0.28 g of a gaseous hydrocarbon was turned in excess oxygen. 0.88 g of carbon dioxide and 0.36 g of water were formed. The volume of 0.28 g of the hydrocarbon at 1.01 x10^5 Pa and 298 k is 123 cm^3. Work out the molecular formula of the hydrocarbon.

For a problem such as this, it is important to break down the question into the individual aspects and use some principles of chemistry that we have learnt previously to tackle the problem one step at a time.
Throughout this example I will be using my Whiteboard to demonstrate how any steps involving maths should be done and why they are important.
As with most numerical problems the information we need has been presented to us in the question, from the mass of the products we can calculate the number of moles of the products and reactants. (Prompting the student to recall how to do this and guiding them through one of the three required calculations). We can then use one of our chemistry principles to create an equation for the reaction based on our previous knowledge of combustion. (A short re cap can be included here if the student struggles). Using the number of moles of the reactant and product we can then find a ratio between the two and therefore use this to balance the symbol equation and correctly identify that the hydrocarbon in question is butene (C4H8). This can be confirmed by working in reverse and prompting the student to do this would help to know that they have fully engaged with the methodology in the question.

CB
Answered by Callum B. Chemistry tutor

2834 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

In organic chemistry, how can functional groups be easily identified and how can I memorise organic mechanisms?


Part 2: from the empirical formula, calculate the molecular formula if the molecular weight of the substance is 180 g/mol


Thinking about the periodicity of the period 3 elements, explain the structure of the Sodium and Phosphorus Oxides and the acid-base behaviour of the Oxide solutions.


What is meant by the term salt? And how would you confirm if the salt had chloride ions in?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning