# What would be the volume of the vapour at STP?

how would i calculate the volume of a vapour at STP? and how would i calculate the desity of the vapour in grams per litre at STP?

here is the information i have:

mass of condensed liquid: 0.81g

temp: 100.3 C

barometrc pressure: 101.7kPa

volume of flask: 0.140

mass of flask+foil: 91.69g

mass of flask+foil+condensed liquid: 92.5g

plz show me how to do this=(

### 1 Answer

- Dr WLv 71 decade agoFavorite Answer
*** volume at STP ***

start with...

P1V1 / T1 = P2V2 / T2

rearrange...

V2 = V1 x (P1 / P2) x (T2 / T1)

where...

V1 = 0.140...what's the units? Liters? I'll assume so...

P1 = 101.7 kPa

P2 = 101.325 kPa (that is the P at STP)

T2 = 273.15 K (that is T at STP)

T1 = 373.45 K... (100.3 C + 273.15 = 373.45 K.. right?)

V2 = 0.140 L x (101.7 kPa / 101.325 kPa) x (273.15K / 373.45K)

V2 = 0.103 L

*** density in g/mL at STP ***

0.81 g / 0.103 L = 7.9 g/L

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