Answer
$18.7 g$
Work Step by Step
$ H_{2}C_{2}O_{4}.2H_{2}O+ heat → H_{2}C_{2}O_{4} + 2H_{2}O$
Molecular mass of oxalic acid dihydrate $ H_{2}C_{2}O_{4}.2H_{2}O =
6 \times 1+2 \times 12+6 \times 16$ = 126 g
Molecular mass of anhydrous oxalic acid $H_{2}C_{2}O_{4} = 2\times1+2 \times 12+4 \times 16$= 90 g
From the dehydration equation we have,
126 g oxalic acid hydrate on complete dehydration yields 90 g of anhydrous oxalic acid.
Therefore anhydrous oxalicacid left after dehydration of 26.2 g oxalicacid dehydrate =$ (26.2 \times 90) \div 126 = 18.7 g $
