Mixture Problems
The amount of substance is conserved when solutions are combined:
(Concentration₁ × Volume₁) + (Concentration₂ × Volume₂) = Concentration_final × Volume_final
Example: 10 L of 40% alcohol — how much pure alcohol (100%) must be added to reach 60%?
(0.40 × 10) + (1.0 × x) = 0.60 × (10 + x) 4 + x = 6 + 0.6x → 0.4x = 2 → x = 5 liters