Question

A solution is made from ethanol, C2H5OH and water is 0.75 m. How many grams of ethanol are contained per 250. g of water?

A

Answer 1

`m_(solute)=8.6g`

Step-by-step explanation:

Hello,

In this case, the unit of concentration is molality which is defined by:

`m=(n_(solute))/(m_(solvent))`

Whereas the mass of the solvent is measured in kilograms. In such a way, with the given data, we first compute the kilograms of water:

`m_(solvent)=250g*(1kg)/(1000g) =0.25kg`

Then, we solve for the moles of the solute:

`n_(solute)=0.75(mol)/(kg)*0.25kg =0.19mol`

Finally since the molar mass of ethanol is 46 g/mol, we compute the grams for the given solution:

`m_(solute)=0.19*(46g)/(1mol) \\\\m_(solute)=8.6g`

Best regards.