chemistry equations Flashcards
R.A.M (Ar) =
∑(isotopic mass x % abundancy)/ 100 (no units)
R.M.M (Mr) =
∑Ar of all atoms in chemical formulae (no units)
= Mr
Molar mass (M)/ g mol-1
Moles/ mol =
mass (g)/ M (g mol-1)
Moles of a gas @ R.T.P/ mol =
volume (dm3)/ 24 (dm3 mol-1)
Concentration/ mol dm-3 =
moles (mol)/ volume (dm3)
Concentration/ g dm-3 =
mass (g)/ volume (dm3)
Concentration/ g dm-3 =
concentration (mol dm-3) x M (g mol-1)
Using the molar gas volume @ RTP: moles (mol)
= volume (dm3)/ Vm
where RTP =
molar gas volume =
room temperature & pressure (20oC & 101 kPa) Vm = 24.0 dm3 mol-1
Ideal Gas Equation:
pV = nRT
where p = V = n = mol R = T =
pressure/ kPa or Pa
volume/ dm3 or m3 moles/
molar gas constant 8.314 J mol-1 K-1
temperature/ K
% yield =
actual yield (g) / theoretical yield (g) x 100
% atom economy =
mass of desired product from balanced equation / total mass of reactants from balanced equation
x 100
ΔrH =
∑E(bonds broken)- ∑E(bonds formed)
where ΔH = enthalpy change of reaction/ kJ mol-1 E = bond enthalpy/ kJ mol-1
ΔrH =
∑(ΔfH products) - ∑(ΔfH reactants)
where ΔrH = enthalpy change of reaction/ kJ mol-1 ΔfH = enthalpy change of formation/ kJ mol-1
ΔrH =
∑(ΔcH reactants) - ∑ ΔcH(products)
where ΔrH = enthalpy change of reaction/ kJ mol-1 ΔcH = enthalpy change of combustion/ kJ mol-1
q =
where q = m= c = T=
mcΔT
heat transferred to or from water/ J
mass of water/ g
specific heat capacity of water/ 4.18 J g-1 K-1 Δ
change in temperature in water/ K
ΔH =
enthalpy topic
ΔH = q/n
Rate of reaction =
gradient = change in Y /
change in X
Equilibrium constants for the general reaction
: aA + bB ⇌ cC + dD
Kc =
[C]c[D]d / [A]a[B]b
General formula of an alkane =
CnH2n+2
General formula of an alkene =
CnH2n
General formula of an alkyl group =
CnH2n+1
k =
where k = rate constant/
ln2/ t1/2
s-1 t1/2 = half-life/ s
k =
where k = rate constant/ various rate
A e-Ea/RT , taking natural logs, ln k = -Ea/ RT + ln A
k = A = Ea = R = T =
k = rate constant/ various units A = pre-exponential factor/ same units as k Ea = activation energy/ J mol-1 R = gas constant = 8.314 J mol-1 K-1 T = temperature/ K
Equilibrium gas constant, Kp, for the general reaction:
aA + bB ⇌ cC + dD
Kp =
p(C)c x p(D)d / p(A)a x p(B)b
