Question 1

1 A student investigated the rate of the reaction between zinc and sulfuric acid.
Hydrogen gas is produced during this reaction.
Figure 1 shows the apparatus.
This is the method used.
1. Add 50 cm3 of sulfuric acid to a conical flask.

Accepted Answer

2. Add 2.0 g of zinc to the conical flask.
3. Quickly put a stopper in the conical flask and start a timer.
4. Measure the time taken to collect 20 cm3 of gas.
5. Repeat steps 1 to 4 three more times.

Question 2

0 1 .2 The student calculated the rate of the reaction for each trial.
Table 1 shows the results of the calculations.

Accepted Answer

Rate of reaction in cm3
/s         
Trial 1 Trial 2 Trial 3  Trial 4  
0.78       0.81     0.68      0.81

Question 3

0 1. 3 The student changed the investigation so that the mean time taken to collect
20 cm3 of gas was greater.
Which two changes would increase the mean time taken to collect 20 cm3 of gas?
[2 marks]

Accepted Answer

Tick () two boxes.
Use a catalyst
Use a larger conical flask
Use a lower temperature
Use smaller pieces of zinc
Use sulfuric acid of a lower concentration

Question 4

0 1 . 4 Hydrogen gas is produced during this reaction.
Describe the test for hydrogen gas.
Give the result of the test

Accepted Answer

(test)
burning / lit splint
(result)
burns with a (squeaky) pop
sound

Question 5

2.1This question is about alcohols and carboxylic acids. box
Alcohols are used as fuels.
A student burned 1.00 g of six alcohols and determined the energy released
from each.
Table 2 shows the results.

Accepted Answer

Alcohol Formula of one molecule of
the alcohol Energy released in kJ/g
Ethanol      C2H5OH   29.6
Propanol  C3H7OH 33.6
Butanol    C4H9OH   36.1
Pentanol  C5H11OH 37.7
Hexanol   C6H13OH  38.9
Heptanol  C7H15OH  39.8

Question 6

0 2 . 2 The energy released in kJ/g varies with the number of carbon atoms in one molecule
of each alcohol.
Plot the data from Table 2 on Figure 2.

Accepted Answer

Estimate the energy released in kJ when 1.00 g of octanol (C8H17OH) is burned.
Use Figure 2.

Question 7

Carbon dioxide is produced when alcohols are burned. box
Carbon dioxide is identified by bubbling the gas through limewater.

Accepted Answer

0 2 . 4 Complete the sentence.
Choose the answer from the box.
[1 mark]
Limewater is an aqueous solution of .

Question 8

0 2 . 5 Give the result of the test when carbon dioxide is bubbled through limewater.

Accepted Answer

(limewater turns) milky / cloudy

Question 9

Ethanoic acid can be produced from ethanol.

Accepted Answer

0 2 . 6 What is reacted with ethanol to produce ethanoic acid?
[1 mark]
Tick () one box.
A halogen
An alkali metal
An oxidising agent
Water

Question 10

0 2 . 7 Ethanoic acid contains the functional group –COOH
Complete the displayed structural formula of this functional group.

Accepted Answer

-C  = O
   |
  O - H

Question 11

0 2 box . 8 Ethanoic acid reacts with different compounds.
Draw one line from each compound to a product of the reaction of the compound with
ethanoic acid.

Accepted Answer

Compd     Prd of rxn with COOH
Ethanol                  Carbon dioxide
Sodium                   Ethene
carbonate             Ethyl ethanoate
                                    Hydrogen
                                    Polyethene

Question 12

0 3 box This question is about chemical analysis.
Potassium bromide is used in medicine.
A scientist tested a sample of medicine to show the presence of potassium ions and
of bromide ions.
The sample is soluble in water

Accepted Answer

0 3 . 1 Plan a method the scientist could use to show that the sample of medicine contains
potassium ions and bromide ions.

Question 13

The scientist could also use an instrumental method to show the presence of box
potassium ions in the medicine.

Accepted Answer

0 3 . 2 Which instrumental method could be used to show the presence of potassium ions in
the medicine?
[1 mark]

Chemistry 23 Higher

Chemistry 2

Question	Answer
1 A student investigated the rate of the reaction between zinc and sulfuric acid. Hydrogen gas is produced during this reaction. Figure 1 shows the apparatus. This is the method used. 1. Add 50 cm3 of sulfuric acid to a conical flask.	2. Add 2.0 g of zinc to the conical flask. 3. Quickly put a stopper in the conical flask and start a timer. 4. Measure the time taken to collect 20 cm3 of gas. 5. Repeat steps 1 to 4 three more times.	1 . 1 Suggest why the stopper must be put in the conical flask as quickly as possible in step 3. [1 mark]	to reduce the escape of gas
0 1 .2 The student calculated the rate of the reaction for each trial. Table 1 shows the results of the calculations.	Rate of reaction in cm3 /s Trial 1 Trial 2 Trial 3 Trial 4 0.78 0.81 0.68 0.81	Determine the mean time taken to collect 20 cm3 of gas. Do not include any anomalous results. Use the equation: mean rate of reaction = volume of gas collected/ mean time taken [5 marks]	(mean rate =) 0.78 + 0.81 + 0.81 /3 0.80 (cm3/s) 0.80 =20/mean time taken (mean time taken =) 20/0.80 = 25 (s)
0 1. 3 The student changed the investigation so that the mean time taken to collect 20 cm3 of gas was greater. Which two changes would increase the mean time taken to collect 20 cm3 of gas? [2 marks]	Tick () two boxes. Use a catalyst Use a larger conical flask Use a lower temperature Use smaller pieces of zinc Use sulfuric acid of a lower concentration	use a lower temperature use sulfuric acid of a lower concentration
0 1 . 4 Hydrogen gas is produced during this reaction. Describe the test for hydrogen gas. Give the result of the test	(test) burning / lit splint (result) burns with a (squeaky) pop sound
2.1This question is about alcohols and carboxylic acids. box Alcohols are used as fuels. A student burned 1.00 g of six alcohols and determined the energy released from each. Table 2 shows the results.	Alcohol Formula of one molecule of the alcohol Energy released in kJ/g Ethanol C2H5OH 29.6 Propanol C3H7OH 33.6 Butanol C4H9OH 36.1 Pentanol C5H11OH 37.7 Hexanol C6H13OH 38.9 Heptanol C7H15OH 39.8	2 . 1 Calculate the mass of ethanol that must be burned to release the same amount of energy as burning 1.00 g of heptanol.	(mass =) 39.8 29.6 (×1) = 1.34 (g)
0 2 . 2 The energy released in kJ/g varies with the number of carbon atoms in one molecule of each alcohol. Plot the data from Table 2 on Figure 2.	Estimate the energy released in kJ when 1.00 g of octanol (C8H17OH) is burned. Use Figure 2.	all six points plotted correctly	40.6 (kJ)
Carbon dioxide is produced when alcohols are burned. box Carbon dioxide is identified by bubbling the gas through limewater.	0 2 . 4 Complete the sentence. Choose the answer from the box. [1 mark] Limewater is an aqueous solution of .	calcium chloride calcium hydroxide calcium nitrate calcium sulfate	calcium hydroxide
0 2 . 5 Give the result of the test when carbon dioxide is bubbled through limewater.	(limewater turns) milky / cloudy
Ethanoic acid can be produced from ethanol.	0 2 . 6 What is reacted with ethanol to produce ethanoic acid? [1 mark] Tick () one box. A halogen An alkali metal An oxidising agent Water	6 an oxidising agent
0 2 . 7 Ethanoic acid contains the functional group –COOH Complete the displayed structural formula of this functional group.	-C = O \| O - H
0 2 box . 8 Ethanoic acid reacts with different compounds. Draw one line from each compound to a product of the reaction of the compound with ethanoic acid.	Compd Prd of rxn with COOH Ethanol Carbon dioxide Sodium Ethene carbonate Ethyl ethanoate Hydrogen Polyethene	Ethanol -Ethyl ethanoate sodium Carbonate-CO2
0 3 box This question is about chemical analysis. Potassium bromide is used in medicine. A scientist tested a sample of medicine to show the presence of potassium ions and of bromide ions. The sample is soluble in water	0 3 . 1 Plan a method the scientist could use to show that the sample of medicine contains potassium ions and bromide ions.	The scientist has: • a Bunsen burner • a metal wire • test tubes • a dropping pipette • distilled water • dilute nitric acid • silver nitrate solution. You should give the results of the tests.	Indicative content (potassium ions) • place sample on (clean metal) wire • introduce into (blue / non-luminous) flame • using (Bunsen) burner • observe lilac flame colour • which shows presence of potassium (ions) bromide ions) • dissolve sample	• in (distilled) water • in test tube • add (dilute) nitric acid • add silver nitrate (solution) • using (dropping) pipette • observe cream precipitate (formed after addition of silver nitrate solution) • which shows presence of bromide (ions)
The scientist could also use an instrumental method to show the presence of box potassium ions in the medicine.	0 3 . 2 Which instrumental method could be used to show the presence of potassium ions in the medicine? [1 mark]

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