ULLADULLA HIGH SCHOOL – Science Faculty
Assessment Task Year 10 Chemical reactions 2020 - D
Name________________________ Group members____________________
YEAR GROUP
10
COURSE
Science
TOPIC
Chemistry
TASK WEIGHTING
20%
PLAGIARISM
All work must be your own and appropriate acknowledgement of sources made
where applicable. Any work found to be plagiarised will result in a mark of zero
and an N-Warning issued.
OUTCOME(S)

Outstanding
90 − 100%
High
70−< 90%
Sound
50−< 70%
GENERAL DIRECTIONS TO STUDENTS
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Total marks – 40 marks
Working time – 100 minutes
Write using black pen
Draw diagrams using pencil
NESA approved calculators may be used
Basic
30−< 50%
Limited
< 30%
ULLADULLA HIGH SCHOOL – Science Faculty
Assessment Task Year 10 Chemical reactions 2020 - D
Investigating the effect of concentration on the rate of a chemical reaction
Introduction
In this investigation you will study the effect of concentration on the rate of reaction.
Reactants: Magnesium metal (Mg) and hydrochloric acid (HCl).
Products: Hydrogen gas (H2) and Magnesium chloride salt (MgCl2).
When reacted in an open container the hydrogen gas (H2) is lost.
The magnesium metal reacts with the acid, visually you will see the metal disappearing.
When you can no longer see the metal the reaction is complete.
Magnesium metal + hydrochloric acid  Magnesium chloride + hydrogen gas
Mg(s)
+
HCl(aq)

MgCl2(aq)
+
H2(g)
Planning questions (15 Marks)
Working individually, answer the following questions. Submit your answers to your
teacher before continuing to the Conducting section.
1.
Identify the independent variable in this experiment. (1 mark)
2.
Identify the dependent variable in this experiment. (1 mark)
3.
Identify three controlled variables in this experiment. (3 marks)
4.
State why these variables need to be controlled. Your answer needs to be specific to
this investigation. (2 marks)
5.
Write a hypothesis for the experiment. (4 marks)
6.
Read the experimental procedure and describe any (at least two) safety
precautions needed for the experiment. Explain why the precautions are needed.
(4 marks)
ULLADULLA HIGH SCHOOL – Science Faculty
Assessment Task Year 10 Chemical reactions 2020 - D
Note: Your teacher will need to review your safety precautions before you proceed to the experimental work.
Conducting (6 Marks)
Working with a partner, complete the experimental as described below.
Marks for conduct of the experiment will be awarded on the following aspects:

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Safe working practices
Competence in conduct of experiment
Equipment cleaned and stored after completion of experimental work
(2 marks)
(2 marks)
(2 marks)
Equipment and chemicals
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3 different strengths of hydrochloric acids
Magnesium metal strips
Test tube rack
3x large clean test tubes
Measuring cylinder
Timing device
Safety glasses
Procedure
Note: Before starting, you will need to choose three concentrations of hydrochloric
acid. (discuss with your teacher)
Safety note: Be extremely careful when working with hydrochloric acid, HCl.
I.
Weigh out 3 equal 1-gram amounts of Magnesium metal strip.
II.
Using the measuring cylinder, pour 10 mL of (1st concentration) hydrochloric acid into a
large test tube.
III.
Have timer ready, place 1g Magnesium metal into acid and time how long it takes for
all the metal to react. (record in results table).
IV.
Repeat steps 2 and 3 for other 2 concentrations of acids. Recording all times.
V.
Repeat steps 1-4 to collect an average
ULLADULLA HIGH SCHOOL – Science Faculty
Assessment Task Year 10 Chemical reactions 2020 - D
Questions continued (4 marks)
7.
Complete results table below. (4 marks)
Results
Hydrochloric acid strength
Time 1st test
Time 2nd test
Data analysis (5 marks)
Working individually, complete the following questions.
8. Plot a graph of your results.
Title
Average
ULLADULLA HIGH SCHOOL – Science Faculty
Assessment Task Year 10 Chemical reactions 2020 - D
Note: Independent variable (what are you changing) on the x-axis and dependant variable
(what are you measuring) on the y-axis. Don’t forget labels and units.
9.
Describe the trend in your data. (2 mark)
10.
Based on your chemistry understanding of the rates of chemical reactions and particle
theory, explain the trend in your data. (3 marks)
Conclusion and evaluation
Working individually, complete the following questions.
11.
Write a conclusion for your experiment. State how the results support your conclusion.
(3 marks)
12.
Identify one way in which the reliability of the results for this experiment could be
improved if it were to be done again. State how this will improve validity. (2 mark)