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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: Bill Ding on October 13, 2012, 12:12:48 pm

Title: Chemistry Help
Post by: Bill Ding on October 13, 2012, 12:12:48 pm: Relevant Delta H's in Jg-1 and Jmol-1, calculate the mass of hydrogen require to supply the energy equivalent to a tank of petrol (Octane 60L)

I really don't know how to start this questions, Please help me. Thanks
Title: Re: Chemistry Help
Post by: Tonychet2 on October 13, 2012, 02:37:44 pm: id imagine the octane is at slc so 60/24.5 to get amount of mol then multiply by joules to get energy released from octane

then algebraically rearrange to get mol of hydrogen, and get mass
Title: Re: Chemistry Help
Post by: Nobby on October 13, 2012, 03:01:59 pm: Quote from: Tonychet2 on October 13, 2012, 02:37:44 pm
id imagine the octane is at slc so 60/24.5 to get amount of mol then multiply by joules to get energy released from octane

then algebraically rearrange to get mol of hydrogen, and get mass
At SLC octane is a liquid.
Title: Re: Chemistry Help
Post by: Aurelian on October 13, 2012, 03:56:06 pm: Yeah, all you need to do is find the energy you would release by burning 60L of octane, using the heat of combustion data at the back of the data booklet, and then do the reverse calculation figure out how much hydrogen would be required to supply the same amount of energy =)
Title: Re: Chemistry Help
Post by: Bill Ding on October 13, 2012, 07:17:22 pm: .
Title: Re: Chemistry Help
Post by: Tonychet2 on October 13, 2012, 09:28:53 pm: Quote from: Nobby on October 13, 2012, 03:01:59 pm
Quote from: Tonychet2 on October 13, 2012, 02:37:44 pm
id imagine the octane is at slc so 60/24.5 to get amount of mol then multiply by joules to get energy released from octane

then algebraically rearrange to get mol of hydrogen, and get mass
At SLC octane is a liquid.

its supposed to be a liquid because the databook gives the value of delta H for liquid octane, and regular fuel from the petrol pump is octane (liquid)

and 96g of hydrogen sounds right because remember hydrogen contains alot of energy because its very reactive ( think hydrogen bomb)
Title: Re: Chemistry Help
Post by: Nobby on October 13, 2012, 10:55:56 pm: Quote from: Tonychet2 on October 13, 2012, 09:28:53 pm
its supposed to be a liquid because the databook gives the value of delta H for liquid octane, and regular fuel from the petrol pump is octane (liquid)

and 96g of hydrogen sounds right because remember hydrogen contains alot of energy because its very reactive ( think hydrogen bomb)

Hydrogen bombs work on a nuclear fusion reaction, not combustion.

You can't use the molar volume at SLC to solve this problem as octane is a liquid at room temperature, not a gas. To determine the number of mole of octane you need to know the density.
Title: Re: Chemistry Help
Post by: Tonychet2 on October 13, 2012, 11:17:43 pm: Quote from: Nobby on October 13, 2012, 10:55:56 pm
Quote from: Tonychet2 on October 13, 2012, 09:28:53 pm
its supposed to be a liquid because the databook gives the value of delta H for liquid octane, and regular fuel from the petrol pump is octane (liquid)

and 96g of hydrogen sounds right because remember hydrogen contains alot of energy because its very reactive ( think hydrogen bomb)

Hydrogen bombs work on a nuclear fusion reaction, not combustion.

You can't use the molar volume at SLC to solve this problem as octane is a liquid at room temperature, not a gas. To determine the number of mole of octane you need to know the density.

woops ok i was wrong lol but with that info dont u have to assume u have to use slc? nothing else is given i think its a bad question
Title: Re: Chemistry Help
Post by: thushan on October 14, 2012, 08:15:02 am: Slc is for gases only, but octane is a liquid. You would be wanting the density of octane to convert its volume to a mass.