IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IB => Sciences => Topic started by: Tutu_93 on October 05, 2009, 07:55:27 pm

Title: Chemistry
Post by: Tutu_93 on October 05, 2009, 07:55:27 pm

I am stuck in a question in chemistry

A 1.39 g sample of hydrated copper (2) sulfate ( cuso4.xH2O)is heated until all the water of hydration is driven off.The anhydrous salt has a mass of 0.89 g . determine the formula of the hydrate ??

Title: Re: Chemistry
Post by: Ghost Of Highbury on October 05, 2009, 08:05:14 pm

First use the mass of the copper sulfate after all the water is gone to determine the moles of CuSO4

0.89/159.5 = 0.0055

The mass loss on heating can be used to determine the moles of water lost:

(1.39 - 0.89)/[(2 x 1) + 16] = 0.0278

Now determine the ratio of water to CuSO4

0.0278/0.0055 ~ 5
----
(because its moles of water to moles of copper sulfate ratio)

Title: Re: Chemistry
Post by: Tutu_93 on October 05, 2009, 08:07:11 pm

Yaa i knw ..
 The actual answer is 5

Title: Re: Chemistry
Post by: Ghost Of Highbury on October 05, 2009, 08:08:03 pm

i edited it..check again

Title: Re: Chemistry
Post by: Tutu_93 on October 05, 2009, 08:11:56 pm

:D:D:D:D :D thhhhnnnnnk u

Title: Re: Chemistry
Post by: Ghost Of Highbury on October 05, 2009, 08:12:32 pm

okay.