Rate of Reactions

Question 1

What can rate of reaction be measured by?

Answer 1

1. Vol. of gas produced per unit time
2. Change in mass of reactant per unit time

Question 2

What are the measuring apparatus needed to measure rate of reaction by change in mass per unit time?

Answer 2

stopwatch and electronic mass balance

Question 2

What are the measuring apparatus needed to measure rate of reaction by vol. of gas produced per unit time?

Answer 2

stopwatch and gas syringe

Question 3

How will the graph for rate od reaction measured by vol. of gas produced per unit time look like?

Answer 3

As the reaction proceeds, the volume of gas collected in the gas syringe increases

Question 4

How will the graph for the rate of reaction measured by change in mass of reactant per unit time look like?

Answer 4

As the reaction proceeds, more gas is produced and escaped from the conical flask. Hence, the mass of the system decreases over time.

Question 5

What are some interpretations of graphs regarding its gradients?

Answer 5

• the steeper the gradient, the faster the rate of reaction
• the gentler the gradient, the slower the rate of reaction
• When the graph is horizontal (gradient=0), the reaction has stopped.

Question 6

For a chemical reaction to occur, what are the reactant particles required to do or have?

Answer 6

• collide with each other
• have energy equal to or greater energy than the activation energy, in order to have effective collisions and formation of products

Question 6

What are factors that affect the rate of reaction?

Answer 6

• temperature
• size of solid reactants
• concentration
• pressure

Question 7

How will size of solid reactants affect the rate of reaction?

Answer 7

• solid reactants with smaller particle size have higher exposed surface area
• this increases the frequency of effective collisions and hence, increases the rate of reaction

Question 7

How will temperature affect the rate of reaction?

Answer 7

• At high temp, the particles have higher kinetic energy and collide more frequently
• more reactant particles will have energy equal to or grater than the activation energy
• this increases the frequency of effective collisions and hence, increases the rate of reaction

Question 8

How will concentration affect the rate of reaction?

Answer 8

• at higher concentrations, particles are closer together and the no. of reactant particles per unit vol. increases
• this increases the frequency of effective collisions and hence, increases the rate of reaction