A gas is know to have a volume of 7.81 liters when the pressure is 754 torr what would be the volume when the pressure is changed to 1.23 atm temperature is constant

The volume when the pressure is changed to 1.23 atm and temperature is constant will be 6.3075 L.

Explanation:

Pressure and volume are related by Boyle's law that says:

"The volume occupied by a certain gas mass at a constant temperature is inversely proportional to the pressure"

Boyle's law is expressed mathematically as:

P * V = k

where:

Assuming a certain volume of gas V1 is at a pressure P1 at the beginning of the experiment. By varying the volume of gas to a new V2 value, then the pressure will change to P2, and the following will be true:

P1 * V1 = P2 * V2

In this case you have:

Replacing:

0.9921 atm*7.82 L=1.23 atm*V2

Resolving:

V2≅6.3075 L

The volume when the pressure is changed to 1.23 atm and temperature is constant will be 6.3075 L.