Chemistry Topic 3

Question 1

What does conservation of mass mean?

Answer 1

• no atoms are lost or made during a chemical reaction —> same no. Of each element on the left and the right
• the mass of the product = mass of the reactants

(Reaction involves gases)

Question 2

Calculate the relative formula mass of Na2o:

Answer 2

(2x23) + (1x16) =62

Question 3

Avogadros constant:

Answer 3

• 6.02 x 10 ^23
• represents the number of atoms in the relative atomic mass of a substance in grams

Question 4

Formula for mass:

Answer 4

-Mass = Mr x mole

-Or rearrange to:
mass/Mr = moles

Question 5

What is concentration?

Answer 5

• a measure of how many dissolved particles are in a set volume of solution

Question 6

Equation for concentration:

Answer 6

Concentration = mass/volume

Question 7

What is the limiting reactant?

Answer 7

The reactant that will run out first

Question 8

What is the excess?

Answer 8

The reactant that is left over