6.1 Rate of Reaction

Hydrogen peroxide, H₂O₂, quickly decomposes to produce water and oxygen when a catalyst is added to the solution:

2H₂O₂ (aq) → 2H₂O (l)  + O₂ (g)

The volume of gas produced was measured and is shown in the graph below:

Which statement is not true for this reaction?

Magnesium metal reacts with an excess of hydrochloric acid solution to form magnesium chloride and hydrogen:

Mg (s) + 2HCl (aq) → MgCl₂ (aq) + H₂ (g)

Which of the following will not increase the rate of this reaction?

Catalysts are often used in chemical reactions.

Which letter represents two correct features of catalysts?

	Feature 1	Feature 2
A	Lower activation energy for the reaction	More products made in total
B	Alternative pathway for the reaction is provided	Not used up over the course of the reaction
C	Makes industrial processes cheaper	Metal catalysts are cheap to buy
D	Reduce the overall energy change of the reaction	Can be present in biological systems as enzymes

Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water and carbon dioxide:

CaCO₃ (s) + 2HCl (aq) → CaCl₂ (aq) + H₂O (l) + CO₂ (g)

Which statement is not true if the temperature of the reaction decreases?

Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas:

Mg (s) + 2HCl (aq) MgCl₂ (aq) + H₂ (g)

During the first 10 s of the reaction, 1.2 g of magnesium was used up.

Calculate the mean rate of reaction in mol/s for this part of the reaction.

Relative atomic masses (A_r):   Mg= 24   H= 1   Cl= 35.5