Electrochemical cell

Aim- to measure the voltage created in an electrochemical (galvanic) cell.

equipment- 2x 250 mL beakers, U-tube (or filter paper), voltmeter, 2x wires with alligator clips, Mg and Cu electrodes, sandpaper, 1.00 mol l -1 solution of Mg (no3)  and CuSO 0.100 mol L-1 KNO solution, electronic scales.
Dangerous chemicals we used

• zinc nitrate solution
• copper nitrate
• potassium nitrate

method- 

1. use sandpaper to remove any oxide coating on the Zn and Cu electrodes. weigh and record the mass of each electrode.
2. set up a galvanic cell as shown in the diagram below. if you do not have a u-tube, soak filter paper in solution KNO<sub>3 to act as a salt bridge.
3. record the voltage displayed on the voltmeter
4.replace the voltmeter with a wire to complete the circuit
5.leave for 10 minutes and then record observations. carefully extract each electrode from the beakers and after drying them, measure and record their mass.</sub>

results- 

discussion *sorry if this is wrong this is my understanding* -

we should have got 1.101 volts (because zinc voltage is 0.72 and the copper voltage is 0.34), but we got  0.883, why?  there are multiple reasons. a couple reasons could be the coating on the metal, the salt bridge, or the acid or base concentration can all cause a change of voltage. the reason why zinc loses electrons is because the zinc is more reactive than the copper. which means the copper must gain electrons because electrons do not just disappear.  the salt bridge was a solution of potassium nitrate (K⁺NO⁻₃). why was the salt bridge there? well the salt bridge is there because since the zinc is losing and the copper is gaining it needs to be made equal. The electrons of the zinc is going to the copper. the copper needs to be levelled out because the copper just has a negative charge. the salt bridge a mix of positive and negative.  the potassium positive goes into the zinc because it lost and the other part of the potassium nitrate is going into the copper.

Leo the lion goes ger, what does this mean? Leo stands for lose electrons oxidation. Ger stands for gain electrons reduction.

evaluation- 

if I could do the experiment again I definitely would. if I could change anything I would make sure I had fewer chemical in the beaker because it made it a bit hard to put the solution back into the container. I wouldn't change who I worked with at all.