A copper salt contains $25.5 %$ $25.5%$ $C u$ $Cu$ , $12.9 %$ $12.9%$ $S$ $S$ , $25.6 %$ $25.6%$ $O$ $O$ , and $36.0 %$ $36.0%$ $water$ $"water"$ ...what is the empirical formula of the hydrate?

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A copper salt contains $25.5 %$ $25.5%$ $C u$ $Cu$ , $12.9 %$ $12.9%$ $S$ $S$ , $25.6 %$ $25.6%$ $O$ $O$ , and $36.0 %$ $36.0%$ $water$ $"water"$ ...what is the empirical formula of the hydrate?

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Answer 1 · 2016-05-31T17:05:35

$C u S O_{4} \cdot 5 H_{2} O$ $CuSO_4*5H_2O$

Explanation:

We ASSUME that there are $100 \cdot g$ $100*g$ of copper salt, and work out the molar quantities:

$C u :$ $Cu:$ $\frac{25.5 \cdot g}{63.55 \cdot g \cdot m o l^{- 1}}$ $(25.5*g)/(63.55*g*mol^-1)$ $=$ $=$ $0.401 \cdot m o l$ $0.401*mol$ $C u$ $Cu$ .

$S :$ $S:$ $\frac{12.9 \cdot g}{32.06 \cdot g \cdot m o l^{- 1}}$ $(12.9*g)/(32.06*g*mol^-1)$ $=$ $=$ $0.401 \cdot m o l$ $0.401*mol$ $S$ $S$ .

$O :$ $O:$ $\frac{25.6 \cdot g}{15.999 \cdot g \cdot m o l^{- 1}}$ $(25.6*g)/(15.999*g*mol^-1)$ $=$ $=$ $1.60 \cdot m o l$ $1.60*mol$ $O$ $O$

$H_{2} O :$ $H_2O:$ $\frac{36.0 \cdot g}{18.01 \cdot g \cdot m o l^{- 1}}$ $(36.0*g)/(18.01*g*mol^-1)$ $=$ $=$ $2.00 \cdot m o l$ $2.00*mol$ $H_{2} O$ $H_2O$

To get the empirical formula, we divide thru by the LOWEST molar quantity, i.e. $0.401 \cdot m o l$ $0.401*mol$ , to give:

$C u S O_{4} \cdot 5 H_{2} O$ $CuSO_4*5H_2O$ , $copper sulfate pentahydrate$ $"copper sulfate pentahydrate"$

I have treated the water here as I would normally treat an element; I am certainly free to do so inasmuch as we could dry the salt and measure the actual water loss.

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A copper salt contains $25.5 %$ $25.5%$ $C u$ $Cu$ , $12.9 %$ $12.9%$ $S$ $S$ , $25.6 %$ $25.6%$ $O$ $O$ , and $36.0 %$ $36.0%$ $water$ $"water"$ ...what is the empirical formula of the hydrate?

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Explanation:

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Humanities

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A copper salt contains 25.5%25.5% CuCu, 12.9%12.9% SS, 25.6%25.6% OO, and 36.0%36.0% water"water"...what is the empirical formula of the hydrate?

1 Answer

Explanation:

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A copper salt contains $25.5 %$ $25.5%$ $C u$ $Cu$ , $12.9 %$ $12.9%$ $S$ $S$ , $25.6 %$ $25.6%$ $O$ $O$ , and $36.0 %$ $36.0%$ $water$ $"water"$ ...what is the empirical formula of the hydrate?