CI.a-k - The chemical industry | CI1-6 |
CI.Q Exam questions from past papers
● Lightning
● Forest fires
Give a natural source of NO in the atmosphere? ● From bacterial processes
● Photodissociation of NO2
● Add NaOH solution and devarda’s alloy (or
Aluminium foil)
Describe a test that would identity nitrate ions (2) ● Warm the solution
● Test gas with red litmus paper and would turn blue
if ammonia is present
● [as the Al in both would reduce the nitrate ions]
(You would see dense white fumes due to ammonia)
Allow use rod dipped in HCl turns blue
Allow Brown Ring Test (add Fe2SO4 solution followed by
conc H2SO4 ) - a brown ring forms at the layer interface
Some students set out to investigate the rate of hydrolysis ● Quench the solution taking certain volume of
of 1-bromobutane. They mix 1-bromobutane with sodium solution at set intervals of time (1)
hydroxide solution and measure the conc of hydroxide ions ● Cool down the samples in ice water (1)
after certain times at 51 degrees? ● Do a titration for each sample to find the
concentration of hydroxide ions (1)
Suggest the procedure the students use to follow the ● By using a water bath
reaction? (3)
How did they maintain the temperature at 51 degrees (1)
● Reactions add to make overall equation (1)
● Step 1 could be rate determining as it uses N2O5 as
a reactant (1)
● Step 3 could be rate determining as it uses N2O5 as
a reactant (1)
Consider which step is the rate-determining? (3)
, ● Thiosulfate reacts with the iodine until thiosulfate is
used up
● Iodine reacts to form blue black colour with starch
● 1/time = rate
1. Suggest why the tubes go dark blue after a period
of time rather than gradually from the start. (3)
2. How can relative rates of reactions be found from
the student’s results?
CI.a-e - Kinetics | CI3 | CI4 | CI5 |
Define Rate of reaction? The change in concentration of a substance per unit time
This is used for consistency as it’s better than say change
in mass per unit time
Give 6 ways of determining the rate of reactions? 1. Use a gas syringe to measure the change in
volume of gas
2. Use a top pan balance to measure the change in
mass as gases escapes (works best with a heavy
gas like CO2)
3. Measure the time taken for a precipitate to form
(cross method)
4. Use colorimetry to measure absorbance of a
wavelength by a chemical
5. Chemical analysis by quenching and titration
6. Do a clock reaction
Also measure a change in electricity conductivity (works
well if ions are released)
What are the 3 orders of reaction with their associated ● Zero-order reaction - rate is not changed by
rate-concentration and concentration-time graphs of the concentration
reactant(s)? ● First-order reaction - rate ∝ conc
● Second-order rate - rate ∝ concx (by some factor
i.e if conc x2 then rate is x4)
CI.Q Exam questions from past papers
● Lightning
● Forest fires
Give a natural source of NO in the atmosphere? ● From bacterial processes
● Photodissociation of NO2
● Add NaOH solution and devarda’s alloy (or
Aluminium foil)
Describe a test that would identity nitrate ions (2) ● Warm the solution
● Test gas with red litmus paper and would turn blue
if ammonia is present
● [as the Al in both would reduce the nitrate ions]
(You would see dense white fumes due to ammonia)
Allow use rod dipped in HCl turns blue
Allow Brown Ring Test (add Fe2SO4 solution followed by
conc H2SO4 ) - a brown ring forms at the layer interface
Some students set out to investigate the rate of hydrolysis ● Quench the solution taking certain volume of
of 1-bromobutane. They mix 1-bromobutane with sodium solution at set intervals of time (1)
hydroxide solution and measure the conc of hydroxide ions ● Cool down the samples in ice water (1)
after certain times at 51 degrees? ● Do a titration for each sample to find the
concentration of hydroxide ions (1)
Suggest the procedure the students use to follow the ● By using a water bath
reaction? (3)
How did they maintain the temperature at 51 degrees (1)
● Reactions add to make overall equation (1)
● Step 1 could be rate determining as it uses N2O5 as
a reactant (1)
● Step 3 could be rate determining as it uses N2O5 as
a reactant (1)
Consider which step is the rate-determining? (3)
, ● Thiosulfate reacts with the iodine until thiosulfate is
used up
● Iodine reacts to form blue black colour with starch
● 1/time = rate
1. Suggest why the tubes go dark blue after a period
of time rather than gradually from the start. (3)
2. How can relative rates of reactions be found from
the student’s results?
CI.a-e - Kinetics | CI3 | CI4 | CI5 |
Define Rate of reaction? The change in concentration of a substance per unit time
This is used for consistency as it’s better than say change
in mass per unit time
Give 6 ways of determining the rate of reactions? 1. Use a gas syringe to measure the change in
volume of gas
2. Use a top pan balance to measure the change in
mass as gases escapes (works best with a heavy
gas like CO2)
3. Measure the time taken for a precipitate to form
(cross method)
4. Use colorimetry to measure absorbance of a
wavelength by a chemical
5. Chemical analysis by quenching and titration
6. Do a clock reaction
Also measure a change in electricity conductivity (works
well if ions are released)
What are the 3 orders of reaction with their associated ● Zero-order reaction - rate is not changed by
rate-concentration and concentration-time graphs of the concentration
reactant(s)? ● First-order reaction - rate ∝ conc
● Second-order rate - rate ∝ concx (by some factor
i.e if conc x2 then rate is x4)
