A-Level Chemistry Equations

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  • Created by: JosephPHS
  • Created on: 31-01-23 00:33
Ar from isotopes
Ar = Σ(% of isotope X relative mass)
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Mass of an atom
Ar
Mass (g) = ----------
L

L = Avogadro's constant 6.022 X 10²³
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Moles (Solid)
Mass
Mol = -------------
Mr
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Moles (Liquid)
Mol = Volume (dm³) X Conc.
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Moles (Gas ⦵)
Volume (dm³)
Mol = ----------------
24

Any gas under ⦵ has a volume of 24 dm³ mol⁻¹
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Moles (Avagadro)
Particles
Moles = -------------
L
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Ideal Gas Equation
PV = nRT

P = Pressure (kPa)
V = Volume (m³)
n = Moles
R = Ideal Gas constant (8.31 J K⁻¹ Mol⁻¹)
T = Temperature (K (= C + 273)
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% Yield
Actual Yield
% Yield = ------------------ X 100
Theoretical Yield
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Atom Economy
Mr of Desired
Product
Atom Economy = --------------- X 100
Mr of all
Reactants
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Density
Mass
Density = -----------
Volume
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% error
Error
% error = ------------ X 100
Reading

Error =
Theoretical value - Experimental Value
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Rate
Change in conc.
Rate = ---------------------
Time
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Rate (Order)
Rate = k[A]ˣ[B]ʸ
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Arrhenius Equation

(Calculating effect of changing environment on rate)
k = Ae⁽⁻ᴱᵃ/ᴿᵀ⁾
k = rate constant
A = frequency factor (No. and orientation of collisions)
e = on calc.
Ea = activation energy (unit = R*T)
R = universal gas constant
T = Temperature (K)
e⁽⁻ᴱᵃ/ᴿᵀ⁾ = fraction of collisions with Ea (AKA f)
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Arrhenius Equation
(Variable and Units)
k = Rate constant
A = Frequency Factor (Frequency of Collisions)
e = Mathematical Constant (on calc)
Eₐ = Activation energy (J)
R = Gas constant (8.31 J K⁻¹ mol⁻¹)
T = Temperature (K)
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Bond Energy
ΔH = Σ(bonds broken)-Σ(bonds made)

ΔH = Enthalpy change
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Enthalpy of Combustion
ΔH =ΣΔH(reactants)-ΣΔH(products)
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Enthalpy of Formation
ΔH =ΣΔH(products)-ΣΔH(reactants)
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Energy change
q = mcΔT

q = energy (J)
m = mass (g)
c = specific heat capacity (J g⁻¹)
ΔT = Temperature change (K)
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Kc (eq constant - conc.)
∏[products]ᵐᵒˡᵉˢ
Kc = ------------------
∏[reactants]ᵐᵒˡᵉˢ

∏ means product and is the multiplication equivalent of ∑
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Kp (eq constant - pressure)
∏(p products)ᵐᵒˡᵉˢ
Kp = ------------------
∏(p reactants)ᵐᵒˡᵉˢ

p = partial pressure
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Mole Fraction
Moles of species
Mole fraction = -------------------
Total moles
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Partial Pressure
Partial Pressure =
Mole Fraction X Total Pressure
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Gibbs free energy

(Feasability of reaction)
ΔG=ΔH-TΔS

ΔS = Entropy Change
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Entropy Change (ΔS)
ΔS = Σ(S products)-Σ(S reactants)
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pH (strong acid)
pH = -log₁₀[H⁺]
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[H⁺] (strong acid)
[H⁺] = 10⁻ᵖᴴ
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pH (Strong base)
Kw and [OH⁻] given in the question
Kw = [H⁺][OH⁻]
Kw
[H⁺] = -------
[OH⁻]
pH = -log₁₀[H⁺]
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pH (Weak acid)
Ka = ([H⁺] X A⁻) / HA
In weak acids [H⁺]≈[A⁻]
So
[H⁺]² OR [A⁻]²
Ka = ---------------
[HA](start)
Rearrange to give [H⁺] = √(Ka X [HA(start)])
Then use -log₁₀ [H⁺] to calculate pH
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pH (Weak base)
Kb = ([OH⁻] X [BH⁺]) / B
Assuming [OH⁻] ≈ [BH⁺]
[OH⁻] = √(Kb X [B])
pH = 14 - (-log₁₀ [OH⁻])
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pKa
Pka = -log₁₀(Ka)
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Ka
(From pKa)
Ka = 10⁻ᵖᴷᵃ
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Kw (Ionic product of water)
Kw = [H⁺][OH⁻]
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Ka
[H⁺][A⁻]
Ka = --------------
[HA]

A⁻ = Dissociated acid
HA = Undissociated acid
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New conc. of solution upon addition of solute
moles of solute
New conc. = ------------------- X 1000
new total volume of
solution
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Other cards in this set

Card 2

Front

Ar
Mass (g) = ----------
L

L = Avogadro's constant 6.022 X 10²³

Back

Mass of an atom

Card 3

Front

Mass
Mol = -------------
Mr

Back

Preview of the back of card 3

Card 4

Front

Mol = Volume (dm³) X Conc.

Back

Preview of the back of card 4

Card 5

Front

Volume (dm³)
Mol = ----------------
24

Any gas under ⦵ has a volume of 24 dm³ mol⁻¹

Back

Preview of the back of card 5
View more cards

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