Imran did an experiment to see how changing the surface area of limestone affected the rate with which it reacts with hydrochloric acid. He timed how long it took for the reaction to produce 50 cm3 of carbon dioxide gas from which he could calculate the rate in cm3 of carbon dioxide produced per second.
size
large chips
small chips
powder
time (s)
150
110
15
rate (cm3/s)
0.33
a. What was the independent variable? (1)
b. What was the dependent variable? (1)
c.i. List four variables that must be controlled. (4)
c.ii. Explain why they must be controlled. (1)
(a) What was the independent variable? (1)
(b) What was the dependent variable? (1)
(c.i) List four variables that must be controlled. (4)
(c.ii) Explain why they must be controlled. (1)
(d) Complete the table by calculating and filling in the missing rates. (2)
(e) Which had the biggest surface area, large chips, small chips or powder? (1)
(f) What is the relationship between the surface area and the time the reaction takes? (1)
(g) What is the relationship between the surface area and the reaction rate? (1)
(h) Explain why changing the surface area affects the reaction rate in this way. (2)