Simple Mole Conversions: Calculating Mass of Methane (CH4) at STP

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In summary: However, if you are only given an approximation, you can still use the formula.The mass of methane is 1.44 kg at standard temperature and pressure.
  • #1
jacksonpeeble
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What is the mass of methane (CH4) if it occupies 32.3 L at STP?

We got a whole bunch of these problems on a worksheet with minimal instruction. If somebody could please aid me in solving this one, then I should be able to solve the rest.

I assume that I must first find the masses of the individual components...

C = 12.0107 * 1 = 12.0107
+H = 1.00794 * 4 = 4.03176
---------------------------
16.0483

Then I honestly don't know what to do... I don't want the answer; I'd just really appreciate if somebody could show me how to do this. I tried searching for a guide online, but none of them really had what I was looking for.

Thank you!
 
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  • #2
STP means Standard Temperature and Pressure.
Use PV=nRT.
 
  • #3
symbolipoint said:
STP means Standard Temperature and Pressure.

Which - sadly - doesn't mean anything.

jacksonpeeble: you have to know what temperature and pressure your teacher want's you to use as STP, as this thing is not precisly defined.
 
  • #4
1 mole = 22.4 L at STP according to my teacher.

What do I do with that equation? I assume that it is the same as (Pressure x Volume)/(Temperature x Moles) = R, but how is this applied?

Thanks for the help so far, though!
 
  • #5
and then let 32.3 L = x mol at STP. you can get x. do you know how to do now? (forget that equation...for this problem, it is useless.)
 
  • #6
jacksonpeeble said:
it occupies 32.3 L at STP?

jacksonpeeble said:
1 mole = 22.4 L at STP

How many moles of methane then?

What is molar mass of methane?

While PV=NRT is the general method, that will give exactly the same results if applied correctly, you can solve the question using just the information quoted above.
 
  • #7
Ah, so it's essentially just a ratio?

So it would be 32.3/22.4 = 1.44 Moles?
 
  • #8
Now moles to mass and you are ready.

Note, that if you will be given exact pressure and/or temperature value you will have to use PV=nRT equation.
 

1. What is a mole?

A mole is a unit of measurement used in chemistry to represent the amount of a substance. It is defined as the amount of a substance that contains the same number of particles as there are atoms in 12 grams of carbon-12.

2. How do you convert moles to grams?

To convert moles to grams, you need to know the molar mass of the substance. This can be found on the periodic table. Then, multiply the number of moles by the molar mass to get the mass in grams.

3. How do you convert moles to molecules?

To convert moles to molecules, you need to use Avogadro's number, which is approximately 6.02 x 10^23. Multiply the number of moles by Avogadro's number to get the number of molecules.

4. How do you convert grams to moles?

To convert grams to moles, you need to know the molar mass of the substance. Then, divide the mass in grams by the molar mass to get the number of moles.

5. How do you convert molecules to moles?

To convert molecules to moles, you need to use Avogadro's number. Divide the number of molecules by Avogadro's number to get the number of moles.

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