Ch 5 Molecules and Compounds Practice Problems
Skillbuilder 5.6 Write a formula for the compound formed from aluminum and nitrogen.
1) Al³⁺ 2) N³⁻ 3) Al₃N₃ 4) Al₃N₃ divided by 3 = AlN 5) Cation 1 x ³⁺ = 3+ Anion 1 x ³⁻ = 3- 3 + -3 = 0
Example 5.5 Write a formula for the ionic compound that forms from aluminum and oxygen.
1) Al³⁺ 2) O²⁻ 3) Al₂O₃ 4) Al₂O₃ → cannot be reduced any further. 5) Cations 2 x ³⁺ = 6+ Anions 3 x ²⁻ = 6- 6 + -6 = 0
Skillbuilder 5.7 Write a formula for the compound that forms from calcium and bromine.
1) Ca²⁺ 2) Br⁻ 3) CaBr₂ 4) CaBr₂ → cannot be reduced 5) Cation 1 x ²⁺=2+ Anion 2 x ⁻=2-, Cancels
5.21 Write a formula for the compound that forms from lithium and sulfate ions.
1) Li⁺ 2) SO₄²⁻ 3) Li₂SO₄ 4) Li₂SO₄ → cannot be reduced 5) Cation 2 x ⁺=2+ Anion 1 x ²⁻ = 2- 2 + 2- = 0
Skillbuilder 5.5 Write a formula for the compound formed from strontium and chlorine.
1) Sr²⁺ 2) Cl⁻ 3) SrCl₂ 4) SrCl₂ → cannot be reduced any further 5) Cations 1 x ²⁺ = 2+ Anions 2 x ⁻ = 2- 2 + -2 = 0
85) Arrange the compounds in order of decreasing formula mass. Ag₂O PtO₂ Al(NO₃)₃ PBr₃
2) Ag₂O → 107.87(2) + 16.00 = 231.74 3) PtO₂ → 195.09 + 2(16.00) = 227.09 4) Al(NO₃)₃→26.98 + 3(14.01+3(16.00)) = 213.01 1) PBr₃→ 30.97 + 3(79.91) = 270.7
61) Name each ionic compound. a) CrCl₂ b) CrCl₃ c) SnO₂ d) PbI₂
A) chromium (?) + 2 chlorine (-) --> anion 2 x - = 2-. Chromium (II) chloride B) chromium (?) + 3 chlorine (-) --> anion 3 x - = 3-. Chromium (III) chloride C) tin (?) + 2 oxygen (2-) --> anion 2 x 2- = 4-. Tin (IV) oxide D) lead (?) + 2 Iodine (-) --> anion 2 x - = 2-. Lead (II) iodide.
5.22) Name the compound Al₂O₃.
Al³⁺ + O²⁻→ Al₂O₃ Aluminum (cation with only 1 type of ion) + Oxygen → aluminum oxide
101) A compound contains only carbon and hydrogen and has a formula mass of 28.06 amu. What is its molecular formula?
C + H = 28.06 amu C = 12.01 H = 1.008 If C(2) = 24.02 - 28.06 = 4.04/1.01 = 4 C₂H₄
Example 5.15) Calculate the formula mass of carbon tetrachloride, CCl₄
C = 12.01 amu Cl = 35.45 amu (12.01) + 4(35.45) = 153.81
89) How many chlorine atoms are in each set? a) three carbon tetrachloride molecules b) two calcium chloride formula units c) four phosphorus trichloride molecules d) seven sodium chloride formula units
Cl a) 3 CCl₄ = 12 b) 2 CaCl = 2 (Wrong). Ca²⁺ + Cl⁻ + Cl⁻ → 2 CaCl₂ = 4 c) 4 PCl₃ = 12 d) 7 NaCl = 7
Example 5.24) Name the compound Co(ClO₄)₂.
Co? + ClO₄⁻ + ClO₄⁻→anion 2 x ⁻=2-, Co must be ²⁺. Cobalt (II) Perchlorate
Skillbuilder 5.11) Name the compound N₂O₄.
Dinitrogen Tetroxide
Example 5.23) Name the compound Fe₂S₃.
Fe₂S₃→Fe₂? + S₃²⁻→Anions 3 x ²⁻=6-. In order to be charge neutral, Fe must have 6 positive charges, divided by 2, then the charge is ³⁺. Therefore the answer is Iron (III) sulfide.
Example 5.28) Name HClO₂ (aq)
H+ so it's an acid. ClO₂⁻ is chlorite. Chlorous acid.
Example 5.27) Name H₂SO₄ (aq)
H+ so it's an acid. SO₄²⁻ is sulfate. Sulfuric acid.
Example 5.12) Give the name of H₂S(aq).
Hydrosulfuric acid
Skillbuilder 5.8 Name the compound KBr.
K⁺ (cation with only 1 type of ion) + Br⁻ → KBr Potassium + Bromine → Potassium bromide
P. 142. Example 5.10) name the compound K₂CrO₄.
K⁺ + CrO₄²⁻ → K₂CrO₄→Potassium Chromate
Example 5.8 Name the compound MgF₂
Mg²⁺ (cation with only 1 type of ion) + F⁻ →MgF₂ Magnesium + Fluorine → Magnesium Fluoride
Skillbuilder 5.10) Name the compound Mn(NO₃)₂.
Mn? + NO₃⁻ + NO₃⁻→ anion 2 x ⁻=2-, cation must be ²⁺. Manganese (II) Nitrate
Skillbuilder 5.15) Calculate the formula mass of dinitrogen monoxide, N₂O
N = 14.01 O = 16.00 2(14.01) + 16.00 = 44.02 amu
Example 5.25) Name the compound NO₂
Nitrogen Dioxide
Example 5.9) Name the compound PbCl₄.
PbCl₄→Pb?+Cl₄⁻→anions 4 x ⁻=4-. In order to be charge neutral, Pb has ⁴⁺. Therefore the answer is lead (IV) chloride.
Skillbuilder 5.9) Name the compound PbO.
PbO→Pb? + O²⁻→anions 1 x ²⁻=2-. In order to be charge neutral, Pb has ²⁺. Therefore the answer is lead (II) oxide.
103) Carbon has 2 naturally occurring isotopes: carbon-12 (mass = 12 amu) and carbon-13 (mass = 13 amu). Chlorine also has two naturally occurring isotopes: chlorine-35 (mass = 34.97 amu) and chlorine-37 (mass = 36.97 amu). How many CCl₄ molecules of different masses can exist? Determine the mass (in amu) of each of them.
WRONG!!! Why is it 10 isotopes? Carbon-12 (12 amu) Carbon-13 (13 amu) Chlorine-35 (34.97 amu) Chlorine-37 (36.97 amu) Average Atomic Mass: CCl₄ → (12.01) + (4)(35.45)=153.81 amu 12 + 4(34.97) = 151.88 amu 12 + 4(36.97) = 159.88 amu 13 + 4(34.97) = 152.88 amu 13 + 4(36.97) = 160.88 amu
83) Calculate the formula mass for each compound. a) HNO₃ b) CaBr₂ c) CCl₄ d) Sr(NO₃)₂
a) 1.008+14.01+3(16.00) = 63.018 → 63.02 amu b) 40.08 + 2(79.91) = 199.9 amu c) Did it above d) 87.62 + 2(14.01 + 3(16.00))= 211.64
65) Name each ionic compound containing a polyatomic ion. a) Ba(NO₃)₂ b) Pb(C₂H₃O₂)₂ c) NH₄I d) KClO₃ e) CoSO₄ f) NaClO₄
a) Ba²⁺+NO₃⁻+NO₃⁻→anions 2 x ⁻=2-, cation 1 x ²⁺ = 2+, Cancels. Barium Nitrate b) Pb? + (C₂H₃O₂⁻)₂→anions 2 x ⁻=2-, cation must be ²⁺. Lead (II) Acetatate. c) NH₄⁺+I⁻→anion 1 x ⁻=1-, cation 1 x ⁺= 1, Cancels. Ammonium Iodide d) K⁺+ClO₃⁻ → Neutral charge. Potassium Chlorate. e) Co? + SO₄²⁻→ Missing ²⁺. Cobalt (II) Sulfate f) Na⁺+ClO₄⁻→Neutral charge. Sodium Perchlorate
Example 5.11) Name each compound. a) CCl₄ b) BCl₃ c) SF₆
a) CCl₄→ Carbon Tetrachloride b) BCl₃→Boron Trichloride c) SF₆→Sulfur Hexafluoride
73) Write a formula for each molecular compound. a) carbon monoxide b) disulfur tetrafluoride c) dichlorine monoxide d) phosphorus pentafluoride e) boron tribromide f) diphosphorus pentasulfide
a) CO b) S₂F₄ c) Cl₂O d) PF₅ e) BBr₃ f) P₂S₅
95) Determine whether each name is correct for the given formula. If not, provide the correct name. a) Ca(NO₂)₂ calcium nitrate b) K₂O dipotassium monoxide c) PCl₃ phosphorus chloride d) PbCO₃ lead (II) carbonate e) KIO₂ potassium hypoiodite
a) Ca²⁺ + (NO₂⁻)₂ → calcium nitrite b) (K⁺)₂ + O²⁻→ potassium oxide c) P⁻ + (Cl⁻)₃→ 2 nonmetals → phosphorus trichloride d) Pb? + CO₃²⁻→ lead (ii) carbonate e) K⁺ + (IO₂)⁻ → potassium iodite
59) Name each ionic compound. a) CsCl b) SrBr₂ c) K₂O d) LiF
a) Cs⁺ (cation with only 1 type of ion) + Cl⁻→CsCl Cesium + Chlorine → cesium chloride b) Sr²⁺ (cation with only 1 type of ion) + Br⁻ → SrBr₂ Strontium + Bromine → strontium bromide c) K⁺ (cation with only 1 type of ion) + O²⁻ → K₂O Potassium + Oxygen → potassium oxide d) Li⁺ (cation with only 1 type of ion) + F⁻→LiF Lithium + Fluorine → Lithium fluoride
69) Write a formula for each ionic compound a) copper (II) bromide b) silver nitrate c) potassium hydroxide d) sodium sulfate e) potassium hydrogen sulfate f) sodium hydrogen carbonate
a) Cu²⁺+Br⁻ + Br⁻ → CuBr₂ b) Ag? + NO₃⁻ → AgNO₃ c) K⁺+OH⁻→ KOH d) Na⁺+SO₄²⁻→Na₂SO₄ e) K⁺+ HSO₄⁻→KHSO₄ f) Na⁺+HCO₃⁻→NaHCO₃
70) Write a formula for each ionic compound. a) copper (I) chlorate b) potassium permanganate c) lead (II) chromate d) calcium fluoride e) iron (II) phosphate f) lithium hydrogen sulfite
a) Cu⁺ + ClO₃⁻ → CuClO₃ b) K⁺+MnO₄⁻→ KMnO₄ c) Pb²⁺+CrO₄²⁻→ PbCrO₄ d) Ca²⁺+F⁻→CaF₂ e) Fe²⁺+ PO₄³⁻→Fe₃(PO₄)₂ f) Li⁺ + HSO₃⁻→LiHSO₃
81) Write a formula for each acid. a) phosphoric acid b) hydrobromic acid c) sulfurous acid
a) H⁺+PO₄³⁻→H₃PO₄ (aq) b) H⁺ + Br⁻→ HBr c) H⁺ + SO₃²⁻→H₂SO₃
Classify compounds as ionic or molecular. If they are ionic, determine whether the metal forms only one type of ion or more than one type of ion. a) FeCl₃ b) K₂SO₄ c) CCl₄
a) Ionic. Fe - transitional metal forms more than one type of ion, Cl - nonmetal b) Ionic. K - metal forms only one type of ion (part of Alkali metals family). SO₄ - polyatomic ion. c) Molecular. C and Cl are nonmetals.
55) Write a formula for the compound that forms from potassium and a) acetate b) chromate c) phosphate d) cyanide`
a) K⁺+C₂H₃O₂⁻→KC₂H₃O₂→cannot be reduced→Cation 1 x ⁺=1+, Anion 1 x ⁻=1-, Cancels. Answer: KC₂H₃O₂ b) K⁺+CrO₄²⁻→K₂CrO₄→cannot be reduced→Cation 2 x ⁺=2+, Anion 1 x ²⁻=2-, Cancels. Answer: K₂CrO₄ c) K⁺+PO₄³⁻→K₃PO₄→cannot be reduced→Cation 3 x ⁺=3+, Anion 1 x ³⁻=3-, Cancels. Answer: K₃PO₄ d) K⁺+ CN⁻→KCN→cannot be reduced→Cation 1 x ⁺=1+, Anion 1 x ⁻=1-, Cancels. Answer: KCN
57) Write formulas for the compounds formed from the element on the left and elements N, O, F. a) Li
a) Li⁺ + N³⁻→Li₃N→cannot be reduced→Cations 3 x ⁺=3+, Anion 1 x ³⁻ = 3-, Cancels. Li⁺+O²⁻→Li₂O→cannot be reduced→Cation 2 x ⁺=2+, Anion 1 x ²⁻=2-, Cancels. Li⁺+F⁻→LiF→cannot be reduced→Cation 1 x ⁺=1+, Anion 1 x ⁻=1-, Cancels.
53) Write a formula for the ionic compound that forms from each pair of elements a) sodium and sulfur b) strontium and oxygen c) aluminum and sulfur d) magnesium and chlorine
a) Na⁺+S²⁻ → Na₂S → cannot be reduced → Cations 2 x ⁺ = 2+, Anion 1 x ²⁻=2-, Cancels. Answer: Na₂S. b) Sr²⁺+O²⁻→Sr₂O₂→divided by 2 = SrO → Cation 1 x ²⁺=2+, Anion 1 x ²⁻=2-, Cancels. Answer: SrO. c) Al³⁺+S²⁻→Al₂S₃→cannot be reduced→Cations 2 x ³⁺=6+, Anion 3 x ²⁻=6-, Cancels. Answer: Al₂S₃. d) Mg²⁺+Cl⁻→MgCl₂→cannot be reduced→Cation 1 x ²⁺=2+, Anion 2 x ⁻=2-, Cancels. Answer: MgCl₂.
75) Determine whether the name shown for each molecular compound is correct. If not, provide the compound's correct name. a) PBr₅ phosphorus (V) pentabromide b) P₂O₃ phosphorus trioxide c) SF₄ monosulfur hexafluoride d) NF₃ nitrogen trifluoride
a) Phosphorus pentabromide b) Diphosphorus Trioxide c) Sulfur Tetrafluoride d) Correct
99) Name each compound and calculate its formula mass a) PtO₂ b) N₂O₅ c) Al(ClO₃)₃ d) PBr₅
a) Pt? + (O²⁻)₂ → metal + nonmetal → ionic → Platinum (IV) oxide. 195.09 + 2(16.00) = 227.09 b) 2 nonmetals → molecular → dinitrogen pentoxide. 2(14.01) + 5(16.00) = 108.02 amu c) Al³⁺ + (ClO₃⁻)₃→ aluminum chlorate d) 2 nonmetals →molecular→ phosphorus pentabromide
97) For each compound, list the correct formula and calculate the formula mass. a) tin (IV) sulfate b) nitrous acid c) sodium bicarbonate d) phosphorus pentafluoride
a) Sn⁴⁺+ SO₄²⁻ → Sn(SO₄)₂ → 118.69 + 2(32.06 + 4(16.00)) = 310.81 amu b) H⁺ + NO₂⁻ → HNO₂ → 1.008 + 14.01 + 2(16.00) = 47.02 amu c) Na⁺ + HCO₃⁻ → NaHCO₃ → 22.99 + 1.008 + 12.01 + (3)16.00 = 84.01 amu d) PF₅→30.97 + 5(19.00) = 125.97 amu
71) Name each molecular compound. a) SO₂ b) NI₃ c) BrF₅ d) NO e) N₄Se₄
a) Sulfure Dioxide b) Nitrogen triiodide c) Bromine pentafluoride d) Nitrogen monoxide e) Tetranitrogen tetraselenide
Classify Elements as atomic or molecular a) sodium b) iodine c) nitrogen
a) atomic (part of the alkali metals) b) molecular (part of the halogens) - I₂ c) molecular - N₂
Classify each substance as an atomic element, molecular element, molecular compound, or ionic compound. a) krypton b) CoCl₂ c) nitrogen d) SO₂ e) KNO₃
a) atomic element (monatomic element in alkali metals family) b) ionic compound (metal + nonmetal) c) molecular element (diatomic element) d) molecular compound (2 nonmetals) e) ionic compound (metal + 2 nonmetals)
93) Formula -- type of Compound (ionic, molecular, acid) -- Name a) N₂H₄ -- molecular -- _____ b) _____ -- _____ -- potassium chloride c) H₂CrO₄(aq) -- _____ -- _____ d) _____ -- _____ -- cobalt (III) cyanide
a) dinitrogen tetrahydride b) KCl -- ionic c) acid -- chromic acid d) Co³⁺+ CN⁻ → Co(CN)₃ -- ionic
79) Name each acid. a) HClO b) HClO₂ c) HClO₃ d) HClO₄
a) hypochlorous acid, (hypochlorite) b) chlorous acid, (chlorite) c) chloric acid, (chlorate) d) perchloric acid, (perchlorate)
Classify each substance as an atomic element, molecular element, molecular compound, or ionic compound. a) chlorine b) NO c) Au d) Na₂O e) CrCl₃
a) molecular element (diatomic element) b) molecular compound (2 nonmetals) c) atomic element (on periodic table) d) ionic compound (2 metals + 1 nonmetal) e) ionic compound (1 metal + 3 nonmetals)
45) Classify each compound as ionic or molecular. a) CS₂ b) CuO c) KI d) PCI₃
a) molecular. C and S are nonmetals. b) ionic. Cu is a transition metal and O is a nonmetal. c) ionic. K is a monatomic cation and I is a nonmetal. d) molecular. P and Cl are nonmetals.
43) Classify each element as atomic or molecular. a) chlorine b) argon c) cobalt d) hydrogen
a) molecular. Cl is a diatomic molecule. Cl₂ b) atomic. Ar is a noble gas. c) atomic. Co is a transition metal. d) molecular. H is a diatomic molecule. H₂
77) Determine whether each acid is a binary acid or an oxyacid and name each acid. If the acid is an oxyacid, also provide the name of the oxyanion. a) HNO₂ (aq) b) HI (aq) c) H₂SO₄ (aq) d) HNO₃ (aq)
a) oxyacid, nitrous acid, nitrite b) binary, hydroiodic acid c) oxyacid, sulfuric acid, sulfate d) oxyacid, nitric acid, nitrate
57) Write formulas for the compounds formed from the element on the left and elements N, O, F. b) Ba
b) Ba²⁺+N³⁻→Ba₃N₂→Cannot be reduced→Cations 3 x ²⁺=6+, Anions 2 x ³⁻=6-, Cancels. Ba²⁺+O²⁻→Ba₂O₂→divided by 2 = BaO→Cation 1 x ²⁺=2+, Anion 1 x ²⁻=2-, Cancels. Ba²⁺+F⁻→BaF₂→cannot be reduced→Cation 1 x ²⁺=2+, Anion 2 x ⁻=2-, Cancels.
57) Write formulas for the compounds formed from the element on the left and elements N, O, F. c) Al
c) Al³⁺+N³⁻→Al₃N₃→divided by 3 = AlN→Cation 1 x ³⁺=3+, Anion 1 x ³⁻=3-. Cancels. Al³⁺+ O²⁻→Al₂O₃→cannot be reduced→Cation 2 x ³⁺=6+, Anion 3 x ²⁻=6-, Cancels. Al³⁺+F⁻→AlF₃→cannot be reduced →cation 1 x ³⁺=3+, Anion 3 x ⁻=3-, Cancels.
Skillbuilder 5.12) Name HF(aq)
hydrofluoric acid
Example 5.26) Name the acid HI(aq)
hydroiodic acid
