Everything Science Grade 12

3.3 CHAPTER 3. REACTION RATES

Exercise 3 - 3

Hydrochloric acid and calcium carbonate react according to the following equation:

CaCO 3 + 2HCl→ CaCl 2 + H 2 O + CO 2

The volume of carbondioxide that is produced during the reaction is measured at
different times. The results are shown in the table below.

Time (mins) Total Volume of CO 2 produced (cm^3 )

1 14

2 26

3 36

4 44

5 50

6 58

7 65

8 70

9 74

10 77

Note: On a graph of production against time, itis the gradient of the graph that shows
the rate of the reaction.

Questions:

1. Use the data in thetable to draw a graph showing the volume ofgas that is
   produced in the reaction, over a period of 10 minutes.


2. At which of the following times is the reaction fastest? Time = 1 minute; time =
   6 minutes or time = 8 minutes.


3. Suggest a reason whythe reaction slows downover time.


4. Use the graph to estimate the volume of gasthat will have been produced after
   11 minutes.


5. After what time do you think the reaction will stop?


6. If the experiment was repeated using a moreconcentrated hydrochloric acid so-
   lution...

(a) would the rate of the reaction increase or decrease from the one shown in

the graph?

(b) draw a rough line onthe graph to show how you would expect the reaction

to proceed with a moreconcentrated HCl solution.

More practice video solutions or help at http://www.everythingscience.co.za

(1.) 01py (2.) 0246 (3.) 0247 (4.) 0248 (5.) 0249 (6.) 024a