Rates of Reaction
Q1.
A student investigated the rate of reaction between marble chips and hydrochloric acid.
Figure 1 shows the apparatus the student used.
Figure 1
 
(a)     What is A?
 
Tick one box.	 	
cotton wool	 	
limestone	 	
poly(ethene)	 	
rubber bung	 	
(1)
(b)     Table 1 shows the student’s results for one investigation.
Table 1
 
 	Time
in s	Mass lost
in g	
 	0	0.0	
 	20	1.6	
 	40	2.6	
 	60	2.9	
 	80	3.7	
 	100	4.0	
 	120	4.0	
On Figure 2:
•        Plot these results on the grid.
•        Draw a line of best fit.
Figure 2
 
(3)
(c)     Use Figure 2 to complete Table 2.
                                      Table 2
 
Mass lost after 0.5 minutes	______ g	
Time taken to complete the reaction	______ s	
(2)
(d)     The equation for the reaction is:
2HCl(aq)    +   CaCO3(s)   →   CaCl2(aq)   +   H2O(l)   +   CO2(g)
Explain why there is a loss in mass in this investigation.
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(2)
(e)     Another student investigated the rate of a different reaction.
Table 3 shows the results from the different reaction.
                                      Table 3
 
Mass lost when the reaction was complete	9.85 g	
Time taken to complete the reaction	2 minutes 30
seconds	
Calculate the mean rate of the reaction using Table 3 and the equation:
                        mean rate of reaction =  
Give your answer to two decimal places.
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Mean rate of reaction = _____________________ g / s
(2)
(f)     The student measured the change in mass of the reactants.
Describe another method, other than measuring the change in mass of the reactions, that the student could have used to find the rate of the reaction between marble chips and hydrochloric acid.
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(2)
(g)     Another student planned to investigate the effect of temperature on the rate of reaction.
The student predicted that the rate of reaction would increase as the temperature was increased.
Give two reasons why the student’s prediction is correct.
 
Tick two boxes.	 	
The particles are more concentrated.	 	
The particles have a greater mass.	 	
The particles have a larger surface area.	 	
The particles have more energy.	 	
The particles move faster.	 	
(2)
(Total 14 marks)