Molarity is moles of solute per liter of solution (M=mol/L). Since we know both molarity and the number of moles, plug them into the equation for molarity and solve for volume. (6.0=4.5/x Liters) x= 0.75L The answer is thus 750mL. Solution Molarity is moles of solute per liter of solution (M=mol/L). Since we know both molarity and the number of moles, plug them into the equation for molarity and solve for volume. (6.0=4.5/x Liters) x= 0.75L The answer is thus 750mL..