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Electrolysis Investigation

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Introduction

Chemistry Science Investigation B Townend 10R 28/06/01 Electrolysis Plan Scientific Knowledge Most inorganic and some organic chemical compounds, when in a molten state or when dissolved in water or other liquids, become ionised; that is, their molecules become dissociated into positively and negatively charged components, which have the property of conducting an electric current. If a pair of electrodes is placed in a solution of an electrolyte, or an ionisable compound, and a source of direct current is connected between them, the positive ions in the solution move toward the negative electrode and the negative ions toward the positive. On reaching the electrodes, the ions may gain or lose electrons and be transformed into neutral atoms (those with a full outer shell) or molecules, the nature of the electrode reactions depending on the potential difference, or voltage, applied. The action of a current on an electrolyte can be understood from a simple example. If the salt copper sulphate is dissolved in water, it dissociates into positive copper ions and negative sulphate ions. ...read more.

Middle

and the amount of time the experiment is left running. By using Faraday's Law and by using my own calculations I can predict the result of the experiment . Half Equations Anode - 4OH > O2 + 4H2O + 4e- 1 mole 2 moles 2 moles Cathode - 2H+ + 2e- > H2 2 moles 2 moles 1 mole Predicted results By using mole calculations and Faraday's law I can predict the results quite accurately: One Coulomb equals one amp for one second ? 0.5 amps for 30 seconds. Quantity = 15 Coulombs 2H= + 2e- > H2 2 MOLES > 1 MOLE 2 FARADAYS > 24 dm3 2 * 96500 > 24 dm3 15 > 24 * 15/2*96500 = 0.0019 dm3 = 1.9 cm3 ?15 C = 1.9 cm3 30 C = 3.8 cm3 45 C = 5.7cm3 What I think will happen Faraday's Law states that the amount of material deposited at an electrode is directly proportional to the amount of electricity passed through it. So it will produce a straight line passing through the origin. ...read more.

Conclusion

AVERAGE VOLUMES (CM3) 30 60 90 120 150 180 Safety PROBLEM LIKELIHOOD DANGER TOTAL PREVENTATIVE Acid on skin or eye 1 3 3 Wear gloves and goggles Electrocution 1 3 3 Keep voltage low Spilling water 2 1 2 Don't turn taps on fully Glass breaking 2 1 2 Be careful with glass Controls VARIABLE CONTROL Concentration of acid Use labelled bottles only to produce an acid of 0.5 molars Time This is what I am changing Current Use a variable resistor and a ammeter to keep the number of amps at 1.3 Apparatus Use the same apparatus each time Voltage Use a P.S.M to produce a constant voltage. Preliminary experiment I performed a preliminary experiment to check my ideas were all right I used the apparatus as shown above and the table as shown above these are my results: TIME PREDICTED RESULTS (CM^3) PRELIMINARY RESULTS (CM^3) 30 60 90 120 150 180 As you can see they are below the predicted results this is due to the inaccuracy of reading from the graduated test tube and recording at the same time it will be easier when there are people with separate jobs to do. ...read more.

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