Question #3093

13.4 g of a sample of unstable hydrated salt: Na2SO4. xH20 was found to contain 6.3g of water. Determine the number of water of crystallization

Expert's answer

The molar mass of the salt is m(Na_{2}SO_{4}* xH_{2}O) = 2*23+32+16*4 + x (2 + 16) = 142 + x*18 [g/mol]

Then let's construct the proportion:

13.4 / 6.3 = (142 + 18x)/18x

13.4 * 18x = (142 + 18x) * 6.3

241.2x = 894.6 + 113.4x

127.8x = 894.6

x = 7

Na_{2}SO_{4}* 7H_{2}O

Then let's construct the proportion:

13.4 / 6.3 = (142 + 18x)/18x

13.4 * 18x = (142 + 18x) * 6.3

241.2x = 894.6 + 113.4x

127.8x = 894.6

x = 7

Na

## Comments

Assignment Expert18.11.14, 16:45Dear Madhav,

You're welcome. We are glad to be helpful.

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Madhav17.11.14, 17:58Thank you sir. This will really help me

Assignment Expert17.11.14, 16:32It is formed by fact that we know the total mass of compound and how much water it contains. Then it is clear the proportion of water mass in compound to the total mass will be the same as the ratio of molar mass of water to the total molar mass of compound.

madhav15.11.14, 15:13Pls tell how is this proportion formed

Assignment Expert29.09.14, 16:09You're welcome. We are glad to be helpful.

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Nishant28.09.14, 20:27Thanks... I needed that.

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