Gas Laws II

STP Standard Temperature and Pressure 0⁰C 1atm

Dalton’s Law of Partial Pressures The pressure of each gas in a mixture is called the partial pressure of that gas. Dalton’s law of partial pressures states that the total pressure of a gas mixture is the sum of the partial pressures of the component gases. Ptotal = P1 + P2 + P3 + ……

Gases produced in the laboratory are often collected over water Water molecules at the liquid surface evaporate and mix with the gas molecules.

A container holds samples of O2, N2, and H2 A container holds samples of O2, N2, and H2. The pressure of the container is 2.1 atm. O2 exerts a pressure of 1.0atm and N2 exerts a pressure of 0.5atm, what is the pressure of the H2?

Oxygen gas from the decomposition of potassium chlorate, KClO3, was collected by water displacement. The barometric pressure and the temperature during the experiment were 731.0 mmHg and 20.0°C. respectively. What was the partial pressure of the oxygen collected?

Ideal Gas Law the mathematical relationship among pressure, volume, temperature, and number of moles of a gas PV = nRT P= pressure V= volume in Liters n= number of moles R= ideal gas constant T= temperature in Kelvin

R Values

What is the pressure in atmospheres exerted by a 10 What is the pressure in atmospheres exerted by a 10.50 g sample of nitrogen gas in a 10.0 L container at 298 K?

How many mol of CO2 gas are in a 2300mL container at 17⁰C and 2.14atm?

Gas Stoichiometry

Avagadro’s Law – molar volume equal volumes of all gases, at the same temperature and pressure, have the same number of molecules For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant

Gas Stoichiometry The coefficients in chemical equations of gas reactions reflect not only molar ratios, but also volume ratios only if: ALL conditions remain the same Substances involved in calc are gases example—reaction of carbon dioxide formation: 2CO(g) + O2(g)  2CO2(g) 2 molecules 1 molecule 2 molecules 2 mole 1 mole 2 mol 2 liters 1 liters 2 liters

C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) What will be the volume, in liters, of oxygen required for the complete combustion of 0.350 L of propane? Assume that all volume measurements are made at the same temperature and pressure.

C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g) What will be the volume of carbon dioxide produced by the complete combustion of 0.350 L of propane? Assume that all volume measurements are made at the same temperature and pressure.

What if conditions are different or on substance is a solid or liquid?

For any gas at STP, 1mol = 22.41L If 5.60L H2 at STP reacts with excess CuO according to the equation below, how many g Cu are produced? CuO(s) + H2(g) → Cu(s) + H2O(g)

If 5.60L H2 at 3.16atm and 54 ⁰C reacts with excess CuO according to the equation below, how many g Cu are produced? CuO(s) + H2(g) → Cu(s) + H2O(g)

If 5.60L H2 at 1.21atm and 27 ⁰C reacts with excess CuO according to the equation below, what volume H2O(g) is produced at 1.74atm and 20.0⁰C? CuO(s) + H2(g) → Cu(s) + H2O(g)