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Edexcel IGCSE Chemistry 1.26 Relative formula mass

Practise finding Mr from Ar values and formula subscripts, including molecular formulae, brackets and atom counts in displayed formulae.

Syllabus
First assessment 2019
Course
Chemistry 4CH1

Exam points

  • calculate Mr by multiplying each Ar by the number of atoms in the formula
  • interpret brackets and subscripts in formulae
  • use molecular mass data and Ar to infer the number of atoms in a molecule

1.26 Relative formula mass question 1

[Maximum number: 1]

Crude oil is a mixture of hydrocarbons.

One of the hydrocarbons in the refinery gas fraction is an alkane with the structural formula CH3CH2CH2CH3\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}

Calculate the relative molecular mass (Mr)\left(M_{\mathrm{r}}\right) of this alkane.

Mr=M_{r}=
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