ConceptConceptDocsDocuments

Edexcel A-Level Chemistry Arithmetic and Numerical Computation

Practise Edexcel A-Level Chemistry arithmetic and numerical computation through percentage composition, density, yield, molar-ratio and unit-conversion calculations.

Syllabus
Pearson Edexcel International Advanced Subsidiary/Advanced Level
Course
Chemistry XCH11/YCH11
Level
AS

Exam points

  • calculate percentage composition by mass from formulae, repeat units or molar masses
  • use density, volume and mass relationships across cm3, dm3, g and tonnes
  • work through yield, percentage error and molar-ratio calculations with correct rounding

Covered syllabus points

B.0.0—Units in calculationsB.0.1—Decimal and standard formB.0.2—Ratios, fractions and percentagesB.0.3—Estimating calculation resultsB.0.4—Powers, exponentials and logarithmsB.0.P—SI unit prefixes

B.0 Arithmetic and numerical computation question 1

[Maximum number: 3]

Many cars use fuels containing ethanol as well as hydrocarbons. The E numbers of these fuels show the percentage by volume of ethanol in the fuel. For example, an E5 fuel contains 5\% ethanol and 95\% hydrocarbons by volume.

Question (a)

(a)

A brand of E10 fuel contains 92.2% hydrocarbons and 7.80% ethanol by mass.

The energy density is the amount of energy released per kg of a fuel burned. The energy densities of the two components of this brand of fuel are shown.

 energy density of hydrocarbons =46.5MJ kg−1 energy density of ethanol =29.7MJ kg−1\begin{array}{ll} \text { energy density of hydrocarbons } & =46.5 \mathrm{MJ} \mathrm{~kg}^{-1} \\ \text { energy density of ethanol } & =29.7 \mathrm{MJ} \mathrm{~kg}^{-1} \end{array}
[ 3 ]

Question (i)

(i)

Calculate the mean energy density of this E10 fuel in MJ kg −1{ }^{-1}.

Give your answer to an appropriate number of significant figures.

[ 2 ]

Question (ii)

(ii)

The density of the E 10 fuel is 0.729 g cm−30.729 \mathrm{~g} \mathrm{~cm}^{-3}.

Calculate the mass of 1500 cm31500 \mathrm{~cm}^{3} of the fuel.

[ 1 ]
All question bank results loaded