Topic 3 Quantitative Chemistry

Question 1

What is the law of conservation of mass?

Answer 1

The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

Question 2

Write a balanced equation of magnesium reacting with hydrochloric acid.

Answer 2

Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)

Question 3

Define relative atomic mass and relative formula
mass.

Answer 3

RAM - average mass of atoms in an element taking into account masses and abundance of its isotopes, relative to 12C.
RFM - sum of RAM’s of all atoms in the formula.

Question 4

What is the relative formula mass of:
A) CaF2
B) C6H12O6

Answer 4

CaF2
- (Ar values: Ca = 40, F = 19)

C2H12O6
- (Ar values: C = 12, H = 1, O = 16)

(12 x 6) + (1 x 12) + (16 x 6) = 180

Question 5

The following reaction occurs in a test tube under a Bunsen
Burner:
4 MgO(s) + CH4(g) → 4 Mg(s) + 2 H2O(g) + CO2 (g)
The carbon dioxide and water escape from the test tube.
Use the equation to explain why.

Answer 5

They are both gases

Question 6

What is Avogadro’s constant?

Answer 6

The number of atoms, molecules or ions in a mole of a given substance.

The value of the constant is 6.02 x 10(23)

Question 7

What is the formula that links mass, molecular mass
and moles together

Answer 7

Mass = Mr x Moles

Question 8

What is the mass of 20 moles of calcium carbonate, CaCO3

Answer 8

Mass = Mr x Moles

Mr = 100

100 x 20 = 2000 g

Question 9

SEE CARDS IN DRIVE