1. Stoichiometery of gases and solutions
(Ideal and combined gas laws)

2. Avogadro’s hypothesis
Why is twice the volume of hydrogen needed to react with oxygen to make water?
Avogadro’s hypothesis states that gases at the same temp. and pressure react in volumes equal to their mole ratios.
-If 10 ml of oxygen reacts with 50 ml of hydrogen, what is the limiting reactant?

3. Molar gas volume Is there a number to convert amounts of gas to moles?
Yes, but only at stp.
Stp=1 atm, 273 K
Molar gas volume is 22.4 dm3/mol or 22.4 L/mol
How many moles of propane are in 48 L at stp? What is the mass?

4. Example
What volume of air (20.0% oxygen) is needed to combust kg of gasoline, (C8H18) at stp?
Equation?
Moles of gasoline?
Moles of oxygen?
Volume of oxygen?
Volume of air?

5. The ideal gas law What does the ideal gas law allow us to do?
It gives us pressure, volume or temperature of a gas given the other 2.
P.V = n.R.T
n = moles
R = J/K.mol

6. The ideal gas law What does the ideal gas law do for chemistry?
The ideal gas law can give moles with pressure, volume and temperature.
This can be use to fill a ratio, determine limiting reactants, or to determine a molar mass.

7. The combined gas law What is the combined gas law? P1V1/T1 = P2V2/T2
Temperature must be in Kelvin, but P and V just have to match units
What can this be used for in chemistry?

8. Solutions What is a: Solution Suspension Solute Solvent
Saturated solution
Supersaturated solution
precipitate

9. Solutions How do we find the concentration of a solution?
Concentration = moles/volume
2 grams of sodium hydroxide is dissolved in 200 cm3 of water. What is the concentration?
Find moles and divide by volume.

10. Solutions How do you dilute a solution? n = c1 x V1 = c2 x V2
Find the volume that 20.0 L of 7.63 mol/L HCl must be diluted to produce a solution with a concentration of 5.00 mol/L.

11. Titration What is titration?
It is a way to measure an exact volume of one solution to neutralize another solution.
This is usually used with a known solution to find the concentration of an unknown solution.

12. Titration How is titration done?
A known solution is put in a flask and second solution is run in from a burette.
The volume from the burette needed to neutralize the known solution is taken from the burette.
The amount of know solute is calculated from volume of known solution and used with the burette reading and a balanced equation to find the unknown.

13. Back titration When is this used?
This can be used when a substance reacts very slowly. The slow reacting substance is reacted with a known solution, and the known solution is then titrated to determine how much reacted.