Question

It is desired to prepare 5 molar solution of C2H5OH.how muvh mass of it must be dissolved in 1200gm of H2O?
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Answer 1

Answer: 400 gm of  C₂H₅OH of it must be dissolved in 1200 gm of H₂O for 5 molar solution

Explanation:

Molarity=moles  of solute /Volume of solution in liters

Let be mass of ethanol is x grams

No of moles = x/46 moles and and mass of solution is (x+1200) gm

Here you did not give the density of solution

then lets assume that density of solution is 0.920 gm/ml

volume in liters =(x+1200)/0.982 ml

then according to formula

Molarity= (x/46)(1000)÷[(x+1200)/0.920]

5=(x/46)(1000)÷[(x+1200)/0.920]

5={x×100×0.92}÷{46×(x+1200)} by simplifying it we get

5={20 x}÷{(x+1200)}

5 x+6000=20 x

x=400 gm