Question 1

In an energy diagram for an endothermic chemical reaction which of the following is true?

Accepted Answer

In an endothermic reaction, the energy of the products is higher than that of the reactants, so A is incorrect. The transition state always has higher energy than the reactants, making B correct.

Question 2

The rate of reaction for the decomposition of hydrogen peroxide to yield water and oxygen is given by the equation: Rate = k[H₂O₂]. Which of the following is indicated by this equation?

Accepted Answer

The rate equation shows that the rate of the reaction is proportional to the concentration of hydrogen peroxide ([H₂O₂]). Therefore, increasing the concentration of H₂O₂ will increase the rate of the reaction.

Question 3

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

Accepted Answer

By grinding the solid to form a powder, the surface area of the solid is increased, allowing for a larger area for the liquid to come into contact with and react with. This will increase the rate of the reaction. Adding more liquid reactant or placing a larger crystal of the solid in the same volume of liquid reactant will not significantly increase the rate of reaction, as the limiting factor is the surface area of the solid.

Question 4

In a particular chemical reaction 2 bonds are broken and no bonds are formed. Based only on this information, which of the following is true?

Accepted Answer

Breaking bonds requires energy input, so if 2 bonds are broken with no bonds formed, the reaction must absorb energy (i.e. be endothermic). The information alone does not give any indication of activation energy.

Question 5

Given that the reaction N₂(g) + 2 O₂(g) → 2 NO₂(g) is endothermic, which of the following is true of the reaction 2 NO₂(g) → 2 N₂(g) + 2 O₂(g) ?

Accepted Answer

The answer of Given that the reaction N₂(g) + 2...

Question 6

When the concentration of a reactant is increased which of the following is true?

Accepted Answer

An increase in the concentration of a reactant will usually increase the frequency of successful collisions between reactant molecules, leading to an increase in the rate of reaction. However, there are some cases where this may not be true (e.g. if the reaction is limited by a different factor such as temperature or catalyst concentration). Therefore, the correct answer is usually increases, making choice (D) the best option.

Question 7

If a reaction occurs very rapidly, even at a relatively low temperature, which of the following is probably true?

Accepted Answer

A low activation energy means that the reactants require less energy to transition to the products, making the reaction occur more quickly. The other options are not necessarily related to the reaction rate.

Question 8

In a particular chemical reaction 4 bonds are broken and 3 bonds are formed. Based only on this information, which of the following is true?

Accepted Answer

The answer of In a particular chemical reaction 4 bonds...

Question 9

When the concentration of a reactant is decreased which of the following is true?

Accepted Answer

When the concentration of a reactant is decreased, the chance of successful collisions between reactant particles is reduced. This means that the frequency of collisions and the rate of reaction usually decrease, as there are fewer reactant particles available to react. However, there may be some cases where decreasing the concentration of a reactant actually increases the rate of reaction, such as when the reaction is limited by the presence of a catalyst. However, this is not always the case, so option C cannot be correct. Similarly, option A cannot be correct, as there may be some cases where the rate of reaction remains the same even when the concentration of a reactant is decreased. Therefore, the best choice is B, as it accurately reflects the common result of decreasing the concentration of a reactant.

Question 10

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

Accepted Answer

Grinding the solid to a powder will increase its surface area, making it easier for the liquid reactant to come into contact with the solid and react with it. This will increase the reaction rate. Adding more liquid reactant or using a larger crystal of the solid will not have as much of an effect on increasing the surface area and may not lead to a significant increase in the reaction rate.

Question 11

Consider a reaction such as A₂(g) + B₂ (g) → 2AB(g). What can we say about the mechanism of the reaction?

Accepted Answer

The answer of Consider a reaction such as A₂(g) +...

Question 12

The reaction H₂O₂(l) + 3 I-(aq) + 2 H⁺(aq) → I₃-(aq) + 2 H₂O(aq) occurs very rapidly. Based on this observation only, what can we say about this reaction?

Accepted Answer

The answer of The reaction H₂O₂(l) + 3 I-(aq) +...

Question 13

Sodium chloride and silver nitrate react to produce silver chloride and sodium nitrate? Which of the following will result in the fastest reaction between sodium chloride and silver nitrate?

Accepted Answer

Solutions of the two reactants are the best choice because the reactants are already in a dissolved state, increasing the chances of their particles colliding and reacting with each other, leading to a faster reaction rate.

Question 14

In a particular chemical reaction 3 bonds are broken and 4 bonds are formed. Based only on this information, which of the following is true?

Accepted Answer

The answer of In a particular chemical reaction 3 bonds...

Question 15

Silver iodide is an insoluble salt. If solid sodium iodide and solid silver nitrate are mixed together a reaction to for sodium nitrate and silver iodide occurs but it is extremely slow. However, if the sodium iodide and silver nitrate are first dissolved in water and the two solutions are mixed the reaction occurs very rapidly. Which of the following explain(s) the difference in reaction rates?

Accepted Answer

In solution, ions have high mobility and can easily collide and react with each other, increasing the reaction rate.

Question 16

Which of the following is true of all multi-step reactions?

Accepted Answer

In a multi-step reaction, the reaction occurs through a series of intermediate steps, and the overall rate of the reaction is limited by the slowest step, also called the rate-determining step. This means that the rate of the overall reaction is only as fast as the slowest step, and thus the answer is D. It is not necessarily true that multi-step reactions involve more than two reactant molecules or that they are all either endothermic or exothermic, as this can vary depending on the specific reaction.

Question 17

Which of the following accounts for the fact that reactions between ions in solution are usually very fast?

Accepted Answer

In reactions between ions in solution, no covalent bonds need to be broken for reaction to occur, which means that the activation energy required for the reaction is generally lower than in reactions involving covalent bonds. This makes the reaction faster. Ionic bonds themselves are strong and the type of reaction (endothermic or exothermic) does not necessarily determine the speed of the reaction.

Question 18

Which of the following does not result from increasing the temperature of a reaction?

Accepted Answer

Increasing the temperature of a reaction can increase the rate of the reaction by increasing the number of collisions, increasing the fraction of effective collisions, and decreasing the activation energy. However, it does not increase the concentrations of the reactants, as their concentrations are determined by the initial conditions and the stoichiometry of the reaction.

Question 19

Given that the reaction 2 H₂(g) + O₂(g) → 2 H₂O(g) is exothermic, which of the following is true of the reaction 2 H₂O(g) → 2 H₂(g) + O₂(g) ?

Accepted Answer

The reverse reaction of an exothermic reaction is endothermic, requiring more energy to overcome the energy barrier, hence a higher activation energy.

Question 20

In an energy diagram for an exothermic chemical reaction which of the following is true?

Accepted Answer

In an exothermic chemical reaction, the energy of the products is lower than that of the reactants (choice A). This means that energy is released during the reaction. Additionally, the energy of the transition state is higher than that of the reactants, as energy must be absorbed to reach the transition state before the reaction can occur (choice B). Therefore, both statements are true, making choice C the best answer.

Quiz 7: Reaction Rates and Chemical Equilibrium

In an energy diagram for an endothermic chemical reaction which of the following is true?

The rate of reaction for the decomposition of hydrogen peroxide to yield water and oxygen is given by the equation: Rate = k[H₂O₂]. Which of the following is indicated by this equation?

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

In a particular chemical reaction 2 bonds are broken and no bonds are formed. Based only on this information, which of the following is true?

Given that the reaction N₂(g) + 2 O₂(g) → 2 NO₂(g) is endothermic, which of the following is true of the reaction 2 NO₂(g) → 2 N₂(g) + 2 O₂(g) ?

When the concentration of a reactant is increased which of the following is true?

If a reaction occurs very rapidly, even at a relatively low temperature, which of the following is probably true?

In a particular chemical reaction 4 bonds are broken and 3 bonds are formed. Based only on this information, which of the following is true?

When the concentration of a reactant is decreased which of the following is true?

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

Consider a reaction such as A₂(g) + B₂ (g) → 2AB(g) . What can we say about the mechanism of the reaction?

The reaction H₂O₂(l) + 3 I-(aq) + 2 H⁺(aq) → I₃-(aq) + 2 H₂O(aq) occurs very rapidly. Based on this observation only, what can we say about this reaction?

Sodium chloride and silver nitrate react to produce silver chloride and sodium nitrate? Which of the following will result in the fastest reaction between sodium chloride and silver nitrate?

In a particular chemical reaction 3 bonds are broken and 4 bonds are formed. Based only on this information, which of the following is true?

Which of the following is true of all multi-step reactions?

Which of the following accounts for the fact that reactions between ions in solution are usually very fast?

Which of the following does not result from increasing the temperature of a reaction?

Given that the reaction 2 H₂(g) + O₂(g) → 2 H₂O(g) is exothermic, which of the following is true of the reaction 2 H₂O(g) → 2 H₂(g) + O₂(g) ?

In an energy diagram for an exothermic chemical reaction which of the following is true?

Quiz 7: Reaction Rates and Chemical Equilibrium

In an energy diagram for an endothermic chemical reaction which of the following is true?

The rate of reaction for the decomposition of hydrogen peroxide to yield water and oxygen is given by the equation: Rate = k[H2O2]. Which of the following is indicated by this equation?

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

In a particular chemical reaction 2 bonds are broken and no bonds are formed. Based only on this information, which of the following is true?

Given that the reaction N2(g) + 2 O2(g) → 2 NO2(g) is endothermic, which of the following is true of the reaction 2 NO2(g) → 2 N2(g) + 2 O2(g) ?

When the concentration of a reactant is increased which of the following is true?

If a reaction occurs very rapidly, even at a relatively low temperature, which of the following is probably true?

In a particular chemical reaction 4 bonds are broken and 3 bonds are formed. Based only on this information, which of the following is true?

When the concentration of a reactant is decreased which of the following is true?

If a chemist wishes to carry out a reaction in which one reactant is a solid and one is a liquid, which of the following will be most effective in speeding up the reaction?

Consider a reaction such as A2(g) + B2 (g) → 2AB(g) . What can we say about the mechanism of the reaction?

The reaction H2O2(l) + 3 I-(aq) + 2 H+(aq) → I3-(aq) + 2 H2O(aq) occurs very rapidly. Based on this observation only, what can we say about this reaction?

Sodium chloride and silver nitrate react to produce silver chloride and sodium nitrate? Which of the following will result in the fastest reaction between sodium chloride and silver nitrate?

In a particular chemical reaction 3 bonds are broken and 4 bonds are formed. Based only on this information, which of the following is true?

Which of the following is true of all multi-step reactions?

Which of the following accounts for the fact that reactions between ions in solution are usually very fast?

Which of the following does not result from increasing the temperature of a reaction?

Given that the reaction 2 H2(g) + O2(g) → 2 H2O(g) is exothermic, which of the following is true of the reaction 2 H2O(g) → 2 H2(g) + O2(g) ?

In an energy diagram for an exothermic chemical reaction which of the following is true?

The rate of reaction for the decomposition of hydrogen peroxide to yield water and oxygen is given by the equation: Rate = k[H₂O₂]. Which of the following is indicated by this equation?

Given that the reaction N₂(g) + 2 O₂(g) → 2 NO₂(g) is endothermic, which of the following is true of the reaction 2 NO₂(g) → 2 N₂(g) + 2 O₂(g) ?

Consider a reaction such as A₂(g) + B₂ (g) → 2AB(g) . What can we say about the mechanism of the reaction?

The reaction H₂O₂(l) + 3 I-(aq) + 2 H⁺(aq) → I₃-(aq) + 2 H₂O(aq) occurs very rapidly. Based on this observation only, what can we say about this reaction?

Given that the reaction 2 H₂(g) + O₂(g) → 2 H₂O(g) is exothermic, which of the following is true of the reaction 2 H₂O(g) → 2 H₂(g) + O₂(g) ?