpolar solvents, such as hexane and carbon tetrachloride, may be miscible even though the enthalpy of mixing of these liquids might be small. A reason that mixing occurs is that mixtures have a greater dispersal of energy relative to pure solvents. The tendency toward greater dispersal of energy is a thermodynamic function called ____.

Which of the following favor(s) the solubility of an ionic solid in a liquid solvent?

Which of the following statements is INCORRECT?

At a particular temperature the solubility of O2 in water is 0.590 g/L at an oxygen pressure of 15.2 atm. What is the Henry’s law constant for O2?

According to the National Institute of Standards webbook, the Henry’s Law constant for N2 gas is 0.00060 mol/kg?bar at 25°C What is the Henry’s law constant in units of mol/kg?atm? (1 bar = 0.9869 atm; 1 atm = 760 mmhg)

The Henry’s law constant for N2 in water at 25 °C is 6.0 × 10-4 mol/kg?bar. What is the equilibrium concentration of N2 in water when the partial pressure of N2 is 586 mm Hg? (760 mm Hg = 1 atm = 0.9869 bar)

Which action(s) will decrease the equilibrium concentration of an inert gas (such as N2) in water?

If the solubility of O2 at 0.360 bar and 25°C is 15.0 g/100 g H2O, what is the solubility of O2 at a pressure of 1.72 bar and 25°C?

What partial pressure of oxygen gas is required in order for 0.00392 g of the gas to dissolve in 23.7 mL of pure water? The Henry’s law constant for oxygen gas is 1.3 × 10-3 M atm-1.

For the following gas-aqueous liquid equilibrium for a closed system at a constant temperature,
O2(g) O2(aq)

For the following gas-liquid equilibrium for an aqueous system at a constant partial pressure of O2,
O2(g) O2(aq)

What is the vapor pressure at 20°C of an ideal solution prepared by the addition of 4.60 g of the nonvolatile solute urea, CO(NH2)2, to 50.2 g of methanol, CH3OH? The vapor pressure of pure methanol at 20°C is 89.0 mmHg.

The vapor pressure of water at 90°C is 0.692 atm. What is the vapor pressure (in atm) of a solution made by dissolving 1.28 mole(s) of CsF(s) in 1.00 kg of water? Assume that Raoult’s law applies.

Ideally, colligative properties depend only on the

Assuming ideal behavior, which of the following aqueous solutions would be expected to exhibit the smallest freezing-point lowering?

What partial pressure of oxygen gas is required in order for 0.00392 g of the gas to dissolve in 23.7 mL of pure water? The Henry’s law constant for oxygen gas is 1.3 × 10-3 M atm-1.

For the following gas-aqueous liquid equilibrium for a closed system at a constant temperature,
O2(g) O2(aq)
what is the effect on the equilibrium composition of the liquid when the partial pressure of O2 gas above the liquid is decreased?

For the following gas-liquid equilibrium for an aqueous system at a constant partial pressure of O2,
O2(g) O2(aq)
what is the effect on the equilibrium composition of the liquid when the temperature of the liquid is decreased?

Which statement concerning relative rates of reaction is correct for the chemical equation given below?
2 CH3OH(g) + 3 O2(g) ? 2 CO2(g) + 4 H2O(g)

Which relationship correctly compares the rates of the following reactants and products?
2 NOCl(g) ? 2 NO(g) + Cl2(g)

Which of the following expressions does not represent a proper expression for the rate of this reaction?
2A + 3B ? F + 2G

The average rate of disappearance of ozone in the following reaction is found to be atm/s.

What is the rate of appearance of during this interval?

For the reaction provided, the rate of disappearance of IO3-(aq) at a particular time and concentration is 2.3 × 10-3 mol/L·s.
IO3-(aq) + 5I-(aq) + 6H+(aq) ? 3I2(aq) + 3H2O(l)
What is the relative rate of appearance of I2(aq)?

Consider the exothermic combustion of coal. Which of the following could increase the rate of reaction?

Which of the following is/are expected to affect the rate of a chemical reaction?

What is the name given to a substance that increases the rate of a chemical reaction but is not itself consumed?

Assume the reaction below
2 NO(g) + O2(g) ? 2 NO2(g)
proceeds via the following rate expression:

Which of the following statements concerning the above chemical reaction and rate equation is/are CORRECT?

What is the overall order of the reaction below
NO(g) + O3(g) ? NO2(g) + O2(g)
if it proceeds via the following rate expression?

For a certain overall third-order reaction with the general form aA ? products, the initial rate of reaction is 0.42 M·s?1 when the initial concentration of the reactant is 0.25 M. What is the rate constant for this reaction?

If a reaction is third-order with respect to a particular reactant, when the concentration of that reactant is decreased by a factor of 2, the reaction rate will _____.

Given the initial rate data for the decomposition reaction,
A ? B + C
determine the rate expression for the reaction.

The following data were obtained in a kinetics study of the hypothetical reaction A + B + C ? products.
[A]0 (M) [B]0 (M) [C]0 (M) Initial Rate (10-3 M/s)
0.4 0.4 0.2 160
0.2 0.4 0.4 80
0.6 0.1 0.2 15
0.2 0.1 0.2 5
0.2 0.2 0.4 20

The reactants A and B are mixed, and the reaction is timed until a color change occurs. The data are as follows:
[A] [B] Time (s)
0.100 0.140 25
0.050 0.140 100
0.100 0.070 25
The order of the reaction with respect to reactant A is

Nitrosyl chloride is produced from the reaction of nitrogen monoxide and chlorine:
2NO(g) + Cl2(g) ? 2NOCl(g)
The following initial rates at a given temperature were obtained for the concentrations listed below.
Experiment Initial Rate (mol·L-1·h-1) [NO]0 (mol·L-1) [Cl2]0 (mol·L-1)
1 2.21 0.25 0.25
2 8.84 0.5 0.25
3 4.42 0.25 0.5
What is the experimental rate law?

The rate law for a reaction is rate = k[A]2[B]. Which of the following mixtures of reactants will give the smallest initial rate?

Given the initial rate data for the reaction A + B ? C, determine the rate expression for the reaction.

[A], M [B], M ?[C]/?t (initial) M/s
0.215 0.150 5.81 × 10-4
0.215 0.300 1.16 × 10-3
0.430 0.150 2.32 × 10-3

Given the initial rate data for the reaction A + B ? C, determine the rate expression for the reaction.

[A], M [B], M ?[C]/?t (initial) M/s
0.0344 0.160 2.11 × 10-2
0.0516 0.160 3.17 × 10-2
0.0344 0.272 6.10 × 10-2

Given the initial rate data for the reaction A + B ? C, determine the rate expression for the reaction.

[A], M [B], M ?[C]/?t (initial) M/s
0.0418 0.122 2.73 × 10-4
0.0836 0.122 10.9 × 10-4
0.0418 0.488 2.73 × 10-4

Which of the following units are consistent with the units of the reaction rate in a first order reaction?

For which of the following hypothetical rate laws would the units of the rate constant have the general form M?2?h?1?

For the reaction A + 2B ? C, the rate law is
.
What are the units of the rate constant where time is measured in seconds?
a. b. c. d. e.

ANS: B

For the reaction 2A + B ? C, the rate law is
.
Which of the factor(s) will affect the value of the rate constant for this reaction?
1. decreasing the temperature
2. adding a catalyst
3. decreasing the concentration of reactant A

The reaction of NO and O2 produces NO2.
2 NO(g) + O2(g) ? 2 NO2(g)
The reaction is second-order with respect to NO(g) and first-order with respect to O2(g). At a given temperature, the rate constant, k, equals 4.7 × 102 M-2s-1. What is the rate of reaction when the initial concentrations of NO and O2 are 0.025 M and 0.015 M, respectively?

How many mechanistic steps are depicted by in this potential energy diagram?

For the overall reaction
2A + B ? C
which of the following mechanisms is/are consistent with a rate equation of rate = k[A]2[B]?

For the overall reaction
A + 2B ? C
which of the following mechanisms yields the correct overall chemical equation and is consistent with the rate equation below?
rate = k[A][B]

A possible mechanism for the gas phase reaction of NO and H2 is as follows:
Step 1 2NO N2O2
Step 2 N2O2 + H2 N2O + H2O
Step 3 N2O + H2 N2 + H2O
Which of the following statements concerning this mechanism is not directly supported by the information provided?

What is the rate law predicted by this mechanism?

The reaction, A + 2B ? B2 + A, proceeds by the following mechanism: (A is a catalyst.)
A + B ? AB (slow)
AB + B ? B2 + A (fast)
What is the rate law expression for this reaction?

Nitrogen dioxide reacts with carbon monoxide to produce nitrogen monoxide and carbon dioxide.
NO2(g) + CO(g) ? NO(g) + CO2(g)
A proposed mechanism for this reaction is
2 NO2(g) NO3(g) + NO(g) (fast, equilibrium)
NO3(g) + CO(g) ? NO2(g) + CO2(g) (slow)
What is a rate law that is consistent with the proposed mechanism?

Consider the following proposed mechanism. If this mechanism for the overall reaction were correct, and if k1 were much less than k2, then the observed rate law would be
2A C + I
I + B C + D

Below is a proposed mechanism for the decomposition of H2O2.
H2O2 + I- ? H2O + IO- slow
H2O2 + IO- ? H2O + O2 + I- fast
Which of the following statements is incorrect?

The mechanism of a chemical reaction is given below.
(CH3)3CCl ? (CH3)3C+ + Cl- (slow)
(CH3)3C+ + OH- ? (CH3)3COH (fast)
Which of the following statements concerning the reaction is/are CORRECT?
1. The overall balanced reaction is: (CH3)3CCl + OH- ? (CH3)3COH + Cl-
2. Hydroxide ion is a reaction intermediate.
3. The following rate law is consistent with the mechanism: rate = k[(CH3)3CCl]OH-].