Calculate the mass of ascorbic acid (Vitamin C, C6H8O6) to be dissolved in 75 g of acetic acid to lower its melting point by 1.5°C. Kf = 3.9 K kg mol−1.
Mass of acetic acid, w1 = 75 g
Molar mass of ascorbic acid (C6H8O6), M2 = 6 × 12 + 8 × 1 + 6 × 16
= 176 g mol−1
Lowering of melting point, ΔTf = 1.5 K
We know that:
`triangleT_f = (K_fxxw_2xx1000)/(M_2xxw_1)`
`= (1.5xx176xx75) /(3.9xx1000)`
= 5.08 g (approx)
Hence, 5.08 g of ascorbic acid is needed to be dissolved.
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