A gas has a pressure of 65.0 mmHg at 740K. What will be the pressure at 300K if the volume does not change?

26.35 mmHg

Explanation:

Given data:

Initial pressure = 65.0 mmHg

Initial temperature = 740 K

Final temperature = 300 K

Final pressure = ?

Solution:

According to Gay-Lussac Law,

The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.

Mathematical relationship:

P₁/T₁ = P₂/T₂

Now we will put the values in formula:

65 mmHg / 740 K = P₂/300 K

P₂ = 65 mmHg× 300 K  / 740 K

P₂ = 19500 mmHg. K /740 K

P₂ = 26.35 mmHg

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e