Rates of Reaction

Which one of the following equations is an example of homogeneous catalysis?
Hydrogen gas is evolved in the reaction between zinc and dilute sulfuric acid. A table showing the volume of hydrogen gas produced during the experiment is shown below. What is the average rate of evolution of the hydrogen gas.
1. 8 mL/min
2. 10 mL/min
3. 53 mL/min
4. 60 mL/min
The graph for reaction time versus concentration of acid for the reaction between sodium thiosulfate and dilute hydrochloric acid is shown below. What deduction can be made from this graph?
1. The greater the concentration of one of the reactants, the shorter the time needed for the reaction to go to completion.
2. The greater the concentration of one of the reactants, the longer the time needed for the reaction to go to completion.
3. The time for the reaction to go to completion is proportional to the concentration of the hydrochloric acid.
4. The concentration of the products used is proportional to the time for the reaction to go to completion.
In an experiment, dilute hydrochloric acid is reacted with sodium thiosulfate. Which one of the following graphs of reaction rate (y-axis) versus temperature (x-axis) is drawn correctly for this reaction?
Which one of the following substances is an enzyme used in washing powders?
1. Hydrolase
2. Pepsin
3. Catalase
4. Amylase
In the reaction between potassium sodium tartrate and hydrogen peroxide using cobalt chloride as a catalyst, a blue-green colour is temporarily observed during the reaction. This is evidence for
1. the Intermediate Formation Theory
2. autocatalysis
3. the Surface Adsorption Theory
4. the Collision Theory
Hydrogen and oxygen react together using platinum as a catalyst according to the equation shown below. Which of the following theories can best explain how this reaction takes place.
1. The Surface Adsorption Theory
2. The Collision Theory
3. The Intermediate Formation Theory
4. The Activation Energy Theory
For the reaction profile diagram shown, which one of the following statements is correct?
1. A represents the energy of the reactants and C represents the energy of the products.
2. A represents the energy of the products, and B is the activation energy.
3. B represents the energy of the products and C represents the energy of the reactants.
4. A represents the energy of the reactants and B represents the energy of the products.
The intermediate substance formed during a catalytic reaction is known as
1. the activated complex
2. the activation energy of the reaction
3. heterogeneous catalysis
4. an inhibitor
Silver nitrate crystals do not appear to react when mixed with sodium chloride crystals, but when mixed together in water at room temperature, a reaction is seen to take place. This can be explained by:
1. in solution, the particles are free to move, resulting in more collisions
2. the solid crystals do not have sufficient energy
3. the water acting as a catalyst
4. the water supplying the activation energy for the reaction to occur
Hydrogen and oxygen gases mixed together at room temperature will not readily react.
Which one of the following conditions is most likely to cause the reaction of these two gases to take place?
1. Create a spark in the mixture as heat energy is required.
2. Dissolve both gases in water.
3. Increase the pressure of the gases.
4. Add a catalyst such as nickel or platinum.
When zinc reacts with dilute hydrochloric acid, hydrogen gas is formed. As the reaction proceeds, the rate of production of hydrogen gas decreases.
Why?
1. The concentration of the reactants decreases.
2. The hydrogen formed acts as an inhibitor.
3. The concentration of hydrogen gas increases.
4. The hydrogen gas formed prevents the zinc and hydrochloric acid particles colliding.
Which one of the following is not a biological catalyst?
1. Hydrogen peroxide
2. Catalase
3. Washing powder enzymes
4. Yeast
Why is leaded petrol no longer used in modern cars?
1. It poisons the catalytic converter.
2. It is expensive.
3. It damages the engine.
4. It reacts with the petrol to produce a greenhouse gas.
In the experiment to study the effect of concentration on the rate of reaction, sodium thiosulfate is reacted with hydrochloric acid to produce a precipitate of sulfur and three other products. The equation for this reaction is Na₂SO₃ + 2HCl → 2X + Y + 2Z
These substances X, Y and Z are
1. NaCl, SO₂ and H₂O
2. NaOH, H₂O and SO₂
3. NaCl, S and O₂
4. NaOH, S and O₂
The graph shows the volume of oxygen produced in the decomposition of hydrogen peroxide for five different concentrations of hydrogen peroxide (H₂O₂).
The concentration of solutions X, Y and Z are
1. 1.0 M, 0.6 M and 0.2 M respectively
2. 0.7 M, 0.6 M and 0.2 M respectively
3. 0.9 M, 0.6 M and 0.5 M respectively
4. 1.0 M, 0.2 M and 0.3 M respectively
For a chemical reaction to take place, an energy barrier between the reactants and the products must first be overcome. This energy barrier is known as the
1. activation energy
2. initiation energy
3. reaction energy
4. kinetic energy
If the temperature of a reaction is increased by 10^oC, the new rate of reaction will be approximately
1. doubled
2. four times greater
3. unchanged
4. ten times greater
In the energy profile diagram shown, what type of reaction is represented?
1. Endothermic reaction
2. Exothermic reaction
3. A reaction where a catalyst is used
4. A reaction that is neither endothermic or exothermic
According to the Collision Theory, which one of the following must always occur for a reaction to take place?
1. The reactants must collide and have sufficient energy to react.
2. The reactants must collide and have equal amounts of energy.
3. The reactants must collide and have a small amount of energy.
4. The reactants must collide with the surface of the container.
If the concentration of one of the reactants in a chemical reaction is increased, what happens to the collisions between the reactants?
1. There are more collisions.
2. There are fewer collisions.
3. There are the same number of collisions, but the reactants have less energy.
4. There are the same number of collisions, but the reactants have more energy.
Which of the following statements about catalysts is TRUE?
1. A catalyst reduces the energy needed for a reaction to take place.
2. A catalyst increases the energy needed for a reaction to take place.
3. A catalyst will increase the number of collisions between the reactants.
4. A catalyst will increase the concentration of the reactants.
The particles of reactants must collide in order for a reaction to take place. The fewer the collisions, the slower the rate of reaction.
Which one of the following will increase the rate of reaction?
1. Breaking a solid reactant into many small pieces.
2. Decreasing the pressure of gaseous reactants.
3. Lowering the temperature of the reactants.
4. Decreasing the concentration of solutions taking part in the reaction.
A catalyst is a substance
1. that increases the rate of reaction but is not used up in the reaction.
2. that increases the rate of reaction and is changed during the reaction.
3. that increases the rate of reaction and increases the amount of mass(es) formed in the reaction.
4. that has no effect on the rate of reaction.
Which one of the following metals would least likely to be used as a catalyst in a catalytic converter?
1. Lead
2. Platinum
3. Rhodium
4. Palladium
Which one of the following reactions does not require a catalyst?
1. The neutralisation of an acid with a base HCl + NaOH → NaCl + H₂O
2. The dehydration of ethanol to produce ethene C₂H₅OH → C₂H₄ + H₂O
3. The production of ammonia in the Haber Process N₂ + 3H₂ → 2NH₃
4. The decomposition of hydrogen peroxide 2H₂O₂ → 2H₂O + O₂
When powdered manganese dioxide is added to a hydrogen peroxide solution, 250 cm³ of oxygen gas are produced in 3 minutes.
If the reaction is repeated with larger pieces of manganese dioxide, which one of the following statements is true?
1. The average rate of reaction is reduced.
2. The reaction is finished in less than 3 minutes.
3. More than 250 cm³ of oxygen gas are produced.
4. Less than 250 cm³ of oxygen gas are produced.
When hydrochloric acid and marble chips are reacted as shown in the diagram, cotton wool is placed in the mouth of the conical flask. What is the reason for this?
1. To prevent the acid from splashing out of the flask.
2. To act as a catalyst.
3. To prevent impurities entering the flask.
4. To stop any gas from escaping.
In a car, the catalytic converter converts harmful compounds in the exhaust into harmless compounds.
Which one of the following reactions does not take place in the catalytic converter?
1. N₂ + 3H₂ → 2NH₃
2. 2CO + O₂ → 2CO₂
3. 2CO + 2NO → 2CO₂ + N₂
4. 2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O
From the energy profile diagram shown, what is the value of the activation energy?
1. 250
2. 350
3. 100
4. 150
What effect will decreasing the temperature have on the rate of a chemical reaction?
1. Decreases the rate of reaction.
2. Increases the rate of reaction.
3. There will be no effect on the rate of reaction.
4. The reaction will stop.
Which one of the following statements about catalysts is true?
1. Catalysts are chemically unchanged at the end of a reaction.
2. Catalysts increase the temperature of a chemical reaction.
3. All catalysts are solids.
4. Catalysts increase the energy required for the reaction to take place.
If we increase the concentration of a reactant, what happens to the collisions between the particles?
1. There are more collisions.
2. There are the same number of collisions but they have more energy.
3. There are the same number of collisions but they have less energy.
4. There are fewer collisions.
By increasing the temperature of a chemical reaction, what happens to the collisions between particles?
1. There are more collisions and the particles have more energy.
2. There are the more collisions but the particles have less energy.
3. There are fewer collisions taking place.
4. There are the same number of collisions and the particles have more energy.
Which of the following is true about the way that catalysts work?
1. Catalysts reduce the energy needed for the reaction to take place.
2. Catalysts increase the energy needed for the reaction to take place.
3. Catalysts have no effect on the energy required but they increase the number of collisions taking place.
4. Catalysts have no effect on the energy required but they increase the concentration of the reactants.
Why does the rate of reaction increase when powdered calcium carbonate is used instead of lumps of marble chips?
1. There is an increase in surface area of the calcium carbonate.
2. Powdered calcium carbonate acts as a catalyst.
3. There is an increase in temperature of the particles.
4. There is an increase in the concentration of the reactants.
Manganese dioxide catalyses the decomposition of hydrogen peroxide.
2H₂O₂ → 2H₂O + O₂
Which one of the following statements about this reaction is incorrect?
1. More oxygen is produced when more catalyst is used.
2. The catalyst increases the rate of reaction.
3. The catalyst does not gain mass in the reaction.
4. Less oxygen is produced when the amount of manganese dioxide is reduced.
Which set of conditions will increase the rate of chemical reaction?
1. Increased temperature and increased concentration of reactants
2. Increased temperature and decreased concentration of reactants
3. Decreased temperature and increased concentration of reactants
4. Decreased temperature and decreased concentration of reactants
Which of the following four reactions would be expected to be the fastest?
1. Zn²⁺_(aq) + S^2-_(aq) → ZnS_(s)
2. C₃H_8(g) + 5O_2(g) → 3CO_2(g) + 4H₂O_(l)
3. Zn_(s) + S_(s) → ZnS_(s)
4. CH_4(g) + 2O_2(g) → CO_2(g) +2H₂O_(g)
The diagram shows a Maxwell-Boltzmann distribution curve for two different temperatures, T₁ and T₂. E_A represents the activation energy.
Which of the following statements is incorrect?
1. Temperature T₁ is greater than temperature T₂
2. There are more collisions possessing the activation energy for temperature T₂ than for temperature T₁
3. The particles at temperature T₁ and T₂ have an equal number of collisions possessing the activation energy
4. If a catalyst were used, both curves would shift to the right of E_A
In the reaction between sulfur dioxide and oxygen to form sulfur trioxide, a platinum catalyst is used.
SO_2(g) + ½O_2(g) ⇌ SO_3(g)
Which one of the following statements about this reaction is correct?
1. After the reaction is complete, the platinum catalyst has not lost any mass.
2. If more catalyst is used, more sulfur trioxide is formed.
3. Adding more catalyst does not increase the rate of reaction.
4. This is an example of homogeneous catalysis.
Which one of these statements explains why increasing the temperature increases the rate of a chemical reaction?
1. More molecules have energy equal to or greater than the activation energy.
2. At a higher temperature, the activation energy for the reaction is lower.
3. More molecules have the correct angle of collision.
4. The reaction proceeds according to Le Châtelier’s principle.
Consider the following reaction:
N_2(g) + 3H_2(g) ⇌ 2NH_3(g) ΔH = − 92kJ
Which of the following affects the value of K_c?
1. Increasing the temperature
2. Increasing the concentrations of nitrogen and hydrogen
3. Increasing the pressure
4. Adding a catalyst
Which changes increase the rate of a chemical reaction? 1. Increase in the concentration of an aqueous solution 2. Increase in particle size of the same mass of a solid reactant 3. Increase in the temperature of the reaction mixture
1. 1 and 3 only
2. 1 and 2 only
3. 2 and 3 only
4. 1, 2 and 3
The reaction between calcium carbonate and hydrochloric acid, carried out in an open flask, can be represented by the following equation:
CaCO_3(s) + 2HCl _(aq) → CaCl_2(aq) + H₂O_(l) + CO_2(g)
Which of the measurements below could be used to measure the rate of the reaction? 1. the mass of the flask and contents 2. the pH of the reaction mixture 3. the volume of carbon dioxide produced
1. 1, 2 and 3
2. 1 and 2 only
3. 1 and 3 only
4. 2 and 3 only
The manufacture of sulfur trioxide can be represented by the following equation:
2SO_2(g) + O_2(g) ⇌ 2SO_3(g), ΔH = −394 kJ mol⁻¹
What happens when a catalyst is added to an equilibrium mixture from this reaction?
1. The rates of both forward and reverse reactions increase.
2. The rate of the forward reaction increases and that of the reverse reaction decreases.
3. The rate of forward reaction decreases and the rate of reverse reaction increases
4. The yield of sulfur trioxide increases.
Which of the quantities in the energy level diagram below is/are affected by the use of a catalyst?
1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3
In the reaction below
N_2(g) + 3H_2(g) ⇌ 2NH_3(g), ΔH = −92 kJ
which of the following changes will increase the amount of ammonia at equilibrium? 1. Increasing the pressure 2. Increasing the temperature 3. Adding a catalyst
1. 1 only
2. 2 only
3. 1 and 2 only
4. 2 and 3 only
The enthalpy/heat change for a forward reaction in the diagram can be represented by
1. y
2. x
3. x+y
4. x-y
Acidified sodium potassium tartrate solution was mixed with hydrogen peroxide solution in a boiling tube.
When pink cobalt(II) chloride solution was added to the mixture, there was rapid effervescence as carbon dioxide was produced and the solution turned green.
C₄H₄O₆²⁻ + 5H₂O₂ + 2H⁺ ➞ 4CO₂ + 8H₂O
After a few seconds, the effervescence stopped and the solution turned back to pink.
From these observations it can be deduced that the cobalt(II) ions are acting as
1. a catalyst.
2. a dehydrating agent.
3. an oxidizing agent.
4. a reducing agent.
Which one of the following would not change the initial rate of reaction between zinc and 1M nitric acid?
1. Using double the volume of nitric acid solution
2. Breaking the zinc down into smaller particles
3. A change in the temperature of the reactants
4. The addition of a catalyst
A burning match is usually used to start combustion of natural gas in air because
1. an energy barrier must be overcome before the reaction can proceed.
2. ΔH for the reaction is larger than the energy available at room temperature.
3. the equilibrium constant for the reaction increases as temperature increases.
4. the reaction is endothermic and must be driven by an external energy source.
Which of the following is a correct statement regarding the addition of a catalyst to a chemical reaction?
1. The reaction proceeds by an alternative pathway with a lower activation energy.
2. The value of the equilibrium constant for the reaction is increased.
3. The heat of reaction is increased thus increasing the rate of reaction.
4. The rate of the forward reaction is increased without changing the rate of the reverse reaction.

Rates of Reaction

Multiple Choice Quiz