Q) Percentage purity of gold in 10g of chain marked 20carat (puregold=24carat)-
1)80% 2)91.6% 3)83.33% 4)96%
Q) The crystalline salt Na2SO4.xH2O on heating loses 55.9% of its weight ; the value of x in the crystalline salt is -
1)5 2)7 3)2 4)10
Asked by shubhamjindal | 19th Jun, 2014, 11:16: PM
Dear shubham.jalandhar@gmail.com
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Solution to second question:
The crystalline salt Na2SO4.xH2O on heating loses 55.9% of its weight ; the value of x in the crystalline salt is -
1)5 2)7 3)2 4)10
Correct option: 4
Consider 100g of Na2SO4.x H2O
On heating it loses 55.90g of water.
Mole proportion Na2SO4 = 44.10, H2O = 55.9
Na2SO4 = 44.10 = 0.3106
142
H2O = 55.90 = 3.106
18
So let us divide by the smallest, so we have mole proportion as Na2SO4.H2O = 1:10
So the salt is Na2SO4.10H2O
We cannot entertain more than 5 questions in a subject per day. In case of multiple questions within a query, please post each question individually and let us know where you are getting stuck so that we would be able to explain things better.
Regards
Topperlearning Team.
Consider 100g of Na2SO4.x H2O
On heating it loses 55.90g of water.
Mole proportion Na2SO4 = 44.10, H2O = 55.9
Na2SO4 = 44.10 = 0.3106
142
H2O = 55.90 = 3.106
18
So let us divide by the smallest, so we have mole proportion as Na2SO4.H2O = 1:10
So the salt is Na2SO4.10H2O
Answered by Vaibhav Chavan | 20th Jun, 2014, 10:32: AM
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