Amount of Substance question
In the second experiment, another flask is used for a combustion reaction.
Method
• Remove all the air from the flask.
• Add 0.0010 mol of 2,2,4-trimethylpentane (C8H18) to the flask.
• Add 0.0200 mol of oxygen to the flask.
• Spark the mixture to ensure complete combustion.
• Cool the mixture to the original temperature.
The equation is
C8H18(g) + 12 O2(g) → 8 CO2(g) + 9 H2O(l)
Calculate the amount, in moles, of gas in the flask after the reaction.
I have sat here trying to do this for 20 minutes and don't get it at all. can someone please explain
This is what the mark scheme says:
M1 amount of CO2 formed in flask = 0.008 mol
Allow ECF from M1 to M2
M2 amount of gas in flask
= 0.0075 (O2) + 0.0080 (M1) = 0.0155 mol
Method
• Remove all the air from the flask.
• Add 0.0010 mol of 2,2,4-trimethylpentane (C8H18) to the flask.
• Add 0.0200 mol of oxygen to the flask.
• Spark the mixture to ensure complete combustion.
• Cool the mixture to the original temperature.
The equation is
C8H18(g) + 12 O2(g) → 8 CO2(g) + 9 H2O(l)
Calculate the amount, in moles, of gas in the flask after the reaction.
I have sat here trying to do this for 20 minutes and don't get it at all. can someone please explain
This is what the mark scheme says:
M1 amount of CO2 formed in flask = 0.008 mol
Allow ECF from M1 to M2
M2 amount of gas in flask
= 0.0075 (O2) + 0.0080 (M1) = 0.0155 mol
You have 20x the amount of O2 (at the start) compared to how many mol of C8H18 you start with.
1 mol of C8H18 uses up 12 mol of O2 - so 8x the amount of O2 compared to the amount of C8H18 must be left over, unreacted (20 - 12 = 8)
1 mol of C8H18 makes a total of 17 mol of gaseous products (8 + 9 = 17)
1 mol of C8H18 uses up 12 mol of O2 - so 8x the amount of O2 compared to the amount of C8H18 must be left over, unreacted (20 - 12 = 8)
1 mol of C8H18 makes a total of 17 mol of gaseous products (8 + 9 = 17)
Quick Reply
Related discussions
- amount of substance Alevel Chemistry
- Chemistry calculations tips pls?
- 🎀GYG-Academic victim to Academic weapon A-level 2024-2026🎀
- Enthalpy Question - help!
- How would I work this out
- Alevel Chemistry harder amount of substance questions
- in NEED of help with amount of substance
- Chemistry amount of substance question
- what are the answers to these questions?
- Igcse edexcel biology
- End of topic test chemistry level aqa
- Quantitative chemistry A level
- Chemistry AS levelAQA
- Chemistry - stoichiometry help
- is it too late?
- Year 12 struggling in A-Level Chemistry
- A level question help
- help with chossing bio or chem for a level
- A-level Chem Help please please please
- aqa gcse physics - waves word bank
Latest
Trending
Last reply 1 month ago
OCR AS Level Chemistry A Paper 2 - Depth ( 21th May 2024)
