Units of Concentration
How to calculate Mass Percentage
(mass component in soln/total mass of soln) x 100
The dissolution of water in octane, C8H18 is principally prevented by:
A) London dispersion forces between octane molecules
B) hydrogen bonding between water molecules
C) dipole-dipole attraction between water and octane molecules
D) repulsion between like-charged water and octane molecules
B) hydrogen bonding between water molecules
The most likely van't Hoff factor for an 0.01 m CaI2 solution is:
A) 1.00
B) 3.00
C) 1.27
D) 2.69
E) 3.29
D) 2.69
Define Beer's Law
A = εbc
TRUE OR FALSE: The effect of a catalyst on a chemical reaction is to speed up the rate of the reaction in the forward direction by lowering the activation energy.
True
How to calculate PPM & PPB?
PPM=(mass of component in soln/total mass of soln) x 10^6
PPB=(mass of component in soln/total mass of soln) x 10^9
The phrase "like dissolves like" refers to the fact that:
A) gases can only dissolve other gases
B) polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes
C) solvents can only dissolve solutes of similar molar mass
D) condensed phases can only dissolve other condensed phases
E) polar solvents dissolve nonpolar solutes and vice versa
B) polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes
The process of a substance sticking to the surface of another is called ________.
A) absorption
B) diffusion
C) effusion
D) adsorption
E) coagulation
D) adsorption
Fritz Haber was awarded the ________ Nobel Prize in chemistry for his development of a process for synthesizing ammonia directly from nitrogen and hydrogen.
A) 1954
B) 1918
C) 1933
D) 1900
B) 1918
Which of the following statements is true?
A) Q does not change with temperature.
B) Keq does not change with temperature, whereas Q is temperature dependent.
C) K does not depend on the concentrations or partial pressures of reaction components.
D) Q does not depend on the concentrations or partial pressures of reaction components.
E) Q is the same as Keq when a reaction is at equilibrium.
E) Q is the same as Keq when a reaction is at equilibrium.
How to calculate Mole Fraction
1. First, calculate moles of component: mass of substance/mass of one mole
2. Calculate Mole Fraction: moles of component/total moles of all components
Which one of the following vitamins is water soluble?
A) A
B) B
C) K
D) D
E) E
B) B
A catalyst can ________ the rate of a reaction by providing an alternative pathway with a ________ activation energy
A) decrease, higher
B) increase, lower
C) decrease, lower
D) increase, higher
E) decrease, constant
B) increase, lower
Which of the following expressions is the correct equilibrium-constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide?
N2O4 (g) <-> 2NO2 (g)
A) [NO2]/[N2O4]
B) [NO2]2/[N2O4]
C) [NO2]/[N2O4]2
D) [NO2][N2O4]
E) [NO2]2[N2O4]
B) [NO2]2/[N2O4]
Of the following, all are valid units for a reaction rate except ________.
A) mol/L
B) M/s
C) mol/hr
D) g/s
E) mol/L-hr
A) mol/L
moles of solute/volume (in liters) of solution
Which of the following substances is least likely to dissolve in water?
A) HOCH2CH2OH
B) CHCl3
C) O
||
CH3(CH2)9CH
D) CH3(CH2)8CH2OH
E) CCl4
E) CCl4
The enzyme ________ converts nitrogen into ammonia.
A) oxygenase
B) hydrogenase
C) oxidase
D) nitroglycerine
E) nitrogenase
E) nitrogenase
The equilibrium-constant expression depends on the ________ of the reaction.
A) stoichiometry
B) mechanism
C) stoichiometry and mechanism
D) the quantities of reactants and products initially present
E) temperature
A) stoichiometry
The following reaction is second order in [A] and the rate constant is 0.025 M-1S-1:
A → B
The concentration of A was 0.65 M at 33 s. The initial concentration of A was ________ M.
A) 2.4
B) 0.27
C) 0.24
D) 1.4
E) 1.2 × 10-2
D) 1.4
How to calculate molality (m)
moles of solute/kilograms of solvent
What is the concentration in ppm of a solution which is prepared by dissolving 15 mg of NaCl in 200 mL water?
A) 1.5 × 10^-5
B) 75
C) 0.075
D) 15
E) 7.5 × 10^-5
B) 75
The half-life of a first-order reaction is 13 min. If the initial concentration of reactant is 0.085 M, it takes for it to decrease to 0.055 M.
A) 8.2
B) 11
C) 3.6
D) 0.048
E) 8.4
A) 8.2
The reaction below is exothermic:
2SO2 (g) + O2 (g) <-> 2SO3 (g)
Le Châtelier's Principle predicts that ________ will result in an increase in the number of moles of in the reaction container.
A) increasing the amount of SO2
B) decreasing the pressure
C) increasing the temperature
D) removing some oxygen
E) increasing the volume of the container
A) increasing the amount of SO2