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Chemistry · Mole concept, molar mass, percentage composition, empirical and molecular formulae

A compound of sodium does not give when heated but it gives when treated with di

A compound of sodium does not give \( C O_{2} \) when heated but it gives \( C O_{2} \) when treated with dilute acids. A crystalline compound is found to have 37.1\% Na and 14.52\% \( \boldsymbol{H}_{\mathbf{2}} \boldsymbol{O} \). Hence, the compound is :

  • A. \( N a H C O_{3} .10 H_{2} O \)
  • B. \( N a H C O_{3} .5 H_{2} O \)
  • C. \( N a_{2} C O_{3} .10 H_{2} O \)
  • D. \( N a_{2} C O_{3} . H_{2} O \)

Step-by-step solution

The compound does not give CO2 on heating, indicating it is not a bicarbonate (which decomposes), but gives CO2 with acids, so it is a carbonate. The given percentages (37.1% Na, 14.52% H2O) match exactly with Na2CO3·H2O (molar mass 124 g/mol: 46/124 = 37.1% Na, 18/124 = 14.52% H2O).
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