[hellokitty123]

Can someone please help me with these questions im confused
1.Find number of moles in following gaseous volumes:
a)240cm3 of H2
b)1200cm3 of methane CH4
 
2.What Volume is occupied by the gas:
a)4.0g of Argon (Ar)
b)17.6g of Carbon dioxide (CO2)
c)0.28g of Carbon Monoxide(C0)

Thanks  

[hellokitty123]

I've had a go at it is this right?

1.Find number of moles in following gaseous volumes:
a)240cm3 of H2
no of moles of H2 = mass/atomic mass = 240/2 = 120 moles
b)1200cm3 of methane CH4
no of moles of CH4 = mass/atomic mass=1200/16 = 75 moles
 
2.What Volume is occupied by the gas:
a)4.0g of Argon (Ar)
no of moles of Ar = mass/molecular mass= 4.0/39.9 = 0.10025 moles.
Vol = 0.10025 X 24 = 2.406dm3
 
b)17.6g of Carbon dioxide (CO2)
no of moles of CO2 = 17.16/44= 0.39 moles.
Vol= 0.39 X 24 = 9.36dm3
 
c)0.28g of Carbon Monoxide(C0)
no of moles of CO = 0.28/28 = 0.01 moles
vol = 0.01 X 24 = 0.24dm3
 

[movies]

Your answers for 2 look okay to me, but I didn't check the numbers.  (The set-up is right though).

For 1, however, you have assumed that the density of the gas is equal to 1, since you assume that 240 mL of H₂ weighs 240 g.  This is very unlikely as it would require incredibly high pressures.  I assume that all of the gasses are at standard temperature and pressure so you can apply the ideal gas law.  At STP an ideal gas has a volume of 24.4 L, which you used in question 2 correctly.  So apply that same reasoning to question 1 to figure out the number of moles.

[smilie_hugs]

For question 1, I thought accroding to mole map, when you want to find the mole for the gas, you always divide the volume by 24 dm3. Only for solids and liquids, then is divide by their RMM or RAM?  

[ssssss]

Your answers for 2 look okay to me, but I didn't check the numbers.  (The set-up is right though).

For 1, however, you have assumed that the density of the gas is equal to 1, since you assume that 240 mL of H₂ weighs 240 g.  This is very unlikely as it would require incredibly high pressures.  I assume that all of the gasses are at standard temperature and pressure so you can apply the ideal gas law.  At STP an ideal gas has a volume of 24.4 L, which you used in question 2 correctly.  So apply that same reasoning to question 1 to figure out the number of moles.

A correction.The Volume of gas at STP is 22.4 Lit not 24.4 lit.

Movies you wrote the Volume for SATP[standard ambient temperatusre and Pressure]

[ssssss]

For question 1, I thought accroding to mole map, when you want to find the mole for the gas, you always divide the volume by 24 dm3. Only for solids and liquids, then is divide by their RMM or RAM?  

First tell me what do you mean by RMM and RAM.

[smilie_hugs]

RMM [Relative Molecular Mass ]  is the mass of a molecule of a substance compared with 1/12th of the mass of an atom of carbon-12.

MAM [ Relative Atomic Mass] is the mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12.

The is a picture of the mole map. From what we have learnt, to find the moles of a gas, we move from 'Volume of gas, L' box to the 'Mole' box, so we divide by 22.4L [okay, so is not 24dm3, my aplogise].

By the way, I saw something.... The unit for H2 is in cm3 not dm3, so is correct to divide by the RAM, so, I'm sorry. But, if the unit is in dm3, I believe is divide by 22.4L

[ssssss]

I know this chart.You got any problem in understanding about moles than Post?

[movies]

Ssssss, you're right about the volume.  I must have made a typo.  Thanks for catching it.  (A scooby snack for you!)

For converting cm³ to dm³ you divide by 1000.

So 100 cm³ = 0.100 dm³