Adrian Dingle, Educator and Chemistry Author with 25 years teaching experience
You need to know the relationship between mass and moles for a solid, and concentration & volume and moles for a solution. Also know that '4M' = 4 mol/L and is a unit of concentration.
- Convert the mass of LiBr to moles, by dividing by the molar mass (taken from the periodic table) of LiBr.
100 g / (7 + 80 g/mol) = 1.15 moles of LiBr
- Knowing that in a solution, moles = (concentration in mol/L) x (volume in L), substitute the values and do the algebra.
1.15 moles = (4 mol/L) x (volume in L)
volume in L = 0.288 L