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Topic: Colorimetry-effect on calibration factor  (Read 3809 times)

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Offline johnsy123

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Colorimetry-effect on calibration factor
« on: September 07, 2011, 08:07:35 AM »
What would be the effect of on the callibration factor if the water isn't stirred properly?

And if 100ml of water is spost to be added but 90ml is added instead?

Offline fledarmus

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Re: Colorimetry-effect on calibration factor
« Reply #1 on: September 07, 2011, 08:38:28 AM »
Two hints:

a) What is your colorimeter actually measuring?

b) Is water colored?

Offline Vidya

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Re: Colorimetry-effect on calibration factor
« Reply #2 on: September 07, 2011, 10:08:01 PM »
you are using
q= ms (delta)t
now you can see the q(heat ) is proportional to mass

Offline johnsy123

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Re: Colorimetry-effect on calibration factor
« Reply #3 on: September 12, 2011, 03:45:48 AM »
Measuring 100ml of water inside the colorimeter, which is mixed with 5.15g of sodium hydroxide crystals.

Offline Cavillus

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Re: Colorimetry-effect on calibration factor
« Reply #4 on: September 12, 2011, 03:58:16 AM »
What would be the effect of on the calibration factor if the water isn't stirred properly?

And if 100ml of water is spost to be added but 90ml is added instead?


Well, given your question, I can try to answer to that.

1. What happens if the solution, after having added water, isn't stirred correctly? Well, in this case we'll have parts of the solution in the flask more concentrated than the average and some part less concentrated. So, depending on which portion you analyse, you'll commit a very large casual error on your measure.

2. What happens if we add 90 ml instead of 100? Well, first of all you NEVER have to add 100 ml of water to fill a 100 ml flask, because the other reactants occupy some volume, and the water required is less than that. Anyway, if we don't reach the mark in the neck of the flask, we'll have a more concentrated solution, and every time we'll analyse that we'll commit a systematic error on the measure.
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Offline fledarmus

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Re: Colorimetry-effect on calibration factor
« Reply #5 on: September 12, 2011, 08:18:07 AM »
Measuring 100ml of water inside the colorimeter, which is mixed with 5.15g of sodium hydroxide crystals.

I'm sorry, I meant "what physical property of your solution is your colorimeter actually measuring?"

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