Question

Sam records the mass of his evaporating dish as 8.649 g. He records the mass of...

Sam records the mass of his evaporating dish as 8.649 g. He records the mass of the evaporating dish and the sample of hydrate as 16.735 g. After heating the sample in the evaporating dish to constant weight, the mass of them combined is 13.031 g. How many moles of water were removed from the sample by the heating process? Report your answer with three digits after the decimal.

Homework Answers

Answer #1

Given : 1) mass of evaporating dish= 8.649 gm

2) mass of evaporating dish + hydrate =16.735 gm

3) mass of hydrate = ( mass of evaporating dish + hydrate)- ( mass of evaporating dish)

= 16.735-8.649

= 8.086 gm

4) mass of dehydrated material= ( mass of evaporating dish + dehydrate)- ( mass of evaporating dish)

= 13.031-8.649

= 4.382 gm

5) mass of water removed = mass of hydrate - mass of dehydrate

= 8.086- 4.382

= 3.704 gm

Molar mass of water = 18 gm/mol

no of moles of water= mass / molar mass

= 3.704/18

= 0.206 mols

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