Stage 2 Chemistry
Investigation Folio: Practical Investigation 1
Name: XXXXXXX
Names of Partner: MMMMMMMMMMMM
Part A
Investigation Design Proposal:
Purpose of Experiment:
To determine the effect of concentration of reactants (Mg2+) on voltage produced by a
Galvanic cell.
Hypothesis:
The greater the concentration of the reactant (Mg2+), the greater the voltage produced
by the galvanic cell
Independent Variable:
Concentration of reactant (Mg2+)
How the Independent Variable is changed:
Changed by diluting the 1 mol L-1 Mg2+ solution supplied with distilled water, while
keeping a constant volume.
Dependent Variable:
Voltage produced by the galvanic cell
How the Dependent Variable is Measured:
Using a multimeter, set on 2V (or lower depending on the voltage produced by the cell)
Application
Uses appropriate
chemical terms,
conventions and
formulae effectively.
Other factors held Constant in the Experiment:






Type of electrodes (metal strips),
Type of reactants (both sulfate solutions);
Volume of solutions used in the galvanic cell
Length of saltbridge
Concentration of saltbridge solution
Surface area of electrode dipping into the electrolyte solutions
Page 1 of 7
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
Procedure:
1.
Fill 1x 250 mL beaker with 1 mol L-1 Cu2+ solution and 1x 250 mL beaker with 1 mol L-1
Mg2+ solution.
2. Measure 40 mL of Cu2+ solution into a 50 mL
3. Measure 40 mL of mg2+ solution into a 50 mL
4. prepare salt bridge by dipping the filter paper into the KCl solution.
5. Place 40 mlL beakers side- by-side and place salt bridge straddling the gap so that
the ends of the saltbridge are in the different reactants
6. Attach positive lead to Mg electrode, and negative lead on Cu electrode, with
multimeter on and set to DC 2 volts.
7. Place electrodes in respective reactants (eg Cu electrode in Cu2+, Mg electrode in
Mg2+)
8. Record voltage.
9. Remove electrodes, and clean.
10. Pour out reactants and rinse beakers with distilled water,
Investigation
Demonstrates an
ability to design a
logical, coherent, and
detailed plan for a
chemistry practical
investigation.
Provides relevant,
accurate and detailed
information in Part A:
Investigation Design
Proposal.
11. Repeat steps 2-10 two more times (so results can be averaged).
12. Repeat steps 2-11 changing the concentrations of the 1 mol L-1 Mg2+ solution to 0.75
mol L-1 Mg2+, 0.50 mol L-1 Mg2+, 0.25 mol L-1 Mg2+, solution.
13. Record and compare the results.
Part B
Results:
Concentration of
Electrolyte (mol)
Trial
Voltage
Produced (V)
Average
Voltage
1.0 M
1
1.854
1.820
2
1.822
3
1.785
1
1.630
2
1.645
3
1.680
1
1.530
2
1.547
3
1.607
1
1.689
2
1.688
3
1.630
0.75 M
0.50 M
0.25 M
Page 2 of 7
Investigation
Obtains, records, and
displays findings of
investigations using
appropriate
conventions and
formats mostly
accurately and
effectively.
1.652
1.570
1.669
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
Graph:
Concentration of Reactants vs
Average Voltage
Investigation
Obtains, records, and
displays findings of
investigations using
appropriate
conventions and
formats mostly
accurately and
effectively; e.g. title
for graph, labelled
axes, and appropriate
scales and units.
Average Voltage (V)
1.85
1.8
1.75
1.7
1.65
Note: Scale of
vertical axis
exaggerates
supposed
relationship.
1.6
1.55
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
1
1.1
Concentration of Reactants (mol)
Pictures of our experimental design practical:
Investigation
Manipulates
apparatus and
technological tools
carefully and highly
effectively using wellorganised safe and
ethical investigation
procedures.
Note: Labels on
digital images and
reference to them in
the report would
further support
evidence of
communication skills.
Page 3 of 7
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
Errors:
Random errors are errors in how the experiment is carried out.
Two random errors could have been corrosion on the alligator clip we used, which
prevented it from consistently touching the electrode, which would have affected the
amount of voltage produced by the cell. Another random error could have been a human
error in measuring the correct amount of electrolyte to be diluted – if more then one
person prepared the diluted electrolyte solution, they may have made them slightly
differently, causing them to be slightly stronger or weaker, which could have affected
the amount of voltage produced.
Systematic errors are consistent errors in materials used in the experiment. Two
systematic errors could have been a problem with the multimeter – it might have been
incorrectly calibrated, which would have caused us to get incorrect result. Another
systematic error could have been that the measuring cylinders we used were incorrectly
calibrated, which would mean that the dilution factor was incorrect, and so our voltages
would not be correct for the stated molar concentration of the electrolyte.
It is important to repeat the experiment with different samples to ensure that any
sources of random error in the experiment have a chance to be changed, then the
experiment is repeated, and the new results can be compared with the old results, to
see if there are any significant outliers, which would indicate an error. This reduces
random errors, and so produces more precise results.
Our results showed little scatter for the trials of each molar concentration. This
indicates a high level of precision in our results, indicating that we had minimal random
errors.
Improvements:
Analysis and
Evaluation
 Ensuring the clips used to connect the metal electrodes to the multimeter are
Critically and
not rusted, and maintain constant consistent connection with the electrodes,
logically evaluates
procedures and
and are not removed in between tests to clean the electrodes.
suggests a range of
 Time how long we leave the electrode in solution for before recording the
appropriate
voltage produced (as some trials took longer than others to settle on a final
improvements.
voltage)
 Make sure that the electrode is in the same position within the beaker each trial,
and not touching the salt bridge.
Page 4 of 7
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
Conclusion:
Our results seemed to follow a pattern which supported our hypothesis (the greater
the concentration of electrolyte, the greater the voltage produced) until we reached
a concentration of 0.25 M. At this concentration, the voltage read was much greater
than the voltages we recorded at 0.50 M.
We were forced to conclude that our experiment was heavily influenced by systematic
errors, since we had a high level of precision for the trials of each molar concentration,
but a low level of accuracy, seen by the fact that our average voltage produced did not
seem to follow a pattern. As such, we cannot make a final conclusion whether the
experiment supporter or denied our hypothesis.
Analysis and
Evaluation
Clearly and logically
analyses data and
their connections
with concepts to
formulate a
conclusion
consistent with data.
Additional comments on evidence
The teacher uses observation supported by questions or discussion with the student during the practical
part of the assessment to assess the student’s ability to:
 manipulate apparatus and technological tools carefully and highly effectively to implement wellorganised safe and ethical investigation procedures. (Investigation)
 demonstrate initiative in applying constructive and focused individual and collaborative work skills.
(Application)
 on-balance, obtain, record, and display findings of investigations using appropriate conventions and
formats accurately and highly effectively. (Investigation)
 use a variety of formats to communicate knowledge and understanding of chemistry coherently and
effectively. (Knowledge and Understanding)
Although the use of equations is not evident in this response, on balance appropriate and effective use of
chemical terms, conventions, formulae, and equations is displayed. (Application)
Evidence from this investigation contributes to an overall assessment for the Investigations Folio of a
student’s:
 use of a variety of formats to communicate knowledge and understanding of chemistry coherently and
highly effectively (Knowledge and Understanding)
 analysis of data and concepts and their connections, to formulate conclusions and make relevant
predictions. (Analysis and Evaluation)
 use of appropriate chemical terms, conventions, formulae, and equations. (Application)
Page 5 of 7
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
Performance Standards for Stage 2 Chemistry
A
Investigation
Analysis and Evaluation
Application
Knowledge and
Understanding
Designs logical, coherent, and detailed
chemistry investigations.
Critically and systematically
analyses data and their
connections with concepts to
formulate logical and perceptive
conclusions and make relevant
predictions.
Applies chemistry concepts and
evidence from investigations to
suggest solutions to complex
problems in new and familiar
contexts.
Consistently demonstrates a
deep and broad knowledge
and understanding of a range
of chemistry concepts.
Critically and logically selects and
consistently and appropriately
acknowledges information about
chemistry and issues in chemistry
from a range of sources.
Manipulates apparatus and
technological tools carefully and highly
effectively to implement well-organised
safe and ethical investigation
procedures.
Critically and logically evaluates
procedures and suggests a range
of appropriate improvements.
Uses appropriate chemical
terms, conventions, formulae,
and equations highly effectively.
Demonstrates initiative in
applying constructive and
focused individual and
collaborative work skills.
Uses a variety of formats to
communicate knowledge and
understanding of chemistry
coherently and highly
effectively.
Applies chemistry concepts and
evidence from investigations to
suggest solutions to problems in
new and familiar contexts.
Demonstrates some depth
and breadth of knowledge and
understanding of a range of
chemistry concepts.
Uses appropriate chemical
terms, conventions, formulae,
and equations effectively.
Uses knowledge of chemistry
logically to understand and
explain social or
environmental issues.
Obtains, records, and displays findings
of investigations using appropriate
conventions and formats accurately
and highly effectively.
B
Designs well-considered and clear
chemistry investigations.
Logically selects and appropriately
acknowledges information about
chemistry and issues in chemistry
from different sources.
Manipulates apparatus and
technological tools carefully and
mostly effectively to implement
organised safe and ethical
investigation procedures.
Clearly and logically analyses data
and their connections with
concepts to formulate consistent
conclusions and make mostly
relevant predictions.
Logically evaluates procedures and
suggests some appropriate
improvements.
Applies mostly constructive and
focused individual and
collaborative work skills.
Obtains, records, and displays findings
of investigations using appropriate
conventions and formats mostly
accurately and effectively.
C
Designs considered and generally
clear chemistry investigations.
Selects with some focus, and mostly
appropriately acknowledges,
information about chemistry and
issues in chemistry from different
sources.
Manipulates apparatus and
technological tools generally carefully
and effectively to implement safe and
ethical investigation procedures.
Obtains, records, and displays findings
of investigations using generally
appropriate conventions and formats
with some errors but generally
accurately and effectively.
Page 6 of 7
Uses knowledge of chemistry
perceptively and logically to
understand and explain social
or environmental issues.
Analyses data and their
connections with concepts to
formulate generally appropriate
conclusions and make simple
predictions with some relevance.
Applies chemistry concepts and
evidence from investigations to
suggest some solutions to basic
problems in new or familiar
contexts.
Evaluates some procedures in
chemistry and suggests some
improvements that are generally
appropriate.
Uses generally appropriate
chemical terms, conventions,
formulae, and equations with
some general effectiveness.
Applies generally constructive
individual and collaborative work
skills.
Uses a variety of formats to
communicate knowledge and
understanding of chemistry
coherently and effectively.
Demonstrates knowledge and
understanding of a general
range of chemistry concepts.
Uses knowledge of chemistry
with some logic to understand
and explain one or more
social or environmental
issues.
Uses different formats to
communicate knowledge and
understanding of chemistry
with some general
effectiveness.
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013
D
Investigation
Analysis and Evaluation
Application
Knowledge and
Understanding
Prepares the outline of one or more
chemistry investigations.
Describes basic connections
between some data and concepts
and attempts to formulate a
conclusion and make a simple
prediction that may be relevant.
Applies some evidence to
describe some basic problems
and identify one or more simple
solutions, in familiar contexts.
Demonstrates some basic
knowledge and partial
understanding of chemistry
concepts.
Attempts to use some chemical
terms, conventions, formulae,
and equations that may be
appropriate.
Identifies and explains some
chemistry information that is
relevant to one or more social
or environmental issues.
Attempts individual work
inconsistently, and contributes
superficially to aspects of
collaborative work.
Communicates basic
information to others using
one or more formats.
Attempts to connect data with
concepts, formulate a conclusion
and make a prediction.
Identifies a basic problem and
attempts to identify a solution in
a familiar context.
Demonstrates some limited
recognition and awareness of
chemistry concepts.
Acknowledges the need for
improvements in one or more
procedures.
Identifies some chemical terms
or formulae.
Shows an emerging
understanding that some
chemistry information is
relevant to social or
environmental issues.
Selects and may partly acknowledge
one or more sources of information
about chemistry or an issue in
chemistry.
Uses apparatus and technological
tools with inconsistent care and
effectiveness and attempts to
implement safe and ethical
investigation procedures.
For some procedures, identifies
improvements that may be made.
Obtains, records, and displays findings
of investigations using conventions
and formats inconsistently, with
occasional accuracy and
effectiveness.
E
Identifies a simple procedure for a
chemistry investigation.
Identifies a source of information
about chemistry or an issue in
chemistry.
Attempts to use apparatus and
technological tools with limited
effectiveness or attention to safe or
ethical investigation procedures.
Attempts to record and display some
descriptive information about an
investigation, with limited accuracy or
effectiveness.
Page 7 of 7
Shows emerging skills in
individual and collaborative work.
Attempts to communicate
information about chemistry.
Stage 2 Chemistry annotated student work
Ref: A185248 (revised January 2013)
© SACE Board of South Australia 2013