1.9 Rates

Question 1

Experimental methods for determining orders of reaction
Example Reaction 1
2Na(s) + 2HCl(aq) –> 2NaCl(aq) + H2(g)
Example Reaction 2
CH3CH2Br + NaOH –> CH3CH2OH + NaBr
Example Reaction 3
H2SO4(aq) + BaCl2(aq) –> BaSO4(s) + HCl(aq)

Answer 1

Example Reaction 1

2Na(s) + 2HCl(aq) –> 2NaCl(aq) + H2(g)

· Collect hydrogen gas in a gas syringe

· Measure volume of gas produced over time

Example Reaction 2

CH3CH2Br + NaOH –> CH3CH2OH + NaBr

· Can measure [NaOH] as it is an alkali

· Titrate with HCl (or use pH meter)

Example Reaction 3

H2SO4(aq) + BaCl2(aq) –> BaSO4(s) + HCl(aq)

· Precipitate will start to make solution opaque as it is produced

· Could measure opacity of solution

Question 2

How would you use these two practicals to measure initial rates

Answer 2

Question 3

• How would you investigate the order of this reaction with respect to the different reactants
• What must be kept constant when repeating this experiment

Answer 3

Question 4

Why is water added to the reaction mixture
Why can you analyse effect of changing volume of S2O3^2- on rate of reaction instead of calculating the Concentration of it

Answer 4

Question 5

• at what point in the reaction does the solution turn blue-black
• Why are most of the reactants combined into one container before starting the reaction
• Why is hydrogen peroxide added last to the reaction solution
• Which other reactants could be added last instead of hydrogen peroxide

Answer 5

Question 6

Show graphs represents zero order, first order and second order for rate against concentration

Answer 6

Question 7

What is quenching a reaction
Why would you quench a reaction
How can you quench a reaction

Answer 7

Question 8

Draw graphs of concentration against time for zero order, first order, second order

Answer 8

Question 9

Answer 9

Question 10

Answer 10

Step 2
Two No and H2 are in one eqaution