Find the mass of urea CH4N2O needed to prepare 51.8g of a solution in water in which the mole fraction of urea is 7.55×10−2.

I would like a hint. Not the solution please.

Question

Find the mass of urea CH4N2O needed to prepare 51.8g of a solution in water in which the mole fraction of urea is 7.55×10−2.

I would like a hint. Not the solution please.

anonymous · Answer

relative molecular mass of urea = 12 + 4 + 14*2 + 16 = 60
i mole of urea weighs 60 g
you can now calculate mass of urea in 1 L of 7.55 x 10^-2 molar and in 51.8 g

anonymous · Answer

I do not understand. What do you mean by relative molar mass? Are you talking about molar mass? (ie. xgrams in one mole of the substance)?