...finding volume (1 Viewer)

[teurino]

im unsure on how to find the volume of gas under specific conditions whether at 0^C (273K) or 25^C (298K).
if anyone can show me the procedure of answering such a question, it will be greatly appreciated.
e.g.
finding 60g of nitrogen gas

would this type of question be in a half-yearly/trial exam?

 

[namburger]

im unsure on how to find the volume of gas under specific conditions whether at 0^C (273K) or 25^C (298K).
if anyone can show me the procedure of answering such a question, it will be greatly appreciated.
e.g.
finding 60g of nitrogen gas

would this type of question be in a half-yearly/trial exam?

Yes but not that easy. Most questions will involve writing an equation, then figure out volume. It gets slightly harder with different mole ratios. Make sure you understand how to do them

N2 = 28 grams in 1 mol
Therefore
n = m/M
= 60/28
= 2.14 mols
In 60 grams of nitrogen gas, there is 2.14 mols

The formula is:
n = volume/ STP or n =volume/RTP

2.14 = V / 22.71 if it is at 0 degrees [and 24.79 at 25 degrees]
V = 48.66 litres

 

[teurino]

ok thnx for that namburger.
are there other formulas in relation to this sort of equation because my chem teacher is seriously bad at teaching chem

 

[namburger]

ok thnx for that namburger.
are there other formulas in relation to this sort of equation because my chem teacher is seriously bad at teaching chem

No i dont think so
Think of it logically is best to do these types of questions

E.G.
Calculate the volume of hydrogen produce at STP when 2.5 g of sodium reacts with water.

Write the BALANCED equation:
2Na(s) +3H2O(l) --> 2NaOH(aq) + H2(g)

There are 23 grams in 1 mol of sodium, so you need to find how many mols is 2.5
n = 2.5/23
= 0.10 mols of sodium

OK this is where you need to understand how to use ratios
IF 2 mols of sodium produces 1 mol of hydrogen, therefore 0.1 mols of sodium produces 0.05 mols of hydrogen

1 mol of gas = 22.79 litres at STP
so therefore 0.05 mols of hydrogen = 1.2L

Prob the typical type of question you would get in your exam. taken from conquering chem

 

[teurino]

thnx once again

 

[RiSeAgAiNSt2538]

these 2 things are written on the formulae sheet that u get in the HSC. ur teacher should have given u one at the start of yr11

 

[minijumbuk]

Hmm, there are only 2 conditions which you have to remember...Actually, you don't even have to remember it, because it's on the data sheet, which they give you...Kinda makes your life easier =P

Anyways, the 2 conditions you only ever use are:
Standard Temperature and Pressure (S.T.P) : 1 mole of gases occupy 22.71 L when conditions are at 0 degrees Celsius and 100 kPa
Room Temperature and Pressure (R.T.P) : 1 mole of gases occupy 24.79 L when conditions are at 25 degrees Celsius and 100 kPa.