Equations

Question 1

n (mols) =

Answer 1

mass(g) / Mr (g mol-1)

Question 2

molar volume (Vm) =

Answer 2

24 dm3 mol-1 at RTP

so Vm= 24 = volume in dm3/mol

Question 3

concentration (mol) =

Answer 3

conc = mol/vol in dm3

Question 4

V1 x M1/n1 (volume x molar conc / coefficient in equation) =

Answer 4

V2 x M2/V2

Question 5

percentage uncertainty =

Answer 5

(uncertainty x no. measurements) / measurement made x100

Question 6

percentage yield =

Answer 6

(actual yield / theoretical yield) x100

Question 7

E⦵cell =

Answer 7

E⦵cell = E⦵red - E⦵oxi
or
E⦵cell = right - left

Question 8

Q=

Answer 8

Q = mCΔT

Q= Energy (J)
m= mass of water (g)
C= specific heat capacity of water (4.13 J g-1 k-1)
ΔT= initial - final temperature

Question 9

pV=

Answer 9

pV=nRT

p= Pressure (Pa)
V= Volume (m3)
n= mols
R= Gas Constant (8.31)
T= Temperature (K)

Question 10

ΔG =

Answer 10

ΔG = ΔH - ΔSsystem

ΔG = -RTlnk

ΔG is measured in kJ mol-1

Question 11

Ka =

Answer 11

Ka = [H+] [A-] / [HA]

Ka = 10 (-pKa)

Question 12

pKa =

Answer 12

pKa = -lg Ka

Question 13

pH =

Answer 13

pH = -lg [H+]

Question 14

when ΔG = 0 ,

Answer 14

when ΔG = 0

ΔH = TΔSsystem

Question 15

ΔSsystem =

Answer 15

ΔSsystem = E(ΔS products) - E(ΔS reactants)

ΔSsystem = ΔH / T

Question 16

T =

Answer 16

T = ΔH / ΔSsystem

Question 17

ΔStotal =

Answer 17

ΔStotal = ΔSsystem + ΔSsurroundings

ΔS is measured in J mol−1 K−1

Question 18

ΔSsurroundings =

Answer 18

ΔSsurroundings = -ΔH / T

Question 19

when ΔStotal = 0 , then

Answer 19

ΔStotal = 0, then

ΔStotal ∝ lnK

0 = ΔSsystem - ΔH/T

Question 20

ΔH =

Answer 20

ΔH = -Q/mols

Question 21

ΔlatticeH =

Answer 21

ΔlatticeH = ΔatH [X(s)] + IE(1)[X(g)] + ΔatH [1/2 Y2(g)] + Eea(1)[Y(g)] + ΔfH[XY(s)]

ΔlatticeH = ΔhydH [X+(g)] + ΔhydH [Y-(g)] - ΔsolH[XY(s)]

Question 22

bond enthalpy (ΔreactionH) =

Answer 22

bond enthalpy (ΔreactionH) = EΔH(bonds broken) - EΔH(bonds made)

Question 23

[H+] =

Answer 23

[H+] = 10 (-pH)

[H+] = (Ka x [HA]) / [A-]

Question 24

Kw =

Answer 24

Kw = [H+] [OH-]

Question 25

pKw =

Answer 25

pKw = -lg Kw

Question 26

k = (Arrhenius equation)

Ea =

A =

T =

Answer 26

k = Ae(-Ea / RT) where -Ea/RT is a power

Ea = -RT ln ( k/A ) not a power here

A = k / e( -Ea/RT) to the power of

T = Ea / -R ln (k/A) not a power

Question 27

Kp =

Answer 27

Kp = (PC)c x (PD)d / (PA)a x (PB)b

Question 28

Kc =

Answer 28

Kc = [products]b / [reactants]a

Question 29

PA =
xA =
xAP =

Answer 29

PA = xAP 
xA = mols of gas A / total mols of gas
xAP = xA multipled by the total pressure in atm