Calculations

Question 1

moles =

Answer 1

mass(g)/Mr

Question 2

% yield =

Answer 2

actual amount/expected amount x 100

Question 3

Q (energy change) (J) =

Answer 3

m(g) x C (4.2) x DeltaT

Question 4

DeltaH (molar enthalpy change) (kJ/mol)=

Answer 4

-Q/mols

Question 5

Concentration (moldm-3) =

Answer 5

mols/volume(dm3)

Question 6

Charge (C) =

Answer 6

current (A) x time (s)

Question 7

mols of e- =

Answer 7

charge (C)/96500

Question 8

96500C =

Answer 8

1 faraday = 1 mol of electrons

Question 9

Relative atomic mass (Ar) =

Answer 9

SUM(isotope mass x isotope abundance) / 100

Question 10

Relative formula mass (Mr) =

Answer 10

SUMAr

Question 11

How to work out empirical formula

Answer 11

Divide each element by their relative atomic mass

Divide by the smallest number of mols

Question 12

Energy change (can be Q or DeltaH) =

Answer 12

SUM(bonds broken) - SUM(bonds made)

Question 13

volume of a gas (dm3) =

Answer 13

mols of gas x 24