Effect of Light on Silver Halide Salts

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Effect of light on Silver Halide Salts
Aim: To investigate the effect of sunlight and UV light on silver salts and to identify an application of this reaction. Hypothesis: The compounds exposed to sunlight (which already contains UV light) will decompose. The compounds which are not exposed to light (put in a dark place) will not decompose. Theory:

Equipment:
* 4 x petri dishes
* 1 x glass stirring rod
* 0.1 mol/L silver nitrate in a dropper bottle
* 0.1 mol/L Sodium chloride in a dropper bottle
* 0.1 mol/L Sodium iodide in a dropper bottle
Method:
1. Ensure you are wearing safety glasses
2. Take the petri dishes and label then 1, 2, 3, and 4.
3. Add 20 drops of silver nitrate solution to each petri dish. 4. Add 20 drops of sodium chloride to petri dish one and three. Mix with stirring rod and observe the reaction. 5. Add 20 drops of sodium iodine to petri dishes 2 and 4. Mix with stirring rod and observe reaction. 6. Put petri dishes 1 and 3 in the sunlight for 5-10 minutes. 7. Put petri dishes 2 and 4 in a dark place, away from any light. 8. After 5-10 minutes, observe the reaction and record results. Risk Assessment:

RISK| PRECAUTION| WHAT CAN BE DONE INCASE|
Chemical solutions getting into eyes| Be careful while handling chemical solutions, always wear safety glasses| In case this happens, inform teacher and wash eyes thoroughly wash eyes with clean cold water| Staining hands with solution| Wear safety gloves and handle with care| Inform teacher; wash affected area under cold water.| Sniffing the gas produced after reaction| Do not open petri dish once the solutions are mixed. Toxic gasses may be present| Inform teacher, immediately seek medical attention|

Results:
The Sodium Chloride NaCl was decomposing faster than Sodium Iodine NaI in the sunlight. Whereas the petri dishes placed in the dark location as a control showed no signs of decomposition or change in colour. Solution|...
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