AP Chem Unit 4

what are the oxidation numbers for H2O?

+1 and -2

what is the oxidation number for hydrogen?

+1 with nonmetal, -1 with metal

what are the oxidation numbers for NaNO3?

+1, +5, -2

what are the oxidation numbers for CO2?

+4 and -2

what are the oxidation numbers for SO4^2-?

+6 and -2

50 mL of 0.1 M HCl is titrated with 0.1 M NaOH. find the pH at the various points: 0 mL NaOH added, 20 mL NaOH added, 30 mL NaOH added, 50 mL NaOH added, and 75 mL NaOH added

1, 1.2, 1.4, 1.6, 7, 12.3

calculate the pH during the titration of 40.00 mL of 0.1 M HCl with 0.2 M NaOH solution after the following additions of base: 0 mL, 10 mL, 19 mL, 19.90 mL, 20 mL, 20.1 mL, 30 mL

1, 1.39, 2.52, 3.48, 7, 10.52, 12.46

pH + pOH = ___

14

what is the % mass of N in Ca(NO3)2?

17%

Al (s) + KOH (aq) + H2SO4 (aq) + H2O (l) --> K[Al(SO4)2] hydrated with 12 H2O (s) + H2 (g) calculate the theoretical yield of the alum using the above balanced equation. use the aluminum foil as the limiting reactant and assume that the foil was pure aluminum

17.8 g

write the net ionic equation for Al (s) + KOH (aq) + H2O (l) --> K[Al(OH)4] (aq) + H2 (g) is it a redox reaction?

2 Al (s) + 2 OH- (aq) + 6 H2O (l) --> 2 Al(OH)4- (aq) + 3 H2 (g) yes, it is a redox reaction

write the net ionic equation for Al(OH)3 (s) + H2SO4 (aq) --> Al2(SO4)3 (aq) + H2O (l) is it a redox reaction?

2 Al(OH)3 (s) + 6 H+ (aq) --> 2 Al3+ (aq) + 6 H2O (l) no, it is not a redox reaction

write the net ionic equation for Al2(SO4)3 (aq) + H2O (l) + K2SO4 (aq) --> K[Al(SO4)2] hydrated with 12 H2O (s) is it a redox reaction?

2 Al3+ (aq) + 4 SO4^2- (aq) + 24 H2O (l) + 2 K+ (aq) --> 2 K[Al(SO4)2] hydrated with 12 H2O (s) no, it is not a redox reaction

write the net ionic equation for KOH (aq) + H2SO4 (aq) --> H2O (l) + K2SO4 (aq) is it a redox reaction?

2 OH- (aq) + 2 H+ (aq) --> H2O (l) no, it is not a redox reaction

what is the mass % of Cl in KClO4

25.6%

an auto mechanic spills 88 mL of 2.6 M H2SO4 solution from an auto battery. how many mL of 1.6 M NaHCO3 must be poured on the spill to react completely with the sulfuric acid?

286 mL

...Ca3(PO4)2 + ...H3PO4 --> ...Ca(H2PO4)2 when the equation above is balanced and all coefficients are reduced to lowest whole-number terms, what is the coefficient for H3PO4?

4

if the theoretical yield of alum was 17.8 g, and the actual sample of alum collected was 9 g, what is the % yield?

51%

2 HCl (aq) + CaCO3 (s) --> CaCl2 (aq) + CO2 (g) + H2O (l) how many mL of 0.383 M HCl are needed to react with 16.2 g of CaCO3?

840 mL HCl

write the net ionic equation for K[Al(OH)4] (aq) + H2SO4 (aq) --> Al(OH)3 (s) + H2O (l) + K2SO4 (aq) is it a redox reaction?

Al(OH)4- (aq) + 5 H+ (aq) --> Al(OH)3 (s) + H2O (l) no, it is not a redox reaction

write a balanced chemical equation for the dissolution of Ca(OH)2 in pure water

Ca(OH)2 --> Ca2+ + 2 OH-

HC2H3O2 + OH- --> C2H3O2- + H2O identify both the Bronsted- Lowry conjugate acid-base pairs in the neutralization reaction

HC2H3O2 & C2H3O2- ; OH- & H2O

a 5.34 g sample of an oxide of tungsten (W) contains 4.23 g of tungsten. what is the empirical formula of the oxide?

WO3

write the net ionic equation for Zn (s) + 2HCl (aq) --> ZnCl2 (aq) + H2 (g)

Zn (s) + 2 H+ (aq) --> Zn2+ (aq) + H2 (g)

write the net ionic equation for Zn (s) + Cu(NO3)2 (aq) --> Zn (NO3)2 (aq) + Cu (s)

Zn (s) + Cu2+ (aq) --> Zn2+ (aq) + Cu (s)

write the net ionic equation for Zn(NO3)2 (aq) + Na2CO3 (aq) --> ZnCO3 (s) + 2NaNO3 (aq)

Zn2+ (aq) + CO32- (aq) --> ZnCO3 (s)

a student was studying physical and chemical changes. the student carried out some procedures in the laboratory and recorded observations. for one of the procedures, the student concluded that a physical change took place, but not a chemical change. which of the following could have been the results of the procedure? a) a cube of metal was changed into a flat sheet of metal b) when two liquids at room temperature were combined in a beaker, the beaker became hot c) when two clear liquids were combined, the resulting mixture was cloudy d) when a colorless liquid was added to a blue liquid, the resulting solution was yellow

a

the half reactions for the redox reaction between Cr (s) and Ag+ (aq) are: Cr (s) --> Cr^3+ (aq) + 3 e- Ag+ (aq) + e- --> Ag (s) a) which substance is being oxidized and which is reduced? b) write the balanced net ionic equation for the redox reaction

a) Cr is oxidized, Ag is reduced b) Cr (s) + 3 Ag+ (aq) --> Cr^3+ (aq) + 3 Ag (s)

proton donor

acid

proton acceptor

base

if there is a greater concentration of OH- than H+, will the solution be basic, neutral, or acidic?

basic

when C2H4 (g) reacts with H2 (g), the compound C2H6 (g) is produced. the reaction is correctly classified as which of the following types? a) acid-base, because 2 hydrogen atoms are donated to C2H4 (g) b) precipitation, because 2 reactant species form a single product c) decomposition, because pure H2 (g) is consumed d) oxidation-reduction, because H2 (g) is oxidized

d

true or false: H2O is always a base

false (H2O can act as an acid or a base)

true or false: all titrations are acid-base reactions

false (can also be a redox reaction)

true or false: the sum of oxidation numbers for a polyatomic ion is 0

false (the sum of oxidation numbers is the charge)

true or false: in a redox reaction, the e- lost by one species must be equal to the e- gained by another

true

what is the oxidation number for oxygen (except in peroxides when it's -1)?

-2

what is the sum of oxidation numbers in a neutral compound?

0

equal volumes of 0.2⁢M solutions of lead (II) nitrate and potassium bromide are combined to form lead(II) bromide as a yellow precipitate. which of the following is the correct net ionic equation for the reaction? a) Pb2+ (aq) + 2 Br- (aq) --> PbBr2 (s) b) K+ (aq) + NO3- (aq) --> KNO3 (aq) c) Pb2+ (aq) + 2 NO3- (aq) + 2 K+ (aq) + 2 Br- (aq) --> 2 K+ (aq) + 2 NO3- (aq) + PbBr2 (s) d) Pb(NO3)2 (aq) + 2 KBr (aq) --> PbBr2 (s) + 2 KNO3 (aq)

a

a reaction when solutions of an acid and a base are mixed, and a neutralization reaction occurs

acid-base reaction

in a titration lab, this is the solution in the flask (most often the solution of unknown concentration)

analyte

2 F2 (g) + 2 NaOH (aq) --> OF2 (g) + 2 NaF (aq) + H2O (l) a 2 mol sample of F2 (g) reacts with excess NaOH (aq) according to the equation above. if the reaction is repeated with excess NaOH (aq) but with 1 mol of F2 (g), which of the following is correct? a) the amount of OF2 (g) produced is doubled b) the amount of OF2 (g) produced is halved c) the amount of NaF (aq) produced remains the same d) the amount of NaF (aq) produced is doubled

b

Al (s) --> Al3+ (aq) + 3 e- Zn2+ (aq) + 2 e- --> Zn (s) the half-reactions for the oxidation-reduction reaction between Al (s) and Zn2+ (aq) are represented above. based on the half-reactions, what is the coefficient for Al (s) if the equation for the oxidation-reduction reaction is balanced with the smallest whole-number coefficients? a) 1 b) 2 c) 3 d) 4

b

NH3 (aq) + HCl (aq) --> NH4+ (aq) + Cl- (aq) the Bronsted-Lowry bases in the reaction are... a) NH3 and NH4+ b) NH3 and Cl- c) NH3 and HCl d) HCl and NH4+ e) HCl and Cl-

b

a 6 mol sample of C3H8 (g) and a 20 mol sample of Cl2 (g) are placed in a container where they react according to the equation: C3H8 + 4 Cl2 --> C3H4Cl4 + 4 HCl. after one of the reactants has been totally consumed, how many moles of HCl have been produced? a) 4.0 mol b) 8.0 mol c) 20 mol d) 24 mol

c

a student was asked to formulate a hypothesis about what would happen if 100.mL of 0.1MNaOH(aq) at 25°C was combined with 100.mL of 0.1MMgCl2(aq) at 25°C. which of the following hypotheses indicates that the student thought a chemical change would occur? a) the volume of the resulting solution will be equal to the sum of the volumes of the original solutions b) the mass of the resulting solution will be equal to the sum of the masses of the original solutions c) the resulting solution would contain a precipitate d) the resulting solution will be clear

c

in a titration lab, this is the solution in the buret (most often the solution of known concentration)

titrant

an experimental technique where a solution of known concentration (standard solution) is combined with a solution of unknown concentration to determine the amount of moles or molarity in the unknown

titration

true or false: chemical properties change after a chemical reaction

true

true or false: conjugate acid-base pairs differ by 1 proton (H+)

true

true or false: if we know the volume of the unknown concentration substance it takes to neutralize a substance of known concentration, we can determine the molarity (concentration) of the unknown concentration substance

true

true or false: mass and matter are conserved in physical and chemical reactions

true

what is the oxidation number for an atom in its elemental form (ex: H2, O2, Fe, Al)?

0

if 25.98 mL of 0.1180 M KOH solution reacts with 52.50 mL of CH3COOH solution, what is the molarity of the acid solution?

0.057 M

if it took 14.9 mL of 0.051 M NaOH to neutralize 10 mL of HCl, what is the molarity of the unknown HCl solution?

0.076 M

C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O the reaction between C6H12O6 and O2 is represented by the balanced equation above. in an experiment, 0.30 mol of CO2 was produced from the reaction of 0.05 mol of C6H12O6 with excess O2. the reaction was repeated at the same temperature and in the same container, but this time 0.60 mol of CO2 was produced. which of the following must be true? a) the initial amount of C6H12O6 in the container must have been 0.10 mol b) exactly 0.30 mol of C6H12O6 must have reacted because C atoms were conserved c) exactly 0.40 mol of O2 must have reacted because the temperature and container volume are the same d) more than 0.60 mol of O2 must have reacted because it was present in excess

a

Zn (s) + 2 HCl (aq) --> ZnCl2 (aq) + H2 (g) when a student adds 50 mL of 1.00 M HCl to 2.35 g of Zn, a reaction occurs according to the equation above a) when the reaction is completed at 273 K and 1 atm, what volume of H2 is produced? b) which of the following changes would increase the volume of H2 (g) produced? i) doubling the mass of Zn ii) doubling the volume of HCl iii) doubling the concentration of HCl

a) 0.56 L H2 b) ii and iii (increases to 0.804 L H2)

2 MnO4-(aq) + 5 H2O + 6 H+ --> 2 Mn2+ + 5 O2 + 8 H2O a student was given the task of determining the molarity of an unknown concentration of H2O2. she analyzed a 10.0 mL sample of H2O2 by titrating it with 0.0330 M KMnO4 was required to reach the equivalence point a) calculate the number of moles of MnO4- that reacted completely with the H2O2 b) calculate the [H2O2] in the solution

a) 3.53 x 10^-4 mol MnO4- b) 0.0882 M H2O2

in an experimental procedure, a student titrates 10.0 mL of 2.0 M HC2H3O2 (aq) with an NaOH (aq) solution of unknown concentration a) write the net ionic equation b) calculate the molar concentration of the NaOH solution if it takes 14 mL of NaOH to reach the equivalence point

a) HC2H3O2 + OH- --> C2H3O2- + H2O b) 1.43 M NaOH

the half-reactions for the oxidation-reduction reaction between Co (s) and Ag+ (aq) are: Co (s) --> Co2+ (aq) + 2 e- and Ag+ (aq) + e- --> Ag (s) a.) which substance is being oxidized and which substance is being reduced? b.) write the balanced net ionic equation for the oxidation-reduction reaction based on the half-reactions above

a.) Co is oxidized and Ag is reduced b.) Co (s) + 2 Ag+ (aq) --> Co2+ (aq) + 2 Ag (s)

the reaction between solid aluminum and aqueous nickel (II) nitrate is represented by the equation: Al (s) + Ni(NO3)2 (aq) --> Al(NO3)3 (aq) + Ni (s) a.) write the oxidation half-reaction and reduction half-reaction b.) write the balanced net ionic equation for the oxidation-reduction reaction shown above

a.) oxidation half-reaction: Al (s) --> Al3+ (aq) + 3 e- reduction half-reaction: Ni2+ (aq) + 2 e- --> Ni (s) b.) 2 Al (s) + 3 Ni2+ (aq) --> 2 Al3+ (aq) + 3 Ni (s)

which of the reactions can be classified as an acid-base reaction? redox? precipitation? a) 2 C6H6 (l) + 15 O2 (g) --> 12 CO2 (g) + 6 H2O (l) b) C2H3O2- (aq) + H3O+ (aq) --> HC2H3O2 (aq) + H2O (l) c) Ca2+ (aq) + SO4^2- (aq) --> CaSO4 (s)

a= redox, b= acid-base, c= precipitation

what are the 3 important chemical reaction types?

acid-base, redox, and precipitation

if there is a greater concentration of H+ than OH-, will the solution be basic, neutral, or acidic?

acidic

Cu (s) + 2 AgNO3 (aq) --> Cu(NO3)2 (aq) + 2 Ag (s) the reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as represented by the balanced equation shown above. based on the balanced equation, which of the following identifies the oxidation and reduction half-reactions? a) oxidation half-reaction: Cu (s) --> Cu+ (aq) + e- reduction half-reaction: Ag2+ (aq) + 2 e- --> Ag (s) b) oxidation half-reaction: Cu (s) --> Cu2+ (aq) + 2 e- reduction half-reaction: Ag+ (aq) + e- --> Ag (s) c) oxidation half-reaction: Ag+ (aq) + e- --> Ag (s) reduction half-reaction: Cu (s) --> Cu2+ (aq) + 2 e- d) oxidation half-reaction: Ag2+ (aq) + 2 e- --> Ag (s) reduction half-reaction: Cu (s) --> Cu+ (aq) + e-

b

HCl (aq) + NaOH (aq) --> NaCl (aq) + H2O (l) a student had 2 dilute, colorless solutions, HCl and NaOH, which were at the same temperature. the student combined the solutions, and the reaction represented above occurred. which of the following results would be evidence that a chemical reaction took place? a) the resulting solution is colorless b) the temperature of the reaction mixture increases c) the total volume of the mixture is approximately equal to the sum of the initial volumes d) the resulting solution conducts electricity

b

a student is asked to form a hypothesis about what would happen to sodium metal when it is placed in water. which of the following hypotheses indicates that the student thinks a CHEMICAL change will occur? a) if sodium is added to water, it will dissolve b) if sodium is added to water, heat and light will be released c) if sodium is added to water, the total mass will be the same d) if sodium is added to water, the water will remain a clear, colorless liquid

b

mass of empty crucible- 12.0 g mass of crucible and sample before heating- 14.4 g mass of crucible and sample after heating- 16.0 g a student places a sample of pure metal in a crucible and heats it strongly in air. data from the experiment is above. the final mass was determined after the sample was cooled to room temperature. which of the following statements related to the experiment is correct? a) the mass of the sample decreased, so physical changes occurred as the metal first melted and then boiled out of the crucible b) the mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance c) there was nothing for the metal to react with, so only a physical change could have occurred d) the sample was only heated, so neither a physical nor a chemical change occurred

b

the reaction between aqueous strontium chloride (SrCl2) and aqueous potassium sulfate (K2SO4) forms a precipitate of strontium sulfate (SrSO4). which of the following represents the net ionic equation for the reaction? a) Cl- (aq) + K+ (aq) --> KCl (aq) b) Sr2+ (aq) + SO42- (aq) --> SrSO4 (s) c) Sr2+ (aq) + 2 Cl- (aq) + SO42- (aq) + 2 K+ (aq) --> SrSO4 (s) + 2 Cl- (aq) + 2 K+ (aq) d) SrCl2 (aq) + K2SO4 (aq) --> SrSO4 (s) + 2 KCl (aq)

b

are heat, light, formation of a precipitate, formation of a gas, and/or color change a sign of a physical or chemical change?

chemical change

occurs when substances are transformed into new substances, typically with different compositions; involves breaking and/or formation of chemical bonds

chemical change

an equation that shows ions in aqueous solution as separate charged particles (can be used to identify spectator ions)

complete ionic equation

a type of ion with a metal ion at its center and a number of other molecules or ions surrounding it

complex ion

a student uses 6 grams of sodium hydroxide and dissolves it in 250 mL of water. determine the resulting concentration and pH of the solution

concentration- 0.6 M pH- 13.78

MgCl2 (aq) + 2 NaOH (aq) --> 2 NaCl (aq) + Mg(OH)2 (s) a 100 mL sample of 0.1 M MgCl2 (aq) and a 100 mL sample of 0.2 M NaOH (aq) were combined, and Mg(OH)2 (s) precipitated, as shown by the equation above. if the experiment is repeated using solutions of the same molarity, which of the following changes in volume will double the amount of Mg(OH)2 (s) produced? a) using the same volume of MgCl2 (aq) but twice the volume of NaOH (aq) b) using twice the volume of MgCl2 (aq) but half the volume of NaOH (aq) c) using twice the volume of MgCl2 (aq) but the same volume of NaOH (aq) d) using twice the volume of MgCl2 (aq) and twice the volume of NaOH (aq)

d

Ni (s) --> Ni2+ (aq) + 2 e- Ag+ (aq) + e- --> Ag (s) which of the following is the balanced net ionic equation for an oxidation-reduction reaction between Ag+ (aq) and Ni (s) based on the half-reactions represented above? a) Ag+ (aq) + Ni (s) --> Ag (s) + Ni2+ (aq) b) 2 Ag+ (aq) + Ni (s) --> Ag (s) + 2 Ni2+ (aq) c) Ag+ (aq) + 2 Ni (s) --> Ag (s) + 2 Ni2+ (aq) d) 2 Ag+ (aq) + Ni (s) --> 2 Ag (s) + Ni2+ (aq)

d

a student mixes 20.0g of white KCl crystals with distilled water in a beaker. after the mixture was stirred, no crystals are visible and the solution is clear. after several days, all of the water evaporates and white crystals are found in the beaker. which of following pieces of experimental evidence would best help the student to confirm that a new compound had not been made and that only a physical change occurred? a) the solution does not change color b) the KCl crystals are no longer visible after mixing w/ H2O c) there is a temperature change during the dissolving process d) after the water has evaporated, the white crystals in the beaker have a mass of 20.0 g

d

which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid? a) NaF (aq) + HCl (aq) --> NaCl (aq) + HF (aq) b) Na+ (aq) + F- (aq) + H+ (aq) + Cl- (aq) --> Na+ (aq) + Cl- (aq) + HF (aq) c) Na+ (aq) + Cl- (aq) --> NaCl (aq) d) F- (aq) + H+ (aq) --> HF (aq)

d

when a substance undergoes a physical process, the composition of that substance DOES/DOESN'T change

doesn't

butyric acid contains 54.2% C, 9.2% H, and 36.6% O. it has a molecular mass of 88.00 g/mole. find the empirical and molecular formulas for butyric acid

empirical formula- C2H4O molecular formula- C4H8O2

oxalic acid is found to have the following composition: 26.7% C, 71.1% O, and 2.2% H. the molecular mass of the compound is 90.0 g/mole. what are the empirical and molecular formulas?

empirical formula- CHO2 molecular formula- C2H2O4

in a titration lab, the point at which the indicator changes color (near the equivalence point)

end point

the point in a titration lab when the amount of titrant added from the buret has completely reacted with all the analyte in the flask (moles of base= moles of acid)

equivalence point

true or false: physical changes AREN'T reversible

false

true or false: the law of conservation of mass ISN'T obeyed in net ionic equations

false

true or false: group 1 metals, NH4+, nitrates, and acetate (C2H3O2) are NEVER soluble in water

false (they are ALWAYS soluble in water)

the amount of products produced (theoretical yield) will be determined by the LIMITING/EXCESS reactant

limiting

what mass of water will be produced when 4.42 g of propane, C3H8, are burned? this reaction actually produced 6.05 g of water when done in the lab. find the % yield. how much energy will be released if 2200 kJ of energy is released per mole of propane burned?

mass of water- 7.22 g % yield- 83.6% energy released- 301 kJ

write the precipitation reaction as a balanced molecular, complete ionic and net ionic equations for iron sulfate and strontium hydroxide

molecular: Fe2(SO4)3 (aq) + 3 Sr(OH)2 (aq) --> 2 Fe(OH)3 (s) + 3 SrSO4 (aq) complete ionic: 2 Fe3+ (aq) + 3 SO4^2- (aq) + 3 Sr2+ (aq) + 6 OH- (aq) --> 2 Fe(OH)3 (s) + 3 Sr^2+ (aq) + 3 SO4^2- (aq) net ionic: 2 Fe3+ (aq) + 6 OH- (aq) --> 2 Fe(OH)3 (s)

write the precipitation reaction as a balanced molecular, complete ionic and net ionic equations for mercury (I) nitrate and potassium iodide

molecular: HgNO3 (aq) + KI (aq) --> HgI (s) + KNO3 (aq) complete ionic: Hg+ + NO3- + K+ + I- --> HgI (s) + K+ + NO3- net ionic: Hg+ (aq) + I- (aq) --> HgI (s)

write the molecular, ionic, and net ionic equation for the reaction between solid magnesium carbonate and sulfuric acid

molecular: MgCO3 (s) + H2SO4 (aq) --> MgSO4 (s) + H2O (l) + CO2 (g) ionic: MgCO3 + 2 H+ + SO4^-2 --> MgSO4 (s) + H2O (l) + CO2 (g) net: MgCO3 + 2 H+ + SO4^-2 --> MgSO4 (s) + H2O (l) + CO2 (g)

an equation that excludes spectator ions; useful to represent only the substances undergoing a chemical change

net ionic equation

if there is an equal concentration of OH- and H+, will the solution be basic, neutral, or acidic?

neutral

reaction between an acid & base to produce water and a salt

neutralization reaction

calculate the pH and pOH of 0.0042 M Ca(OH)2

pOH= 2.08 pH= 11.92

occurs when substance undergoes a change in properties but not in composition (ex: phase change)

physical change

when ice melts on a warm day, is that a physical or chemical change?

physical change

when 10.0 g of potassium reacts with 10.0 g of iodine, how much potassium iodide can be produced? what is the limiting reactant? how much excess material is left?

potassium iodide produced- 13.15 g limiting reactant- I2 excess potassium- 6.92 g

a reaction frequently involving mixing ions in aqueous solution to produce an insoluble ionic compound (a solid) called a precipitate

precipitation reaction

a reaction involving the transfer of one or more electrons between reactants

redox reaction

an acid that completely separates into ions in solution

strong acid

true or false: oxidation and reduction are always accompanied by the other (electrons don't disappear or appear)

true

true or false: the spot where the pH increases the most on a titration curve graph is the equivalence point

true

an acid that only partially separates into ions in solution. mostly stays as neutral molecules

weak acid