factors affecting reaction rates sample questions

What is the primary goal of this experiment?

A) To identify reaction products
B) To measure stoichiometric coefficients
C) To observe how various factors affect the rate of reaction
D) To calculate equilibrium constants

C

A chemical reaction rate is defined as:

A) The time needed for a solution to reach equilibrium
B) The change in concentration of reactants or products per unit time
C) The total volume of gases produced
D) The slope of an equilibrium constant vs time graph

B

What are the five major factors tested in this lab?

A) Catalyst, pressure, solubility, entropy, concentration
B) Metal activity, acid strength, concentration, temperature, catalyst
C) Metal type, color, pH, solubility, time
D) Temperature, pH, gas evolution, density, catalyst

B

Which of the following metals reacted the fastest with HCl?

A) Zinc
B) Magnesium
C) Copper
D) Aluminum

B

Which metal showed no visible reaction?

A) Magnesium
B) Copper
C) Zinc
D) Iron

B

Why did copper not react with HCl?

A) It forms a passivating oxide layer.
B) It is below hydrogen in the activity series and cannot displace H⁺.
C) The acid was too diluted.
D) It reacted too quickly to observe.

B

In Part II, which variable was held constant?

A) Type of acid
B) Type of metal
C) Temperature
D) Catalyst presence

B

In Part II, which variable was changed?

A) Type of metal
B) Type of acid
C) Temperature
D) Concentration

B

All acids in Part II reacted with which metal?

A) Zinc
B) Iron
C) Magnesium
D) Copper

C

Which acid produced the fastest visible reaction?

A) HCl
B) H₃PO₄
C) H₂SO₄
D) CH₃COOH

C

Which acid was the weakest and reacted slowest with Mg?

A) HCl
B) H₂SO₄
C) H₃PO₄
D) CH₃COOH

D

What was the main visible indicator of reaction progress in Parts I & II?

A) Gas bubbles forming (H₂ gas)
B) Color change to blue
C) Precipitate formation
D) Temperature drop

A

What conclusion can be drawn from Part II?

A) Stronger acids react slower.
B) Weak acids ionize less, so reactions occur slower.
C) Acid concentration has no effect.
D) All acids react at equal rates.

B

In Part III, which factor was tested?

A) Temperature
B) Catalyst presence
C) Concentration
D) Type of acid

C

What type of chemical reaction occurred in Part III?

A) Decomposition
B) Iodine clock redox reaction
C) Neutralization
D) Combustion

B

Which color change indicated the end of the reaction?

A) Clear → Pink
B) Yellow → Blue (starch–iodine complex)
C) Blue → Colorless
D) Clear → Cloudy white

B

What was the relationship between [HIO₃] and rate?

A) Inverse
B) Direct / proportional
C) Exponential decay
D) Random

B

What did increasing [HIO₃] do to the time required for color change?

A) Increased the time
B) Decreased the time
C) Had no effect
D) Made it inconsistent

B

Which physical quantity was on the x-axis of the Part III graph?

A) Reaction time
B) Initial [HIO₃]
C) Temperature
D) 1/time

B

Which factor was investigated in Part IV?

A) Concentration
B) Temperature
C) Catalyst presence
D) Metal activity

B

Which temperature produced the fastest rate?

A) 3 °C
B) 31 °C
C) 68 °C
D) 0 °C

C

Why does increasing temperature speed up reactions?

A) It decreases activation energy directly.
B) It increases kinetic energy, leading to more collisions above activation energy.
C) It changes the catalyst activity.
D) It increases the volume of solution.

B

What was the catalyst used in Part V?

A) FeCl₃
B) MnO₂
C) CuO
D) NaCl

B

What visible observation confirmed catalyst activity in Part V?

A) Blackening of the solution and rapid O₂ bubbling
B) Blue solution
C) Precipitate of white powder
D) No visible change

A

What is the function of a catalyst in a chemical reaction?

A) Lowers activation energy and increases rate
B) Increases activation energy
C) Increases product yield
D) Shifts equilibrium toward reactants

A

Volume per drop (from 1.00 mL / 20 drops) is:

A) 0.10 mL/drop
B) 0.050 mL/drop
C) 0.025 mL/drop
D) 0.005 mL/drop

B

11 drops of HIO₃ (0.010 M) equals what volume?

A) 0.22 mL 

B) 0.55 mL 

C) 1.10 mL 

D) 0.05 mL

B

Total solution volume when mixing 11 drops HIO₃, 1 starch, 2 DI water, and 11 H₂SO₃ is approximately:

A) 1.00 mL 

B) 1.25 mL 

C) 2.00 mL 

D) 5.00 mL

B

The correct pre-lab answer for [HIO₃] was:

A) 0.0012 M 

B) 0.0020 M 

C) 0.0046 M 

D) 0.010 M

C

If reaction time = 26.53 s, what is the relative rate (1/t)?

A) 0.0038 s⁻¹ 

B) 0.0377 s⁻¹ 

C) 0.0265 s⁻¹ 

D) 0.00038 s⁻¹

B

Which concentration produced the fastest reaction?

A) 1.50 × 10⁻⁶ M
B) 6.00 × 10⁻⁶ M
C) 1.00 × 10⁻⁵ M
D) 3.00 × 10⁻⁶ M

C

As concentration doubles, the rate approximately:

A) Halves
B) Doubles
C) Quadruples
D) Decreases slightly

B

If reaction order is first, rate law expression is:

A) Rate = k[HIO₃]
B) Rate = k[HIO₃]²
C) Rate = k[HIO₃][H₂SO₃]
D) Rate = k/[HIO₃]

A

Units of reaction rate are typically:

A) mol
B) M/s
C) s⁻¹
D) M⁻¹ s⁻¹

B

If the reaction is second order overall, what are units of k?

A) s⁻¹
B) M⁻¹ s⁻¹
C) M⁻² s⁻¹
D) M² s

B

Convert stopwatch reading 00:07:39.64 to seconds.

A) 45.96 s 

B) 459.64 s 

C) 739.64 s 

D) 7.39 s

B

Convert 00:17:58.96 to seconds.

A) 107.896 s 

B) 1,078.96 s 

C) 179.89 s 

D) 10.79 s

B

In Part IV, if the warm bath trial takes 20 s and the cold trial takes 200 s, the rate ratio warm:cold is:

A) 1:1
B) 1:10
C) 10:1
D) 100:1

C

For the catalyzed decomposition of H₂O₂, what gas forms?

A) H₂
B) O₂
C) CO₂
D) N₂

B

In the Part III graph, the slope of time vs [HIO₃] shows:

A) Rate decreases with increasing concentration
B) Rate increases with increasing concentration
C) No correlation
D) Negative activation energy

B

In the Part IV graph, plotting 1/time vs temperature gives:

A) Upward slope (rate ↑ with T)
B) Downward slope
C) Flat line
D) Random scatter

A

Increasing temperature affects the Maxwell–Boltzmann distribution by:

A) Lowering average kinetic energy
B) Shifting curve left (slower molecules)
C) Shifting curve right (faster molecules)
D) Removing activation energy barrier

C

What is the activation energy (Eₐ)?

A) Minimum energy required for a reaction to occur
B) Energy released during the reaction
C) Energy of products
D) Work done by the system

A

How does a catalyst affect the energy profile of a reaction?

A) Increases the height of the energy barrier
B) Decreases activation energy
C) Decreases product energy
D) Increases both Ea and ΔH

B

Which graph correctly represents a catalyzed vs uncatalyzed pathway?

A) Catalyzed line higher than uncatalyzed
B) Catalyzed line lower than uncatalyzed
C) Both lines identical
D) Both show no activation barrier

B

In which part of the lab did the solution turn black?

A) Metal reactivity
B) Acid strength
C) Catalyst (H₂O₂ + MnO₂)
D) Concentration

C

Why does MnO₂ not appear in the overall chemical equation?

A) It’s consumed during the reaction.
B) It is produced as a byproduct.
C) It is a catalyst and not consumed.
D) It reacts with O₂ gas.

C

Which factor increases collision frequency and percentage of effective collisions?

A) Concentration
B) Temperature
C) Catalyst
D) All of the above

D