Chapter 4
What is the OIL RIG rule?
Oxidation is losing, Reduction is gaining
The density of chlorine gas at STP, in grams per liter, is approximately:
What formula do we use for this problem?
3.2 g/L
Law of Conservation of Energy
Energy cannot be created nor destroyed
Write the formation equation for FeCl3
Fe + 3/2 Cl2 --> FeCl3
The relationship of wavelength to frequency
frequency = c / wavelength
How to know if it is reducing or oxidizing agents?
- Reducing agent: oxidation# increases, lose e-, oxidation
- Oxidizing agent: oxidation# decreases, gain e-, reduction
If I have a 50 liters container that holds 45 moles of gas at a temperature of 200oC, what is the pressure inside the container?
What formula do we use?
P = 34.9 atm
Endothermic or Exothermic?
"Wood burning in a fire"
Exothermic
Determine the specific heat capacity of an alloy that requires 59.3 kJ to raise the temperature of 150.0 g alloy from 25oC to 125oC.
3.95 J/goC
What is the constant speed of light (c)
3.00 x 108 m/s
Oxidation States Rules (in order of priority)
1. Free elements: 0
2. Monoatomic ions: same with charge
3. A) Compound: sum = 0
B) Polyatomic ion: same with charge
4. A) Group 1 metals: +1
B) Group 2 metals: +2
5. Special Nonmetals: - Fluorine (F): -1
- Hydrogen (H): +1 - Oxygen (O): -2
- Group 7A: -1
- Group 6A: -2
- Group 5A: -3
Calculate the density of nitrogen gas at 125oC and a pressure of 755 mmHg.
What formula do we use?
d = (P*molar mass)/(R*T)
d = 0.851 g/L
A 5.00g sample of liquid water at 25oC is heated by the addition of 84.0 J of energy. What is the final temperature of the water? The specific heat capacity of liquid water is 4.18 J/goC.
What formula do we use to solve this problem?
q = m*Cs*(Tfinal - Tinitial)
Tfinal = 29oC
What is Hess Law and relationships involving enthalpy change of reaction?
- Hess's Law: If a reaction can be expressed as a series of steps, then the change in enthalpy for the overall reaction is the sum of the heats of reaction for each step.
- When the reaction is multiplied by a factor, the change in enthalpy for the overall reaction will be multiplied by the same factor.
- When the reaction is reversed, the sign of enthalpy change will change
What happened to the frequency and wavelength if the energy of a photon increases?
Frequency increases, wavelength gets shorter
2H2(g) + O2(g) --> 2H2O(g)
Which is the reducing agent and which is the oxidizing agent?
Reducing agent: H2
Oxidizing agent: O2
A real gas most closely approaches the behavior of an ideal gas under conditions:
low Pressure and high Temperature
Question 5
-62 kJ
1.68 x 103 kJ
Determine the wavelength of light required to remove an electron from a sample of potassium metal, if the binding energy for an electron in K is 1.76 x 103 kJ/mol.
What formula do we use to solve the problem?
E = (hc)/wavelength
wavelength = 1.13 x 10-25 m
COMBUSTION ANALYSIS PROBLEM:
12.912 g of a biochemical substance containing only carbon, hydrogen, and oxygen was burned in an atmosphere of excess oxygen. Subsequent analysis of the gaseous result yielded 18.942 g of carbon dioxide and 7.749 g of water. Determine the empirical formula of the substance.
CH2O
A 12.5L scuba diving tank contains a helium-oxygen (heliox) mixture made up of 24.2g of He and 4.32g of O2 at 298K. Calculate the partial pressure of each component in the mixture and the total pressure of the mixture.
Explain how to solve the problem
nHe = 6.05 mol --> PHe = 11.8 atm
nO2 = 0.135 mol --> PO2 = 0.264 atm
Ptotal = 12.064 atm
Question 7
-24.08 kJ
Question 2
-117 kJ
Calculate the wavelength of an electron (m=9.11 x 10-31 kg) moving at 3.66 x 106 m/s.
What formula do we use?
wavelength = h/(mv)
wavelength = 2.02 x 10-10