Q11-14:
2g of powdered calcium carbonate (an excess) was reacted with 50cm3 of 0.5mol/dm3 dilute hydrochloric acid at 25°C. The volume of carbon dioxide produced was measured at regular time intervals and the solid line on the graph below was obtained:

Rates graph 3


Which graph would be obtained when the experiment is repeated with the following changes (all other quantities remain the same)?

  
11. A catalyst was added?
12. A temperature of 50°C was used?
13. A 2g lump of calcium carbonate was used?
14. 50cm3 of 0.25mol/dm3 hydrochloric acid was used?

Q15-16:
A student carried out an experiment to investigate the rate of reaction between marble chips and dilute hydrochloric acid using the following apparatus:

 rate of reaction acid + marble chips
15. The purpose of the cotton wool is to..
  • A.   add mass to the flask
  • B.   prevent any air from entering the flask
  • C.   prevent any gas from leaving the flask
  • D.   prevent acid spraying out

16. He recorded the total mass of the flask at regular time intervals. Which graph could represent his results?

rate of reaction graph 4

17. Which of the following statements explain why the rate of a reaction increases when the temperature increases?

     I. The frequency of collisions between particles increases
   II. The activation energy decreases
 III. There are more particles with energy equal to or greater than the activation energy 
 
  • A.   I, II and III
  • B.   I and II only
  • C.   I and III only
  • D.   II and III only

 18. Sulfur dioxide and oxygen gases react together as follows:

  2SO2(g)   +   O2(g)  →  2SO3(g)

  

The rate of this reaction can be increased by..

  • A.   decreasing the temperature of the mixture
  • B.   decreasing the pressure of the gases
  • C.   decreasing the volume of the container
  • D.   increasing the volume of the container
19. Which of the following will increase the frequency of collisions between reactant particles?
  • A.   increase the size of solid pieces
  • B.   increase the concentration
  • C.   decrease the surface area
  • D.   decrease the temperature

20. Which of the following will increase the proportion of successful collisions?

  • A.   decrease the size of solid pieces
  • B.   increase the concentration
  • C.   increase the pressure of gases
  • D.   increase the temperature