C3 - Quantitative Chemistry

Question 1

What is the law of conservation?

Answer 1

Mass is conserved in a chemical reaction
- The total mass of reactants equals the total mass of products.

Question 2

What is the relative formula mass?

Answer 2

The sum of the relative atomic masses (Ar) of all atoms in a compound.

Question 3

What is a mole?

Answer 3

A specific number of atoms or molecules.
- Used to compare quantities of substances

6.02 × 10²³ particles (Avogadro’s number) of a substance

Question 4

How do you calculate the number of moles?

Answer 4

Moles = Grams / Rams

Moles = Mass (g) / Relative atomic mass

Question 5

What is the stoichiometry?

Answer 5

The ratio of moles of one substance to another in a reaction

Question 6

What is a limiting reactant?

Answer 6

The reactant that is completely used up first, which stops the reaction.

Question 7

What is concentration and how is it calculated?

Answer 7

When a substance is dissolved in water, it dissociated into its ions as does the water (into H+ and OH- ions)

Concentration can be given in g/dm³ or mol/dm³

Concentration = moles / volume of solution (dm³)

Question 8

How do you convert cm³ to dm³?

Answer 8

Divide by 1000 (e.g., 250 cm³ = 0.25 dm³)