Kinetics Practice 1

Which change increases the rate of formation of hydrogen when zinc reacts with excess hydrochloric acid, assuming all other conditions remain the same?

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

• Adding water to the hydrochloric acid

• Decreasing the temperature

• Increasing the volume of hydrochloric acid

• Decreasing the size of the zinc particles while keeping the total mass of zinc the same

Tags

NGSS.HS-PS1-5

Which statements (I through III, shown) are correct?

• I and II only

• I and III only

• II and III only

• I, II and III

The potential energy profile for the reversible reaction,

X + Y ⇄ Z is shown.

Which arrow represents the activation energy for the reverse reaction, Z → X + Y, with a catalyst?

• A

• B

• C

• D

Which factors can affect the rate of reaction?

• I and II only

• II and III only

• II and III only

• 1, II and III

Excess magnesium powder was added to a beaker containing hydrochloric acid, HCl (aq). The mass of the beaker and its contents was recorded and plotted against time (line I).

Which change could give line II?

• Doubling the mass of powdered Mg

• Using the same mass of Mg ribbon

• Increasing the temperature

• Using the same volume of more concentrated HCl

Tags

NGSS.HS-PS1-5

Copper catalyses the reaction between zinc and dilute sulfuric acid.

Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)

Why does copper affect the reaction?

• Decreases the activation energy

• Increases the activation energy

• Increases the enthalpy change

• Decreases the enthalpy change

100 mL (100 cm³) of 10% hydrogen peroxide solution decomposes at 298 K to form water and oxygen.

H₂O₂(aq) → H₂O(l) + O₂(g)

The dotted line graph represents the volume of oxygen produced. Which graph represents the decomposition of an equal volume of a 20% solution under the same conditions?

• A

• B

• C

• D

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

Which change does not increase the initial rate of reaction when CaCO₃(s) is added to excess HCl(aq)?

• Decrease in the size of the CaCO₃(s) particles

• Increase in the temperature of the reaction mixture

• Increase in the concentration of HCl(aq), keeping the same volume

• Increase in the volume of HCl(aq), keeping the same concentration

Tags

NGSS.HS-PS1-5

Which conditions must be met for a reaction to take place?

• I and II only

• II and III only

• II and III only

• 1, II and III

Graph 1 shows a plot of volume of CO₂(g) against time for the reaction of CaCO₃(s) with 1.00 mol/L HCl (aq). The acid is the limiting reagent and entirely covers the lumps of CaCO₃(s).

Which set of conditions is most likely to give the data plotted in graph 2 when the same mass of CaCO₃(s) is reacted with the same volume of HCl(aq) at the same temperature?

• Larger lumps CaCO₃(s) and [HCl] = 1.00 mol/L

• Smaller lumps CaCO₃(s) and [HCl] = 0.05 mol/L

• Smaller lumps CaCO₃(s) and [HCl] = 1.00 mol/L

• Larger lumps CaCO₃(s) and [HCl] = 0.05 mol/L