Concentration terms: molarity, molality, mole fraction, normality, ppm
Mole Concept and Stoichiometry · Chemistry
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Dissolve 8 g NaOH in water to make 500 mL solution. Find molarity and molality (assume solution density ≈ 1 g/mL). Step 1: Moles NaOH = 8/40 = 0.2 mol. Step 2: Molarity = 0.2 mol / 0.5 L = 0.4 M. Step 3: Solution mass ≈ 500 g; solvent = 500 − 8 = 492 g = 0.492 kg. Step 4: Molality = 0.2 / 0.492 ≈ 0.406 m. Dilute solutions: M ≈ m; they differ when concentrated.