Two gas-containers, A and B, are connected with a valve. The first container, A, has a volume of 135 mL, and the second container, B, has a volume of 117 mL. A sample of gas originally in container A is at 22.5 C and the pressure is 165 mmHg. What is the pressure (in mmHg) of the gas sample when the valve is opened and the gas now occupies both containers at a temperature of 12.7 C

85.5 mmHg is the pressure of the gas sample when the valve is opened.

Explanation:

The combined gas equation is,

where,

= initial pressure of gas in container A = 165 mmHg

= final pressure of gas = ?

= initial volume of gas in container A=

= final volume of gas = 135 mL + 117 mL = 252 mL

= initial temperature of gas in container A =

= final temperature of gas =

Now put all the given values in the above equation, we get:

85.5 mmHg is the pressure of the gas sample when the valve is opened.

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

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