Edexcel IGCSE Chemistry 1.35C Gas volume calculations
Practise gas volume calculations at rtp using 24 dm3 or 24000 cm3 per mole with balanced equations and yield data.
- Syllabus
- First assessment 2019
- Course
- Chemistry 4CH1
Exam points
- convert gas volume at rtp into moles using 24 dm3 or 24000 cm3 per mole
- use equation ratios to link reacting masses to gas volumes
- apply percentage yield or standard form when calculating large or industrial gas volumes
1.35C Gas volume calculations question 1
[Maximum number: 5]
This question is about octane (C8H18) which is produced in the gasoline fraction during fractional distillation of crude oil.
A car is driven at constant speed for 4.00 km .
The exhaust gases are collected and their volume at room temperature and pressure (rtp) is 5.02×105 cm3.
The exhaust gases include carbon dioxide and oxides of nitrogen.
The carbon dioxide is removed from the exhaust gases. The volume of the remaining gases at rtp is 2.96×105 cm3.
Show that the car produces less than 100 g of carbon dioxide per km.
[molar volume of carbon dioxide at rtp =24000 cm3 ]
- volume of carbon dioxide = 206000 cm3 / 2.06 x 10^5 cm3 / 206 dm3
- volume of carbon dioxide per km = 51500 cm3 / 5.15 x 10^4 cm3 / 51.5 dm3
- 51500 / 24000 = 2.15 mol
- Mr of carbon dioxide is 44
- mass of carbon dioxide per km = 94.4 g
Allow:
- 94-95 g
- error carried forward from an incorrect Mr
Marking guidance:
- Division by 4 can happen in the volume, mole, or mass steps.
- Correct answer of 94-95 g scores 5 marks.
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