0.65 moles of O2 originally at 85°C is cooled
such that it now occupies 8.0 L at 40.°C.
What is the final pressure exerted by the gas?

0.65 moles of O₂ at 40. °C and 2.1 atm occupy a volume of 8.0 L.

0.65 moles (n) of O₂ originally at 85°C is cooled. It occupies 8.0 L (V) at 40.°C (T). We will convert the final temperature to Kelvin using the following expression.

We can calculate the final pressure (P) exerted by the gas using the ideal gas equation.

0.65 moles of O₂ at 40. °C and 2.1 atm occupy a volume of 8.0 L.

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2.09 atm

Explanation:

We can solve this problem by using the equation of state for an ideal gas, which relates the pressure, the volume and the temperature of an ideal gas:

where

p is the pressure of the gas

V is its volume

n is the number of moles

R is the gas constant

T is the absolute temperature

In this problem we have:

n = 0.65 mol is the number of moles of the gas

V = 8.0 L is the final volume of the gas

is the temperature of the gas

is the gas constant

Solving for p, we find the final pressure of the gas:

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.