Number of moles and molecules

In summary: Please provide a calculation instead of just a number.n=PV/RTP=1.5x10^6V=0.8x10^-3T=300 kR=8.31n=(1.5x10^6 x 0.8x10^-3)/8.31x300)1200 / 2493 = 0.481347774This is correct.
  • #1
nafo man
13
0

Homework Statement


A gas cylinder contains of 0.8 × 10^-3 m^3 volume oxygen.the temperature of the oxygen is 320k,and the pressure of the gas is 1.5 × 10^6 Pa.how to calculate:
number of moles and molecules of Oxygen?
mass of Oxygen if its molar mass is 32.0 × 10^-3 kg ?
The mass of a single molecule of gas?

Homework Equations



PV = nRT → n=PV/RT

The Attempt at a Solution


PV = nRT → n=PV/RT
p=1.5 × 10^6 Pa
T=320 k
V= 0.8 × 10^-3 m^3 = 0.8 litre.
Is the value of the R is 0.082L atm/mol K ?
so n= 1.5 x10^6 x 0.8/0.082 x 320

n=5 716.46341
is this the right way for part one?
thanks
 
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  • #2
You are on the right track, but R value is wrong. Please check wikipedia page on gas constant and select R value that fits all units you use. Alternatively, convert all data to units of your R constant.
 
  • #3
i am not sure,where did i go wrong?
 
  • #4
For example: you have pressure in Pascals, but you try to use R with pressure in atm.
 
  • #5
if i am using atm and liters, then the value of R to use is 0.082L atm/mol K ?
 
  • #7
n=PV/RT
P=1.5x10^6
V=0.8x10^-3
T=300 k
R=8.31
n=(1.5x10^6 x 0.8x10^-3)/8.31x300)
 
  • #8
1200 / 2493 = 0.481347774
 
  • #9
am i on right track?
 
  • #10
the value of R=0.082 is in litre
n=1200/24.6 =48.78
I hope this is the right answer
 
  • #11
It is not about hope, it is about calculations.

Please don't ignore units - you do it all the time:

nafo man said:
n=PV/RT
P=1.5x10^6
V=0.8x10^-3
T=300 k
R=8.31
n=(1.5x10^6 x 0.8x10^-3)/8.31x300)

so you are not sure what units your answer has.

List all the units in your calculations - see what cancels out, what is left, then you will know if what you did is OK.

Even if I will tell you if the number you listed is right, you will still have no idea why.
 

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 as many particles as there are atoms in 12 grams of pure carbon-12.

2. How is the number of moles calculated?

The number of moles can be calculated by dividing the mass of a substance by its molar mass. The molar mass is the mass of one mole of a substance and is usually expressed in grams per mole.

3. What is Avogadro's number?

Avogadro's number is a constant used to relate the number of particles in a substance to the number of moles. It is approximately 6.022 x 10^23 and is often rounded to 6.02 x 10^23 for easier calculations.

4. How is the number of molecules calculated?

The number of molecules can be calculated by multiplying the number of moles by Avogadro's number. This will give the total number of molecules in a substance.

5. Can the number of moles and molecules be converted to other units?

Yes, the number of moles and molecules can be converted to other units such as mass, volume, or concentration. This can be done using conversion factors and the appropriate unit conversion formulas.

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