Experiments to measure the rate of reaction
3 marks · EasyA student is investigating how the concentration of hydrochloric acid affects the rate of reaction with excess marble chips. The student collects the gas produced during the reaction.
Name the gas produced in this reaction.
State a piece of equipment the student can use to measure the volume of this gas.
Explain why marble chips are added in excess, rather than using the exact amount needed for the acid.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) carbon dioxide · must show CO2, carbon dioxide
(b) gas syringe or measuring cylinder (over water) · must show gas syringe, measuring cylinder, inverted measuring cylinder
(c) To make sure all the acid reacts; so that the rate depends on the acid’s concentration, not on how much marble is present; to ensure marble is not the limiting reagent.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States 'carbon dioxide' (or CO2) as the gas produced.
B1 (b) · 1 mark · States gas syringe or measuring cylinder (over water) or another valid apparatus.
B1 (c) · 1 mark · Explains marble chips are in excess so all the acid reacts / acid is limiting; not the marble.
Worked solution
a) The gas produced is carbon dioxide (CO2). b) The volume can be measured using a gas syringe or an inverted measuring cylinder over water. c) Marble chips are added in excess to make sure the acid is completely reacted (the acid is the limiting reactant).