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An 0.8M solution of ethanol has density 0.99gcm^{-3}. The molality of the solution is

  • Option 1)

    0.8

  • Option 2)

    Less than 0.8

  • Option 3)

    0.84

  • Option 4)

    0.4

 

Answers (1)

best_answer

As learnt in

Molality -

Molality = \frac{Moles \: of \: solute}{Mass \, \: o\! f\: solution(Kg)}

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 We know, m = \frac{1000M}{1000\ d - Mm_{1}}

m1 = molar mass of solute

M = Molarity

d = density of solution

m = molality

\therefore  we have, m = \frac{1000 \times 0.8}{1000\times 0.99-0.8\times 46}

                            = 0.84


Option 1)

0.8

This answer is incorrect

Option 2)

Less than 0.8

This answer is incorrect

Option 3)

0.84

This answer is correct

Option 4)

0.4

This answer is incorrect

Posted by

divya.saini

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