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# How Much Hydrogen In A Litre Of Diesel?

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Hi,

As the title suggests, I'd like to know how much hydrogen there is in a litre of diesel.

Thanks!

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Hi,

As the title suggests, I'd like to know how much hydrogen there is in a litre of diesel.

Thanks!

Looks like homework, so forgive me if I don't just give you an answer.

But I don't mind helping a bit if I can. If you take a C16 alkane as typical, you won't be far off. Diesel is a complex mixture of hydrocarbons, mostly in the range C12 - C20, and largely paraffinic (i.e mostly alkanes). So you can get the %wt from that using the well-known formula for alkanes with n carbon atoms.

Then all you need to know is the density of diesel, which is a bit over 0.8, say 0.83 kg/l.

Do you want to try that and see how you get on?

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Looks like homework, so forgive me if I don't just give you an answer.

But I don't mind helping a bit if I can. If you take a C16 alkane as typical, you won't be far off. Diesel is a complex mixture of hydrocarbons, mostly in the range C12 - C20, and largely paraffinic (i.e mostly alkanes). So you can get the %wt from that using the well-known formula for alkanes with n carbon atoms.

Then all you need to know is the density of diesel, which is a bit over 0.8, say 0.83 kg/l.

Do you want to try that and see how you get on?

Ha. I'm 40. I'm just trying to figure something out, but I'm way out of my industry here. The only answers that Google throws up is stuff about "moles", and stuff like moles=AMUs=grams=moles and so on.

If the average diesel molecule is something like C10H20, then is the mass of diesel 66.66% H and 33.33% C?

Or, as the atomic mass of carbon is 12.0107 compared to hydrogen's 1.0079, does that mean that the Carbon-Hydrogen mass ratio is roughly 12:1?

Thanks

Edited by FalconHoof
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I was going to say half of it is hydrogen but none of it is free as it is all bonded to oxygen in one way or another, aromatics or non-aromatics. How far off am I? :pardon:

I wasn't quizzing, I genuinely want to know.

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I wasn't quizzing, I genuinely want to know.

Oh well, in that case I will tell you as I happen to be an expert on diesel fuels. At least, I should be seeing that I burn tons of it every year in "my" ship.

Hydrogen makes up about  13% by weight of diesel fuel ASTM D975 the specific gravity is 0.85.

You can work out the number of grams in a liter by yourself, it isn't difficult.

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Oh well, in that case I will tell you as I happen to be an expert on diesel fuels. At least, I should be seeing that I burn tons of it every year in "my" ship.

Hydrogen makes up about  13% by weight of diesel fuel ASTM D975 the specific gravity is 0.85.

You can work out the number of grams in a liter by yourself, it isn't difficult.

Why not just tell me?

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Hydrocarbon Diagram

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Hydrocarbon Diagram

That means nothing to me I'm afraid.

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It doesn't mean anything to VictorM either

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Why not just tell me?

The answer is about 110 grams of hydrogen per liter of diesel fuel.

You should try to see how that number is derived from the information I already gave you, if you are really interested in this.

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That means nothing to me I'm afraid.

Well, Diesel is a mixture of hydrocarbons thus that diagram is the Lewis diagram of different hydrocarbons in diesel, you can calculate from the different hydrocarbons the amount of hydrogen in Diesel.

Some Common Diesel Hydrocarbons

n-Butylcyclohexane Naphthene C10H20

n-Pentylcyclopentane Naphthene C10H20

Decane n-Paraffin C10H22

Anthracene Aromatic C14H10

"Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes). The average chemical formula for common diesel fuel is C12H24, ranging approximately from C10H20 to C15H28.""

Hydrogen = 1 atomic mass

Carbon = 12 atomic mass

So, C12H24  makes 1* 24  / ((12 * 12) + 1 * 24 ) = ‭14.2% Hydrogen in the most common diesel formula.

Edited by VictorMedvil
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Ha. I'm 40. I'm just trying to figure something out, but I'm way out of my industry here. The only answers that Google throws up is stuff about "moles", and stuff like moles=AMUs=grams=moles and so on.

If the average diesel molecule is something like C10H20, then is the mass of diesel 66.66% H and 33.33% C?

Or, as the atomic mass of carbon is 12.0107 compared to hydrogen's 1.0079, does that mean that the Carbon-Hydrogen mass ratio is roughly 12:1?

Thanks

Haha OK, sorry to muck you about but we do sometimes get schoolkids trying to cheat on their homework on these forums!

Just to go through the chemistry while we're at it, in case of other readers, a C16 alkane molecule will have 16 carbon atoms, each with atomic mass of 12. The formula I referred to is the one by which the the number of H atoms in an alkane (paraffinic hydrocarbon) with n C atoms is always 2n + 2. So in this case 2x16 +2 =34 hydrogen atoms each of which has a mass of 1.  So the mass of the molecule is 16x12 + 34 = 192 + 34 = 226. So the proportion by weight that is H will be 34/226 i.e. 15%.

A litre of diesel has a mass of about 0.8kg, so the proportion of that which is H is 0.12kg or 120g, approx.

I looked up another source which told me the proportion of H in diesel is typically 14%, so the estimate is not too far out. You will get a range of values from the literature, I'm sure, as the composition of diesel is not fixed, but it's going to be of this order.

If you go to marine diesel fuel (MDF) you may get a lower number, as sometimes this contains more aromatic hydrocarbons than automotive diesel, on the basis that marine engines are more tolerant to poor cetane number than truck engines.

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Well, Diesel is a mixture of hydrocarbons thus that diagram is the Lewis diagram of different hydrocarbons in diesel, you can calculate from the different hydrocarbons the amount of hydrogen in Diesel.

Some Common Diesel Hydrocarbons

n-Butylcyclohexane Naphthene C10H20

n-Pentylcyclopentane Naphthene C10H20

Decane n-Paraffin C10H22

Anthracene Aromatic C14H10

"Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes). The average chemical formula for common diesel fuel is C12H24, ranging approximately from C10H20 to C15H28.""

Hydrogen = 1 atomic mass

Carbon = 12 atomic mass

So, C12H24  makes 1* 24  / ((12 * 12) + 1 * 24 ) = ‭14.2% Hydrogen in the most common diesel formula.

Nice post. I knew you could do better with a little needling.

We use a flat 13% for hydrogen content as recommended by ASTM standards and for calculating the amount of carbon in our fuel for the environmental impact statement.

With 13% hydrogen, the rest works out to 740 grams carbon + 1970 grams oxygen (in combustion) = 2710 CO2/liter diesel

We are in the process of switching the turbines to LNG.

Edited by OceanBreeze
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Well, Diesel is a mixture of hydrocarbons thus that diagram is the Lewis diagram of different hydrocarbons in diesel, you can calculate from the different hydrocarbons the amount of hydrogen in Diesel.

Some Common Diesel Hydrocarbons

n-Butylcyclohexane Naphthene C10H20

n-Pentylcyclopentane Naphthene C10H20

Decane n-Paraffin C10H22

Anthracene Aromatic C14H10

"Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes). The average chemical formula for common diesel fuel is C12H24, ranging approximately from C10H20 to C15H28.""

Hydrogen = 1 atomic mass

Carbon = 12 atomic mass

So, C12H24  makes 1* 24  / ((12 * 12) + 1 * 24 ) = ‭14.2% Hydrogen in the most common diesel formula.

Well, maybe YOU can calculate it; past basic arithmetic I'm not a maths person.That's for putting the answer at the end anyway. Someone on here reckons it's ~11% though.

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Nice post. I knew you could do better with a little needling.

We use a flat 13% for hydrogen content as recommended by ASTM standards and for calculating the amount of carbon in our fuel for the environmental impact statement.

With 13% hydrogen, the rest works out to 740 grams carbon + 1970 grams oxygen (in combustion) = 2710 CO2/liter diesel

We are in the process of switching the turbines to LNG.

I thought there wasn't any oxygen in diesel..?

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The answer is about 110 grams of hydrogen per liter of diesel fuel.

You should try to see how that number is derived from the information I already gave you, if you are really interested in this.

Thanks. I'm not going to be dealing with this sort of thing again, otherwise I would have learned formulas etc., but as it's a one-off I just wanted to get the answer.

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Haha OK, sorry to muck you about but we do sometimes get schoolkids trying to cheat on their homework on these forums!

Just to go through the chemistry while we're at it, in case of other readers, a C16 alkane molecule will have 16 carbon atoms, each with atomic mass of 12. The formula I referred to is the one by which the the number of H atoms in an alkane (paraffinic hydrocarbon) with n C atoms is always 2n + 2. So in this case 2x16 +2 =34 hydrogen atoms each of which has a mass of 1.  So the mass of the molecule is 16x12 + 34 = 192 + 34 = 226. So the proportion by weight that is H will be 34/226 i.e. 15%.

A litre of diesel has a mass of about 0.8kg, so the proportion of that which is H is 0.12kg or 120g, approx.

I looked up another source which told me the proportion of H in diesel is typically 14%, so the estimate is not too far out. You will get a range of values from the literature, I'm sure, as the composition of diesel is not fixed, but it's going to be of this order.

If you go to marine diesel fuel (MDF) you may get a lower number, as sometimes this contains more aromatic hydrocarbons than automotive diesel, on the basis that marine engines are more tolerant to poor cetane number than truck engines.

Ha, fair enough. I'm actually working with a habitat restoration project, and I've been asked to research this without telling anyone why and it's the least favourite task I've had since joining! I don't suppose there's any chance you could let me know the grams of hydrogen in petrol & kerosene too..?

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