CHM1045 Review Topics Test 2

Review Topics Chapters 3 and 11 (part)

  1. Balancing Reactions (Coefficients represent mole ratios or particle ratios).
  2. Simple Stoichiometry. Conversions between grams, moles, atoms, molecules of reagent A to reagent B or product A or product B. When converting between reactant and product only amount of one reactant is given. The other reactant will be in excess.
  3. Limiting and Excess reagents. If given amounts of two reactants then you must first determine which reactant is in excess.
  4. Percent Yield

5.     Solution terminology: solute, solvent

6.     Concentration of Solutions: Molarity, Percent by Weight.

7.     Inter-conversions among concentration units: i.e.  from % to M;  from M to %.

8.     Dilution of solutions. You always start with the more concentrated solution. The formula is C1V1=C2V2. The concentration can be molarity or % by weight. The volume can be L or mL as long as it is the same unit on both sides of the equation.

9.     Solution Stoichiometry : Use the balanced equation and use the mole ratio to convert from one reactant or product to another reactant or product. There could be a limiting reagent type problem involving solution stoichiometry and determination of the amount of excess reactant left over, whether in grams, moles or molarity. Note that if asked for molarity you need to plug into the formula. Never use the dilution formula (M1V1=M2V2) for stoichiometry problems.

10.  Be able to write acid-base reactions and predict the products and balance.

11.  Be familiar with the concept of titrations, primary standards (e.g. KHP), equivalence point (when the indicator changes color), and neutralization point (when you have added the exact stoichiometric amount of acid or base to react with the base or acid you have so that there is no acid or base left over

 

 

 

Review Topics Chapters 5 (part) and 6:

Nomenclature :

  1. Binary ionic compounds with fixed charge on the metals:  i.e. sodium chloride, aluminum oxide, etc.(Group IA (1+), IIA (2+), Al 3+, Zn 2+, Cd 2+, Ag 1+
  2. Binary ionic compounds with Variable charges on the metals, both the stock system and the classic system:  i.e. ferric chloride or iron (III) chloride
  3. Ionic compounds with polyatomic ions:  i.e. potassium phosphate, copper (II) hydroxide, etc
  4. Binary acids:  i.e.  hydrochloric acid (HCl(aq)) if dissolved in water, hydrogen chloride (HCl(g)) if in the gas phase. The most confusing one is H2S(aq) is hydrosulfuric acid, as opposed to the ternary acid H2SO4 which is sulfuric acid.
  5. Ternary or Oxy acids: “ate” polyatomic ions form “ic “acids  and “ite” form “ous“ acids

       6.   Nomenclature of Acid Salts: i.e.  stannous hydrogen phosphite

       7. Nomenclature of Binary Compounds of 2 nonmetals:  i.e. carbon dioxide, dinitrogen pentoxide…

       8. Nomenclature of hydrates (monohydrate, dehydrate, etc.)

       9. Remember to never use prefixes for ionic nomenclature or binary acids. “Hydrogen” is only used for binary acids in the gas phase and for acid salts. “Hydro” is only used for binary acids dissolved in water.

 

Oxidation numbers:

1.     Remember that elements in their natural state (not in combination with other elements) have an         oxidation number of 0.

 

2.     The sum of the oxidation numbers for a compound is 0 and for a polyatomic ion is equal to the charge of the ion.

 

3.     The oxidation number or single element ions is the same as the charge.

 

4.     Oxygen always has an oxidation number of -2 except in peroxides, O22- where it has -1.

 

5.     H has an oxidation number of +1 when bonded to a nonmetal and -1 when bonded to a metal.

 

6.     F has an oxidation number of -1. Cl, Br and I have an oxidation number of -1 unless bonded to a more electronegative element (like F or O).

Reactions:

1)     Types of Reactions: be able to identify the type of reaction.  

2)     Combination- May or may not be redox

3)     Decomposition –May or may not be redox

4)     Single Replacement-Always redox. Two types:

 

a)     Metal or H replaces another metal or H. Occurs only if metal or H by itself is more reactive than the metal     or H in the compound. Check activity series. For metals more reactive than H, the bolded can replace H for H2O liquid or gas or in acids. The bolded underlined only H in H2O gas or in acids. The double underlined H only in acids.

b)    Halogen replaces another halogen. Occurs only if halogen by itself is more reactive than the halogen in the compound. F>Cl>Br>I

 

5)     Double Replacement. Never redox. These include precipitation, gas evolution, or neutralization.                These reactions occur if either a reactant or a product is a weak electrolyte or if water is a product. Be  able to determine the complete ionic equation, the spectator ions, and the net ionic equation . If  every reactant and product is a strong electrolyte there is no reaction. Make sure that you ionize only the strong electrolytes. Weak acids and NH4OH are soluble in water yet they are weak electrolytes. They don’t get ionized.

 

6)     Combustion- C, H, and O containing compound reacts with O2(g) to produce CO2 (g) and H20(l).-Always redox

 

7)     Ionization -Never redox. Be able to indicate with a single arrow or a double arrow (whether the                                substance is a strong electrolyte (strong acids, strong bases and soluble salts), a weak electrolyte (weak acids, weak bases and insoluble salts), or a nonelectrolyte (covalent compounds other than acids)). Both the strong and the weak electrolytes will be shown ionized but the weak electrolytes take a double arrow (equilibrium, not 100% reaction (actually much less than 100%).

 

8)     Make sure you know which are the strong acids and the strong bases. The rest of the acids and bases are weak.