CHEM 101 1st EditionExam # 3 Study Guide Lectures: 10 - 12This exam will cover every section from chapter 6 and section 5.6 chapter 5. Remember that in order to succeed in this class you must stay familiar and review information from past chapters, as what we learn builds on itself. It will be helpful to review the following tables before this exam: 4.2, 4.3 and 4.4. For extra practice try working out the following problems at the end of chapter 6: 33, 35, 41, 42, 43, 44, 45, 46,47,48,49, 51, 52, 63 and 64.Lecture 10 This lecture was an introduction to the concepts in chapter 6. Solutions are a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent). In this chapter we focused on what is known as aqueous solutions, which means they are water based. Every chemical reaction we looked at this semester involved aqueous solutions. The reaction we covered during this lecture is called the Disassociation reaction; which involvesthe separation of something from something else or a state of being disconnected. These reactions are also referred to as double displacement reactions. AB + CD  AD + CBExample: Dissociation of NaClNaCl(aq) Na+(aq) + Cl- (aq)The state of matter in the reaction is identified by the (aq) = aqueous, (l)= liquid, (s)= solid subscripts. You will have to be able to determine what the solid compounds in a precipitation reaction by its solubility. You should memorize the solubility rules on pages 169 and 170. A precipitation reaction is a double displacement reaction distinguished by the formation of a solid. Precipitation reactions occur when cations and anions in aqueous solution combine to form an insoluble ionic solid called a precipitate (a substance) to be deposited in solid form from a solution.Professor Franco then goes on to discuss the properties of solutions- which you should be familiar with:a. Electrolyte: a liquid or gel that contains ions and can be decomposed by electrolysis, e.g., that present in a battery. All compounds that disassociate into ions in water. (“charged”)b. Non-electrolyte: a substance that does not readily ionize when dissolved or melted and is a poor conductor of electricity. Nonionic compounds such as sugarand ethanol (“no charge”)If a nonelectrolyte is dissolved in water, ions do not form and electricity will not pass through the light bulb. Charges indicate electrolytes (anions and cations) And then there are strong and weak electrolytes and weak electrolytes. Strong electrolytes fullydissociate into ions while weak electrolytes only partially dissociate into free ions. It’s the free ions that will conduct electricity. REMEMBER that covalent compounds are incapable of forming ions and therefore cannot be an electrolyte. Acids and bases, as will be discussed, both form electrolytes. a. Total ionic equation: the complete ionic equation is used to describe the chemical reaction while also clearly indicating which of the reactants and/or products exist primarily as ions in aqueous solution. Spectator ions: is an ion that does not actively form a new compound in a chemical equation. They can be canceled out to give you the net ionic equation.b. Net ionic equation: are equations that show only the soluble, strong electrolytesreacting (these are represented as ions) and omit the spectator ions, which go through the reaction unchanged.How do you know if your equation is a precipitate?The determining factors of the formation of a precipitate can vary. Some reactions depend on temperature, such as solutions used for buffers, whereas others are dependent only on solution concentration. The solids produced in precipitate reactions are crystalline solids, and can be suspended throughout the liquid or fall to the bottom of the solution. The remaining fluid is called supernatant liquid. The two components of the mixture (precipitate and supernate) can be separated by various methods, such as filtration, centrifuging, or decanting.Now let’s talk about Concentration calculations: These are important. The concentration of a solution is the quantity of a solute that is contained in a particularquantity of solvent or solution. Knowing the concentration of solutes is important in controllingthe stoichiometry of reactants for solution reactions.The most common unit of concentration is molarity, which is also the most useful forcalculations involving the stoichiometry of reactions in solution. The molarity (M) is a commonunit of concentration and is defined as the number of moles of solute present in exactly 1 L ofsolution. It is, equivalently, the number of millimoles of solute present in exactly 1 mL ofsolution:In the lab you would prep the solution before the solvent 1. Calculate the number of moles of solute present.2. Calculate the number of liters of solution present.3. Divide the number of moles of solute by the number of liters of solution.This is something you will simply need to practice. There are practice problems on pages 170 and at the end of chapter 6.Lecture 11 During this lecture professor Franco tackles Acids and Bases as well as Neutralization reactions from chapter 6. You will have to be able to determine if a solution is a strong acid orbase, as well as which are weak acids and bases. Acids are chemical substances that form hydrogen ions [H+] in aqueous solutions. Acids neutralize alkalis, they react with reactive metals. They also react with some organic dyes to cause them to change color such as turning litmus red. Acids are typically a corrosive or sour-tasting liquid of this kind and as stated before ACIDS ARE ELECTROLYTES.Remember that Dissociation Reaction: in chemistry and biochemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into smaller particles such as atoms, ions or radicals, usually in a reversible manner. Below is an example of aacidic dissociation reaction:Molarity (M) = moles soluteliters solutionHCl  H+ + Cl-You will need to look to the table on page 178 in your chemistry textbooks and memorize the following Names, Formulas, strengths and sources of the following various acids:i. Hydrochloric acid / HCl / strong / pool chemicalsii. Nitric acid / HNO3 / strong / acid rainiii. Sulfuric acid / H2SO4 / strong / car batteriesiv. Acetic acid / HC2H3O2 / weak / Vinegarv. Carbonic acid / H2CO3 / weak / Soft