after its pressure is changed from 12 atm to 4 atm?
Solution: P 1 = 12 atm P 2 = 4 atm
V 1 = 1 L V 2 = unknown
P 1 V 1 = P 2 V 2
12 atm (1 L) = 4 atm (V 2 )
V 2 = 3 LDALTON’S LAW OF PARTIAL PRESSURES
When two or more ideal gases are found in one vessel without chemical interaction, each gas will
behave independently of the other(s). Therefore, the pressure exerted by each gas in the mixture
will be equal to the pressure that gas would exert if it were the only one in the container. The
pressure exerted by each individual gas is called the partial pressure of that gas. In 1801, John
Dalton derived an expression, now known as Dalton’s law of partial pressures, which states that the
total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual
components:
PT = PA + PB + PC + ...
TEST STRATEGY
Look for opposing answers in the answer selections. If two answers are close in wording or if
they contain opposite ideas, there is a strong possibility that one of them is the correct
answer.The mole fraction of a gas A in a mixture of gases is defined as:
The partial pressure of a gas is related to its mole fraction and can be determined using the
following equation: