Exam prep presentation from 10/15/17.

1. Test 2
Charles Bergen, Eleanor Cockerell, and Kirsten
Smirl

2. Agenda
● Limiting Reactants
● Acids and Bases
● Gas Laws
● Questions

3. Limiting Reactants
What is a limiting reactant?

4. Limiting Reactants Question 1
Calculate the mass of magnesium oxide possible if 3.0 g Mg reacts with 8.0 g O2
A.) Balanced Equation
B.) What is the Limiting Reactant?
C.) How much magnesium oxide is produced?
2Mg + O2 → 2MgO
Mg
4.97g

5. Limiting Reactants Question 2
28.7 grams of SiO2 reacts with 22.6 grams of H2F2.
A.) What is the balanced equation?
B.) What is the limiting reactant?
C.) What is the max amount of SiF4 formed?
SiO2+2H2F2→SiF4+2H2O
H2F2
29.558g

6. Limiting Reactants Cont.
D.) How much is in excess? (answer in g)
E.) At the end of the experiment, 20g of SiF4 is measured. What is the percent
yield?
11.64g
67.7%

7. Acids and Bases
any substances that dissolves in water to produce H+ ions
any substance that dissolves in water to produce OH- ions
dissociate completely in water
acid and base reaction that yields a solution that is not acidic or basic.
Can take the role of an acid or a base (water)
What are examples of strong acids/bases and weak acids/bases?
Acid:
Base:
Strong Acids/Bases
Neutralization
Amphoteric

8. Common Acids/bases
Oven cleaner- NaOH
Vinegar - Acetic Acid

9. How many mL of 0.45M HCl must be added to 25 mL of 1.00M KOH to make a
neutral reaction?
1. Write the balanced chemical equation.
2. Find the mols of the known solution.
3. Solve for the unknown solution.

10. Gas Laws
Units of Gas Laws: 1atm = 760mmHg = 760torr = 101.325kPa
Variables: STP (Standard
Temperature and Pressure):
(P) - Pressure (atm) - 273 K or 0oC
(V) - Volume (L) - 1 atm
(T) - Temperature (K) or (C)
(n) - Number of Moles
(R)- Gas Constant 0.0821 (L*atm/K*mol)
Ideal Gas - a hypothetical gas with molecules of no intermolecular forces and on a
molecular level occupy no volume.

11. Equations
Ideal Gas Law Avogadro’s Principle
PV = nRT n1/V1 = n2/V2
Charles Law Density of a Gas
V1/T1 = V2/T2 PV = nRT → PV = (m/M)*RT → p =
m/V = PM/RT
(m) = mass
Boyles Law
P1V1 = P2V2
Gay-Lussac’s Law
P1/T1 = P2/T2

12. Various Gas Conditions

13. Problems
1. What volume would 12g of Helium occupy at 27oC and a pressure of 380mmHg?
2. Ideal Gases (Ans: ii):
i. Have no Volume
ii. Have particles with no attractive forces between them
iii. Have no mass
3.) Container with 4 moles of a gas, pressure of 6 atm, and volume 12L.
What is the temperature?
Ans: c Ans: D
Ans: C