Science · Grades 11–12
Chemistry · Formula sheet
Rules, conditions and small examples in one printable reference.
Remember this
Mass and amount of substance
Use compatible mass units: grams with grams per mole.
n = m/M
154/77 = 2
Molar concentration
Use solution volume in litres when the answer is in mol/L.
c = n/V
8/10 = 4/5
Atomic number and mass number
Atomic number counts protons; mass number counts protons plus neutrons.
neutrons = mass number − atomic number
62 − 27 = 35
Half-life models
This idealized model halves the expected amount after each equal half-life interval.
N = N₀(½)ᵏ after k half-lives
1792 ÷ 2^6 = 28
Solution dilution
Solute amount is conserved; V₂ is final solution volume, not added solvent volume.
C₁V₁ = C₂V₂
2 × 130 ÷ 0.4 = 650
Gas volume and temperature
Assume an ideal gas with constant pressure and amount; temperatures must be in kelvins.
V₁/T₁ = V₂/T₂
14 × 680 / 340 = 28
Model isotope averages
The given masses and abundances describe a hypothetical element; fractions sum to one.
average mass = Σ(fraction × isotope mass)
60 × 0.9 + 63 × 0.1 = 60.3
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.