Chapter Two Atoms & The Periodic Table

Chapter Two Atoms & The Periodic Table

A solution is a homogeneous mixture Gas example: air Liquid liquid: salt water Solid example: brass Solute:

substance being dissolved Typically lesser in quantity Solvent: substance doing the dissolving

Typically greater in quantity Electrolyte: substance that when dissolved in water conducts electricity Sodium Chloride (or table salt) Has ions in solution (dissociation)

Nonelectrolyte: substance that when dissolved in water does NOT conduct electricity Sucrose (or sugar) Does NOT have ions in solution, but molecules All

water-soluble ionic compounds will dissociate completely Therefore, they are strong electrolytes (i.e. substances that completely dissociate) There are only 7 molecular compounds that are also considered

strong electrolytes HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4 Most molecular compounds are weak electrolytes OR nonelectrolytes Weak electrolytes produce some ions upon

dissolving but exist mostly of molecules that arent ionized Acids are electrolytes (they produce H+ ions) HCl(g) H+(aq) + Cl-(aq)

Bases are electrolytes (they produce OH- ions) NH3(g) NH4+(aq) + OH-(aq) For

acids/bases that are WEAK, the reaction goes in both directions simultaneously HC2H3O2(l) H+(aq) + C2H3O2-(aq) reaction occurs in both directions Dynamic Chemical Equilibrium

A + B2 AB2 Sucrose (C12H22O11) Fructose Sodium

(C6H12O6) Citrate (Na3C6H5O7) Potassium Ascorbic Citrate (K3C6H5O7)

Acid (H2C6H6O6) Reaction where a precipitate forms Maximum amount of

solute that will dissolve in a given quantity of solvent at a specific temperature Pb(NO3)2(aq) +

NaI(aq) Ionic Equation: Shows equation with ions dissociated Net

Ionic Equation: Shows only whats involved in the reaction Removes Spectator Ions For the following reaction, correctly predict the products to write the

balanced molecular equation. Then write the ionic equation and the net ionic equation. Aqueous solutions of Lead Acetate and Calcium Chloride

Arrhenius Model: Acids produce H+ ions Bases produce OH- ions Bronsted

Model: Acids are H+ donors (or proton donors) Bases are H+ acceptors (or proton acceptors) Reaction

between an acid and base Produce water (most of the time) and a salt (ionic compound) A.K.A. Redox Reactions

Chemical Reaction where electrons are being transferred from one reactant to another. Consider

Cu(s) Zn(s) + CuCl2(aq) ZnCl2(aq) + Oxidation is loss of electrons Reduction is gain of electrons OIL

RIG Oxidizing Agent: species that causes oxidation Takes the electrons

Reducing Agent: species that causes reduction Gives the electrons A.K.A.

Oxidation State (or charge) Help us determine what elements were oxidized and reduced In

order to determine an elements oxidation number, you must follow the guidelines on the next two slides: What is the oxidation number of each atom in the following:

SO2 NaH CO32 H2SO4 2Fe N2 + 6HBr 3H2 + 2FeBr3

+ 3H2 2NH3 2KClO3 2KCl + 3O2 What is the oxidation number for

chlorine in the compound HClO4? What species is the reducing agent in the following equation? Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) Does the following equation represent a redox reaction? Why?

2Mg(s) + O2(g) 2MgO(s) Measure of amount of solute dissolved in a certain amount of solvent or solution More

solute: Concentrated Less solute:

Diluted Molarity = moles of solute/ L of solution A.K.A. molar concentration Represented by M ex: 1.5 M

If you have exactly 1 L of 1.5 M glucose, it contains 1.5 moles of glucose Suppose

you wanted to make a 0.150 M solution of KMnO4 using a 25o.00 mL volumetric flask. How would you do this? You need to make 500. mL of a 0.650 M solution of Sodium

Hydroxide (NaOH). What mass of NaOH do you need to use? What is the molar concentration (M) of a solution prepared by dissolving 58.50 g of Copper Chloride (CuCl2) in water to yield a 1.50 L solution?

Preparing less concentrated solutions Typically done by adding water to concentrated solution

Dilution formula: McVc = MdVd C = concentrated D = diluted What

volume in mL of a 1.20 M HCl solution must be diluted in order to prepare 1.00 L of 0.0150 M HCl? How much water was added? Recall:

Soluble Ionic Compounds dissociate completely (all ionize) If you have 0.500 M of KMnO4, then there is 0.500 M of K+ and 0.500 M of MnO4- (1:1 ratio between ions)

[ ] are usually used to show concentration [KMnO4] = 0.500 M, [K+] = 0.500 M, [MnO4-] = 0.500M

If you have soluble ionic compounds with ratios other than 1:1 for ions, use subscripts to determine ion concentration Suppose you had a Ex: Na2SO4 1.55 L solution of this

ionic compound. How [Na2SO4] = 0.35 M, many moles of each ion do you have? How [Na+] = 0.70 M, many individual ions do [SO42-] = 0.35 M you have? Analytical

technique based on mass Uses percent composition Ex: A 0.8633-g sample of an ionic compound containing chloride ions and

unknown metal cations is dissolved in water and treated with excess AgNO3. If 1.5615 g of AgCl precipitate, what is the percent by mass of Cl in the original compound? Process where

Solution of known concentration (standard solution) is added gradually to Another solution of unknown concentration till The reaction is complete Equivalence point: # of moles of H+ ions equals # of moles of OH- ions

End point: Color change in solution (visually indicates the equivalence point) What volume of a 0.203 M NaOH solution is needed to neutralize 25.0 mL of a 0.188 M H2SO4 solution?

If it takes 26.79 mL of 0.560 M HCl solution to neutralize 85.70 mL of Ba(OH)2, what is the molarity of the base? What

is the molar mass of a diprotic acid if 30.5 mL of 0.1112 M NaOH is required to neutralize a 0.1365-g sample? How many milliliters of a 1.89 M H2SO4 solution are needed to

neutralize 91.9 mL of a 0.336 M KOH solution? Explain the difference between an endpoint and an equivalence point.

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