1.determine the percentage composition of a mixture of anhydrous sodium carbonate and sodium bicarbonate from the following data:

wt of mixture taken = 2g , loss in weight on heating = 0.11g

2.how many grams of 90% pure Na2so4 can be produced from 250 gm of 95% pure Nacl?

(1). When the mixture of sodium carbonate and sodium bicarbonate (2 g) is heated, then sodium bicarbonate decomposes to give sodium carbonate, water and carbon-di-oxide, which are evolved as gases. Therefore the loss in the weight (0.11 g) of the mixture will be due to evolution of theses gases as shown below:

62 g (18g+44g) of gas is produced from 168 g of Sodium Bicarbonate.

Therefore, 0.11 g of gas will be produced form (0.11x168)/62 = 0.298 g of Sodium Bicarbonate.

The weight of sodium bicarbonate is 0.298 g, so, weight of sodium carbonate will be (2g-0.298g) = 1.702g.


The given weight of Sodium chloride = 250 g

Sodium chloride is 95% pure. Therefore actual weight of Sodium chloride = (95x250)/100 = 237.5 g

117 g of Sodium chloride gives 142 g of Sodium sulphate.

Thus, 237.5 g of Sodium chloride will give (237.5x142)/117 = 288.24 g of Sodium sulphate.

Now, the sodium sulphate obtained will be 90% pure. Therefore, the actual weight of Sodium sulphate will be = (90x288.24)/100 = 259.46 g of sodium sulphate.

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