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Question
Washing soda has the formula Na2CO3.10H2O.What is the mass of anhydrous sodium carbonate left when all the water of crystallization is expelled by heating 57.2 g of washing soda?
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Solution
\[\ce{Na2CO3.10H2O ->[\Delta] Na2CO2 + 10H2O}\]
molecular weight of washing soda is 286.14g
molecular weight of sodium carbonate is 106g
286.14g of Na2CO3. 10H2O forms 106g of sodium carbonate on heating 57.2 g of Na2CO3. 10H2O forms = 106 X 57.2/286.14 = 21.2g
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