Chem mock test 2
6) When the equation, ___N2 + ___H2 → ___NH3 is balanced, the coefficient of hydrogen is: B) 2 C) 3 D) 4 E) none of the above
3 N2+3H2->2NH3 n:2 h:6 -> n:2 h:6
7) When the equation, ___O2 + ___C5H12 → ___CO2 + ___H2O is balanced, the coefficient: of O2 is: A) 4 B) 3 C) 8 D) 5 E) none of the above
8 8O2 + C5H12 -> 5CO2 + 6H2O O:16 C:5 H:12 -> C:5 O:10 H:12 O:6 10+6=16/2=8
8) What are the coefficients for the following reaction when it is properly balanced? ___HCl + ___Mg → ___MgCl2 + ___H2 A) 2, 1, 1, 1 B) 2, 1, 2, 2 C) 1, 1, 1, 2 D) 1, 2, 1/2, 1 E) none of the above
A 2HCl + 1Mg -> 1MgCl2 + 1H2 H:2 Cl:2 Mg:1 -> Mg:1 Cl:2 H:2
20) In writing the chemical equation for a precipitation reaction, what abbreviation of the physical state must appear with one of the products? A) (s) B) (l) C) (aq) D) (g) E) none of the above
A) (s) precipitation reactions form a solid
10) Liquid heptane, C7H16, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 25.5 mL of heptane? (density of heptane = 0.6838 g/mL) A) 61.3 g B) 30.6 g C) 89.6 g D) 8.14 g E) 5.57 g
A) 61.3 C7H16 + 11O2 -> 7CO2 + 8H2O mass = vol x density so 25.5 x 0.6838 = 17.44g 17.44g / ((12.01x7)+(1.006x16)) = 0.1741 g/mol 0.1741 x 11 = 1.915 mol x (16x2) = 61.28
12) Which of the following processes is exothermic? A) CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) B) CO2(g) + 2 H2O(l) → CH4(g) + 2 O2(g) C) 6 H2O(g) + 4 CO2(g) → 2 C2H6(g) + 7 O2(g) D) CO2(s) →CO2(g) E) H2O(l) →H2O(g)
A) CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) B) CO2(g) + 2 H2O(l) → CH4(g) + 2 O2(g) C) 6 H2O(g) + 4 CO2(g) → 2 C2H6(g) + 7 O2(g) All exothermic, O produced in all CO2(s) →CO2(g) = compound, compounds cant be endo or exothermic H2O(l) →H2O(g) = energy absorbed to break water molecule bonds, endothermic
10) Three separate 3.5g blocks of Al, Cu, and Fe at 25°C each absorb 0.505 kJ of heat. Which block reaches the highest temperature? The specific heats of Al, Cu, and Fe are 0.900 J/g·°C, 0.385J/g·°C, and 0.444 J/g·°C, respectively. A) Cu B) Al and Cu C) Al D) Fe E) Fe and Cu
A) Cu q=m⋅c⋅ΔT , Whereas, m is the mass of block s is specific heat dT is change in temperature. Copper block having the lowest specific heat and thus having the higher change in temperature and therefore having the higher final temperature.
10) Which of the following is NOT an acid-base conjugate pair? A) H2S and OH- B) NH4+ and NH3 C) H2CO3 and HCO3- D) H2O and OH- E) none of the above
A) H2S and OH- donate or take H, not O
4) When water is heated, bubbles form in the water. Is this evidence of a chemical reaction? Why? A) No, boiling water is a physical change. B) Yes, the formation of a gas is proof a new compound has been made. C) No, the formation of gas bubbles is a secondary chemical reaction which is ignored. D) Yes, the formation of a gas is evidence of a chemical reaction. E) none of the above
A) No, boiling water is a physical change.
24) Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) What is the correct complete ionic equation? A) Pb2+ + 2NO3- + 2K+ + 2I- → PbI2(s) + 2K+ + 2NO3- B) Pb2+ + 2NO3- + 2K+ + 2I- → Pb2+ + 2I- + 2K+ + 2NO3- C) Pb2+ + (NO3)2- + 2K+ + 2I- → PbI2(s) + 2K+ + 2NO3- D) Pb2+ + 2NO3- +2K+ + I- → PbI2(s) + 2K+ + NO3- E) none of the above
A) Pb2+ + 2NO3- + 2K+ + 2I- → PbI2(s) + 2K+ + 2NO3-
19) In a solution that has a pH = 7.0: A) [H3O+] = [OH-] B) [H3O+] > [OH-] C) [H3O+] < [OH-] D) [H3O+] + [OH-] = Kw E) none of the above
A) [H3O+] = [OH-]
15) Which of the following is a weak base? A) ammonia B) calcium hydroxide C) potassium hydroxide D) sodium fluoride E) none of the above
A) ammonia weak bases: Ammonia (NH3) Lead hydroxide (Pb(OH)2) Aluminium hydroxide (Al(OH)3) Copper hydroxide (Cu(OH)2) Ferric hydroxide (Fe(OH)3) Trimethylamine (N(CH3)3) Zinc hydroxide (Zn(OH)2) Aniline (C6H5NH2)
4) If a particular process is endothermic, the reverse process must be a (an): A) exothermic process. B) chemical change. C) isothermal process. D) endothermic process. E) none of the above
A) exothermic process. exothermic: release heat endothermic: absorb heat
15) Which of the following compounds is SOLUBLE? A) potassium carbonate B) strontium carbonate C) copper carbonate D) calcium carbonate E) none of the above
A) potassium carbonate K+ group 1 cation, those have no exceptions soluble: (group 1 cations, Li+, Na+, K+, Rb+, Cs+) and (Cl-,Br-,I - unless with Ag+, Hg22+, and Pb2+) and (F- unless with compounds with group 2 metal cations, Pb2+ and Fe3+) and (C2H3O2-, HCO3-, NO3-, ClO3-) and (SO42- unless with compounds with Ag+, Ba2+, Ca2+, Hg2 2+, Pb2+ and Sr2+)
10) When the equation __NO2 + __H2O + __O2 → __HNO3 is balanced, the coefficient of HNO3 is: A) 5 B) 4 C) 3 D) 2 E) none of the above
B 4NO2 + 2H2O + O2 -> 4HNO3 N:4 O:8 H:4 O:2 O:2 -> H:4 N:4 O:12 8+2+2=12
4) A sample of iron metal is placed in a graduated cylinder. It is noted that 10.4 mL of water is displaced by the iron. The iron is then reacted with excess hydrochloric acid to produce iron (II) chloride and hydrogen gas. Given the density for iron is 7.86 g/mL, how many grams of iron (II) chloride are produced in the reaction? Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g) A) 47.2 g B) 185 g C) 81.7 g D) 23.6 g E) 3.00 g
B) 185 g vol = 10.4 density = 7.86 mass= vxd mass =81.744 81.744/55.85= 1.464 mole 126.75 x 1.464 = 185 g
19) If you had an aqueous mixture that contained Ag+, K+, and Pb2+ cations, how many different insoluable solids should precipitate out if a chloride solution was added? A) 1 B) 2 C) 3 D) 4 E) no solids will precipitate
B) 2 Cl- not soluble with Ag+ and Pb2+ soluble: (group 1 cations, Li+, Na+, K+, Rb+, Cs+) and (Cl-,Br-,I - unless with Ag+, Hg22+, and Pb2+) and (F- unless with compounds with group 2 metal cations, Pb2+ and Fe3+) and (C2H3O2-, HCO3-, NO3-, ClO3-) and (SO42- unless with compounds with Ag+, Ba2+, Ca2+, Hg2 2+, Pb2+ and Sr2+)
6) Calculate the mass of excess reagent remaining at the end of the reaction in which 90.0 g of SO2 are mixed with 100.0 g of O2. 2SO2 + O2 → 2SO3 A) 67.5 g B) 77.5 g C) 11.5 g D) 400 g E) 22.5 g
B) 77.5 g molar mass so2 = 64.0638 molar mass of o2 = 32 90.0 g / 64.0638amu x 1/2mol x 32g of O2= 22.4776 g O2 so O2 is excess and SO2 is limiting. 100.0 g O2 - 22.4776 g O2 = 77.5 g excess
2) Vanadium(V) oxide reacts with calcium according to the chemical equation below. When 10.0 moles of V2O5 are mixed with 10.0 moles of Ca, which is the limiting reagent? V2O5(s) + 5Ca(l) → 2V(l) + 5CaO(s) A) V2O5 B) Ca C) V D) No reagent is limiting. E) CaO
B) Ca 10.0 mole Ca x 1 Mole V2O5/ 5 mole Ca = 2 mole V2O5. 10-2=8, excess.
11) In the following reaction: NH4+ (aq) + H2O (aq) → NH3 (aq) + H3O+ (aq) A) NH4+ is an acid and H2O is its conjugate base. B) H2O is a base and H3O+ is its conjugate acid. C) H2O is a base and NH3 is its conjugate acid. D) NH4+ is a base and H2O is its conjugate acid. E) NH4+ is an acid and H3O+ is its conjugate base.
B) H2O is a base and H3O+ is its conjugate acid. NH4+ (conjugate acid) -> NH3 (base) H2O (base) -> H3O+ (conjugate acid) acid gains H
26) Which is a spectator ion from the following complete ionic equation: Ag+(aq) + NO3-(aq) + K+ (aq) + Br-(aq) → AgBr(s) + K+(aq) + NO3- (aq) A) AgBr B) K+ C) Br- D) Ag+ E) none of the above
B) K+ NO3- and K+ are spectator ions
7) Which of the following is the active ingredient of baking soda? A) KOH B) NaHCO3 C) NaOH D) NH3 E) none of the above
B) NaHCO3
17) The compound sodium sulfate is soluble in water. When this compound dissolves in water, which ion listed below would be present in solution? A) O2- B) SO42- C) Na22+ D) S2- E) none of the above
B) SO42- Na will dissolve in the water
18) When solid NaCl is stirred into water, which of the following is NOT true? A) The solution will taste salty. B) The NaCl will fail to dissociate. C) Individual sodium and chloride ions are present. D) The solution will conduct electricity. E) none of the above
B) The NaCl will fail to dissociate.
34) What type of reaction is the generic equation AB-> A + B? A) synthesis/combination B) decomposition C) single displacement D) double-displacement E) none of the above
B) decomposition
30) What type of a reaction occurs when potassium metal reacts with fluorine gas? A) acid-base neutralization B) oxidation-reduction C) gas evolution D) precipitation E) no reaction
B) oxidation-reduction 2K+ + 2F- -> 2KF charge became neutral
2) Which of the following items is NOT a common unit of energy? A) calorie B) torr C) joule D) kilowatt-hour E) none of the above
B) torr torr is a unit of pressure
3) Sulfur dioxide gas reacts with oxygen gas and water according to the chemical reaction below. When 4.5 g of SO2 are mixed with excess O2 and H2O, how many grams of H2SO4 are theoritecally produced? 2SO2(g) + O2(g) + 2H2O(l) → 2H2SO4(l) A) 14 g B) 4.5 g C) 6.9 g D) 440 g E) 9.0 g
C) 6.9 g 4.5 g / (64.06) = 0.0702g/mol 98.076 (H2SO4 molecular mass) x 0.0702 = 6.9
29) When a solution of MgCl2 and one of AgNO3 are mixed, the net ionic equation is: A) Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3- (aq) → Mg(NO3)2 (aq) + 2 AgCl(s) B) Mg2+(aq) + 2NO3-(aq) → Mg(NO3)2(aq) C) Cl-(aq) + Ag+(aq) → AgCl(s) D) Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3- (aq) → Mg2+(aq) + 2NO3-aq) + 2AgCl(s) E) none of the above
C) Cl-(aq) + Ag+(aq) → AgCl(s) Mg+2 + 2Cl-1 + 2Ag+ + 2NO3- -> 2ClAg (s) + Mg+2 + 2NO3- 2Cl- + 2Ag+ -> 2ClAg(s)
28) What is the net ionic equation for the reaction of hydrochloric acid with potassium hydroxide? A) 2H+ +2Cl- + K2+ + 2OH- → H2O + K2+ +2 Cl- B) H+ + Cl- + K+ + OH- → H2O + K+ + Cl- C) H+ + OH- → H2O D) HCl + KOH → H2O + KCl E) none of the above
C) H+ + OH- → H2O 2H+ + 2OH- -> H2O
17) The pH of a solution is 5.00. Which of the following is TRUE about the solution? A) Its [H3O+] is 1.0 × 10-9 M B) Its [H3O+] is 1.0 × 105 M C) Its [H3O+] is 1.0 × 10-5 M D) It is more acidic than a solution whose pH is 4.00. E) none of the above
C) Its [H3O+] is 1.0 × 10-5 M
9) What is the conjugate base of H2O? A) H3O+ B) O2- C) OH⁻ D) NaOH E) none of the above
C) OH⁻
25) Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) What is the correct net ionic equation? A) Pb2+ + 2NO3- + 2K+ + 2I- → PbI2(s) + 2K+ + 2NO3- B) 2NO3- + 2K+ → 2KNO3 C) Pb2+ + 2I- → PbI2(s) D) Pb2+ + I2- → PbI2(s) E) none of the above
C) Pb2+ + 2I- → PbI2(s)
21) What would be the formula of the precipitate that forms when Pb(NO3)2 (aq) and K2SO4 (aq) are mixed? A) K(NO3)2 B) H2O C) PbSO4 D) PbK2 E) none of the above
C) PbSO4 Pb(NO3)2 (aq) + K2SO4 (aq)-> PbSO4 (s) + KNO3 (aq) NO3 charge - so pb must be +2 soluble: (group 1 cations, Li+, Na+, K+, Rb+, Cs+) and (Cl-,Br-,I - unless with Ag+, Hg22+, and Pb2+) and (F- unless with compounds with group 2 metal cations, Pb2+ and Fe3+) and (C2H3O2-, HCO3-, NO3-, ClO3-) and (SO42- unless with compounds with Ag+, Ba2+, Ca2+, Hg2 2+, Pb2+ and Sr2+)
2) The Bronsted-Lowry definition of an acid is: A) a proton acceptor. B) produces H⁺ in solution. C) a proton donor. D) produces OH⁻ in solution. E) none of the above
C) a proton donor.
27) What type of a reaction occurs when a sodium hydroxide solution is mixed with an acetic acid solution? A) oxidation-reduction B) precipitation C) acid-base reaction D) gas evolution E) no reaction
C) acid-base reaction acetic acid is an acid. sodium hydroxide is a base. therefore, it is an acid-base neutralization reaction. NaOH + CH3CO2H -> NaCH3CO2 + H2O salt and water formed
12) Which of the following compounds is INSOLUBLE? A) lithium carbonate B) potassium acetate C) aluminum sulfide D) magnesium bromide E) none of the above
C) aluminum sulfide insoluble contain: (CO32-, CrO42-, PO43-, S2- unless with group 1 and NH4+) and OH unless with group 1 and Ba2+
12) A substance that acts as an acid OR a base is called: A) hydrophillic. B) a salt. C) amphoteric. D) isoprotic. E) none of the above
C) amphoteric.
13) Which of the following acids is a diprotic, weak acid? A) phosphoric acid B) carbonic acid C) sulfuric acid D) hydrobromic acid E) none of the above
C) carbonic acid weak acids: Formic acid (chemical formula: HCOOH) Acetic acid (chemical formula: CH3COOH) Benzoic acid (chemical formula: C6H5COOH) Oxalic acid (chemical formula: C2H2O4) Hydrofluoric acid (chemical formula: HF) Nitrous acid (chemical formula: HNO2) Sulfurous acid (chemical formula: H2SO3)
1) What type of energy is associated with the burning of gasoline? A) electrical B) kinetic C) chemical D) potential E) none of the above
C) chemical
20) Which solution below is considered to have basic character? A) pOH = 4 B) pOH = 7 C) pOH = 13 D) pH = 2 E) none of the above
C) pOH = 13
1) The Arrhenius definition of an acid is: A) produces OH⁻ in solution. B) a proton acceptor. C) produces H⁺ in solution. D) a proton donor. E) none of the above
C) produces H⁺ in solution.
33) What type of reaction is the generic equation A + BC → AC + B? A) synthesis/combination B) decomposition C) single displacement D) double-displacement E) none of the above
C) single displacement
9) What are the coefficients for the following reaction when it is properly balanced? ___Na3PO4 + ___Ba(NO3)2 → ___NaNO3 + ___Ba3(PO4)2 A) 2, 3, 1, 6 B) 6, 1, 3, 2 C) 2, 1, 1, 3 D) 2, 3, 6, 1 E) none of the above
D 2Na3PO4 + 3Ba(NO3)2 -> 6NaNO3 + 1Ba3(PO4)2 Na:6 P:2 O:8 Ba:3 N:6 O:18 -> Na:6 N:6 O:18 Ba:3 P:2 O:8
6) Consider the following reaction: 2 Mg + O2 → 2 MgO △H rxn = -1203 kJ Calculate the amount of heat (in kJ) associated with complete reaction of 4 moles of Mg. A) -601.5 kJ B) -1203 kJ C) -4812 kJ D) -2406 kJ E) none of the above
D) -2406 kJ 4 mol/2mol= 2 mole -1203 x 2 = 2,406
7) Consider the following equation: CO + 2 H2 → CH3OH △H rxn = -128 kJ Calculate the amount of heat (in kJ) associated with complete reaction of 8.08 g H2. A) -1024 kJ B) -1034 kJ C) -512 kJ D) -256 kJ E) none of the above
D) -256 kJ 8.08g/2 mol = 4 mole 128x2= 256
5) What is the theoretical yield of chromium that can be produced by the reaction of 40.0 g of Cr2O3 with 8.00 g of aluminum according to the chemical equation below? 2Al + Cr2O3 → Al2O3 + 2Cr A) 7.7 g B) 30.8 g C) 49.9 g D) 15.4 g E) 27.3 g
D) 15.4 40.0 g / ((52 x 2)+(16x3)) = 0.2632 g/mol 0.2632g x 2/1 = 0.5264g x 52 = 27.3728 g 8.00 g / 26.98 = 0.2965 g/mol 0.2965 x 1 = .2965 x 52 = 15.418 g limiting reactant is Al, produced only 15.418 g which would be the theoretical yield.
9) Aluminum metal has a specific heat of 0.900 J/g·°C. Calculate the amount of heat required to raise the temperature of 10.5 moles of Al from 30.5 °C to 225°C. A) 65.1 kJ B) 57.3 kJ C) 2.41 kJ D) 49.6 kJ E) 1.84 kJ
D) 49.6 kJ q=m⋅s⋅ΔT , where q - the amount of heat added / removed m - the mass of the substance s - the specific heat of the substance ΔT - the change in temperature, defined as the difference between the final temperature and the initial temperature of the sample (.900 j/gC) x (10.5g) x (26.98) x (225 - 30.5)= 49,589.9145 J = 49.6 kj
4) Which of the following statements about acids are TRUE? 1. An acid is used in car batteries. 2. A component of vinegar is an acid. 3. Acids can dissolve some metals. A) 1 and 3 only B) 1 and 2 only C) 2 and 3 only D) All of 1, 2, and 3 E) Neither 1, 2, or 3
D) All of 1, 2, and 3
31) Identify the oxidation-reduction reactions among the following: 1. Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) 2. 2 Na(s) + Cl2(aq) → 2NaCl(s) 3. 2 Mg(s) + O2(g) → 2 MgO A) 1 and 2 only B) 2 and 3 only C) 1 and 3 only D) All of 1, 2, and 3 E) None of 1, 2, and 3
D) All of 1, 2, and 3 1. Zn -> Zn2+, Cu2+ -> Cu 2. 2Na+ + 2Cl- -> 2NaCl(s) 3. Mg(s) -> 2Mg+2, O2 -> 2O-2
5) The reaction of one mole of nitrogen gas with three moles of hydrogen gas releases 92 kJ of thermal energy to the surroundings. Which of the following is TRUE? A) Complete reaction of two moles of nitrogen gas would release 184 kJ of thermal energy in this reaction. B) This reaction has a negative enthalpy of reaction. C) This reaction is exothermic. D) All of the above are true. E) None of the above are true.
D) All of the above are true.
6) Which of the following is NOT a property of bases? A) Bases turn litmus paper blue. B) Bases have a bitter taste. C) Bases have a slippery feel. D) Bases dissolve many metals. E) All of the above are properties of bases.
D) Bases dissolve many metals.
16) All of the following compounds are soluble in water EXCEPT: A) FeCl3. B) NaCl. C) CaCl2. D) PbCl2. E) NH4Cl.
D) Cl- is soluble unless with Pb2 soluble: (group 1 cations, Li+, Na+, K+, Rb+, Cs+) and (Cl-,Br-,I - unless with Ag+, Hg22+, and Pb2+) and (F- unless with compounds with group 2 metal cations, Pb2+ and Fe3+) and (C2H3O2-, HCO3-, NO3-, ClO3-) and (SO42- unless with compounds with Ag+, Ba2+, Ca2+, Hg2 2+, Pb2+ and Sr2+)
8) What is the conjugate acid of OH⁻? A) O2- B) NaOH C) OH⁻ D) H2O E) none of the above
D) H2O
22) Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) Which compound would not form ions in the complete ionic equation? A) Pb(NO3)2 B) KNO3 C) KI D) PbI2 E) All compounds form ions in the complete ionic equation
D) PbI2 Pb2+ + 2NO3- + 2K+ + 2I- -> PbI2 (s) + 2K+ + 2NO3-
18) In order for a solution to be acidic: A) [H3O+] > [OH-] B) [H3O+] < [OH-] C) pH = pOH D) [H3O+] = [OH-] E) none of the above
D) [H3O+] > [OH-]
8) Heat is A) a measure of the change in temperature. B) a measure of temperature. C) a measure of thermal energy. D) a measure of thermal energy transferred between two bodies at different temperature.
D) a measure of thermal energy transferred between two bodies at different temperature.
3) The Bronsted-Lowry definition of a base is: A) produces OH⁻ in solution. B) produces H⁺ in solution. C) a proton donor. D) a proton acceptor. E) none of the above
D) a proton acceptor.
32) The reaction CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g) is: A) a redox reaction. B) a combustion reaction. C) an exothermic reaction. D) all of the above E) none of the above
D) all of the above combustion: AB + O2 → AO + BO combustion 1. is a redox reaction 2. is an exothermic reaction (heat releasing)
13) Which of the following compounds is SOLUBLE? A) aluminum sulfide B) aluminum hydroxide C) aluminum carbonate D) aluminum sulfate E) none of the above
D) aluminum sulfate SO4-2 is sulfate soluble: (group 1 cations, Li+, Na+, K+, Rb+, Cs+) and (Cl-,Br-,I - unless with Ag+, Hg22+, and Pb2+) and (F- unless with compounds with group 2 metal cations, Pb2+ and Fe3+) and (C2H3O2-, HCO3-, NO3-, ClO3-) and (SO42- unless with compounds with Ag+, Ba2+, Ca2+, Hg2 2+, Pb2+ and Sr2+)
35) What type of reaction is the generic equation AB + CD → AD + CB? A) synthesis/combination B) decomposition C) single displacement D) double-displacement E) none of the above
D) double-displacement
14) Which of the following acids is a monoprotic, strong acid? A) sulfuric acid B) phosphoric acid C) carbonic acid D) hydrobromic acid E) none of the above
D) hydrobromic acid strong acids: HBr hydrobromic acid HCl hydrochloric acid HI hydroiodic acid HNO3 nitric acid HClO4 perchloric acid H2SO4 sulfuric acid
5) Which among the following acids is commonly used for etching and frosting glass? A) hydrobromic acid B) hydrochloric acid C) nitric acid D) hydrofluoric acid E) All of the above are used.
D) hydrofluoric acid
14) Which of the following compounds is INSOLUBLE? A) magnesium sulfate B) magnesium iodide C) magnesium nitrate D) magnesium phosphate E) none of the above
D) magnesium phosphate phosphate is PO43- and mg is 2+ insoluble contain: (CO32-, CrO42-, PO43-, S2- unless with group 1 and NH4+) and OH unless with group 1 and Ba2+
5) Before a chemical equation can be correctly written, one must know: A) the atomic mass of all the elements involved. B) the molar mass of all the compounds. C) the number of moles of all reactants and products. D) the symbols and formulas of all reactants and products. E) none of the above.
D) the symbols and formulas of all reactants and products.
11) Sodium metal reacts with water to form aqueous sodium hydroxide and hydrogen gas. Which equation below best describes the balanced equation for this reaction? A) Na + H2O → NaOH (aq) + H (g) B) S + H2O → SOH (aq) + H (g) C) 2Na + H2O → Na2OH (aq) + H (g) D) Na + H2O → NaOH (aq) + H2 (g) E) 2Na + 2H2O → 2NaOH (aq) + H2 (g)
E 2Na + 2H2O -> 2NaOH + H2
16) What is the value of the ion product constant for water (Kw)? A) 1.0 x 10^14 B) 1.0 x 10^7 C) 0.0 D) 1.0 x 10^-7 E) 1.0 x10^-14
E) 1.0 x10^-14 the product of the concentrations of the hydrogen ions and hydroxide ions in water Kw = [H⁺] X [OH⁻] = 1.0 X 10⁻¹⁴
9) Aluminum hydroxide reacts with nitric acid to form aluminum nitrate and water. What mass of water can be formed by the reaction of 15.0 g of aluminum hydroxide with excess nitric acid? A) 6.14 g B) 1.15 g C) 45.0 g D) 3.46 g E) 10.4 g
E) 10.4 g Al(OH)3 + 3HNO3 -> 3H2O + Al(NO3)3 15.0g / (26.98 + (16x3) + (1.008x3)) = 0.1923 g/mol 0.1923 x 3/1 x (1.008x2+16) = 10.39
13) The reaction that represents the standard enthalpy of formation for sucrose (C12H22O11) is: A) 12 C(diamond) + 11 H2(g) + 11/2 O2(g) → C12H22O11(s) B) C12H22O11(s) →12 C(graphite) + 11 H2(g) + 11/2 O2(g) C) C12H22O11(s) + 12 O2 → 12 CO2(g) + 11 H2O(g) D) 24 C(diamond) + 22 H2(g) + 11 O2(g) → 2 C12H22O11(s) E) 12 C(graphite) + 11 H2(g) + 11/2 O2(g) →C12H22O11(s)
E) 12 C(graphite) + 11 H2(g) + 11/2 O2(g) →C12H22O11(s)
7) What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 2.0 moles of V2O5 with 6.0 moles of calcium based on the chemical reaction below? V2O5(s) + 5Ca(l) → 2V(l) + 5CaO(s) A) 2.0 mol B) 1.6 mol C) 4.0 mol D) 1.0 mol E) 2.4 mol
E) 2.4 mol 5 Ca form 2 V 1 mole Ca form 2/5 V 6 x 2/5 = 2.4 mol
15) Concerning the reaction: C(graphite) + O2 (g) -> CO2 (g) dh= -393 kj/mol. How many grams of C(graphite) must be burned to release 275 kJ of heat? A) 0.70 g B) 22.3 g C) 12.0 g D) 17.1 g E) 8.40 g
E) 8.40 g 1 mole carbon -> -393kj/mol 275kj/393= 0.6997 mol C 0.6997 x 12.01 (carbons atomic mass) = 8.40 g
8) The reaction of 44.1 g of Cr2O3 with 35.0 g of Al produced 25.6 g of Cr. What is the percent yield for this reaction? 2Al + Cr2O3 → Al2O3 + 2Cr A) 58.0 % B) 100. % C) 37.9 % D) 73.1 % E) 84.9%
E) 84.9% 44.1g / 152 = 0.2901 g/mol 0.2901 x 2/1 x 52 = 30.17 35.0g / 26.98 = 1.297 g/mol 1.297 x 2/2 x 52 = 67.44 so theoretical yield is 30.17 25.6/30.17= 0.8485 x 100 = 84.9%
23) Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) Which ion would NOT be present in the complete ionic equation? A) I- B) Pb2+ C) K+ D) NO3- E) All the above ions are in the complete ionic equation.
E) All the above ions are in the complete ionic equation. Complete ionic equation: Pb2+ + 2NO3- + 2K+ + 2I- -> PbI2 (s) + 2K+ + 2NO3- Net ionic is when only used ions are shown
14) Which of the following has a ΔH°f= 0 kJ/mol? A) O3(g) B) Cl-(aq) C) NH3(aq) D) CO2(g) E) I2(s)
E) I2(s) O3 g= 142.7 Cl- aq = -167.2 NH3 aq= -80.886 CO2 g= -393.51 I2 s= 0
1) Ammonia reacts with oxygen to form nitric oxide and water vapor: 4NH3 + 5O2 → 4NO + 6H2O When 40.0 g NH3 and 50.0 g O2 are allowed to react, which is the limiting reagent? A) NO B) No reagent is limiting. C) O2 D) H2O E) NH3
E) NH3
3) How many joules are there in a 255 calorie snack bar? A) 1.07 × 106 B) 2.55 × 105 C) 1.07 × 103 D) 6.09 × 104 E) none of the above
b. 1.07 x 10^3 1 calorie = 4.184 joules 255 x 4.184 = 1066.92 sf = 3 so 1.07x10^3
3) A reaction in which a substance reacts with oxygen, emitting heat and forming carbon dioxide is an example of a(n): A) combustion reaction. B) precipitation reaction. C) acid-base reaction. D) gas evolution reaction. E) none of the above
combustion reaction
1) A reaction which forms a gaseous product is called a(n)________. A) precipitation reaction B) oxidation-reduction reaction C) gas evolution reaction D) combustion reaction E) none of the above
gas evolution reaction
2) A reaction which forms a solid product is an example of a(n): A) combustion reaction.+ B) oxidation-reduction reaction. C) gas evolution reaction. D) precipitation reaction. E) none of the above
precipitation reaction
11) A 135 g sample of H2O at 85°C is cooled. The water loses a total of 15 kJ of energy in the cooling process. What is the final temperature of the water? The specific heat of water is 4.184 J/g·°C. A) 84°C B) 112°C C) 70°C D) 58°C E) 27°C
q=m⋅s⋅ΔT = msT(t2-t1) t2=t1+ q/ms q - the amount of heat added / removed m - the mass of the substance c - the specific heat of the substance ΔT - the change in temperature, defined as the difference between the final temperature and the initial temperature of the sample so t2= 85C + -15000 j/135g x 4.184 j/gc t2 = -26.556 + 85 = 58.44 C so 58C