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Aqueous solutionsWater is a versatile solventSolvent: a substance, often a liquid, that is capable of dissolving one or more pure substances. Solute: the solid, liquid or gas that dissolves in a solventSolution: a homogeneous (of uniform composition) mixture of a solvent and one or more solutesAqueous solutions: solutions in which water is the solvent

Solute, solvent, and solutionAqueous solution concentration Molarity (M): a unit of concentration represented by the number of moles of solute present in 1 Liter of solution M = moles of solute/liter of solutionUnit namePercent (%)Parts per million/billion (ppm/ppb)Molarity (M)Definition Parts per hundred1 g of solute per 1106 g of solventMoles of solute per 1 L of solution usesFor common purposesFor measuring very low concentrationSolution concentrationEquation

More on molaritySince molarity,Fill in the table Container AContainer BThe volume is DecreasedIncreasedThe moles of solute is3 moles3 molesThe concentration isHigherlowerContainer AContainer BA closer look at solutesSolutions with different solutes can have different characteristics, such as the ability to conduct electricity Conductivity meter: an apparatus that produces a signal to indicate that electricity is being conductedNonelectrolyte: a solute that is non-conducting in aqueous solutionsElectrolyte: a solute that conducts electricity in aqueous solutions

A closer look at solutesWhy does the NaCl solution conduct electricity but the sugar solution does not?Because when solid NaCl dissolves in water, the molecule separates into Na+(aq) and Cl-(aq) ions to carry electric chargesIon: an atom or group of atoms that has acquired a net electric charge as a result of gaining or losing one or more electrons cation: a positively charged ionAnion: a negatively charged ion Ionic bond: the chemical bond formed when oppositely charged ions attract, most often it occur between a metal and a nonmetal elementIonic compound: composed of ions that are present in fixed proportions and arranged in a regular, geometric structure; namely, compounds linked together by ionic bondingHow are ions formed?Remember electronegativity?

Metals with low EN have a strong tendency to give up electrons to form positive cations (Ex: Group 1A and 2A)Non-metals with high EN have a strong attraction for electrons to form negative anions (Ex: Group 7A)

Increase ENdecrease EN

Ionic vs. covalent bondingIonic bondingForces of attraction between positive and negative ionsOccurs between a metal and non-metal elementElectrically charged ions are formed Electrons are transferred Ex: Na+ Cl-Covalent bondingForces of attraction between shared electrons and positive nucleiOccurs between non-metal elements onlyElectrically neutral atoms are combinedElectrons are shared between atomsEx: CH4

9predicting ionic chargePredict whether these atoms will form an anion or a cation based on their electronegativity values Li, S, K, NPredict the ion that each of these will form. Then draw a lewis structure for the atom and the ion, clearly labeling the charge on the ionBr, Mg, O, AlHint: use the periodic table as a guide to the number of outer electrons. Then determine how many electrons must be lost or gained to achieve stability with an octet of electrons Homework 10/05/2011Calculate the molarity of a 0.175 L sugar solution that was prepared with 0.15 mole of sugarDetermine the volume of 0.235 M sugar solution that can be prepared with 0.470 moles of sugar For 1.5 M and 0.15 M NaCl(aq), how many moles of solute are present in 500 mL of each solutions?A solution is prepared by dissolving 0.50 mol NaCl in enough water to form 250 mL of solution. A second solution is prepared by dissolving 0.60 mol NaCl to form 200 mL of solution. Which solution is more concentrated? ExplainIf a solution is diluted, say by adding an additional 100.0 mL of solvent, does the number of moles of solute change? Does the concentration increase, decrease, or stay the same?What is a situation that you have encountered where it was important to know a solution concentration?Nomenclature From formula to nameName the first element Name the second element and modify the suffix to ide Use prefixes to indicate the number of atoms for each elementOmit the prefix mono- for the first elementUse common names if there are one

From name to formulaIdentify the symbol for the first elementIdentify the symbol for the second element Convert the prefixes for each element to numbers and apply them as subscripts for each element

Remember how to name binary covalent compounds and formulas?Name these compoundsSO2 Sulfur dioxideO3 OzoneN2O4 Dinitrogen tetroxidePCl3 Phosphorous trichlorideAsCl3 Arsenic trichloride

Write these formulasArsenic pentachloride AsCl5Sulfur hexachloride SCl6Disulfur dichloride S2Cl2

From name to formulaIonic compoundsDoes the formula contains a metal?Its an Ionic compound Does the compound contain ammonium ion, NH4+?No Yes Can the metal be able to form more than one charge? i.e. is it a transition metal?Yes No Its a molecular compound The # of charges on the anion is equal to the number of spaces to the right that the non-metal have to move in the PT to get to a noble gas. write the non-metal symbol and assign chargewrite the metal symbol and assign + chargeM+AX BGroup 1A and 2A metals, the # of + charges are the same as the group number they are inCross the charges, subscript must be in smallest whole number and all charges cancel outMBXA Transition metals (group 3B to 2B), the # of + charges are the same as the Roman numerals in formulaNoYesFrom formula to nameIonic compoundsDoes the formula contains a metal?Its an Ionic compound Name the non-metal anion by adding ide to the stem of the name of the non-metalDoes the anion consist of just one element?Name the anion as one of the polyatomic anions in Table 5.7Does the compound contain ammonium ion, NH4+?No Yes No Yes Use Roman numerals in parentheses to indicate the charge of the metalUse just the English name of the metal Yes No Is the metal a transition metal? i.e. a metal that can form more than one positive ion? (group 3B to 2B)Yes No Its a molecular compound

Polyatomic ions16Each pair of elements forms one or more ionic compounds. For each, write the chemical formulas and names

Possible cationsPossible anionsPossible formulasFormula namesCa and SCa2+S2-CaSCalcium sulfideF and KK+F-KFPotassium fluorideMn and OMn2+Mn3+O2-MnOMn2O3 Manganese(II) oxideManganese(III) oxideCl and AlAl3+Cl-AlCl3Aluminum trichlorideCo and BrCo2+Co3+Br-CoBr2CoBr3Cobalt(II) bromide Cobalt(III) bromideWrite the chemical formula for the ionic compound formed from each pair of ionsNa+ and SO42-Mg2+ and OH-Al3+ and C2H3O2-CO32- and K+Na2SO4Mg(OH)2Al(C2H3O2)3K2CO3Name these compounds and formulasCaCO3NaHCO3KNO3Ammonium sulfatePotassium carbonateCalcium hydroxideCalcium carbonateSodium bicarbonatePotassium nitrate(NH4)2SO4KCO3Ca(OH)2