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Edexcel IGCSE Chemistry 1.33 Formula calculations

Practise calculating empirical and molecular formulae from percentage composition, mass data and experimental results tables.

Syllabus
First assessment 2019
Course
Chemistry 4CH1

Exam points

  • divide percentage composition by Ar values, then simplify the mole ratio to an empirical formula
  • use heating or reduction data to calculate element masses before deriving an oxide formula
  • convert hydrated salt mass loss into moles of water and anhydrous salt to find x

1.33 Formula calculations question 1

[Maximum number: 5]

The table shows the structures of six organic compounds.

Table for Question 1.33 Formula calculations question 1 — Edexcel IGCSE Chemistry

Question (a)

(a)

Another compound, G, has this percentage composition by mass.

C=37.8%H=6.3%Cl=55.9%\mathrm{C}=37.8 \% \quad \mathrm{H}=6.3 \% \quad \mathrm{Cl}=55.9 \%

Show by calculation that the empirical formula of compound G is C2H4Cl\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}

[ 3 ]

Question (b)

(b)

The relative formula mass ( MrM_{\mathrm{r}} ) of G is 127

Determine the molecular formula of G .

[ 2 ]
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