Amount of substance

Question 1

Define relative atomic mass

Answer 1

the average mass of an atom over 1/12th of the mass of one atom of 12C.

Question 2

Define relative molecular mass

Answer 2

Average mass of a molecule over 1/12th of the mass of one atom of 12C.

Question 3

Define relative formula mass

Answer 3

the sum of the relative atomic masses of the atoms ina formula unit of a compound.

Question 4

working out relative atomic mass from isotopic abundance and isotopic mass.

Answer 4

isotopic abundance X isotopic mass
Add them up
Divide by 100

Question 5

unit for concentration

Answer 5

mol dm^-3

Question 6

formula for mol

Answer 6

mol= m/mr

Question 7

avogadro constant

Answer 7

6.02 X 10^23

number of particles found in one mol

Question 8

equation to find number of particles

Answer 8

mol X avogadro constant

Question 9

concentration formula

Answer 9

mol/volume(dm^-3)

Question 10

ideal gas equation

Answer 10

PV=nRT
p: pa
v: m^3
T: k

Question 11

degrees celcius to kelvin

Answer 11

degrees celcius + 273

Question 12

KPa to Pa

Answer 12

X 1000

Question 13

Cm^3 to m^3

Answer 13

cube root
divide by 100
cube it

Question 14

what is Empirical formula?

Answer 14

Empirical formula is the simplest whole number ratio of

atoms of each element in a compound.

Question 15

what is molecular formula?

Answer 15

Molecular formula is the actual number of atoms of each

element in a compound.

Question 16

how to work out empirical formula

Answer 16

percentage of each element/Ar

then divide all elements by the smallest number.

Question 17

How to work out molecular formula

Answer 17

work out empirical mass
divide molecular mass by empirical mass
multiply empirical formula by the answer from step above

Question 18

Atom economy formula

Answer 18

mr of desired product / sum of mr of all reactants X 100

Question 19

Law of conservation of mass

Answer 19

in a closed system, mass of the system remains constant over time and cannot change.

(substances can’t be added or removed)

Question 20

what is a spectator ion?

Answer 20

an ion that doesn’t change state or charge in reaction

Question 21

state symbols

Answer 21

metals (s)
Acids (aq)
certain elements e.g. oxygen, nitrogen,hydrogen (g)
Reactions in solutions (aq)

Question 22

percentage yield

Answer 22

(actual yield / theoretical yield) X 100