I need help with this

Question

A gas at STP is cooled to -125 degrees celsius. What is its pressure in torr? (Consider the values of STP to be exact to three significant figures.)

Answer 1

STP = Standard Temperature and Pressure = 760 torr pressure and 273 degrees Kelvin

760 torr = 1 atm

P1 = initial pressure = 760 torr

T1 = initial temperature = 273K

P2 = final pressure = ?

T2 = final temperature = -125ºC + 273 = 148K

Use P1/T1 = P2/T2 assuming the volume in constant

760 torr / 273K = P2 / 148K

P2 = 412 torr (3 sig. figs.)