AI: Mole concept & Stoichiometry (Chemistry)

Define relative atomic mass (Ar).

Average mass of an atom relative to 1/12 of carbon-12

One mole contains ______ × 10²³ particles.

6.02

Relative atomic mass has units.

False

Find Mr of CO₂.

44

24 dm³

Volume of 1 mole of gas at r.t.p.

Why is chlorine’s Ar = 35.5?

Weighted average of isotopes

“Mole = 6.02 × 10²² particles”

Incorrect; should be 6.02 × 10²³

2 mol of H₂ contains how many molecules?

1.204 × 10²⁴ molecules

Formula for moles from mass?

moles = mass ÷ molar mass

Empirical formula shows the ______ ratio of atoms.

Simplest whole-number

Molecular formula is always simpler than empirical formula.

False

Empirical formula = CH₂, Mr = 28 → molecular formula?

C₂H₄

Molar mass = 44 g/mol

CO₂

At r.t.p., 1 mol gas = ______ dm³

24

What does Avogadro’s law state?

Equal volumes of gases at same conditions contain equal particles

How many moles in 48 dm³ gas (r.t.p.)?

2 mol

Limiting reactant

Reactant used up first, determines product amount

Concentration (mol/dm³) = ______ ÷ ______

moles ÷ volume

1 dm³ = 100 cm³

False (1 dm³ = 1000 cm³)

0.5 mol in 0.25 dm³ → concentration?

2.0 mol/dm³

% yield formula

actual yield ÷ theoretical yield × 100%

% purity = ______ ÷ ______ × 100%

pure mass ÷ total mass

“Excess reactant determines product amount”

Incorrect; limiting reactant does

In Mg + 2HCl → MgCl₂ + H₂, ratio HCl:Mg = ?

2:1

6.02 × 10²³

Avogadro constant

Molar mass unit = ______

g/mol

Empirical formula gives exact number of atoms.

False

Moles in 12 g of carbon?

1 mol

Stoichiometry

Mole relationships in reactions

Number of particles = moles × ______

6.02 × 10²³

Why convert cm³ to dm³ in concentration?

Because mol/dm³ uses dm³

24 g Mg (Ar=24) → moles?

1 mol

1 mol NaCl produces how many ions?

2 mol ions

Volume ratio of gases = ______ ratio

mole ratio

Gas volume depends on temperature and pressure.

True

60 cm³ NO reacts → O₂ needed?

30 cm³

End-point in titration

Indicator colour change

In titration, known solution = ______

titrant

“Molar mass of NaCl = 23”

Incorrect; should be 58.5

1 mol H₂SO₄ produces how many ions?

3 mol ions