This is just a study guide to help you think about the concepts we covered in this unit, but study guides do not always cover or review everything. Here's some things you can do to prepare for the Unit 4 Exam:
1) Review your notes. We covered the following topics this unit:
Names and formulas of Ionic and Covalent Compounds
Physical and Chemical Changes
Types of Reactions
Balancing Equations
Oxidation States
Redox Reactions (half reactions and net ionic equations)
Precipitation "Double Replacement" Reactions (including complete and net ionic equations)
Empirical and Molecular Formulas
Hydrates
Stoich (all the different conversions) - NOT REVIEWED IN THIS FORMATIVE LOOK AT YOUR MIXED STOICH HANDOUT
Limiting and Excess Reactants - NOT REVIEWED IN THIS FORMATIVE LOOK AT YOUR MIXED STOICH HANDOUT
2) You can complete additional practice questions on AP Classroom (Unit 4 Progress Check) or on Khan Academy. Keep in mind that we will be covering acids and bases over the next couple of weeks.
The hardest part of AP exams is that you have to think flexibly. If you truly understand a topic, you can answer a question no matter how it is presented.
What type of compound use prefixes in its name?
What type of compound do you have to balance the charges when you write the formula?
What type of atom needs to have a roman numeral to specific it's charge.
HCl (aq) + NaOH (aq) → NaCl (aq) +H2O (l)
A student had two dilute, colorless solutions, HCl (aq) and NaOH(aq), which were at the same temperature. The student combined the solutions, and the reaction represented above occurred. Which of the following results would be evidence that a chemical reaction took place?
A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations, a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?
Zn(s) + 2HCl (aq)→ ZnCl2 (aq) + H2(g)
When the reaction represented above proceeds, heat is produced. Which of the following best describes the reaction?
5 Fe2+ (aq) + MnO4− (aq) + 8H+ (aq)→5 Fe3+ (aq) + Mn2+(aq) + 4 H2O(l)
Which of the following represents the oxidation half-reaction based on the balanced ionic equation shown above?
Hint: Review the rules of assigning oxidation states.
Al (s) → Al3+ (aq) +3e−
Sn2+ (aq) + 2e−→ Sn (s)
Based on the half-reactions represented above, which of the following is the balanced ionic equation for the oxidation-reduction reaction between Al(s) and Sn2+(aq) ?
Use the information below to answer questions 9 - 14.
Zinc metal reacts with copper (II) nitrate. Remember: Zinc ALWAYS forms a +2 charge.
Write a balanced equation for the reaction.
Note: You will not be be able to type subscripts.
Write the oxidation half reaction.
Note: You will not be be able to type subscripts.
Use the information below to answer questions 15-17.
Sodium sulfate reacts with strontium chloride.
Remember you do not get solubility rules on the AP exam. The species that are always soluble are:
All group 1 metals
NO3-
HCO3-
C2H3O2-
NH4+
ClO3-
ClO4-
Write a balanced equation for the reaction. INCLUDE STATES OF MATTER ON ALL SPECIES.
Note: You will not be be able to type subscripts.
Write the complete ionic equation for the reaction. INCLUDE STATES OF MATTER ON ALL SPECIES.
Note: You will not be be able to type subscripts.
Write the net ionic equation for the reaction. INCLUDE STATES OF MATTER ON ALL SPECIES.
Note: You will not be be able to type subscripts.
Determine the molecular formula for ibuprofen, a common headache remedy. Analysis of ibuprofen yields a molar mass of 206.31 g and a percent composition of 75.7% C, 8.80% H, and 15.5% O. Determine the molecular formula.
A 5.018 gram sample of a certain hydrate of magnesium sulfate, MgSO4•xH2O, is heated until all the water is driven off. The resulting anhydrous compound weighs 2.449 grams. What is the formula of the hydrate?
There are no stoich or limiting and excess reactant problems on this formative, but you will be tested on it.
Please review your notes and complete the Mixed Stoichiometry Practice Problem handout for more practice. The answer key to this handout can be found on Schoology.
Which species is oxidized?
Which species is reduced?
Write the reduction half reaction.
Note: You will not be be able to type subscripts.
Write the net ionic equation.
Note: You will not be be able to type subscripts.
Draw a model to show what you think happens in this double replacement reaction.