Chemistry 101 - Chapter 4
Oxidation Number
(oxidation state) A positive or negative whole number assigned to an element in a molecule or ion on the basis of a set of formal rules: to some degree it reflects the positive or negative character of that atom Rules: 1) Monoatomic ions - oxidation number is the same as the charge 2) Neutral and Polyatomic ions - the oxidation number of a given atom is a hypothetical charge
Oxidation Rules
1) for an atom in its elemental form, (neutral or diatomic), the oxidation number is always 0 ex: each H atom in H2 has an oxidation number of 0 2) For any monoatomic ion the oxidation number equals the ionic charge ex: the K+ has an oxidation number of +1 3) Nonmetals usually have negative oxidation numbers Few exceptions; a) like O2 2-, each atom has a 1- oxidation number b) Oxidation number of H is usually +1 when bonded to nonmetals, and -1 when bonded to metals c) Oxidation number of flourine is -1 in all compounds; other Halogens have an oxidation number of -1 in binary compounds unless paired with oxygen which makes them +1 4) The sum of oxidation numbers in all neutral compounds is 0. The sum of the oxidation numbers in a polyatomic ion equals the charge of the ion
Displacement Reaction
A reaction between a metal and either an acid or a metal salt An ion in solution is displaced (replaced) through oxidation of an element Ex: A + BX --> AX + B or Zn + 2 HBr --> ZnBr2 + H2 Usually results in a salt and H2 gas
Neutralization Reaction
A reaction in which an acid and a base react in stoichiometrically equivalent amounts; the neutralization reaction between and a metal hydroxide produces water and salt
Precipitation Reaction
A reaction that occurs between substances in solution in which one of the products is insoluble
Electrolyte
A solute that produces ions in solution; an Electrolytic solution conducts an electric current Generally these are ionic compound such as metals-nonmetals *THIS IS NOT THE SAME AS SOUBILITY, some molecules readily dissolve but are not electrolytes
Aqueous Solution
A solution in which water is the solvent
Standard Solution
A solution of known concentration
Chemical Equilibrium
A state of dynamic balance in which the rate of formation of the products and the rate of formation of reactants from the products are equal; once at equilibrium the concentrations of the reactants and products remain constant
Strong Electrolytes
A substance (Strong acids, strong bases and most salts) that is completely ionized in solution Water-Soluble Ionic Compounds are Strong Electrolytes Usually an ionic compound, metal to nonmetal, with the exception of NH4+
Indicator
A substance added to a solution that changes color when the added solute has reacted with all the solute present in solution. The most common type of indicator is an acid-base whose color changes as a function of pH
Solutes
A substance dissolved in a solvent to form a solution; this is normally the component present in the smaller amount
Nonelectrolyte
A substance that not ionize in water and consequently gives a nonconducting solution Generally these are substances with C and H (exceptions are acids)
Weak Electrolytes
A substance that only partially ionizes ex: Acetic Acid, CH3COOH may only dissociate 1 H+ ion and CH3OO- results
Strong Acids
Acids that completely ionize in water
Weak Acids
Acids that partially ionize in water
Precipitate
An insoluble solid formed by a reaction in solution
Which of the following compounds is insoluble in water? a) (NH4)2S b) CaCO3 c) NaOH d) Ag2SO4 e) Pb(CH3COO)2
Answer: A
Which of the following combinations results in a redox reaction? a) Pb(s) and Fe(s) b) Pb(NO3)2 (aq) and Fe(s) c) Pb(NO3)2 (aq) and Fe(NO3)2 (a) d) Pb (s) and Fe(NO3)2 (aq)
Answer: B
Which reaction will result in formation of a precipitate? a) Pb(NO3)2 (aq) + AgCH3COO (aq) --> b) NaBr (aq) + (NH4)2CO3 (aq) --> c) SrCl2 (aq) + Na2SO4 (aq) --> d) LiNO3 (aq) + Na3PO4 (aq) -->
Answer: C
Salt
Any ionic compound whose cation comes from a base and whose anion comes from an acid
Will a precipitate form when solutions of Ba(NO3)2 and KOH are mixed?
Ba(NO3)2 + 2 KOH ->Ba(OH)2 + 2 KNO3 No it will not form a precipitate because Ba(OH)2 is soluble
a) Predict the identity of the precipitate that forms when aqueous solutions of BaCl2 and K2SO4 are mixed b) Write the balanced chemical equation for the reaction
BaCl2 + K2SO4 -> BaSO4 (s) + 2 KCl According to the soubility table, Ba2+ is not very soluble and therefore makes the precipitate
Strong bases
Bases that completely ionize in water Only soluble metal hydroxides are considered strong bases
Why isn't Al(OH)3 classified as a strong base?
Because it is insoluble
Why does this solution turn blue? check image
Because the Cu is reduced to Cu(NO3)2
Which of the following metals will be oxidized by Pb(NO3)2: a) Zn b) Cu c) Fe
Both Zn and Fe
A set of aqueous solutions are prepared containing different acids at the same concentration: acetic acid, chloric acid, and hydrobromic acid. Which solution(s) are the most electrically conductive? a_ Chloric Acid b) Hydrobromic Acid c) Acetic Acid d) Both Chloric Acid and Hydrobromic Acid e) all three solutions have the same electrical conductivity
CH3COOH, HClO3 and HBr Answer: B
What is the molar concentration of each ion present in a 0.025 M aqueous solution of calcium nitrate?
Ca(NO3)2 The subscripts in the chemical formula of the compound can be used to determine the relative ion concentrations mol NO3-/L = (0.025 mol Ca(NO3)2/L) x (2 mol NO3-/1 mol Ca(NO3)2) = 0.050 M NO3- mol Ca2+/L = (0.025 mol Ca(NO3)2/L) x (1 mol Ca2+/1 mol Ca(NO3)2) = 0.025 M Ca2+
Consider solutions in which 0.1 mol of each of the following compounds is dissolved in 1 L of water: Ca(NO3)2, C6H12O6, NaCH3COO, and CH3COOH. Rank the solutions in order of increasing electrical conductivity, knowing that the greater the number of ions in solution, the greater the conductivity.
Ca(NO3)2 > NaCH3COOH > CH3COOH > C6H12O6
How many grams of Ca(OH)2 are needed to neutralize 25.0 mL of 0.100 M HNO3?
Ca(OH)2 + 2 HNO3 --> Ca(NO3)2 + 2 H2O moles of solute = M x V = 0.100 M HNO3 x 0.025 L HNO3 = 0.0025 mol HNO3 0.0025 mol HNO3 x (1 mol Ca(OH)2/ 2 mol HNO3) x (74.1 g Ca(OH)2/1 mol Ca(OH)2) = 0.093 g Ca(OH)2
Write the net ionic equation for the precipitation reaction that occurs when aqueous solutions of calcium chloride and sodium carbonate are mixed.
CaCl2 (aq) + Na2CO3 (aq) --> CaCO3 (s) + 2 NaCl (aq) Ca+ (aq) + 2Cl- (aq) + 2Na+ (aq) + CO3 2- (aq) --> CaCO3 (s) + 2Na+ (aq) + 2Cl- (aq) Ca+ (aq) + CO3 2- (aq) --> CaCO3 (s)
How many moles of hydrogen gas would be produced for every mole of magnesium added into the HCl solution?
1 based on the stoichiometry
Weak Bases
Bases that partially ionize in water
Corrosion
Happens in metal slowly errods the structural integrity of the metal by means of Redox Reactions When a metal corrodes, each metal atom loses one or more electrons to form a cation
Monoprotic Acids
acids that yield only 1 H+ion per molecule of acid
Calculate the molarity of a solution made by dissolving 5.00 g of glucose (C6H12O6) in sufficient water to form exactly 100 mL of solution.
5.00 g C6H12O6 x (1 mol/ 180.2 g) = 0.0277 mol C6H12O6 100 ml x (1 L/1000 ml) = 0.1 L 0.0277 mol/0.1 L = 0.277 M
Molarity
(M) expresses the concentration of a solution as the # of moles of solute in 1 L of solution Check image Ex: 1M solution = 1.00 mol/1 L
Write the balanced molecular and net ionic equations for the reaction of aluminum with hydrobromic acid.
2 Al (s) + 6 HBr (aq) --> 2 AlBr3 (aq) + 3 H2 (g) 2 Al3+ (aq) + 6 H+ (aq) + 6 Br- (aq) --> 2 Al3+ (aq) + 3 H2 (g) + 6 Br - (aq) 2 Al (s) 6 H+ --> 2 Al3+ (aq) + 3 H2 (g)
How many electrons does each oxygen atom gain during the course of this reaction? Check Image
2 electrons
Which is the correct net ionic equation for the reaction of aqueous ammonia with nitric acid? Check image for possible answer choices
NH3+ (aq) + HNO3 (aq) --> NH3NO3 (aq) + H2O (aq) NH3+ + 3H+ + NO3- --> NH4+ + H2O + NO3- NH3+ + 3H+ --> NH4+ + H2O answer: D
Classify these dissolved substances as a strong electrolyte, weak electrolyte, or nonelectrolyte: CaCl2, HNO3, C2H5OH (ethanol), HCOOH (formic acid), KOH
Strong = CaCl2, KOH, HNO3 Weak = HCOOH Nonelectrolyte = C2H5OH
Concentration
the amount of solute dissolved in a given quantity of solvent or quantity of solution
Titration
the process of reacting a solution of unknown concentration with one of known concentration
Will an aqueous solution of iron(II) chloride oxidize magnesium metal? If so, write the balanced molecular and net ionic equations for the reaction.
FeCl2 (aq) + Mg (s) --> Fe(s) + MgCl2 (aq) Fe2+ (aq) + 2Cl- (aq) + Mg(s) --> Fe (s) + Mg2+ (aq) + 2Cl- (aq) Fe2+ (aq) + Mg (s) --> Fe (s) + Mg2+ (aq)
By analogy to examples given in the text, predict what gas forms when Na2SO3 (a) reacts with HCl (aq).
H2S (g) Hydrogen Sulfide, which is the substance that gives off the rotten egg odor
If you have an aqueous solution that contains 1.5 mol of HCl, how many moles of ions are in the solution?
HCl + H2O -> Cl- + H2O + H+ HCl is a strong electrolyte that completely ionizes in water, thus 1.5 mol of hydrogen ions are formed and 1.5 mol of chloride ions are formed to give a total of 3.0 mol of ions when in aqueous solution
How would the volume of standard solution added change if that solution were Ba(OH)2 (aq) instead of NaOH(aq) Check image
HCl + NaOH --> NaCl + H2O 2 HCl + Ba(OH)2 -> BaCl2 + 2 H2O The volume of acid would have to be doubled, so that stoichiometrically everything reacts
Which of these metals is the easiest to oxidize? a) gold b) lithium c) iron d) sodium e) aluminum
Lithium Answer: B
Calculate the Molarity of a solution made by dissolving 23.4 g of sodium sulfate (Na2SO4) in enough water to form 125 mL of solution
M = mol/L Molar Mass Na2SO4 2(22.99)+32.06+4(16) = 142.04 g/mol 23.4 g Na2SO4 x (1 mol Na2SO4/142.04 g Na3SO4) = 0.165 mol Na2SO4 Now mL to L 125 mL x (1 L/1000 ml) = 0.125 L 0.165 mol/0.123 L = 1.32 M
How many grams of Na2SO4 are required to make 0.350 L of 0.500 M Na2SO4?
M = mol/L mol = MxL mol = )0.500 Na2SO4) x (0.350 L = 0.175 mol Na2SO4 0.175 mol Na2SO4 x (142.04 g/ 1 mol Na2SO4) = 24.9g Na2SO4
How many milliliters of 3.0 M H2SO4 are needed to make 450 mL of 0.10 M H2SO4
M1V1 = M2V2 (3.0 M)(V1) = (0.10 M)(450 mL) V1 = (0.10 x 450)/3.0 = 15 mL
What volume of a 1.00 M stock solution of glucose muse be used to make 500.0 mL of a 1.75x10^-2 M glucose solution in water? a) 1.75 mL b) 8.75 mL c) 48.6 mL d) 57.1 mL e) 28,570 mL
M1V1 = M2V2 1.00 M x 500.0 mL = 1.75x10^2 M x (V 2) V2 = (1x500)/ 1.75x20^-2 = 28571.4 mL Answer: E
What is the concentration of ammonia in a solution made by dissolving 3.75 g of ammonia in 120.0 L of water? a) 0.0313 M b) 7.05 M c) 1.84 M d) 3.78x10^-2 M e) 1.84x10^-3 M
M=mol/L 3.75 g NH3 x (1 mol NH3/17.03 g) = 0.220 mol NH3 M = 0.220 mol NH3/120.0 L = 0.00183 or 1.83x10^-3 M Answer: E
How is the molarity of a 0.50 M KBr solution changed when water is added to double its volume?
M=mol/L so it would decrease if L were to increase
What is the molarity of an HCl solution if 27.3 mL of it neutralizes 134.5 mL of Ba(OH)2? a) 0.0444 M b) 0.0813 M c) 0.163 M d) 0.325 M e) 3.35 M
M=mol/L 1 g = 1 ml 0.10 mol/L = moles 2 HCl (aq) + Ba(OH)2 (aq) --> BaCl2(s) + 2 H2O (aq) 27.3 ml HCl x (1 L/1000 ml) x (0.10 mol HCl/1L) = 0.00273 mol HCl M HCl = 0.00273 mol/0.0273 L = 0.1 M Answer: B
a) What volume of 2.50 M lead(II) nitrate solution contains 0.0500 mol of Pb2+? b) How many milliliters of 5.0 M K2Cr2O7 solution must be diluted to prepare 250 mL of 0.10 M solution? c) If 10.0 mL of a 10.0 M stock solution of NaOH is diluted to 250 mL, what is the concentration of the resulting stock solution?
M=mol/L L = mol/M a) 0.0500 mol/2.50 M = 0.02 L Pb+ b) (5.0 M)(V1) = (0.10M)(250 mL) V1 = 0.10 x 250/5.0 = 5.0 mL c) 10.0 ml x 10.0 M = (M2) x 250 ml M2 = 10 x 10/250 = 0.40 M
a) How many grams of Na2SO4 are there in 15 mL of 0.50 M Na2SO4 b) How many milliliters of 0.50 M Na2SO4 solution are needed to provide 0.038 mol of this salt?
M=mol/L mol = LxM L = mol/M 15 ml = 0.015 L a) mol = 0.015 L x 0.50 M = 0.0075 mol Na2SO4 0.0075 mol Na2SO4 x (142.04 g/1 mol Na2SO4) = 1.1 g Na2SO4 b) 0.038 mol Na2SO4/0.50 M = 0.076 L 0.076 L to ml 76 mL
The quantity of Cl- in a municipal water supply is determined by titrating the sample with Ag+. The precipitation reaction taking place during the titration is Ag+ (aq) + Cl- (aq) --> AgCL(s) a) How many grams of chloride ion are in a sample of the water if 20.2 mL of 0.100 M Ag+ is needed to react with all the chloride in the sample? b) If the sample has a mass of 10.0 g, what percentage of Cl- does it contain?
M=mol/L mol = MxL a) mol = 0.100 M Ag+ x 0.0202 L = 0.00202 mol Ag+ 0.00202 mol Ag+ x (1 mol Cl-/1 mol Ag+ ) x (35.45 g Cl-/1 mol cl-) = 0.0072 g Cl- b) (0.0072/10 g) x 100 = 0.716 %
A sample of an iron ore is dissolved in acid, and the iron is converted to Fe2+. The sample is then titrated with 47.20 mL of 0.02250 M MnO4 (-) soln. The oxidation-reduction reaction that occurs during titration is MnO4(1-) (aq) + 5 Fe(2+) (aq) + 8 H+ (aq) --> Mn2+ (aq) + 5 Fe(3+ (aq) + 4 H2O (l) a) How many moles of MnO4 (1-) were added to the solution? b) How many moles of Fe2+ were in the sample? c) How many grams of iron were in the sample? d) If the sample had a mass of 0.8890 g, what is the percentage of iron in the sample?
M=mol/L mol= M x L a) mol of MnO4(1-) = 0.02250 M x 0.04720 L = 1.1x10^-3 mol MnO4(1-) b) 1.1x10^-3 mol MnO4(1-) x (5 mol Fe2+/1 mol MnO4(1-)) = 5.31 x 10^-3 mol Fe2+ c) 5.31 x10^-3 mol Fe2+ x (55.85 g/1 mol Fe2+) = 0.297 g Fe2+ d) (0.297 g Fe2+/0.8890 g total) x 100 = 33.4%
What is the molarity of a NaOH solution if 48.0 mL neutralizes 35.0 mL of 0.144 M H2SO4?
M=mol/L of soln mol = M x L 2 NaOH + H2SO4 --> Na2SO4 (s) + 2 H2O mol of H2SO4 = 0.144 x 0.035 L = 0.00504 mol H2SO4 0.00504 mol H2SO4 x (2 mol NaOH/1 mol H2SO4) = 0.0101 mol NaOH M = 0.0101 mol NaOH/ 0.048 L = 0.210 M NaOH
Interconverting Molarity, Moles and Volume
Moles of x = (L soln) x (mol of x/L soln) Liters of soln = (mol of x) x (1 L soln/mol of x) Liters = mol x (1/M) or mol x (L/mol)
How many milligrams of sodium sulfide are needed to completely react with 25.00 mL of a 0.0100 M aqueous solution of cadmium nitrate, to form a precipitate of CdS(s)? a) 13.8 mg b) 19.5 mg c) 23.5 mg d) 32.1 mg e) 39.0 mg
Na2S (s) + Cd(NO3)2 (aq) --> CdS (s) + 2 NaNO3 (aq) M = mol/L mol = M x L = 0.0100 M Cd(NO3)2 x 0.025 L Ch(NO3)2 = 0.00025 mol Cd(NO3)2 0.00025 mol Cd(NO3)2 x (1 mol Na2S/1 mol Cd(NO3)2) x (78.04 g Na2S/ 1 mol Na2S) = 0.0195 g Na2S 0.195 g x 1000 = 19.5 mg Answer: B
Do both, just one, or neither of the following solutions conduct electricity? If just one, which one?
NaCl will conduct electricity, but not Methanol
Which solute will cause the light bulb in Figure 4.2 to glow most brightly, CH3OH, NaOH, or CH3COOH
NaOH strongest, CH3COOH weakest
Net Ionic Equation
Once the spectator ions are canceled out from the complete ionic equation, we are left with a net ionic equation It includes only ions and molecules directly involved in the reaction ex: Pb2+ (aq) + 2 I- (aq) --> PbI2(s)
Exchange Reactions (Metathesis Reactions)
Reactions between compounds that when written, seem to trade cations and anions Most precipitation reactions, and acid/base neutralization reactions do this
Bases
Substances that accept H+ ions; can produce OH- ions when they dissolve in water Common bases are NaOH, KOH, Ca(OH)2 and NH3+ Most bases are weak bases, except for a select few (See image)
Acids
Substances that ionize in aqueous solution to form H+ ions; They are able to donate an H+ ion "Proton Donors" H+ are also called protons Most Acids are weak except for a few
Equivalence Point
The point in a titration at which the added solute reacts completely with the solute present in solution
Dilution
The process of preparing a less concentrated solution from a more concentrated one by adding solvent Moles solute before dilution = moles solute after dilution Mconc x Vconc = Mdil x Vdil M1V1 = M2V2
Oxidized
The substance that lost one or more electrons
Reduced
The substance that recieved electrons in a redox reaction
Which of the following statements is true about the reaction between zinc and copper sulfate? a) Zinc is oxidized, and copper ion is reduced. b) Zinc is reduced, and copper ion is oxidized. c) All reactants and products are soluble strong electrolytes. d) The oxidation state of copper in copper sulfate is 0. e) More than one of the previous choices are true.
Zn2+ (s) + CuSO4 (aq) --> ZnSO4 (aq) + Cu 2+ (aq) Answer: B
A sample of 70.5 mg of potassium phosphate is added to 15.0 mL of 0.050 M silver nitrate, resulting in the formation of a precipitate. a) Write the molecular equation for the reaction. b) What is the limiting reactant in the reaction? c) Calculate the theoretical yield, in grams, of the precipitate that forms.
a) K3PO4 (aq) + 3 AgNO3 (aq) --> Ag3PO4 (s) + 3 KNO3 (aq) b) 70.5 mg K3PO4 x (1g/1000mg) x (1 mol K3PO4/212.3 g K3PO4) = 3.32x10^-4 mol K3PO4 3.32x10^-4 mol K3PO4 x (3 mol AgNO3/1 mol K3PO4) = 9.96x10^-4 mol AgNO3 mol AgNO3 = 0.050Mx 0.015 L = 7.5x10^-4 mol AgNO3 7.5x10^-4 mol AgNO3 x (1 mol AG3PO4/ 3 mol AgNO3) = 2.5x10^-4 mol K3PO4 3.32x10^-4 - 2.5x10^-4 mol K3PO4 = 8.2x10^-5 mol K3PO4 7.5x10^-4 mol AgNO3 - 9.96x10^-4 mol AgNO3 = -2.46x10^4 mol AgNO3 Limiting reagent is AgNO3 c) 7.5x10^-4 mol AgNO3 x (1 mol K3PO4/ 3 mol Ag3PO4) x (418.7 g Ag3PO4/1 mol Ag3PO4) = 0.104 g Ag3PO4
a) Write the balanced molecular and net ionic equations for the reaction between magnesium and cobalt(II) sulfate. b) What is oxidized, and what is reduced in the reaction?
a) Molecular: Mg (s) + CoSO4 (aq) --> MgSO4 (aq) + Co(s) Net Ionic: Mg(s) + Co2+ (aq) + SO4- (aq) --> Mg2+ (aq) + SO4- (Aq) + Co(s) Mg(s) + Co2+ (aq) --> Mg2+ (aq) + Co(s) b) the Mg(s) is Oxidized, and the Co2+ is reduced
What is the oxidation state of the boldfaced element? a) P2O5 b) NaH c) Cr2O7 (2-) d) SnBr4 e) BaO2
a) O = is 2-; P = +5 b) H normally is +1 unless bonded to a metal so it equals -1 c) O = 2-, Cr = +6 d) Br = -1; Sn = +4 e) Ba = +2; O = -1
Classify these ionic compounds as soluble or insoluble in water: a) Sodium Carbonate, Na2CO3 b) Lead Sulfate, PbSO4
a) Soluble b) Insoluble
Does a reaction occur a) when an aqueous solution of NiCl2 (Aq) is added to a test tube containing strips of metallic zinc, and b) when NiCl2 (aq) is added to a test tube containing Zu(NO3)2 (aq)?
a) Yes, Nickel is below zinc in activity series b) No, because the Zn2+ ions cannot be further oxidized
For the reaction between aqueous solutions of acetic acid (CH3COOH) and barium hydroxide, Ba(OH)2, write a) the balanced molecular equation, b) the complete ionic equation, c) the net ionic equation.
a)2 CH3COOH + Ba(OH)2 --> Ba(CH3COOH)2 (aq) + 2 H2O (l) b) 2 CH3COOH (aq) + Ba 2+ (aq) + 2OH- (aq) --> 2 CH3COO- (aq) + Ba 2+ (aq) + 2H2O (l) c) CH3COOH (Aq) + 2 OH- (aq) --> 2 H2O (l) + CH3COO- (aq)
Diprotic Acid
acids that yield 2 H+ ions per molecule of acid they also require 2 steps to ionize into water ex: H2SO4 --> H+ + HSO4- then HSO4 --> H+ + SO4 2-
Solvation
the clustering of solvent molecules around a solute particle which helps to stabilize the ions in solution; Prevents cations and anions from recombining
In which compound is the oxidation state of oxygen -1? a) O2 b) H2O c) H2SO4 d) H2O2 e) KCH3COO
d) H is +1, so O has to be O2 2- meaning O = -1 Answer: D
Spectator Ions
Ions that appear on both sides of a complete ionic equation; they remain unchanged by the reaction
What is the ratio of the concentration of potassium ions to the concentration of carbonate ions in a 0.015 M solution of potassium carbonate? a) 1:0.015 b) 0.015:1 c) 1:1 d) 1:2 e) 2:1
K+ to CO32- K2CO3 0.015 mol K2CO3/L x (2 mol K+/1 mol K2CO3) = 0.03 mol K+ 0.015 mol K2CO3/L x (1 mol CO3 2-/1 mol K2CO3) = 0.015 M CO3 2- 0.03 M K+:0.015 M CO3 2- or 2:1 Answer: E
Complete Ionic Equation
A chemical equation in which dissolved strong electrolytes are written as separate ions ex: Pb2+ (aq) + 2NO3- (aq) + 2 K+ (aq) --> PbI2 (s) + 2K+ (aq) + 2 NO3- (aq)
Molecular Equation
A chemical equation in which the formula for each substance is written without regard for whether it is an electrolyte or a nonelectrolyte
Activity Series
A list of metals in order of decreasing ease of oxidation Any of the ions can be oxidized by a metal or ion below it ONLY metals ABOVE hydrogen in the activity series are ABLE TO REACT WITH ACIDS TO FORM H2 See image
What is the molar concentration of K+ ions in a 0.015 M solution of potassium carbonate?
0.015 M K2CO3 x (2 mol K+/1 mol K2CO3) = 0.03 M K+
What happens when you mix an aqueous solution of sodium nitrate with an aqueous solution of barium chloride? a) Both barium nitrate and sodium chloride precipitate b) Only sodium chloride precipitate c) Only barium nitrate precipitates d) There is no reaction; all possible products are soluble e) Barium chloride is not soluble and it stays as a precipitate
2 NaNO3 (aq) + BaCl2 (aq) --> 2 NaCl (aq) + Ba(NO3)2 (aq)
a) How many grams of NaOH are needed to neutralize 20.0 mL or 0.150 M H2SO4 solution? b) How many liters of 0.500 M HCl (aq) are needed to react completely with 0.100 mol of Pb(NO3)2 (aq) forming a precipitate of PbCl2 (s)
2 NaOH + H2SO4 --> Na2SO4 + 2 H2O M = mol/L mol = M x L L = mol/M = 0.150 M H2SO4 x 0.02 L H2SO4 = 0.003 mol H2SO4 0.003 mol H2SO4 x (2 mol NaOH/ 1 mol H2SO4) x (40 g NaOH/1 mol NaOH) = 0.24 g NaOH b) 2 HCl (aq) + Pb(NO3)2 (aq) --> PbCl2 (s) + 2 HNO3 (aq) 0.100 mol Pb(NO3)2 x (2 mol HCl/1 mol Pb(NO3)2) = 0.200 mol HCl L = 0.200 mol HCl/0.500 M HCl = 0.400 L HCl
One commercial method used to peel potatoes is to soak them in a NaOH solution for a short time and then remove the potatoes and spray off the peel. The NaOH concentration is normally 3 to 6 M, and the solution must be analyzed periodically. In one such analysis, 45.7 mL of 0.500 M H2SO4 is required to neutralize 20.0 mL of NaOH solution. What is the concentration of the NaOH solution?
2 NaOH + H2SO4 --> Na2SO4 + 2 H2O M=mol/L mol = M x L mol H2SO4 = 0.500 M x 0.0457 L = 0.0229 mol H2SO4 0.0229 mol H2SO4 x (2 mol NaOH/1 mol H2SO4) = 0.0456 mol NaOH M=mol/L M of NaOH = 0.0456 mol NaOH/0.02 L NaOH = 2.28 M NaOH
Write the net ionic equation for the precipitation reaction that occurs when aqueous solutions of silver nitrate and potassium phosphate are mixed.
3 AgNO3 (aq) + K3PO4 (aq) --> Ag3PO4 (s) + 3 KNO3 (aq) 3 Ag+ (aq) + PO4 3- (aq) --> Ag3PO4 (s)
What is the molarity of a solution that is made by dissolving 3.68 g of sucrose (C12H22O11) in sufficient water to form 275.0 mL of solution? a) 13.4 M b) 7.43x10^-2 M c) 3.91 x 10^-2 M d) 7.42x 10^-5 M e) 3.91x 10^-5 M
3.68 g C12H22O11 x (1 mol/342.296 g) = 0.0108 mol C12H22O11 275.0 mL x (1 L/1000 ml) = 0.275 L 0.0108 mol/0.275 L = 0.0393 M or 3.93x10^-2 M Answer: C
The structural formula of citric acid, a main component of citrus fruits, is (see image) How many H+ (aq) can be generated by each citric acid molecule dissolved in water?
4, Hydrogens can only dissociate from the COO-H bonds. Never from C-H bonds
Solution
A homogeneous mixture of two or more substances
Which ions, if any, are spectator ions in this reaction? AgNO3 (aq) + NaCl (aq) ---> AgCl (s) + NaNO3 (aq)
Ag+ (aq) + NO3- (aq) + Na+ (aq) + Cl-(aq) --> AgCl(s) + Na+ (aq) + NO3- (aq) Ag+ (aq) + Cl- (aq) --> AgCl(s) Spectators: NO3- and Na+
Which of these substances, when dissolved in water, is a strong electrolyte? a) ammonia b) hydrofluoric acid c) folic acid d) sodium nitrate e) sucrose
D
Solubility
The amount of a substance that dissolves in a given quantity of solvent at a given temperature to form a saturated solution Anything with a solubility of less that 0.01 mol/L is generally INSOLUBLE All compounds containing NO3- will be soluble in water
Imagine a diagram showing 10 Na+ ions and 10 OH- ions. If this solution were mixed with the one pictured above for HY, what species would be present in a diagram that represents the combined solutions after any possible reaction?
The diagram would show 10 Na+ ions, 2 OH- ions, 8 Y- ions and 8 H2O molecules
Solvent
The dissolving medium of a solution; it is normally the component of a solution present in the greater amount
Reduction
The gain of electrons
Oxidation
The loss of electrons
A mysterious white powder is found at a crime scene. A simple chemical analysis concludes that the powder is a mixture of sugar and morphine (C17N19NO3), a weak base similar to ammonia. The crime lab takes 10.00 mg of the mysterious white powder, dissolves it in 100.00 mL water, and titrates it to the equivalence point with 2.84 mL of a standard 0.0100 M HCl solution. What is the percentage of morphine in the white powder? a) 8.10% b) 17.3% c) 32.6% d) 49.7% e) 81.0%
X = C17N19NO3 Molar mass = 285.34 g/mol # of moles of morphine = # of moles of HCl mol of HCl = 0.0100 M x 0.00284 L = 2.84x10^-5 mol HCl = 2.84x10^-5 mol Morphine Mass of Morphine = # of moles x Molar mass =2.84x10^-5 mol Morphine x 285.34 g/mol = 8.1x10^-3 g Morphine (8.1x10^-3 g/0.01 g) = 81% Answer: E
a) What compound precipitates when aqueous solutions of Fe2(SO4)3 and LiOH are mixed? b) Write a balanced equation for the reaction.
a&b) Fe2(SO4)3 + 6 LiOH --> 3 Li2SO4 + 2 Fe(OH)3 (s)
If you were to draw diagrams representing aqueous solutions of a) NiSO4 b) Ca(NO3)2 c) Na3PO4 d) Al2(SO4)3 How many anions would you show if each diagram contained six cations?
a) 6 b) 12 c) 2 d) 9
What is the oxidation number of nitrogen a) in aluminum nitride, AlN b) in Nitric Acid, HNO3?
a) Al is normally 3+, so N = 3- b) H+, O = 3 x (2-) = 6 - N must be +5
Determine the oxidation number of sulfur in a) H2S b) S8 c) SCl2 d) Na2SO3 e) SO4 2-
a) H = 2+, S = 2- b) S = 0 c) Cl = 2-, S = 2+ d) O = 6-, Na = 2+, S = 4+ e) O = -8, S= +6
For the reaction of phosphorous acid (H3PO3) and potassium hydroxide (KOH), write a) the balanced molecular equation and b) the net ionic equation. Note that phosphorous acid is a diprotic acid.
a) H3PO3 + 3 KOH --> K3PO3 + 3 H2O b) 3H+ + PO3- + 3K+ + 3 OH- --> 3K+ + PO3 - + 3H2O (l) 3H+ (aq) + 3 OH- (aq) --> 3 H2O (l)
Classify the following compounds as soluble or insoluble in water: a) Cobalt(II) Hydroxide b) Barium Nitrate, c) Ammonium Phosphate
a) Insoluble b) Soluble c) Soluble
What dissolved species are present in a solution of a) KCN b) NaClO4
a) K+ and SN- b) Na+ and ClO4-
Active metals
metals that react most readily to form compounds