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# Can someone explain these steps to me? watch

1. (question posted below) The question states this is math based, so you dont need to know what the equations are. I found the answer, but I don't understand the steps, so I was wondering why they are as they are.

To get A in terms of a, you should add the log of the factor between both units to the A parameter. So:

AkPa = ATorr + log10 (because 1 Torr = 0.133 kPa or 760 Torr = 101.325 kPa)

I dont understand why you do this? (why log and why not add it to B and C as well, why just A)

To change from log to ln, you should multiply A and B by ln(10). I dont understand why you do this, and why not multiply C as well.

2. (Original post by G A B R I E L)
...
If you're still stuck, drop me a PM, and I'll add some details to the thread sometime later today, otherwise not, as the Latex is going to be a pain in the ....
3. (Original post by G A B R I E L)
...
As you're not a maths student, I'll give you a full description. Lets start from:

I've changed the format slightly, but hopefully the meaning is clear.

Now we know that 760 Torr = 101.325 kPa

Or 1 Torr = 101.325/760 kPa.

So inverting that we have

1 kPa = 760/101.325 Torr.

So if is the pressure in kPa, then the pressure in Torr is

So substituting this into our equation we get:

And so, splitting the log:

Then:

And using the fact that -log x = log(1/x) we have:

Now lets do the temperature conversion. I think it's clear that

So we get:

All that remains is the log conversion. Now,

So substituting this into the left hand side of our equation:

Then multiplying through by ln 10 and grouping terms together we have:

So now just compare terms with the modern formula. I've had a bottle of wine, but hopefully that's correct. Do check it through, and any questions, get back to me.

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