CHEMISTRY – GCSE EDEXCEL (HIGHER TIER) FINAL SPRING EXAMINATION [2025/2026] PAPER 1 – COMBINED SCIENCE OR SEPARATE SCIENCE (HIGHER) Atomic Structure, Bonding, Quantitative Chemistry, Organic and Physical Chemistry Applications

CHEMISTRY – GCSE EDEXCEL (HIGHER TIER)
FINAL SPRING EXAMINATION [2025/2026]
PAPER 1 – COMBINED SCIENCE OR SEPARATE SCIENCE (HIGHER)
Atomic Structure, Bonding, Quantitative Chemistry, Organic and Physical
Chemistry Applications




Empirical Formula

A formula with the lowest whole-number ratio of elements in a compound




Molecular Formula

A chemical formula that shows the number and kinds of atoms in a molecule, but not the
arrangement of the atoms eg C6H1206




Q. Compound X has the empirical formula of C2H6N, the Mr of compound X is 88, work out its
molecular formula

Mr of EP= 44

88/ 44 = 2

C4H12N2




Moles


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, amount of particles equal to Avogadro's constant (6.02x10^23)




Mole equation involving avogadro's constant

no. particles = moles x 6.02x10^23




Q. How many atoms in 5 moles of oxygen?

6.02x10^23 x 5 = 3.01x10^24

3.01x10^24 x 2 = 6.02x10^24




Q. How many atoms are there in 3.4 g of ammonia (NH3)? (Ar of N = 14, Ar of H = 1). Assume
Avogadro's constant is 6 x 10^23.

Mr = 17

Moles = 3.4/17 = 0.2

Molecules = 0.2 x 6x10^23 = 1.2x10^23

There are 4 atoms in each molecule so

1.2x10^23 x 4 = 4.8 x 10^23




Mole equation involving formula mass

Mass = Mr x Moles

(Massive Mr Mole)




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