Chem 116 1st EditionFinal Exam Study GuideUnit 1Significant FIguresUncertain Digits: 1 digit past the last significant figure Express in 3 sig. figs. - 1.2551 – 1.22- 1.2143 – 1.21 - 1.4972 – 1.50Calculated results can not be more “precise” than the measurements1. Mult/Div: keep least # of sig figs2. Add/Sub: keep least # of decimal places3. Do not take into account exact numbersExample 1.2 Using significant figures in calculations. Perform the following calculations and round the answers to the correct number of significant figures.a.2.568×5.8 ÷ 4.186 (fewest # of sig figs is 2 in 5.8, so final answer is limited to 2 sig figs) = 3.558146202 = 3.6b. 5.41−0.398 (fewest decimal place is 2, so final answer is limited to 2 decimal places or thousandth place) = 5.012 = 5.01c. 3.38−3.01 (2 decimal places) = 0.37d. 4.18−58.16×(3.38−3.01) (2 sig figs) = -17- do parentheses first- multiplication is next, but the answer can only have 2 sig figs bc .037 has 2)-keep track of sig figs as you go and use the rules as you goe. 5.41 + 0.0000001 = 5.41UnitsSI Units: metric system, based on factors of 10o Base Units slide 44, first 5 need to be committed to memoryo SI Prefixes – know all 14 and the differences in the scales between them (given 5 choices, each will have a set of inequalities and you will order them in increasing or decreasing order)Exercise 1.4 a. 1.84 nmb. 5.67 psc. 7.85 mgd. 9.7 kge. .732 ms or 732 usf. 0.154 nm or 154 pmPhysical vs. Chemical PropertiesLaw of Conservation of Mass – matter cannot be created or destroyed but can change state.Unit 2Atoms, Molecules, and Ions Nomenclature- Polyatomic Ions o Make index cards to memorize common ions Proton – positive charge, relative mass 1 amu(atomic mass unit)Neutron – neutral charge, relative mass 1 amuElectron – negative charge, relative mass 0- Protons and neutrons are located in the nucleus and determine nuclear properties of an atom - Electrons are located outside the nucleus in the “electron cloud” and determines the chemical properties - All atoms of the same element have the same number of protons - The number of protons is the Atomic Number (Z)- All atoms do not have to have the same number of neutrons o Atoms with the same number of protons and different numbers of neutrons are called isotopeso You can distinguish isotopes from one another by Nuclide Symbolo - The number of protons + the number of neutrons is called the Mass number (A)- The weighted average atomic mass of an element is calculated by multiplying the atomic mass ofeach isotope of an element by the fractional abundance of the isotope o AM(WA) = AM(isotope 1) x FA(isotope1) + AM(isotope2) x FA(isotope2)… AM = atomic mass WA = weighted average FA = fractional abundance Parts of the Periodic TableA Groups are the main groups or Representative Elements (predictable)1A – Alkali metals (form hydroxide in water)2A – Alkaline earth metals (form hydroxide in water)8A – Noble gases 7A – Halogens (salt former)6A – Chalcogens (rock/mineral formers)B Groups are Transition Metals (not predictable)Metalloids- an element that borders the stair step on the periodic table with the exception of Aluminum.Not a metal or nonmetal, but somewhere in between. Metals- to the left of the stair step on the periodic table with the exception of Hydrogen. Typically have high melting points. Nonmetals- to the right of the stair step on the periodic table along with Hydrogen. Chemical formula- notation representing the relative proportions of atoms in a substanceExample. Aluminum oxide, Al2O3 2:3 ratio of aluminum to oxygenSodium chloride, NaCl 1:1 ratio of sodium to chlorineWater, H2O 2:1 ratio of hydrogen to oxygenSulfuric acid, H2SO4(aq) 2:1:4 ratio of hydrogen to sulfur to oxygenMolecular compounds - composed of identical molecules- A small definite grouping of atoms - Non-metals with non-metalso Ex. H2O, NH3Ionic compounds – composed of ions held together by electrostatic forces- A charged atom or molecule- Metals with non-metalso Ex. NaCl, Al2O3*Also know common Ions*Be able to balance chemical equationsUnit 3Percentage Composition – mass percentages of each element in a compoundFind the molecular mass of the entire compound. Then divide the individual masses into this overall mass. m/MStoichiometry – chemical equations interpreted in terms of molecules, moles, and molar masses- Chemical equations are used as conversion factors- Chemical equation must be balanced- Reactant to product, product to reactantExample. In an industrial process, hydrogen chloride, HCl, is prepared by burning hydrogen gas, H2, in anatmosphere of chlorine, Cl2. Write the chemical equation for the reaction.Below the equation, give the molecular, molar, and mass interpretations.Mole-to-mole conversionsExample. Mole-mole conversions using a chemical equation Answer the following questions for the balanced reaction: N2(g) + 3H2(g) −−→2NH3(g)a. How many moles of NH3 can be produced from 2.4 moles of N2? b. How many moles of H2 are required to produce 15.0 moles of NH3? c. How many moles of N2 are needed to completely react with 6.8 mole of H2Gram-to-Gram conversions- For grams to moles, divide by the Molecular Mass- For moles to grams, multiply by the Molecular MassExample. Relating the quantity of reactant to quantity of product Hematite, Fe2O3, is an important ore of iron. The free metal is obtained by reacting hematite with carbon monoxide, CO, in a blast furnace. Carbon monoxide is formed in the furnace by partial combustion of carbon. The reaction is Fe2O3(s) + 3CO(g) −−→2Fe(s) + 3CO2(g) How many grams of iron can be produced from 1.00kg of Fe2O3?Limiting Reactant – the reactant that is totally consumed, less of and therefore limits the reactionExcess Reactant – the reactant that is not totally consumedTheoretical Yield – max amount of product (g or mol) that can be produced form a given amount of reactantsActual Yield – amount of product that is actually produced (less than theoretical) Percent Yield = (Actual Yield ÷ Theoretical Yield) x 100*Know how to calculate molar and molecular massYou will be looking for the limiting reactant if the problem gives you two masses of two reactants and asks for an amount of product produced. To get Limiting Reactant:Grams of 1st reactant – mol 1st reactant – mol of productGrams of 2nd reactant – mol 2nd reactant – mol of productThe smallest result of reactant is your limiting