Download C3 3.1-3.4 part 2 Alcohols, carboxlic acids and esters progress ticket

Progress check: C3 5.1-5.4
Alcohols, carboxylic acids and
esters – part 2
Name:
Classwork
Homework
Q1.This question is about organic compounds.
(a)
Ethanol is an alcohol.
One use of ethanol is in alcoholic drinks.
Give two other uses of ethanol.
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(2)
(b)
Which gas is produced when sodium reacts with ethanol?
Carbon dioxide
Carbon monoxide
Hydrogen
Oxygen
(1)
(c)
Ethanoic acid (CH3COOH) can be produced from ethanol (CH3CH2OH).
(i)
What type of reaction produces ethanoic acid from ethanol?
......................................................................................................................................
(1)
(ii)
Complete the displayed structure of ethanoic acid.
(1)
(iii)
Solutions of ethanoic acid and hydrochloric acid with the same concentration have
different pH values.
Explain why the solution of ethanoic acid has a higher pH than the solution of
hydrochloric acid.
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(2)
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(d)
Ethanol and ethanoic acid react in the presence of a catalyst to form an ester.
(i)
Name the ester made from ethanol and ethanoic acid.
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(1)
(ii)
What type of chemical is used as a catalyst in this reaction?
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(1)
(iii)
Esters are used in perfumes because they smell pleasant and are volatile.
What does volatile mean?
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(1)
(Total 10 marks)
Q2.(a)
Ethanol (C2H5OH) is an alcohol.
(i)
Draw the displayed structure of ethanol.
(1)
(ii)
Complete combustion of ethanol produces carbon dioxide and water.
Complete the balanced symbol equation for this reaction.
C2H5OH + ............................................................................................
(3)
(iii)
Explain, in terms of bond breaking and bond forming, why the combustion of ethanol
is exothermic.
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(3)
(b)
A group of students investigated the amount of energy given out when different alcohols
are burned.
In one experiment the temperature of 50 g of water increased from 22.5 °C to 38.3 °C.
The mass of alcohol burned was 0.85 g.
(i)
The energy used to heat the water, Q, can be found using the equation:
Q = m × c × ΔT
Calculate the heat energy, in joules, given out by burning 0.85 g of the alcohol.
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Assume that all of the heat energy given out by burning the alcohol is used to heat
the water (specific heat capacity of water = 4.2 J / g / °C).
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Heat energy = .................................................. J
(2)
(ii)
Use your answer to part (b)(i)and the fact that 0.85 g of alcohol were burned to
calculate the heat energy that would be given out by 1 g of alcohol.
...............................................................................................................................................
Heat energy = .................................................. J
(1)
(c)
Another group of students investigated the amount of heat energy given out when
different alcohols are burned. They used a different, better, set of apparatus than the first
group of students.
They used the results from their investigation to calculate the heat energy given out by
burning 1 g of each alcohol.
They used a data book to find the theoretical amount of heat energy 1 g of each alcohol
should have given out when burned completely.
The students recorded their experimental results and the theoretical values in the table
below.
Number of carbon
atoms in one
molecule of alcohol
Experimental amount of
heat energy given out
when 1 g is burned in kJ
Theoretical amount of heat
energy given out when 1 g is
burned completely in kJ
Methanol
1
11.4
22.7
Ethanol
2
14.5
29.7
Propanol
3
16.0
33.7
Butanol
4
16.8
36.2
Pentanol
5
17.2
37.8
Hexanol
6
17.4
39.1
Name of
alcohol
(i)
What is the relationship between the number of carbon atoms in one molecule of the
alcohol and the heat energy given out when the alcohol is burned?
...............................................................................................................................................
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(1)
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(ii)
Suggest one reason why the students’ experimental results are lower than the
theoretical values.
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(1)
(iii)
The students observed that as the number of carbon atoms in one molecule of the
alcohol increased:
•
the flame was more orange
•
more carbon was left on the bottom of the calorimeter.
Suggest why.
...............................................................................................................................................
...............................................................................................................................................
(1)
(iv)
The heat energy given out when 1 g of ethanol (C2H5OH) is burned is 29.7 kJ.
Calculate the heat energy, in kilojoules, that will be given out when 1 mole of
ethanol is burned.
Give your answer to three significant figures.
Relative atomic masses: H = 1; C = 12; O = 16
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Heat energy = .................................................. kJ
(3)
(Total 16 marks)
Learning outcomes:
o Explain why carboxylic acids are described as ‘weak’ acids
o Complete energy calculations for the combustion of different alcohols
Outcomes:
1=
2=
3=
RAG 123 your performance on this topic and say why:
GREEN: I tried to push my understanding
RED: I let things distract me from learning
Comment…
Pupil
AMBER: I didn't really push myself
Page 4
Rating…
Teacher
1 I am confident to explain this to others
2 I understand most of this
3 I really struggled with this – HELP!
NEXT STEPS…
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Rating…
M1.(a)
any two from:
•
•
•
fuel
allow source of energy
solvent
allow perfume / aftershave
antiseptic
allow antibacterial
2
(b)
Hydrogen
1
(c)
(i)
oxidation
do not allow redox
1
(ii)
correct structure
1
(iii)
ethanoic acid is a weak / weaker acid
it = ethanoic acid
1
because it does not completely ionise.
allow because it does not completely dissociate
allow it has a lower concentration of hydrogen ions
allow converse for hydrochloric acid
do not allow ionising
1
(d)
(i)
ethyl ethanoate
1
(ii)
acid
allow any strong acid
allow correct formulae
1
(iii)
evaporates easily / quickly
allow low boiling point
do not allow flammable
1
[10]
M2.(a)
(i)
allow –OH
1
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(ii)
(C2H5OH +) 3O2 ➔ 2CO2 + 3H2O
formulae
all 3 formulae gain 2 marks;
2 formulae gain 1 mark
2
balanced
dependent on formulae
accept multiples
1
(iii)
energy is required to break bonds
1
energy is released when bonds are formed
1
exothermic because more energy is released than taken in
1
(b)
(i)
3318 or 3320 (J)
correct answer with or without working gains 2 marks
if answer incorrect, allow 1 mark for correct working, eg:
temperature change = (38.3 – 22.5 = ) 15.8 or Q = (50 x 4.2 x 15.8
=)
allow ecf from temp change
2
(ii)
if answer from part (i) used:
(3318 / 0.85) = 3904
allow ecf from part (i)
1
(c)
(i)
the more carbon atoms in one molecule, the more heat energy is given out
do not accept proportional
1
(ii)
heat loss (to surroundings or to the can or to the air)
accept not all energy used to heat water
allow incomplete combustion
allow not all burned
ignore thermometer or balance errors
1
(iii)
incomplete combustion (occurs when more C atoms in molecule)
1
(iv)
1370
correct answer with or without working gains 3 marks
(Mr ethanol =) 46 gains 1 mark
46 x 29.7 gains 2 marks
max 2 marks if incorrect sig figs (1366.2, 1366, 1400)
final answer ecf on incorrect Mr max 2 marks
3
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