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Couple of chemistry questions about equipment choices/iodine clock reaction :) watch

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    I'm recording the temperature of a solution in a test tube, but I don't really want to use a therometer as I find it hard to accurately read the temperature on them. Is there anything else I could use?

    Why is sodium thiosulphate needed in the reaction between peroxodisulphate and iodide ions? (and starch) I understand that the starch forms a blue/black complex with the iodine produced so we can see the colour change but why is thiosulphate needed?

    What other pieces of equipment can be used instead of scales to record the mass of something as I need to justify my choice and I don't know why :P

    Why is a stopwatch a good piece of equipment to record the time taken? What other equipment could I use?

    Thanks
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    (Original post by SmileyGurl13)
    I'm recording the temperature of a solution in a test tube, but I don't really want to use a therometer as I find it hard to accurately read the temperature on them. Is there anything else I could use?

    Why is sodium thiosulphate needed in the reaction between peroxodisulphate and iodide ions? (and starch) I understand that the starch forms a blue/black complex with the iodine produced so we can see the colour change but why is thiosulphate needed?

    What other pieces of equipment can be used instead of scales to record the mass of something as I need to justify my choice and I don't know why :P

    Why is a stopwatch a good piece of equipment to record the time taken? What other equipment could I use?

    Thanks
    1. Use your finger to tell the temperature.

    2. thiosulphate is there to remove iodine which forms, until all thiosulphate is used up. Otherwise the reaction would be instantaneous and you would not be able to obtain a rate.

    3. Just measure it out onto your hand. With practice you can get to within 0.1grams of being correct.

    4. Sundial
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    (Original post by SmileyGurl13)
    Is there anything else I could use?

    Why is a stopwatch a good piece of equipment to record the time taken? What other equipment could I use?

    Thanks
    anything else : data logger - much more accurate and precise

    Why is a stopwatch a good piece of equipment: again, much more accurate and precise than say a wall clock

    What other equipment could I use: a stopwatch is probably the best if you're in a school setting
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    Bump, any other help.
 
 
 
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