Rates and Equilibrium questions

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Rates and Equilibrium question collection

Review Rates and Equilibrium questions for Chemistry, with correct answers shown and coverage across collision theory; factors affecting rate; catalysts and activation energy.

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Question 1

What is the rate of reaction?
  1. How quickly reactants are changed into products
  2. The total mass of reactants used
  3. The final temperature only
  4. The color of the products

Question 2

Which change usually increases the rate of most reactions?
  1. Increasing temperature
  2. Decreasing concentration
  3. Using larger lumps instead of powder
  4. Removing all catalysts then cooling

Question 3

Why does increasing temperature often speed up a reaction?
  1. Particles move faster, so more collisions have enough energy to react
  2. Particles become heavier
  3. Fewer collisions happen each second
  4. The reaction stops at a lower temperature

Question 4

Marble chips react with acid. Which gives the fastest rate?
  1. Small powdered marble chips
  2. One large marble chip of the same mass
  3. Marble chips kept in a freezer
  4. Marble chips in pure water only

Question 5

How does concentration affect reaction rate in solutions?
  1. Higher concentration usually gives a faster rate
  2. Higher concentration always stops reactions
  3. Concentration has no effect on collisions
  4. Lower concentration always gives more products per second

Question 6

What does a catalyst do?
  1. Speeds up a reaction without being used up
  2. Slows every reaction and is used up
  3. Adds extra reactant atoms to products
  4. Makes reactions happen at lower concentration only

Question 7

In decomposition of hydrogen peroxide, manganese dioxide acts as a catalyst. What is true about the catalyst at the end?
  1. It is still present and can be reused
  2. It is completely converted into oxygen
  3. It is always the main product
  4. It disappears only if gas is collected

Question 8

Which is a valid way to measure reaction rate when a gas is made?
  1. Measure gas volume every set time interval
  2. Measure mass once at the start only
  3. Count atoms directly by eye
  4. Measure beaker color every second

Question 9

On a graph of gas volume against time, what does a steeper slope mean?
  1. A faster reaction rate
  2. A lower concentration of reactants
  3. The reaction has stopped
  4. No products are being formed

Question 10

Why does a reaction eventually stop in a closed flask?
  1. One reactant is used up so effective collisions can no longer continue
  2. All products turn back instantly into reactants
  3. Catalysts always switch off after \(10\,\mathrm{s}\)
  4. Temperature becomes negative

Question 11

If a catalyst is added, what usually happens to the amount of product after the reaction is fully complete?
  1. It stays the same, but it is made faster
  2. It always doubles
  3. It always halves
  4. No product forms with a catalyst

Question 12

Diluting hydrochloric acid before reacting with magnesium usually makes the reaction?
  1. Slower
  2. Faster
  3. Instantly explosive
  4. Unchanged in every case

Question 13

Which change would have little direct effect on reaction rate?
  1. Changing the color of the reaction flask
  2. Heating the reactants
  3. Adding a catalyst
  4. Increasing reactant concentration

Question 14

What is meant by the extent of reaction?
  1. How far reactants have been converted into products
  2. How hot the flame is
  3. The number of atoms in one molecule
  4. How many different colors are present

Question 15

If a reaction goes to completion, what is true about the limiting reactant?
  1. It has been completely used up
  2. Its amount increases over time
  3. It becomes the catalyst
  4. It stays unchanged throughout

Question 16

What is a reversible reaction?
  1. A reaction where products can react to form reactants again
  2. A reaction that can only happen once
  3. A reaction that never forms products
  4. A reaction that only occurs in water

Question 17

At dynamic equilibrium in a closed system, which statement is correct?
  1. Forward and reverse reactions happen at equal rates
  2. Both reactions stop completely
  3. Only the forward reaction continues
  4. Only the reverse reaction continues

Question 18

A gas syringe reads \(30\,\mathrm{cm^3}\) after \(15\,\mathrm{s}\). What is the average gas production rate?
  1. \(2\,\mathrm{cm^3\,s^{-1}}\)
  2. \(0.5\,\mathrm{cm^3\,s^{-1}}\)
  3. \(15\,\mathrm{cm^3\,s^{-1}}\)
  4. \(45\,\mathrm{cm^3\,s^{-1}}\)

Question 19

Which condition gives the most frequent particle collisions in a gas reaction?
  1. High pressure with the same amount of gas
  2. Low pressure with the same amount of gas
  3. Lower temperature and larger volume
  4. Using a larger reaction flask at lower concentration

Question 20

In the reaction \(\mathrm{CaCO}_3 + 2\mathrm{HCl} \to \mathrm{CaCl}_2 + \mathrm{CO}_2 + \mathrm{H}_2\mathrm{O}\), what does a faster fizzing rate indicate?
  1. CO2 is being produced more quickly
  2. Less CO2 is produced overall
  3. No acid is reacting
  4. The reaction has reached equilibrium and stopped

Question 21

What is the rate of reaction?
  1. The amount of reactant used or product formed per unit time
  2. The total mass of products at the end
  3. The temperature change only
  4. The pH of the reaction mixture only

Question 22

\(40\,\mathrm{cm^3}\) of gas is produced in \(20\,\mathrm{s}\). What is the mean rate?
  1. \(2\,\mathrm{cm^3\,s^{-1}}\)
  2. \(0.5\,\mathrm{cm^3\,s^{-1}}\)
  3. \(20\,\mathrm{cm^3\,s^{-1}}\)
  4. \(800\,\mathrm{cm^3\,s^{-1}}\)

Question 23

Why does increasing temperature usually increase reaction rate?
  1. More particles have energy greater than activation energy
  2. Particles become heavier
  3. Activation energy increases
  4. There are fewer collisions per second

Question 24

Why does increasing concentration often increase reaction rate?
  1. Particles are closer together so collisions happen more frequently
  2. Particles move more slowly
  3. Activation energy is removed
  4. Reactant particles become catalysts

Question 25

Why does increasing pressure usually increase the rate of gas reactions?
  1. Gas particles are closer so collision frequency increases
  2. Gas particles lose kinetic energy
  3. There are fewer gas particles present
  4. Only catalysts are affected by pressure

Question 26

Why does powdered calcium carbonate react faster than marble chips of the same mass?
  1. Powder has a larger surface area, so more frequent successful collisions occur
  2. Powder has stronger ionic bonds
  3. Powder has higher activation energy
  4. Marble chips contain no carbonate

Question 27

What does a catalyst do to a reaction profile?
  1. Lowers activation energy but does not change overall energy change
  2. Lowers the energy of products only
  3. Increases activation energy and yield
  4. Changes an endothermic reaction to exothermic always

Question 28

Why does rate usually decrease as a reaction proceeds?
  1. Reactant concentration decreases, so fewer successful collisions occur
  2. Activation energy increases over time automatically
  3. Products always block all collisions
  4. Catalyst concentration always drops to zero

Question 29

A reversible reaction is best described as one where?
  1. Products can react to re-form reactants
  2. The reaction can only go forward
  3. No products are formed
  4. All reactions stop at room temperature

Question 30

What does dynamic equilibrium mean in a closed system?
  1. Forward and reverse reactions occur at equal rates
  2. Both reactions have stopped
  3. Only forward reaction occurs
  4. Amounts of reactants and products must be equal

Question 31

Why is a closed system needed for equilibrium?
  1. So reactants/products cannot escape and concentrations can stabilise
  2. So temperature cannot change
  3. So catalysts are not needed
  4. So pressure is always zero

Question 32

At equilibrium, increasing reactant concentration shifts the equilibrium in which direction?
  1. Toward products
  2. Toward reactants
  3. Nowhere because equilibrium cannot move
  4. Randomly with no pattern

Question 33

At equilibrium, what happens when a product is removed?
  1. Shift toward products to replace what was removed
  2. Shift toward reactants only
  3. Stop reacting immediately
  4. Become irreversible

Question 34

For an exothermic forward reaction, increasing temperature shifts equilibrium?
  1. Toward reactants (the endothermic direction)
  2. Toward products always
  3. Nowhere because temperature has no effect
  4. Toward the side with fewer molecules only

Question 35

For \(\mathrm{N}_2 + 3\mathrm{H}_2 \rightleftharpoons 2\mathrm{NH}_3\), increasing pressure shifts equilibrium?
  1. Toward NH3 because there are fewer gas molecules on that side
  2. Toward N2 and H2 because pressure breaks NH3
  3. Nowhere because pressure has no effect on gases
  4. Toward the side with more molecules

Question 36

What is the effect of a catalyst on the position of equilibrium?
  1. No change in position; it speeds up both forward and reverse reactions
  2. Shifts equilibrium toward products permanently
  3. Shifts equilibrium toward reactants permanently
  4. Stops the reverse reaction

Question 37

Which graph feature indicates a faster initial rate when plotting gas volume against time?
  1. A steeper initial gradient
  2. A lower final gas volume
  3. A longer time to reach plateau
  4. A flatter initial gradient

Question 38

What is collision theory?
  1. Reactions occur when particles collide with enough energy and correct orientation
  2. Reactions occur when particles are motionless
  3. Only ionic particles can react
  4. Collisions always cause reactions regardless of energy

Question 39

In the equilibrium \(2\mathrm{NO}_2(\mathrm{g}) \rightleftharpoons \mathrm{N}_2\mathrm{O}_4(\mathrm{g})\), increasing pressure shifts equilibrium?
  1. Toward N2O4 (fewer gas molecules)
  2. Toward NO2 (more gas molecules)
  3. Nowhere because pressure does not affect equilibrium
  4. Toward whichever side is endothermic only

Question 40

In a rate experiment, \(12\,\mathrm{g}\) of reactant are used in \(4\,\mathrm{min}\). What is the mean rate in \(\mathrm{g\,min^{-1}}\)?
  1. \(3\,\mathrm{g\,min^{-1}}\)
  2. \(0.33\,\mathrm{g\,min^{-1}}\)
  3. \(8\,\mathrm{g\,min^{-1}}\)
  4. \(48\,\mathrm{g\,min^{-1}}\)

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Review Rates and Equilibrium questions for Chemistry, with correct answers shown and coverage across collision theory; factors affecting rate; catalysts and activation energy.

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