Question:
The compound Na$_2$CO$_3 \cdot x$H$_2$O has 50 % H$_2$O by mass. The value of $x$ is
The compound Na$_2$CO$_3 \cdot x$H$_2$O has 50 % H$_2$O by mass. The value of $x$ is
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Use percentage formula directly to find water of crystallization.
Updated On: May 1, 2026
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The Correct Option is
Solution and Explanation
Concept:
Percentage composition: \[ \%\text{H}_2O = \frac{\text{mass of water}}{\text{total molar mass}} \times 100 \]
Step 1: Molar masses.
Na$_2$CO$_3$ = 106 g/mol
Water = $18x$
Step 2: Apply condition.
\[ \frac{18x}{106 + 18x} \times 100 = 50 \]
Step 3: Solve.
\[ \frac{18x}{106 + 18x} = 0.5 \] \[ 18x = 53 + 9x \] \[ 9x = 53 \Rightarrow x \approx 6 \]
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