Question

When 4 gram of a mixture of Nahco₃ and NaCl is heated 0.66 gram co₂ gases evolved. determine the %composition of the original mixture

Answer 1

The mixture of NaHCO3 and NaCl is approximately 31.5% NaHCO3 and 68.5% NaCl.

Step-by-step explanation:

When sodium bicarbonate (NaHCO3) is heated, it decomposes to produce sodium carbonate (Na2CO3), water (H2O), and carbon dioxide (CO2). The balanced chemical equation for this reaction is: 2NaHCO3 → Na2CO3 + H2O + CO2. It's known that the molar mass of CO2 is about 44 g/mol and from the equation, 1 mol of CO2 is produced from 2 mol NaHCO3. Therefore, if 0.66g of CO2 were produced, this equates to 0.66g/44g/mol = 0.015 mol of CO2 and hence 0.015 mol of NaHCO3. Given the molar mass of NaHCO3 is about 84 g/mol, the weight of NaHCO3 in the original mixture is around 0.015 mol x 84 g/mol = 1.26 g. The rest of the original mixture (4g - 1.26g = 2.74g) must be NaCl. Hence the original mixture is approximately 31.5% NaHCO3 and 68.5% NaCl.

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