Optimising Galvanic Cells by differentiating the concentrations of the electrodes

Optimising Galvanic Cells by differentiating the concentrations of the electrodes

Area of Chemistry: Galvanic cells are an electrochemical cell that uses spontaneous redox reactions to generate an electric current. These redox reactions are formed from oxidation and reduction and can be utilised to produce electrical charge. Through the redox reaction the electrons produce kinetic energy that transfer from each half-cell. The galvanic cells are made up of two electrodes which consist of an anode and cathode. The electrode that is negative will always be the most reactive metal that will push against the ions of the less reactive metal. This causes a transfer of ions, and thus a transfer in the state of matter.

8001093956Exploring viable independent variables

0Exploring viable independent variables

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2420112657870242011284074What factors affect the efficiency of a battery/fuel cell?

00What factors affect the efficiency of a battery/fuel cell?

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466953692836Concentration of the electrodes:

The level of concentration can be measured using the formula for molarity C=nv, Although, this method will require a dilution using the formula: V1C1 = V2C2. This will be used to calculate an unknown quantity. By increasing the concentration of reactants in galvanic cells, this will cause the voltage of the cell to increase. The voltage can be measured using a voltmeter. Limitations: calculations could be difficult to interpretate, method may be complex. Advantages: results can be easily quantified.

00Concentration of the electrodes:

The level of concentration can be measured using the formula for molarity C=nv, Although, this method will require a dilution using the formula: V1C1 = V2C2. This will be used to calculate an unknown quantity. By increasing the concentration of reactants in galvanic cells, this will cause the voltage of the cell to increase. The voltage can be measured using a voltmeter. Limitations: calculations could be difficult to interpretate, method may be complex. Advantages: results can be easily quantified.

46329601968500-61214174498Surface Area of the Salt Bridge:

The main purpose of the salt bridge is to simply complete the circuit, and thus allow current to flow from one half cell to another. By optimizing the amount of salt bridges in a galvanic cell, the cross-sectional area will increase, and this may impact the electric current droppage caused in a displacement reaction. Limitations: Practical could be subjected to a significant amount of random error, due to the size of the salt bridges imprecise, it is time consuming, and research is limited. Advantages: Method has low risk factors, and it is easy to collect, and interpretate data.

00Surface Area of the Salt Bridge:

The main purpose of the salt bridge is to simply complete the circuit, and thus allow current to flow from one half cell to another. By optimizing the amount of salt bridges in a galvanic cell, the cross-sectional area will increase, and this may impact the electric current droppage caused in a displacement reaction. Limitations: Practical could be subjected to a significant amount of random error, due to the size of the salt bridges imprecise, it is time consuming, and research is limited. Advantages: Method has low risk factors, and it is easy to collect, and interpretate data.

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2420112110871Temperature of solution:

The temperature of the solution would showcase the rate of reaction. If the temperature is high, then the particles will be having more frequent and successful collisions. Thus, the rate of reaction is faster. This is vice versa for lower temperatures. Limitations: methods will be difficult to pursue, solutions may take longer to change temperatures. Advantages: Easy to collect and interpretate data.

00Temperature of solution:

The temperature of the solution would showcase the rate of reaction. If the temperature is high, then the particles will be having more frequent and successful collisions. Thus, the rate of reaction is faster. This is vice versa for lower temperatures. Limitations: methods will be difficult to pursue, solutions may take longer to change temperatures. Advantages: Easy to collect and interpretate data.

Final Independent variable: Concentration of the electrodes. Justification: even though all the considered factors were subjected to easier and faster methods than the one that is chosen, utilising this independent variable will increase the validity, precision, and reliability, as the results will be easily quantified. The

The Deconstruct question/statement: Aspects of the Question:

Variables:

Independent

Dependent

Controlled What is the Science Understanding?

What are the links to the course content?

Methods to obtain results/data

Predicted outcome Sources of uncertainty and limitation Mindmap can be added on an additional page!

Part B: Design an experiment

Hypothesis Justification Variables Independent:

Dependent:

Justification Factors that must be held constant Why the factor must be held constant How this factorwill be held constant

Materials Precautions taken to ensure safety

150mL of 0.50M, 0.75M, 1M Copper Sulfate solution

150mL of 0.50M, 0.75M, 1M Zinc Sulfate solution

3 x Copper strips

3 x Zinc strips

1 x Salt Bridge 1M potassium chloride

6 x 100mL beakers

Clamps

Crimping tool

1 x Digital Multi metre

1 x Digital Stopwatch

Sandpaper

Masking Tape

Marker Outline of procedureto befollowed Before practical commences, ensure safety equipment has been placed on. Including gloves, safety goggles and lab coat.

As this practical consists of chemicals and electric current, wearing a lab coat, goggles and gloves has been advised to minimise health effects

Using a 100mL beaker, fill this with 50mL of 0.05M Zinc Sulfate solution (Anode).

Fill the Cathode beaker with 0.05M Copper Sulfate solution up to 50mL.

A 100mL beaker is used even though there is only 50mL of the solution being used, to minimise effects of spillage and the reduce any safety concerns.

Using of Sodium sulfate fill a 25mL beaker and place the salt bridge into the solution and allow it to soak for 30 seconds

The salt bridge needs to be placed in the sodium sulfate solution as this solution is soluble and allows the system to be neutralised due to the anions and cations. Thus, the salt bridge can complete the circuit.

The copper and zinc strips are thoroughly sanded using the sandpaper, until they are reflective and shiny.

Reactive metals are sanded, as these metals can displace ions in oxygen gas. When these ions are displaced, they create a thin oxide layer. Therefore, sanding (removing) this oxide layer is crucial to not allow random errors to occur.

Place the metal strips into their respective electrolyte (place the copper strip into the Copper Sulfate solution and the Zinc strip into the Zinc Solfate solution).

By placing the electrodes in the electrolyte, this allows the electrolyte to conduct electricity via a displacement reaction.

Place both beakers with a 10-15cm radius from each othe.

If the beakers are too far away, then this effects the ion transfer via the salt bridge

Using the soaked salt bridge from step 4, place the salt bridge on top of both the solutions, while ensuring the ends of the salt bridge are evenly distributed within the electrolytes. Refer to figure

By placing the salt bridge in the electrolyte solution, this allows the reduction and oxidation half-cells to connect and transfer spontaneous ions to the other half cell. The salt bridge allows the galvanic cell to remain electrically neutral.

Turn the digital multi metre on

To calculate the voltage produced from the reaction.

Connect the black copper wire to the anode, and the red copper wire to the cathodes electrode (metal strip)

The wires need to be connected to the electrodes for the voltage to be produced when a displacement reaction occurs.

Turn on the stopwatch

The stopwatch must be on for each trial as its required to be controlled variable in the practical. By doing this the effects of increasing the concentration of the electrolytes can be identified.

While the digital multi metre is on, simultaneously set a timer for 60 seconds.

The stopwatch has been set to 60 seconds, to minimise random errors.

Analyse the voltage that has been produced using the digital multi metre.

To fill the results table with the amounts of volts produced.

Repeat steps 1 to 13 for this concentration of the electrolytes, 3 times.

Once an increment has been tested on, repeat steps 1 to 14 again, however change the concentrations of the electrolytes. (0.10M and 0.15M)

To prove the hypothesis and determine if a change in concentration can affect the amount of voltage produced in a galvanic cell.

Results Table (does not need to be filled in with data)

Independent variable = electrolyte concentration

Dependent variable = voltage

Change the concentration of the electrolytes but they remain the same as each other. This will increase the voltage.

STAGE 2 CHEMISTRY

ASSESSMENT TYPE 1: Investigations Folio

Practical (Deconstruct & Design): Galvanic or Electrolytic Cell

Purpose

Galvanic cells are electrochemical cells that generates an electron current (electricity), which converts chemical energy into electrical energy

Electrolytic cells are used industrially to produce a variety of chemicals.

This assessment provides you with the opportunity to investigate concepts relating to electrolysis, and to demonstrate your ability to:

deconstruct a problem in order to design and conduct an investigation

formulate an investigable question or hypothesis

select and use appropriate equipment, apparatus, and techniques

identify variables

collect, record and display data using appropriate conventions and formats

analyse and interpret data to form a justified conclusion

evaluate procedures and their effect on the data

communicate your knowledge and understanding of the relevant concepts

Description of the problem (choose one for the deconstruct!)

Galvanic cell related: What factors affect the efficiency of a battery/fuel cell?

OR

Electrolytic cell related: What factors affect the efficiency of metal production using electrolytic cells?

Part A Deconstruct the problem IAE1

You will need to provide evidence of your deconstruction of the problem, your choice of question and justification for the various parts of your method.

investigate a chemical that is produced by electrolysis that is suitable for you to produce in the laboratory.

brainstorm possible factors that could affect the time taken to produce a specific amount of this chemical.

investigate a variable that can be manipulated to test the impact on the efficiency of a galvanic cell.

Present your deconstruction ideas, your proposed method and a justification of your method on a maximum of 4 sides of an A4 page. Consider using a concept map, flow chart, tables etc. to present your ideas succinctly.

Submit your deconstruction evidence for teacher feedback and your list of requirements three days before undertaking the practical investigation.

Part B Design an investigation procedure

Before the design phase students need to write a proposal outlining the following components:

State a research questions / hypothesis

Identify independent, dependent and constant variables

List of materials

Possible drawing of the set-up

procedure

Predicted outcome/result

The proposal needs to be submitted to the teacher and needs to be approved before conducting the experiment! (no proposal = no experiment!)

Use your findings from the deconstruct and proposal to design a method for an investigation.

Select one independent variable to investigate and write an appropriate hypothesis.

List the factors to be held constant and factors that may not be able to be controlled.

List the types and quantities of materials required and a detailed procedure.

Use the results of your trials to justify the details of your method.

Identify ethical and safety considerations.

Submit your deconstruction and design for teacher feedback.

Part C Practical investigation

Carry out your approved investigation and record results. Consider a pre- and post-experiment (if needed!)

Part D Investigation Report IAE2, IAE3, IAE4, KA4

The practical report should include:

introduction with relevant chemistry concepts, hypothesis and variables

materials/apparatus

method that was implemented

identification and management of safety and/or ethical risks

results, including table(s) and/or graph(s)

analysis of results, identifying trends, and linking results to concepts

evaluation of procedures and their effect on data, and identifying sources of uncertainty

conclusion, with justification.

The report should be a maximum of 1500 words if written, or a maximum of 10 minutes for an oral presentation, or the equivalent in multimodal form.

Your deconstruction evidence should be attached to the report.

Only the following sections of the report are included in the word count:

introduction

analysis of results

evaluation of procedures

conclusion and justification.

Part A: Deconstruct proforma

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The Deconstruct question/statement: Aspects of the Question:

Variables:

Independent

Dependent

Controlled What is the Science Understanding?

What are the links to the course content?

Methods to obtain results/data

Predicted outcome Sources of uncertainty and limitation Mindmap can be added on an additional page!

Part B: Design an experiment

Hypothesis Justification Variables Independent:

Dependent:

Justification Factors that must be held constant Why the factor must be held constant How this factorwill be held constant

Hazards Precautions taken to ensure safety

Outline of procedureto befollowed (in red you need to justify each step of the method)

Results Table (does not need to be filled in with data)

Performance Standards for Stage 2 Chemistry

A B C D E

Investigation, Analysis and Evaluation 1

2

3

4 Critically deconstructs a problem and designs a logical, coherent, and detailed chemistry investigation.

Obtains records, and represents data, using appropriate conventions and formats accurately and highly effectively.

Systematically analyses and interprets data and evidence to formulate logical conclusions with detailed justification.

Critically and logically evaluates procedures and their effects on data. Logically deconstructs a problem and designs a well-considered and clear chemistry investigation.

Obtains, records, and represents data, using appropriate conventions and formats mostly accurately and effectively.

Logically analyses and interprets data and evidence to formulate suitable conclusions with reasonable justification.

Logically evaluates procedures and their effects on data. Deconstructs a problem and designs a considered and generally clear chemistry investigation.

Obtains, records, and represents data, using generally appropriate conventions and formats with some errors but generally accurately and effectively.

Undertakes some analysis and interpretation of data and evidence to formulate generally appropriate conclusions with some justification.

Evaluates procedures and some of their effects on data. Prepares a basic deconstruction of a problem and an outline of a chemistry investigation.

Obtains, records, and represents data, using conventions and formats inconsistently, with occasional accuracy and effectiveness.

Describes data and undertakes some basic interpretation a basic conclusion.

Attempts to evaluate procedures or suggest an effect on data. Attempts a simple deconstruction of a problem and a procedure for a chemistry investigation.

Attempts to record and represent some data, with limited accuracy or effectiveness.

Attempts to describe results and/or interpret data to formulate a basic conclusion.

Acknowledges that procedures affect data.

Knowledge and Application 1

2

3

4

Demonstrates deep and broad knowledge and understanding of a range of chemical concepts.

Applies chemical concepts highly effectively in new and familiar contexts.

Critically explores and understands in depth the interaction between science and society.

Communicates knowledge and understanding of chemistry coherently with highly effective use of appropriate terms, conventions and representations. Demonstrates some depth and breadth of knowledge and understanding of a range of chemical concepts.

Applies chemical concepts mostly effectively in new and familiar contexts.

Logically explores and understands in some depth the interaction between science and society.

Communicates knowledge and understanding of chemistry mostly coherently with effective use of appropriate terms, conventions, and representations. Demonstrates knowledge and understanding of a general range of chemical concepts.

Applies chemical concepts generally effectively in new or familiar contexts.

Explores and understands aspects of the interaction between science and society.

Communicates knowledge and understanding of chemistry generally effectively using some appropriate terms, conventions, and representations. Demonstrates some basic knowledge and partial understanding of chemical concepts.

Applies some chemical concepts in familiar contexts.

Partially explores and recognises aspects of the interaction between science and society.

Communicates basic chemical information, using some appropriate terms, conventions, and/or representations. Demonstrates some limited recognition and awareness of chemical concepts.

Attempts to apply chemical concepts in familiar contexts.

Attempts to explore and identify an aspect of the interaction between science and society.

Attempts to communicate information about chemistry.

STAGE 2 BIOLOGY

SUMMATIVE ASSESSMENT TYPE 1: Investigations Folio

Practical (Deconstruct & Design)

Purpose

This assessment provides you with the opportunity to investigate concepts relating to a specific biological concept of your choice, related to tolerance limits in organisms to demonstrate your ability to:

deconstruct a problem in order to design and conduct an investigation

formulate an investigable question or hypothesis

select and use appropriate equipment, apparatus, and techniques

identify variables

collect, record and display data using appropriate conventions and formats

analyse and interpret data to form a justified conclusion

evaluate procedures and their effect on the data

communicate your knowledge and understanding of the relevant concepts

Description of the problem related to tolerance limits in organisms (choose ONE for the deconstruct!).

Option 1: What factors affect the efficiency of energy production in the absence of oxygen? OR

Option 2: What factors affect the efficiency of energy production in plants?

Option 3: What factors affect the rate osmosis? OR

Option 4: What factors affect the germination rate of seeds/ propagation of plants? OR

Choose one out of the above options (Scientific studies students need to select the option that is overlapping with practical conducted in Scientific studies!)

Part A Deconstruct the problem (to completed and submitted by week 3!)

You will need to provide evidence of your deconstruction of the problem, your choice of question and justification for the various parts of your method.

Individually:

investigate the biological concepts related to your deconstruct question above.

brainstorm possible factors that could affect the question above and consider variables you can manipulate in the laboratory

Present your deconstruction ideas, your proposed method and a justification of your method on a maximum of 4 sides of an A4 page. Consider using a concept map, flow chart, tables etc. to present your ideas succinctly.

Submit your deconstruction evidence for teacher feedback and your list of requirements three days before undertaking the practical investigation.

Part B Design an investigation procedure (to completed and submitted for approval by week 5!)

Individually:

Before the design phase students need to write a proposal outlining the following components:

State a research questions / hypothesis

Identify independent, dependent and constant variables

List of materials

Possible drawing of the set-up

procedure

Predicted outcome/result

The proposal needs to be submitted to the teacher and needs to be approved before conducting the experiment! (no proposal = no experiment!)

Use your findings from the deconstruct and proposal to design a method for an investigation.

Select one independent variable to investigate and write an appropriate hypothesis.

List the factors to be held constant and factors that may not be able to be controlled.

List the types and quantities of materials required and a detailed procedure.

Use the results of your trials to justify the details of your method.

Identify ethical and safety considerations.

Submit your deconstruction and design for teacher feedback and approval. No approval, no practical!!!

Part C Practical investigation

Carry out your approved investigation and record results. Consider a pre- and post-experiment (if needed!)

Practical to done between week 6-10 of term 10, based on approval!

Part D Investigation Report IAE1, IAE2 IAE3, IAE4, KA1, KA2, KA4.

The practical report should include:

introduction with relevant chemistry concepts, hypothesis and variables

materials/apparatus

method that was implemented

identification and management of safety and/or ethical risks

results, including table(s) and/or graph(s)

analysis of results, identifying trends, and linking results to concepts

evaluation of procedures and their effect on data, and identifying sources of uncertainty

conclusion, with justification.

The report should be a maximum of 1500 words if written, or a maximum of 10 minutes for an oral presentation, or the equivalent in multimodal form.

Your deconstruction evidence should be attached to the report.

Only the following sections of the report are included in the word count:

introduction

analysis of results

evaluation of procedures

conclusion and justification.

Timeline of checkpoints:

Deconstruct submission: Week 5

Design (including Materials and methods) submission: Week 5

Final draft due date for the practical report: Week 9

Final submission due date for the practical report: Week 10

Part A: Deconstruct proforma

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2494107141201OPTION SELECTED

00OPTION SELECTED

The Deconstruct question/statement: Aspects of the Question:

Variables:

IV

DV

CV What is the Science Understanding?

What are the links to the course content?

Methods to obtain results/data

Predicted outcome Sources of uncertainty and limitation Mindmap can be added on an additional page!

Part B: Design an experiment

Aim Hypothesis Justification Variables Independent:

Dependent:

Justification Factors that must be held constant Why the factor must be held constant How this factorwill be held constant

Uncontrollable Variable Why it cannot be controlled

Materials list Justification

Hazards Precautions taken to ensure safety

Outline of procedureto befollowed (in red you need to justify each step of the method)

Results Table (does not need to be filled in with data)

You need to show expected/predicated result

Limitation of design

SACE board recommendations

Assessment Type 1: Investigations Folio

The Investigations Folio must include at minimum 2 practical tasks and one Science as a Human Endeavour investigation. Included as a part of at least one of the practical tasks is the opportunity for students to deconstruct a problem and design a method to investigate one aspect of the problem. Assessment design criteria to be used for this assessment type include Investigation, Analysis and Evaluation and Knowledge and Application.

The more successful responses commonly:

deconstructed a problem that was open-ended, in a logical and clear manner and using a suitable format

provided detailed justification for the relevant components of the deconstruct and/or steps of the method designed. This often included justifying:

- the choice of independent variable to test and how the results would be obtained

- why a particular number of repeat samples was chosen

- how and why some variables needed to be controlled

had detailed materials and equipment lists and methods that were logical and could be repeated, as each step was detailed

appropriately and accurately identified the independent and dependent variables, controlled variables, factors that cannot be controlled and a suitable corresponding hypothesis written in a testable format

effectively identified appropriate limitations design

included all components of a practical report that are specified in the subject outline for each practical investigation report

The less successful responses commonly:

had limited evidence of deconstruction of a problem

provided limited analysis of some of the data and made little reference to the data collected or relevant biological concepts

provided a generic evaluation of the procedures with limited consideration of the effect the errors of uncertainty could have on the data

were not able to correctly identify and explain the effect of random and/or systematic errors

lacked sufficient detail or did not use appropriate terminology

were repetitive when attempting to evaluate procedures and inappropriately referred to strengths and weaknesses

used terminology incorrectly

Performance Standards for Stage 2 Biology

A B C D E

Investigation, Analysis

and Evaluation 1

2

3

4 Critically deconstructs a problem and designs a logical, coherent, and detailed Biology investigation.

Obtains records, and represents data, using appropriate conventions and formats accurately and highly effectively.

Systematically analyses and interprets data and evidence to formulate logical conclusions with detailed justification.

Critically and logically evaluates procedures and their effects on data. Logically deconstructs a problem and designs a well-considered and clear Biology investigation.

Obtains, records, and represents data, using appropriate conventions and formats mostly accurately and effectively.

Logically analyses and interprets data and evidence to formulate suitable conclusions with reasonable justification.

Logically evaluates procedures and their effects on data. Deconstructs a problem and designs a considered and generally clear Biology investigation.

Obtains, records, and represents data, using generally appropriate conventions and formats with some errors but generally accurately and effectively.

Undertakes some analysis and interpretation of data and evidence to formulate generally appropriate conclusions with some justification.

Evaluates procedures and some of their effects on data. Prepares a basic deconstruction of a problem and an outline of a Biology investigation.

Obtains, records, and represents data, using conventions and formats inconsistently, with occasional accuracy and effectiveness.

Describes data and undertakes some basic interpretation a basic conclusion.

Attempts to evaluate procedures or suggest an effect on data. Attempts a simple deconstruction of a problem and a procedure for a Biology investigation.

Attempts to record and represent some data, with limited accuracy or effectiveness.

Attempts to describe results and/or interpret data to formulate a basic conclusion.

Acknowledges that procedures affect data.

Knowledge and Application 1

2

3

4

Demonstrates deep and broad knowledge and understanding of a range of chemical concepts.

Applies chemical concepts highly effectively in new and familiar contexts.

Critically explores and understands in depth the interaction between science and society.

Communicates knowledge and understanding of chemistry coherently with highly effective use of appropriate terms, conventions and representations. Demonstrates some depth and breadth of knowledge and understanding of a range of chemical concepts.

Applies chemical concepts mostly effectively in new and familiar contexts.

Logically explores and understands in some depth the interaction between science and society.

Communicates knowledge and understanding of chemistry mostly coherently with effective use of appropriate terms, conventions, and representations. Demonstrates knowledge and understanding of a general range of chemical concepts.

Applies chemical concepts generally effectively in new or familiar contexts.

Explores and understands aspects of the interaction between science and society.

Communicates knowledge and understanding of chemistry generally effectively using some appropriate terms, conventions, and representations. Demonstrates some basic knowledge and partial understanding of chemical concepts.

Applies some chemical concepts in familiar contexts.

Partially explores and recognises aspects of the interaction between science and society.

Communicates basic chemical information, using some appropriate terms, conventions, and/or representations. Demonstrates some limited recognition and awareness of chemical concepts.

Attempts to apply chemical concepts in familiar contexts.

Attempts to explore and identify an aspect of the interaction between science and society.

Attempts to communicate information about Biology.