Question

when a hydrate of na2co3 is heated until all the water removed,it loses 54.3 ℅ of its mass.the formula of hydrate is???

a Na2co3.10 H2O b na2co3.7h2o
c na2co3.5h2O d na2co3.3h2O​

Answer 1

Answer:

The formula of the hydrate is $Na_2CO_3.7H_2O$.

Explanation:

Mass of sodium carbonate,M = 106 g/mol

Mass of water present molecules present in hydrate state = x

Mass of hydrated sodium carbonate = M +x

$54.3\%=\frac{x}{M+x}\times 100$

$54.3\%=\frac{x}{106g/mol+x}\times 100$

$x=125.94 g.mol$

Number of molecules of water = $\frac{125.94 g/mol}{18}=6.99\approx 7$

The formula of the hydrate is $Na_2CO_3.7H_2O$.

Answer 2

The formula of the hydrate is Na_2CO_3.7H_2ONa2CO3.7H2O .