Question

A solution of an unknown compound has a concentration of 11.5 % by mass. Howmany moles are present in 1.055 kg of solution if the solute has a molar mass of105.1 g/mol?

Answer 1

In this question we have a few informations:

11.5% of concentration by mass, which means that in the calculation mass of solute/mass of solution, we had 11.5% of the concentration of this solute in the solution

1.055 kg of solution

105.1g/mol is the molar mass

Now to solve this we will use that formula that I have mentioned in the concentratione explanation:

% = mass of solute/mass of solution

0.115 = mass of solute/1055 grams

mass of solute = 1055*0.115

mass of solute = 121.3 grams of solute

Now we have the molar mass, 105.1g/mol, and also the mass of solute, let's find the number of moles:

105.1g = 1 mol

121.3g = x moles

x = 1.15 moles of this solute