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#### sexysummer

##### Full Member

Why is it choice B? Is ideal gas @ STP 0 Celsius and 1 atm?

Thanks

#### goutamk

##### Full Member
5+ Year Member
When I took it I said that it was -273 C because that translates to 0 Kelvin and there should be no gas phase but only a solid.

#### danchoi03

##### Full Member
10+ Year Member
When Ideal gas has no volume, you use PV = nRT formula to find that Temperature equals to zero Kelvin. Next you use the formula K = 273 + Celsius and you will find that Celsius is -273 deg C when Kelvin equals to zero.

#### kobbix

##### Full Member
Is there a solid rule when to use 0.0821 vs 8.314?

#### danchoi03

##### Full Member
10+ Year Member
for PV = nRT , you will want to use 0.0831 because the unit is L-atm / mole-K. Both volume and pressure are used in the equation. The R constant 8.314 is J/mole-K and there is no volume or pressure in there, so you cannot use this. When you are solving any chemistry problem, the first thing you will look at is the unit. This will give you clue how to solve the problem. Sometimes the unit even helps you eliminate the answer choices that are wrong.

1 users
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#### Frank22

Is there a solid rule when to use 0.0821 vs 8.314?

A general rule would be to use 0.0821 when you're working with atmospheric pressure, and 8.314 when you're working with kilopascals.

#### gooperwooper

##### Full Member
is the constant given to us or do we have to memorize it?

F

#### Frank22

is the constant given to us or do we have to memorize it?

Definitely memorize it.

#### tyunup

##### Full Member
Do they ever provide you with constants? Like more obscure ones, ie. mass of an electron?

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#### Frank22

Do they ever provide you with constants? Like more obscure ones, ie. mass of an electron?

No.