Edexcel IAL Chemistry A2 Substitution into Equations

Edexcel IAL Chemistry A2 Substitution into Equations
Pearson Edexcel International Advanced Subsidiary/Advanced Level in Chemistry, Issue 1, September 2017Chemistry XCH11/YCH11

Practise Edexcel IAL Chemistry substitution into algebraic equations through enthalpy, energy density, concentration and multi-step mole calculations.

How this is tested

  • Substitute gradients into relationships such as gradient = -H/R and report enthalpy with correct units.
  • Combine density, percentage by volume and molar mass steps to calculate moles in multi-stage problems.
  • Use previous calculated values in energy or electrode equations, carrying units through to the final answer.

Question 19(c)(iii)

[Maximum number: 4]

In recent years, there have been health and safety concerns over "liquitabs". These are capsules which contain concentrated liquid detergents.

The soluble packaging breaks down upon contact with water during a laundry cycle to release the detergent.

Some liquitabs are small and colourful, which makes them attractive to young children who may be tempted to put them in their mouth or play with them. When moist, liquitabs can burst in a child's hand, potentially irritating the eyes and skin. They can also dissolve quickly and may burst in a child's mouth in a very short period of time. This allows the contents to escape quickly and if swallowed can cause severe breathing difficulties.

In liquitab detergents, glycerol is added to the poly(ethenol).

glycerol

glycerol

Glycerol is added to the polymer at 0.110%, by volume.

Calculate the number of moles of glycerol added to 1 tonne of poly(ethenol).
Data: 1 tonne =1000 kg=1000 \mathrm{~kg}
density of glycerol: 1.26 g cm−31.26 \mathrm{~g} \mathrm{~cm}^{-3}
density of poly(ethenol): 1.19 g cm−31.19 \mathrm{~g} \mathrm{~cm}^{-3}