chapter 3 textbook questions – Flashcards

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question
Write empirical formulas for the compounds represented by the molecular formulas. (a) C4H8 (b) B2H6 (c) CCl4
answer
a) CH2 b)BH3 c) CCl4
question
Write the empirical formula for the compounds represented by the molecular formulas. (a) C5H12 (b) Hg2Cl2 (c) C2H4O2
answer
a. C5H12 b. HgCl c. CH2O
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Classify each of the substances as an atomic element, molecular element, molecular compound, or ionic compound. (a) xenon (b) NiCl2 (c) bromine (d) NO2 (e) NaNO3
answer
a) atomic element b) ionic compound c) molecular element d) molecular compound e) ionic coupound
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Classify each of the substances as an atomic element, molecular element, molecular compound, or ionic compound. (a) fluorine (b) N2O (c) silver (d) K2O (e) Fe2O3
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a. molecular element b. molecular compound c. atomic element d. ionic compound e. ionic compound
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Write the formula for the ionic compound that forms between aluminum and oxygen.
answer
Al2O3
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Write the formula for the ionic compound that forms between calcium and oxygen.
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CaO
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Write the formula for the compound formed between potassium and sulfur.
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K2S
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Write the formula for the compound formed between aluminum and nitrogen.
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AlN
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Name the compound CaBr2
answer
calcium bromide
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Name the compound ag3n .
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silver nitride
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Write the formula for rubidium sulfide.
answer
Rb2S
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Name the compound FeS.
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iron(II) sulfide
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Name the compound PbCl4
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lead(IV) chloride
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Write the formula for ruthenium(IV) oxide
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RuO2
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Name the compound Li2Cr2O7 .
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lithium dichromate
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Name the compound Sn(ClO3)2 .
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tin(II) chlorate
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Write the formula for cobalt(II) phosphate
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Co3(PO4)2
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Name each compound. (a) NI3 (b) PCl5 (c) P4S10
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a) nitrogen triiodide b) phosporus pentachloride c) tetraphosphorus decasulfide
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Name the compound N2O5 .
answer
dinitrogen pentoxide
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Write the formula for phosphorus tribromide.
answer
PBr3
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Name HI( aq ).
answer
hydroiodic acid
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Name HF( aq ).
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hydrofluoric acid
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Name HC2H3O2(aq) .
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acetic acid
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Name HNO2(aq) .
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nitrous acid
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Write the formula for perchloric acid.
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HClO4
question
Calculate the formula mass of glucose, c6h12o6 .
answer
180.16 amu
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Calculate the formula mass of calcium nitrate
answer
164.10 amu
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An aspirin tablet contains 325 mg of acetylsalicylic acid (C9H8O4) . How many acetylsalicylic acid molecules does it contain?
answer
1.09 * 1021 C9H8O4 molecules
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Find the number of ibuprofen molecules in a tablet containing 200.0 mg of ibuprofen (C13H18O2) .
answer
5.839 * 1020 C13H18O2 molecules
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What is the mass of a sample of water containing 3.55 * 1022 H2O molecules?
answer
1.06 g H2O
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Calculate the mass percent of Cl in Freon-112 (C2Cl4F2) , a CFC refrigerant
answer
69.58%
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Acetic acid (C2H4O2) is the active ingredient in vinegar. Calculate the mass percent composition of oxygen in acetic acid.
answer
53.29%
question
Calculate the mass percent composition of sodium in sodium oxide.
answer
74.19% Na
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The U.S. Food and Drug Administration (FDA) recommends that a person consume less than 2.4 g of sodium per day. What mass of sodium chloride (in grams) can you consume and still be within the FDA guidelines? Sodium chloride is 39% sodium by mass.
answer
6.2 g NaCl
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What mass (in grams) of iron(III) oxide contains 58.7 grams of iron? Iron(III) oxide is 69.94% iron by mass.
answer
83.9 g Fe2O3
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If someone consumes 22 g of sodium chloride per day, what mass (in grams) of sodium does that person consume? Sodium chloride is 39% sodium by mass.
answer
8.6 g Na
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Hydrogen may potentially be used in the future to replace gasoline as a fuel. Most major automobile companies are developing vehicles that run on hydrogen. These cars are environmentally friendly because their only emission is water vapor. One way to obtain hydrogen for fuel is to use an emission-free energy source such as wind power to form elemental hydrogen from water. What mass of hydrogen (in grams) is contained in 1.00 gallon of water? (The density of water is 1.00 g>mL.)
answer
4.23 * 102 g H
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Determine the mass of oxygen in a 7.2 g sample of Al2(SO4)3
answer
4.0 g O
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Butane (C4H10) is the liquid fuel in lighters. How many grams of carbon are present within a lighter containing 7.25 mL of butane? (The density of liquid butane is 0.601 g>mL.)
answer
3.60 g C
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A compound containing nitrogen and oxygen is decomposed in the laboratory and produces 24.5 g nitrogen and 70.0 g oxygen. Calculate the empirical formula of the compound.
answer
N2O5
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A laboratory analysis of aspirin determined the following mass percent composition: C 60.00% H 4.48% O 35.52% Find the empirical formula.
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C9H8O4
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A sample of a compound is decomposed in the laboratory and produces 165 g carbon, 27.8 g hydrogen, and 220.2 g oxygen. Calculate the empirical formula of the compound.
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CH2O
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Ibuprofen has the following mass percent composition: C 75.69%, H 8.80%, O 15.51%. What is the empirical formula of ibuprofen?
answer
C13H18O2
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Butanedione—a main component responsible for the smell and taste of butter and cheese—contains the elements carbon, hydrogen, and oxygen. The empirical formula of butanedione is C2H3O , and its molar mass is 86.09 g>mol. Find its molecular formula.
answer
c4h6o2
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A compound has the empirical formula CH and a molar mass of 78.11 g>mol. What is its molecular formula?
answer
C6H6
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A compound with the percent composition shown next has a molar mass of 60.10 g>mol. Determine its molecular formula. C, 39.97% H, 13.41% N, 46.62%
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C2H8N2
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Upon combustion, a compound containing only carbon and hydrogen produces 1.83 g CO2 and 0.901 g H2O. Find the empirical formula of the compound.
answer
C5H12.
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Upon combustion, a 0.8233 g sample of a compound containing only carbon, hydrogen, and oxygen produces 2.445 g CO2 and 0.6003 g H2O. Find the empirical formula of the compound.
answer
C10H12O1
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Upon combustion, a compound containing only carbon and hydrogen produced 1.60 g CO2 and 0.819 g H2O. Find the empirical formula of the compound.
answer
C2H5
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Upon combustion, a 0.8009 g sample of a compound containing only carbon, hydrogen, and oxygen produced 1.6004 g CO2 and 0.6551 g H2O. Find the empirical formula of the compound.
answer
C2H4O
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Write a balanced equation for the reaction between solid cobalt(III) oxide and solid carbon to produce solid cobalt and carbon dioxide gas.
answer
2 Co2O3(s) + 3 C(s) --> 4 Co(s) + 3 CO2(g)
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Write a balanced equation for the combustion of gaseous butane (C4H10), a fuel used in portable stoves and grills, in which it combines with gaseous oxygen to form gaseous carbon dioxide and gaseous water.
answer
2 C4H10(g) + 13 O2(g) --> 8 CO2(g) + 10 H2O(g)
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Write a balanced equation for the reaction between solid silicon dioxide and solid carbon to produce solid silicon carbide and carbon monoxide gas.
answer
SiO2(s) + 3 C(s)-->SiC(s) + 2 CO(g)
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Write a balanced equation for the combustion of gaseous ethane (C2H6), a minority component of natural gas, in which it combines with gaseous oxygen to form gaseous carbon dioxide and gaseous water.
answer
2 C2H6(g) + 7 O2(g)-->4 CO2(g) + 6 H2O(g)
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Write a balanced equation for the reaction between aqueous strontium chloride and aqueous lithium phosphate to form solid strontium phosphate and aqueous lithium chloride.
answer
3 SrCl2(aq) + 2 Li3PO4(aq) --> Sr3(PO4)2(s) + 6 LiCl(aq)
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Write a balanced equation for the reaction between aqueous lead(II) nitrate and aqueous potassium chloride to form solid lead(II) chloride and aqueous potassium nitrate.
answer
Pb(NO 3 ) 2 (aq) + 2 KCl(aq)--> PbCl 2 (s) + 2 KNO 3 (aq)
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What is the empirical formula of a compound with the molecular formula C10H8? a) C5H3 b) C2H4 c) C5H4 d) CH
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c
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Which substance is an ionic compound? a) SrI2 b) N2O4 c) He d) CCl4
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a
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What is the correct formula for the compound formed between calcium and sulfur? a) CaS b) Ca2S c) CaS2 d) CaS3
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a
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Name the compound SrI2 . a) strontium iodide b) strontium diiodide c) strontium(II) iodide d) strontium(II) diiodide
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a
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What is the formula for manganese(IV) oxide? a) Mn4O b) MnO4 c) Mn2O d) MnO2
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d
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Name the compound Pb(C2H3O2)2 . a) lead(II) carbonate b) lead(II) acetate c) lead bicarbonate d) lead diacetate
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b
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Name the compound P2I4 . a) phosphorus iodide b) phosphorus diiodide c) phosphorus(II) iodide d) diphosphorus tetraiodide
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d
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Name the compound HNO2( aq ). a) hydrogen nitrogen dioxide b) hydrogen nitrate c) nitric acid d) nitrous acid
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d
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Determine the number of CH2Cl2 molecules in 25.0 g CH2Cl2 . a) 0.294 molecules b) 1.77 * 10^23 molecules c) 1.28 * 10^27 molecules d) 1.51 * 10^25 molecules
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b
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List the elements in the compound CF2Cl2 in order of decreasing mass percent composition. a) C 7 F 7 Cl b) F 7 Cl 7 C c) Cl 7 C 7 F d) Cl 7 F 7 C
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b
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Determine the mass of potassium in 35.5 g of KBr. a) 17.4 g b) 0.298 g c) 11.7 g d) 32.9 g
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c
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A compound is 52.14% C, 13.13% H, and 34.73% O by mass. What is the empirical formula of the compound? a) c2h8o3 b) C2H6O c) C4HO3 d) C3HO6
answer
b
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A compound has the empirical formula CH2O and a formula mass of 120.10 amu. What is the molecular formula of the compound? a) CH2O b) C2H4O2 c) C3H6O3 d) c4h8o4
answer
d
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Combustion of 30.42 g of a compound containing only carbon, hydrogen, and oxygen produces 35.21 g CO2 and 14.42 g H2O. What is the empirical formula of the compound? a) C4H8O6 b) C2H4O3 c) c2h2o3 d) C6HO12
answer
b
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What are the correct coeffi cients (reading from left to right) when the chemical equation is balanced? __PCl3(l) + __H2O(l) S __H3PO3(aq) + __HCl(aq) a) 1, 3, 1, 3 b) 1, 2, 1, 1 c) 1, 3, 2, 1 d) 3, 6, 1, 9
answer
a
question
Determine the number of each type of atom in each formula: a. Mg3(PO4)2 b. BaCl2 c. Fe(NO2)2 d. Ca(OH)2
answer
a. 3 Mg, 2 P, 8 O b. 1 Ba, 2 Cl c. 1 Fe, 2 N, 4 O d. 1 Ca, 2 O, 2 H
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Classify each element as atomic or molecular. a. neon b. fluorine c. potassium d. nitrogen
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a. atomic b. molecular c. atomic d. molecular
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Classify each compound as ionic or molecular. a. CO2 b. NiCl2 c. NaI d. PCl3
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a. molecular b. ionic c. ionic d. molecular
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Write a formula for the ionic compound that forms between each pair of elements. a. calcium and oxygen b. zinc and sulfur c. rubidium and bromine d. aluminum and oxygen
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a. CaO b. ZnS c. RbBr d. Al2O3
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Write a formula for the compound that forms between calcium and each polyatomic ion. a. hydroxide b. chromate c. phosphate d. cyanide
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a. Ca(OH) 2 b. CaCrO4 c. Ca3(PO4)2 d. Ca(CN)2
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Name each ionic compound. a. Mg3N2 b. KF c. Na2O d. Li2S e. CsF f. KI
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a. magnesium nitride b. potassium fluoride c. sodium oxide d. lithium sulfide e. cesium fluoride f. potassium iodide
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Give each ionic compound an appropriate name. a. SnO b. Cr2S3 c. RbI d. BaBr2
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a. tin(II) oxide b. chromium(III) sulfide c. rubidium iodide d. barium bromide
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Name each ionic compound containing a polyatomic ion. a. cuno2 b. Mg(C2H3O2)2 c. Ba(NO3)2 d. Pb(C2H3O2)2
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a. copper(I) nitrite b. magnesium acetate c. barium nitrate d. lead(II) acetate
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Write a formula for each ionic compound. a. sodium hydrogen sulfite b. lithium permanganate c. silver nitrate d. potassium sulfate e. rubidium hydrogen sulfate f. potassium hydrogen carbonate
answer
a. NaHSO3 b. limno4 c. AgNO3 d. K2SO4 e. RbHSO4 f. KHCO3
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Write the name from the formula or the formula from the name for each hydrated ionic compound. a. CoSO4 # 7H2O b. iridium(III) bromide tetrahydrate c. Mg(BrO3)2 # 6H2O
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a. cobalt(II) sulfate heptahydrate b. IrBr3 # 4 H2O c. Magnesium bromate hexahydrate d. K2CO3 # 2 H2O
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Name each molecular compound. a. CO b. NI3 c. SiCl4 d. N4Se4
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a. carbon monoxide b. nitrogen triiodide c. silicon tetrachloride d. tetranitrogen tetraselenide
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Write a formula for each molecular compound. a. phosphorus trichloride b. chlorine monoxide c. disulfur tetrafluoride d. phosphorus pentafluoride
answer
a. PCl3 b. ClO c. S2F4 d. PF5
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Name each acid. a. HI( aq ) b. hno3 ( aq ) c. H2CO3 ( aq )
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a. hydroiodic acid b. nitric acid c. carbonic acid
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Write formulas for each acid. a. hydrofluoric acid b. hydrobromic acid c. sulfurous acid
answer
a. HF b. HBr c. H2SO3
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Use the nomenclature flow chart ( Figure 3.10 ) to name each compound. a. SrCl 2 b. SnO 2 c. P 2 S 5 d. HC 2 H 3 O 2( aq )
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a. strontium chloride b. tin(IV) oxide c. diphosphorus pentasulfide d. acetic acid
question
name each compound. a. KClO 3 b. I 2 O 5 c. PbSO 4
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a. potassium chlorate b. diiodine pentoxide c. lead(II) sulfate
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Calculate the formula mass for each compound. a. NO2 b. C4H10 c. C6H12O6 d. Cr(NO3)3
answer
a. 46.01 amu b. 58.12 amu c. 180.16 amu d. 238.03 amu
question
Calculate the number of moles in each sample. a. 72.5 g CCl 4 b. 12.4 g C 12 H 22 O 11 c. 25.2 kg C 2 H 2 d. 12.3 g of dinitrogen monoxide
answer
a. 0.471 mol b. 0.0362 mol c. 968 mol d. 0.279 mol
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Determine the number of moles (of molecules or formula units) in each sample. a. 25.5 g NO2 b. 1.25 kg CO2 c. 38.2 g KNO3 d. 155.2 kg Na2SO4
answer
a. 0.554 mol b. 28.4 mol c. 0.378 mol d. 1093 mol
question
How many molecules are in each sample? a. 6.5 g H2O b. 389 g CBr4 c. 22.1 g O2 d. 19.3 g C8H10
answer
a. 2.2 * 1023 molecules b. 7.06 * 1023 molecules c. 4.16 * 1023 molecules d. 1.09 * 1023 molecules
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Calculate the mass (in g) of each sample. a. 5.94 * 1020 SO3 molecules b. 2.8 * 1022 H2O molecules c. 1 glucose molecule (C6H12O6)
answer
a. 0.0790 g b. 0.84 g c. 2.992 * 10-22 g
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A sugar crystal contains approximately 1.8 * 1017 sucrose (C12H22O11) molecules. What is its mass in mg?
answer
0.10 mg
question
Calculate the mass percent composition of carbon in each carbon-containing compound. a. CH4 b. C2H6 c. C2H2 d. C2H5Cl
answer
a. 74.87% C b. 79.88% C c. 92.24% C d. 37.23% C
question
Most fertilizers consist of nitrogen-containing compounds such as NH3 , CO(NH2)2 , NH4NO3 , and (NH4)2SO4 . The nitrogen content in these compounds is used for protein synthesis by plants. Calculate the mass percent composition of nitrogen in each of the fertilizers named. Which fertilizer has the highest nitrogen content?
answer
NH3: 82.27% N CO(NH2)2: 46.65% N NH4NO3: 35.00% N (NH4)2SO4: 21.20% N NH3 has the highest N content
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Copper(II) fluoride contains 37.42% F by mass. Calculate the mass of fluorine (in g) contained in 55.5 g of copper(II) fluoride
answer
20.8 g F
question
The iodide ion is a dietary mineral essential to good nutrition. In countries where potassium iodide is added to salt, iodine deficiency (or goiter) has been almost completely eliminated. The recommended daily allowance (RDA) for iodine is 150 mg/day . How much potassium iodide (76.45% I) should you consume if you want to meet the RDA?
answer
196 mg KI
question
Determine the number of moles of hydrogen atoms in each sample. a. 0.0885 mol C4H10 b. 1.3 mol CH4 c. 2.4 mol C6H12 d. 1.87 mol C8H18
answer
a. 0.885 mol H b. 5.2 mol H c. 29 mol H d. 33.7 mol H
question
Calculate mass (in grams) of sodium in 8.5 g of each sodium containing food additive. a. NaCl (table salt) b. Na3PO4 (sodium phosphate) c. NaC7H5O2 (sodium benzoate) d. Na2C6H6O7 (sodium hydrogen citrate)
answer
a. 3.3 g Na b. 3.6 g Na c. 1.4 g Na d. 1.7 g Na
question
A chemist decomposes samples of several compounds; the masses of their constituent elements are shown below. Calculate the empirical formula for each compound. a. 1.651 g Ag, 0.1224 g O b. 0.672 g Co, 0.569 g As, 0.486 g O c. 1.443 g Se, 5.841 g Br
answer
a. Ag2O b. Co3As2O8 c. SeBr4
question
Calculate the empirical formula for each stimulant based on its elemental mass percent composition. a. nicotine (found in tobacco leaves): C 74.03%, H 8.70%, N 17.27% b. caffeine (found in coffee beans): C 49.48%, H 5.19%, N 28.85%, O 16.48%
answer
a. c5h7n b. C4H5N2O
question
The elemental mass percent composition of ibuprofen (an aspririn substitute) is 75.69% C, 8.80% H, and 15.51% O. Determine the empirical formula of ibuprofen.
answer
C13H18O2
question
A 0.77 mg sample of nitrogen reacts with chlorine to form 6.61 mg of the chloride. Determine the empirical formula of nitrogen chloride
answer
NCl3
question
The empirical formula and molar mass of several compounds are listed next. Find the molecular formula of each compound. a. c6h7N, 186.24 g>mol b. C2HCl, 181.44 g>mol c. C5H10NS2, 296.54 g>mol
answer
a. C12H14N2 b. C6H3Cl3 c. C10H20N2S4
question
Combustion analysis of a hydrocarbon produced 33.01 g CO2 and 13.51 g H2O . Calculate the empirical formula of the hydrocarbon.
answer
CH2
question
The foul odor of rancid butter is due largely to butyric acid, a compound containing carbon, hydrogen, and oxygen. Combustion analysis of a 4.30 g sample of butyric acid produced 8.59 g CO2 and 3.52 g H2O . Determine the empirical formula for butyric acid.
answer
C2H4O
question
Sulfuric acid is a component of acid rain formed when gaseous sulfur dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous sulfuric acid. Write a balanced chemical equation for this reaction. (Note: this is a simplified representation of this reaction.)
answer
2 SO2(g) + O2(g) + 2 H2O(l)-->2 H2SO4(aq)
question
In a popular classroom demonstration, solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide. Write a balanced chemical equation for this reaction.
answer
2 Na(s) + 2 H2O(l)-->H2(g) + 2 NaOH(aq)
question
Write a balanced chemical equation for the fermentation of sucrose (C12H22O11) by yeasts in which the aqueous sugar reacts with water to form aqueous ethyl alcohol )C2H5OH) and carbon dioxide gas.
answer
C12H22O11(s) + H2O(l)-->4 C2H5OH(aq) + 4 CO2(g)
question
Write a balanced chemical equation for each reaction. a. Solid lead(II) sulfide reacts with aqueous hydrobromic acid to form solid lead(II) bromide and dihydrogen monosulfide gas. b. Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane (CH4) and liquid water. c. Aqueous hydrochloric acid reacts with solid manganese(IV) oxide to form aqueous manganese(II) chloride, liquid water, and chlorine gas. d. Liquid pentane (C5H12) reacts with gaseous oxygen to form carbon dioxide and liquid water.
answer
a. PbS(s) + 2 HBr(aq)-->PbBr2(s) + H2S(g) b. CO(g) + 3 H2(g)-->CH4(g) + H2O(l) c. 4 HCl(aq) + MnO2(s)--> MnCl2(aq) + 2 H2O(l) + Cl2(g) d. C5H12(l) + 8 O2(g)-->5 CO2(g) + 6 H2O(g)
question
Write a balanced chemical equation for the reaction of aqueous sodium carbonate with aqueous copper(II) chloride to form solid copper(II) carbonate and aqueous sodium chloride
answer
Na 2 CO 3 ( aq ) + CuCl 2 ( aq )-->CuCO 3 ( s ) + 2 NaCl( aq )
question
Balance each chemical equation. a. CO2(g) + CaSiO3(s) + H2O(l)-->SiO2(s) + Ca(HCO3)2(aq) b. Co(NO3)3(aq) + (NH4)2S(aq)-->Co2S3(s) + NH4NO3(aq) c. Cu2O(s) + C(s)-->Cu(s) + CO(g) d. H2(g) + Cl2(g)-->HCl(g)
answer
a. 2 CO2(g) + CaSiO3(s) + H2O(l)-->SiO2(s) + Ca(HCO3)2(aq) b. 2 Co(NO3)3(aq) + 3 (NH4)2S(aq)-->Co2S3(s) + 6 NH4NO3(aq) c. Cu2O(s) + C(s)-->2 Cu(s) + CO(g) d. H2(g) + Cl2(g)-->2 HCl(g)
question
Classify each compound as organic or inorganic. a. CaCO3 b. C4H8 c. C4H6O6 d. LiF
answer
a. inorganic b. organic c. organic d. inorganic
question
Write a formula based on the name, or a name based on the formula, for each hydrocarbon. a. propane b. CH3CH2CH3 c. octane d. CH3CH2CH2CH2CH3
answer
a. CH3CH2CH3 b. propane c. CH3CH2CH2CH2CH2CH2CH2CH3 d. pentane
question
How many molecules of ethanol (C2H5OH) (the alcohol in alcoholic beverages) are present in 145 mL of ethanol? The density of ethanol is 0.789 g/cm3 .
answer
1.50 * 1024 molecules EtOH
question
Determine the chemical formula of each compound and then use it to calculate the mass percent composition of each constituent element. a. potassium chromate b. lead(II) phosphate c. sulfurous acid d. cobalt(II) bromide
answer
b. Pb3(PO4)2, 76.60% Pb, 7.63% P, 15.77% O c. H2SO3, 2.46% H, 39.07% S, 58.47% O d. CoBr2, 26.94% Co, 73.06% Br
question
A Freon leak in the air-conditioning system of an old car releases 25 g of CF2Cl2 per month. What mass of chlorine does this car emit into the atmosphere each year?
answer
1.80 * 102 g Cl / yr
question
A metal (M) forms a compound with the formula MCl3 . If the compound contains 65.57% Cl by mass, what is the identity of the metal?
answer
M = Fe
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Estradiol is a female sexual hormone that causes maturation and maintenance of the female reproductive system. Elemental analysis of estradiol gives the following mass percent composition: C 79.37%, H 8.88%, O 11.75%. The molar mass of estradiol is 272.37 g>mol. Find the molecular formula of estradiol.
answer
estradiol = C18H24O2
question
Combustion analysis of a 13.42 g sample of equilin (which contains only carbon, hydrogen, and oxygen) produces 39.61 g CO2 and 9.01 g H2O . The molar mass of equilin is 268.34 g/mol. Find its molecular formula.
answer
C18H20O2
question
Epsom salts is a hydrated ionic compound with the following formula: MgSO4 * xH2O . A 4.93 g sample of Epsom salts was heated to drive off the water of hydration. The mass of the sample after complete dehydration was 2.41 g. Find the number of waters of hydration ( x ) in Epsom salts.
answer
7 H2O
question
A compound of molar mass 177 g/mol contains only carbon, hydrogen, bromine, and oxygen. Analysis reveals that the compound contains 8 times as much carbon as hydrogen by mass. Find the molecular formula.
answer
C6H9BrO
question
Find the total number of atoms in a sample of cocaine hydrochloride, C17H22ClNO4 , of mass 23.5 mg.
answer
1.87 * 10^21 atoms
question
The chloride of an unknown metal is believed to have the formula MCl3 . A 2.395 g sample of the compound is found to contain 3.606 * 10^-2 mol Cl . Find the atomic mass of M.
answer
92.93 amu
question
A chromium-containing compound has the formula FexCryO4 and is 28.59% oxygen by mass. Find x and y .
answer
x = 1, y = 2
question
A particular brand of beef jerky contains 0.0552% sodium nitrite by mass and is sold in an 8.00 oz bag. What mass of sodium does the sodium nitrite contribute to sodium content of the bag of beef jerky?
answer
41.7 mg
question
A mixture of NaCl and NaBr has a mass of 2.00 g and contains 0.75 g of Na. What is the mass of NaBr in the mixture?
answer
0.224 g
question
A mixture of CaCO3 and (NH4)2CO3 is 61.9% CO3 by mass. Find the mass percent of CaCO3 in the mixture.
answer
22.0% by mass
question
Because of increasing evidence of damage to the ozone layer, chlorofluorocarbon (CFC) production was banned in 1996. However, there are about 100 million auto air conditioners in operation that still use CFC-12 (CF2Cl2) . These air conditioners are recharged from stockpiled supplies of CFC-12. If each of the 100 million automobiles contains 1.1 kg of CFC-12 and leaks 25% of its CFC-12 into the atmosphere per year, how much chlorine, in kg, is added to the atmosphere each year due to auto air conditioners? (Assume two significant figures in your calculations.)
answer
1.6 * 107 kg Cl
question
Lead is found in Earth's crust as several different lead ores. Suppose a certain rock is 38.0% PbS (galena), 25.0% PbCO3 (cerussite), and 17.4% PbSO4 (anglesite). The remainder of the rock is composed of substances containing no lead. How much of this rock (in kg) must be processed to obtain 5.0 metric tons of lead? (A metric ton is 1000 kg.)
answer
7.8 * 103 kg rock
question
A compound of molar mass 229 contains only carbon, hydrogen, iodine, and sulfur. Analysis shows that a sample of the compound contains 6 times as much carbon as hydrogen, by mass. Calculate the molecular formula of the compound.
answer
C5H10SI
question
A compound of X and Y is 13 X by mass. The atomic mass of element X is 13 the atomic mass of element Y. Find the empirical formula of the compound.
answer
X2Y3
question
When molecules are represented by molecular models, what does each sphere represent? How big is the nucleus of an atom in comparison to the sphere used to represent an atom in a molecular model?
answer
The sphere in the molecular models represents the electron cloud of the atom. On this scale, the nucleus would be too small to see.
question
Explain the problem with the following statement and correct it. "The chemical formula for ammonia (NH3) indicates that ammonia contains three grams of hydrogen to each gram of
answer
The statement is incorrect because a chemical formula is based on the ratio of atoms combined, not the ratio of grams combined. The statement should read, "The chemical formula for ammonia ( NH3 ) indicates that ammonia contains three hydrogen atoms to each nitrogen atom."
question
Without doing any calculations, arrange the elements in H2SO4 in order of decreasing mass percent composition.
answer
O, S, H
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