The mass of one mole of a substance in grams is called its …A… Here, A refers to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

# Solution The mass of one mole of a substance in grams is called its **molar mass** (or molecular weight). **Step-by-step reasoning:** 1. **Definition**: One mole contains $6.022 \times 10^{23}$ particles (Avogadro's number) 2. **Molar mass concept**: The mass of exactly one mole of any substance, expressed in grams, equals its molar mass numerically 3. **Example**: - One mole of $H_2O$ has mass = $2(1) + 16 = 18$ g - Therefore, molar mass of $H_2O$ = 18 g/mol 4. **Key distinction**: - Atomic mass units are used for individual particles - Molar mass (in g/mol) is the scaled-up version for one mole of particles **Answer: A = "Molar Mass"** (or "Molecular Weight") This is a fundamental concept in stoichiometry, as molar mass connects mass (grams) to moles via the relationship: $$\text{moles} = \frac{\text{mass in grams}}{\text{molar mass}}$$