Dalton's+Law.dj

Dalton's law states that the total pressure of a gas mixture is the sum of the partial pressures of the component gases. The pressure of each gas in a mixture is called the partial pressure of that gas. This law holds true no matter how many different gases are present. The equation to represent this law looks like: P(total) = P1 + P2 + P3 + ... P(total) is the total pressure while P1, P2, P3, aree partial pressures.

Gases produced in the labortatory are often collected over water. The gas produced in the reaction displaces the water, which is more dense. One can apply Dalton's law in calculating the pressures of gases collected this way by using this equation: P(atm)=P(gas)+P(H2O)

Oxygen gas from the decomposition of ptassium chlorate, KClO3, was collected by water displacement. The barometric pressure and the temperature during the experiment were 731.0 torr and 20.0ºC. What was the partial pressure of the oxygen collected?
 * Example Problem:**

__Step One:__ Given: P(total) = P(atm) = 731.0 torr; P(H2O) = 17.5 torr; P(atm) + P(O2) + P(H2O)

__Step Two:__ The partial pressure of the collected oxygen is found by subtracting the partial pressure of water vapor from the atmospheric pressure, according to Dalton's law.

__Step Three:__ Substitute the values for the equation P(O2) = 731.o torr - 17.5 torr = 713.5 torr

The oxygen partial pressure is less than atmospheric pressure. It is reasonably close to an estimated value of 713
 * Conclusion:**

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