Rates Of Reaction

Question 1

Describe the effect of an increase in SA on the rate of reaction.

Answer 1

• increasing overall SA means there are more spaces for the particles to collide
• this leads to an increased frequency of (successful) collisions
• resulting in a faster rate of reaction

Question 2

Describe the effect of increasing concentration/pressure on the rate of reaction

Answer 2

• increasing concentration/ pressure means there are more particles in a given volume
• this leads to an increased frequency of (successful) collisions between the particles
• resulting in a faster rate of reaction

Question 3

Describe the effect of increasing temperature on the rate of reaction

Answer 3

• when particles are heated, they move around faster
• resulting in an increased frequency of collisions, increasing ROR
• particles also have more energy so more particles will have the required activation energy
• resulting in an increased frequency of successful collisions
• increasing the rate of reaction

Question 4

Describe the effect of a catalyst on the rate of reaction

Answer 4

• a catalyst is a substance that increases the rate of chemical reactions
• but is left chemically unchanged at the end
• it provides an alternate reaction pathway with lower activation energy
• this increases the frequency of successful collisions

Question 5

Describe an experiment to investigate effect of SA on ROR

Answer 5

• marble chip experiment
• CaCO3(s) + 2HCl(aq) —> CaCl2(aq)+ H2O(l) + CO2(g)
• use a gas syringe to measure how much gas is produced
• or a balance to record the change in mass

Question 6

Describe an experiment to investigate effect of concentration on ROR

Answer 6

• marble chip experiment
• CaCO3(s) + 2HCl(aq) —> CaCl2(aq) + H2O(l) + CO2(g)
• use a gas syringe to measure how much gas is produced
• or a balance to record the change in mass

Question 7

Describe an experiment to investigate effect of temperature on ROR

Answer 7

• black cross experiment
• Na2S2O3(s) + 2HCl(aq) —> 2NaCl(s) + SO2(g) + S(s) + H2O(l)
• use a conical flask and paper and stopwatch

Question 8

Describe an experiment to investigate effect of a catalyst on ROR

Answer 8

• Hydrogen Peroxide decomposition
• 2H2O2(l)—> 2H2O(l) + O2 (g)
• change the catalyst
• use delivery tube, upside down measuring cylinder to collect gas