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Question:

In Signals Notebook, it only shows one decimal number and rounds it up to this, which is very inaccurate. Could you please explain why?

 

Answer:

It seems the number of decimal digits you receive at the end will depend on the number of significant digits on the values the user enters.

For example:

They have a reagent with a FM of 232.06. If they add 0.6 mol (1sf) that equates to 0.6x232.06 g = 139.236g. In kg that is 0.13926, which to 1sf is 0.1 kg.

In reverse, if they specify 0.1kg then that is 100g/232.06 = 0.4309 mol = 0.4 mol to 1 sf

The system is doing what is mathematically appropriate, which is reflecting the same level of accuracy as their least accurate user entered value. If they changed the accuracy of their entered value as follows they would see a different accuracy:

They have a reagent with a FM of 232.06. If they add 0.60 mol (2sf) that equates to 0.6x232.06 g = 139.236g. In kg that is 0.13926, which to 2sf is 0.14 kg.

In reverse, if they specify 0.10 kg then that is 100g/232.06 = 0.4309 mol = 0.43 mol to 2 sf

They have a reagent with a FM of 232.06. If they add 0.600 mol (3sf) that equates to 0.6x232.06 g = 139.236g. In kg that is 0.13926, which to 3sf is 0.139 kg.

In reverse, if they specify 0.100 kg then that is 100g/232.06 = 0.4309 mol = 0.431 mol to 3 sf



Created on: 12/7/2017
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