Question

If the mass %of urea is 25%(w/w) in its aqueous solution then the molality of urea in the solution will be?​

Answer 1

ANSWER:-

Given (w/w)% of 1st solution =15

$= > 15 = \frac{500}{weight \: of \: solution(x_{1} )} \times 100$

$= > x_{1} = \frac{(500)(100)}{15}$

$= > x_{1} = \frac{ {10}^{4} }{3}$

$given \: ( \frac{w}{w} )\% \: of \: 2nd \: solution = 25$

$= > 25 = \frac{400}{weight \: of \: solution x_{2} } \times 100$

$= > x_{2} = \frac{(400)(100)}{25}$

$x_{2} = 1600$

$total \: ( \frac{w}{w} )\% = | \frac{500 + 400}{ \frac{ {10}^{4} }{3} + 1600 } | \times 100 = \frac{900}{33.3 + 16} = \frac{900}{49.3} = 18$

$\small \red{∴weight \: by \: weight \: \% \: of \: resulting \: solution \: is \: 18\%}$

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