Concentration Calculation

1. Enter the values for "Solution A mass (g)", "Solution A concentration (%)", "Solution B mass (g)", "Solution B concentration (%)", "Added water (g)", "Solute type", "Concentration type", "Mass percent concentration (%)", and "Temperature (℃)".
2. The "Total solution mass", "Total solute mass", and "Final concentration" will be displayed.

What is concentration?

Concentration is an indicator of how much solute (e.g., salt) is contained in a solution (e.g., saline).
There are four common ways to express it.

1. Mass Percent Concentration (%)

The most commonly used way of expressing concentration.

Mass % = (Mass of solute (g) ÷ Mass of solution (g)) × 100

Example: 10 g of salt dissolved in 90 g of water → Total solution mass = 100 g
10 ÷ 100 × 100 = 10 %

2. Molarity (mol/L)

Useful in chemical reaction equations, expressed based on the amount of substance.

Molarity (M) = Amount of solute (mol) ÷ Volume of solution (L)

Example: Dissolving 58.44 g of NaCl in water to make 1 L of solution:
Amount of NaCl = 58.44 ÷ 58.44 = 1 mol
Thus concentration = 1 mol/L = 1 M

3. Mole Fraction

Expresses the ratio of the number of molecules of a component to the total number of molecules.

Mole fraction = Moles of solute ÷ (Moles of solute + Moles of solvent)

Example: Water 90 g (90 ÷ 18 = 5 mol)
Salt 10 g (10 ÷ 58.44 ≈ 0.17 mol)
Mole fraction = 0.17 ÷ (5 + 0.17) ≈ 0.033

4. Normality (N)

A special unit often used in acid-base chemistry.
It represents how many equivalents are present per liter of solution.

Normality (N) = Equivalents of solute ÷ Volume of solution (L)

Example: H₂SO₄ (sulfuric acid) provides 2 equivalents per mol (2 H⁺).
0.5 mol/L H₂SO₄ solution is 1 N.

Summary

• Everyday use or lab preparation → Mass percent concentration
• Chemical reactions and stoichiometry → Molarity
• Expressing ratios in terms of molecule count → Mole fraction
• Acid-base strength expression → Normality