# Combustion question chemistry help

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#1
https://imgur.com/gallery/263l7gD
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4 weeks ago
#2
(Original post by iqraali2002)
https://imgur.com/gallery/263l7gD

The volume of all gases is proportional to the moles.

So the equation can be thought of as:

2 vol of hydrocarbon + 7 vol of oxygen ==> volumes of products

This means that 100cm3 represents 2 volumes, i.e. 1 volume is 50cm3.

The reactants disappear and the products appear.

So, reduce the total volume by the volume of the reactants and increase the volume by the volume of the products. The overall change is the answer.
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#3
(Original post by charco)
The volume of all gases is proportional to the moles.

So the equation can be thought of as:

2 vol of hydrocarbon + 7 vol of oxygen ==> volumes of products

This means that 100cm3 represents 2 volumes, i.e. 1 volume is 50cm3.

The reactants disappear and the products appear.

So, reduce the total volume by the volume of the reactants and increase the volume by the volume of the products. The overall change is the answer.
Aah okay so the total change is therefore 50cm^3 thanks. Do you know how to work out part b? I’m so confused
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4 weeks ago
#4
(Original post by iqraali2002)
Aah okay so the total change is therefore 50cm^3 thanks. Do you know how to work out part b? I’m so confused
The second part is just simple algebra.

Construct an expression for each stage.
The sodium hydroxide removes all carbon dioxide and the water has no volume (it's a liquid)

Total intial volume = total oxygen + hydrocarbon
Final volume = excess oxygen + carbon dioxide
Final volume after NaOH = excess oxygen
Total oxygen = excess oxygen + oxygen reacted

Use the x and y values to construct simultaneous equations.
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