Amount Of Substance

Question 1

Define the mole

Answer 1

The mole is the amount of substance in grams that has the same number of particles as there are atoms in 12g of carbon-12

Question 2

Define relative atomic mass

Answer 2

The average mass of an atom compared to 1/12 of the mass of one atom of carbon-12

Question 3

Define relative molecular mass

Answer 3

The average mass of a molecule compared to 1/12 of the mass of one atom of carbon-12

Question 4

How do you convert from dm^3 to m^3

Answer 4

Divide by 1000

Question 5

If asked to round to significant figures, for which there are multiple in the question, how many do you round to

Answer 5

The smallest number rounded to in the question

Question 7

How do you find number of particles

Answer 7

Moles of substance x avogadros constant

Question 8

Define empirical formula

Answer 8

The simplist ratio of atoms of each element in the compound

Question 9

How do you calculate the concentration in g/dm^-3

Answer 9

Mr x concentration in mol dm^-3

Question 10

How do you calculate new diluted concentration

Answer 10

Original concentration x original volume
————————
New diluted volume

Question 11

What are 3 potential errors when using a gas syringe

Answer 11

1) gas escapes before bung is inserted

2) syringe sticks

3) some gases dissolve in water, so true amount of gas is not measured