The Mole Flashcards

All 6 cards in this deck

What is the unit used to measure chemical amounts, and what is its symbol?

The mole, symbol $\mathrm{mol}$.

What is the mass of one mole of a substance in grams?

Numerically equal to its relative formula mass ($M_r$).
e.g. $M_r$ of $\mathrm{CO_2}$ = 44, so one mole has a mass of 44 g.

What is the Avogadro constant?

$6.02 \times 10^{23}$ per mole — the number of atoms, molecules or ions in one mole of a substance.

What are the steps to calculate the number of moles in a given mass of a substance?
e.g. 88 g of $\mathrm{CO_2}$ ($M_r$ = 44)

1. Find the $M_r$: 44
2. moles = mass ÷ $M_r$ = $88 \div 44$ = 2 mol

What are the steps to calculate the number of particles in a given mass of a substance?
e.g. molecules in 88 g of $\mathrm{CO_2}$ ($M_r$ = 44)

1. moles = mass ÷ $M_r$ = $88 \div 44$ = 2 mol
2. particles = moles $\times 6.02 \times 10^{23}$ = $1.204 \times 10^{24}$ molecules

True or false? One mole of carbon (C) contains the same number of atoms as the number of molecules in one mole of carbon dioxide ($\mathrm{CO_2}$).

True. One mole of any substance contains the same number of the stated particles as one mole of any other substance.