Ask Singapore Homework?

Upload a photo of a Singapore homework and someone will email you the solution for free.



Question

secondary 3 | A Maths
One Answer Below

Anyone can contribute an answer, even non-tutors.

Answer This Question
Clara
Clara

secondary 3 chevron_right A Maths chevron_right Singapore

Why

Date Posted: 2 years ago
Views: 257
J
J
2 years ago
Only carbon dioxide and water are formed.

The options indicate that the gas contains carbon and hydrogen atoms only.

In other words, it is a hydrocarbon.

Let the chemical formula of the hydrocarbon be CxHy.

Write the chemical equation, keeping in view that CxHy ≡ 5 O2

CxHy + 5O2 → y/2 H2O + xCO2

The equation must be balanced. Number of oxygen atoms on both sides must be the same.


5 × 2 = y/2 × 1 + x × 2

10 = ½y + 2x

20 = y + 4x

y = 20 - 4x


Now the options indicate that the gas is an alkane. Remember that alkanes have general formula CnH(2n+2)

So y = 2x + 2

Solving for x,

20 - 4x = 2x + 2
6x = 18
x = 3


y = 2(3) + 2 = 8

C3H8 (propane) is the answer.

See 1 Answer

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Ismail Putra
Ismail Putra's answer
14 answers (Tutor Details)
1st
Hope this helps :)