C9. Rate of Reaction-2

The following graph shows two different reaction pathways for the same overall reaction at the same temperature.

Which pathway is slower and why?

• Red, because the activation energy is larger

• Blue, because the activation energy is lower

• both reaction progress at the same rate

The following equation shows the reaction between calcium carbonate, CaCO₃ and hydrochloric acid, HCl:

CaCO_3(aq) + 2HCl_(aq) → CaCl_2(aq) + CO_{2 (g)­­} + H₂O_(l)

Which of the following is the suitable method to determine the rate of reaction?

• Change in the temperature of the solution with time

• Change in the volume of carbon dioxide gas with time

• Change in the mass of water with time

• Change in the concentration of hydrochloric acid with time

Diagram 4 shows the graph of volume of carbon dioxide gas against time when 5 g of marble chips is added to

50 cm³ of 0.2 mol dm^-3 hydrochloric acid.

At what time the rate of reaction the highest?

• t1

• t2

• t3

• t4

Diagram 7 shows a graph of the volume of gas produced against time for the reaction between zinc granules and hydrochloric acid.

The gradient of the graph decreases with time because

• catalyst is not used

• volume of mixture decreases

• 
  temperature of reaction decreases

• concentration of hydrochloric acid decreases

The equation represents the reaction between sodium carbonate and hydrochloric acid.

Na₂CO₃ + 2 HCl → 2 NaCl + H₂O + CO₂

The mass of the beaker and its contents is plotted against time.

Which graph represents what happens when sodium carbonate reacts with an excess of dilute hydrochloric acid?

• 
• 
• 
• 

What letter represents the activation energy?

• A

• B

• C

• D

• E

Activation energy is required to start a chemical reaction. What is activation energy?

• The maximum energy needed for a reaction to occur

• The minimum amount of energy needed for a reaction to potentially occur

• The energy added by a catalyst

• The energy possessed by the products

What is collision theory?

• Molecules must collide with each other with enough energy to bond.

• Atoms constantly collide and react

• The minimum energy needed for a reaction to occur

• Atoms constantly move in random direction

If the reactant particles collide with less than the activation energy, no reaction will occur.

• True

• False

A ______________ is a substance that increases the rate of a reaction without being used up during the reaction. 

• Reactant

• Product

• Catalyst

• Solute