Chemistry Ch 5 HW

How many moles of H2SO4 are in 36 grams of H2SO4?

0.367

A mineral contains only metal A and nonmetal X. If analysis indicates that a 2.66 g sample of the mineral contains 1.025 g of metal A, what is the mass fraction of X in the mineral?

0.61

A mineral contains only lead and sulfur. If analysis indicates that a 3.75 g sample of the mineral contains 1.26 g of lead, what is the mass fraction of sulfur in the mineral?

0.66

Refer to the following unbalanced equation: C6H14 + O2 --> CO2 + H2O What mass of oxygen (O2) is required to react completely with 10.4 g of C6H14? 1. 36.7 g 2. 0.121 g 3. 3.86 g 4. 3.16 × 103 g 5. 18.3 g

1. 36.7 g

A certain compound has the percent composition (by mass) 85.63% C and 14.37% H. The molar mass of the compound is 42.0 g/mol. Calculate the empirical formula and the molecular formula. 1. CH2 and C3H6 2. CH3 and C2H6 3. C2H6 and C3H9 4. CH3 and C3H6 5. C2H3 and C4H6

1. CH2 and C3H6

What is the formula mass of the hypothetical compound A2R1Q2 if the atomic masses of A, R and Q are 21.2, 12.3 and 34.4, respectively? Enter your answer with one decimal place and do not enter units.

123.5

How many moles of H atoms are present in 20,278,335,234,576,827,000,000,000 molecules of CH4? Enter your answer in decimal format with two digits to the right of the decimal and no units.

134.68

When 1.0 mol of Fe reacts with Cl2 forming FeCl3, how many moles of Cl2 are required to react with all of the iron? 1. 1.0 mol 2. 1.5 mol 3. 0.3 mol 4. none of these 5. 0.7 mol

2. 1.5 mol

If 40.0 g of CO2 is produced in the reaction of C2H2 with O2 to form CO2 and H2O, how many grams of H2O are produced in this reaction? 1. 32.7 g 2. 8.19 g 3. none of these 4. 16.37 g 5. 5.46 g

2. 8.19 g

What is the molecular (formula) mass of a compound with the formula <M2(XO3)2> if the atomic mass of M is 28.3 amu and that of X is 36 amu? Do not enter units with your answer.

224.594

Calculate the number of chlorine atoms present in 33.1 g of chloroform, CHCl3. When you have the answer, determine its log (base 10) and enter its value with three decimal places and no units.

23.699

Calculate the number of chlorine atoms present in 35.14 g of CCl4. When you have the answer, take the log (base 10) of it and enter the value with three decimal places and no units

23.741

An ionic compound contains only a metal, M, and bromine. If analysis indicates that a 3.55 g sample of the compound contains 1.78 g of M, what mass of Br in g is contained in 478 g of the mineral? Enter your answer in decimal format with three decimal places and no units.

238.3

For the reaction N2(g) + 2H2(g) → N2H4(l), if the percent yield for this reaction is 77.5%, what is the actual mass of hydrazine (N2H4) produced when 27.70 g of nitrogen reacts with 4.45 g of hydrogen? A. 32.2 g N2H4 B. 24.6 g N2H4 C. 31.7 g N2H4 D. 40.9 g N2H4 E. 27.4 g N2H4

24.6 g N2H4

How many molecules are contained in 6.86 moles of H2O? Once you have the answer, determine the log (base 10) of it and enter that value with three decimal places into the answer box. Do not add units.

24.616

What is the theoretical yield of bismuth when 300.6 g of Bi2O3 reacts with excess carbon as shown below? Bi2O3 + C(s) => Bi(s) + CO(g) (not balanced) Enter your answer with one decimal place and no units.

269.6

How many moles of O2 are required for the complete reaction of 54.7 g of C2H4 to form CO2 and H2O? 1. 3.90 mol 2. 0.975 mol 3. 7.80 mol 4. 5.85 mol 5. none of these

4. 5.85 mol

Calculate the mass of carbon dioxide produced from 16.6 g of octane, C8H18, in the following reaction. C8H18 + O2 --> CO2 + H2O (unbalanced) 1. 102 g CO2 2. 0.799 g CO2 3. 57.6 g CO2 4. 51.2 g CO2 5. 1.163 g CO2

4. 51.2 g CO2

A gaseous hydrocarbon was analyzed and found to consist of 83.65% carbon by mass. The molar mass of the compound is 86.2 g/mol. What is the molecular formula of the compound? 1. C2H4 2. C18H21 3. C3H7 4. C6H14 5. CH2

4. C6H14

What is the theoretical yield of bismuth when 447.8 g of Bi2O3 reacts with excess carbon as shown below? Bi2O3 + C(s) => Bi(s) + CO(g) (not balanced) Enter your answer with one decimal place and no units.

401.7 +- 2%

When 10.9 g CaCO3 reacts with excess hydrochloric acid, as below, 2.35 g of CO2 is produced. What is the percent yield of CO2? Do not type the units with your answer. CaCO3(s) + HCl(aq) => CO2(g) + CaCl2(aq) + H2O(l) (not balanced)

49.0 +- 1%

How many moles of H atoms are present in 77,984,082,786,302,920,000,000,000 molecules of CH4? Enter your answer in decimal format with two digits to the right of the decimal and no units.

517.99

Aluminum will react with bromine to form aluminum bromide (Al2Br6). What mass of bromine (g) is needed to form 1.23 mol of Al2Br6? Do not enter units with your answer.

590 +- 1%

What is the mass (in g) of 0.215 mol of H2S? a. 6.31x10-3 b. 7.33 c. 7.11 d. 3.57x10-25 e. 1.29x1023

7.33

Calcium reacts with oxygen to make calcium oxide, CaO. What is the theoretical yield (g) of CaO(s) that could be prepared from 8.49 g of Ca(s) and 2.56 g of O2(g)? Enter your answer with two decimal places. Do not type units with your answer.

8.97 +- 1%

Nitric oxide, NO, is made from the oxidation of NH3, and the reaction is represented by the equation: 4NH3 + 5O2 → 4NO + 6H2O What mass of O2 would be required to react completely with 7.77 g of NH3? A. 18.3 g O2 B. 9.13 g O2 C. 14.6 g O2 D. 11.7 g O2 E. 5.17 g O2

A. 18.3 g O2

The atomic mass of rhenium is 186.2. Given that 37.1% of natural rhenium is rhenium-185, what is the other stable isotope? A. 187/75 Re B. 190/75 Re C. 183/75 Re D. 181/75 Re E. 189/75 Re

A. 187/75 Re

How many of the following statements are true concerning chemical equations? I. Coefficients can be fractions. II. Subscripts can be fractions. III. Coefficients represent the relative masses of the reactants and/or products. IV. Changing the subscripts to balance an equation can only be done once. V. Atoms are conserved when balancing chemical equations. A.2 B. 4 C. 1 D. 3 E. 5

A. 2

A chloride of rhenium contains 63.6% rhenium. What is the formula of this compound? A. ReCl3 B. ReCl C. Re2Cl3 D. ReCl5 E. ReCl7

A. ReCl3

Consider a specific chemical reaction represented by the equation aA + bB → cC + dD. In this equation the letters A, B, C, and D represent chemicals, and the letters a, b, c, and d represent coefficients in the balanced equation. How many possible values are there for the quantity "c/d"? A. infinite B. 1 C. 4 D. 3 E. 2

B. 1

How many oxygen atoms are there in 2 formula units of Al2(SO3)3? A. 11 B. 18 C. 9 D. 21 E. 12

B. 18

The mineral vanadinite has the formula Pb5(VO4)3Cl. What mass percent of chlorine does it contain? A. 7.51 % B. 2.50 % C. 9.91 % D. 3.08 % E. 1.13 %

B. 2.50 %

A 5.95-g sample of AgNO3 is reacted with BaCl2 according to the equation 2AgNO3(aq) + BaCl2(aq) → 2AgCl(s) + Ba(NO3)2(aq) to give 3.20 g of AgCl. What is the percent yield of AgCl? A. 31.9% B. 63.7% C. 45.4% D. 100% E. 53.8%

B. 63.7%

Phosphoric acid can be prepared by reaction of sulfuric acid with "phosphate rock" according to the equation: Ca3(PO4)2 + 3H2SO4 → 3CaSO4 + 2H3PO4 Suppose the reaction is carried out starting with 125 g of Ca3(PO4)2 and 75.0 g of H2SO4. Which substance is the limiting reactant? A. Ca3(PO4)2 B. H2SO4 C. CaSO4 D. H3PO4 E. none of these

B. H2SO4

Potassium forms an oxide containing 1 oxygen atom for every 2 atoms of potassium. What is the coefficient of oxygen in the balanced equation for the reaction of potassium with oxygen to form this oxide? A. 2 B. 3 C. 1 D. 4 E. 0

C. 1

Give (in order) the correct coefficients to balance the following reaction: H2SnCl6 + H2S → SnS2 + HCl A. 2, 4, 2, 6 B. 1, 1, 1, 6 C. 1, 2, 1, 6 D. 6, 2, 1, 1 E. 1, 2, 2, 2

C. 1, 2, 1, 6

How many moles of hydrogen chloride are contained in a 48.8-g sample of this gas? A. 85.3 mol B. 48.4 mol C. 1.34 mol D. 0.747 mol E. 2.68 mol

C. 1.34 mol

Roundup, an herbicide manufactured by Monsanto, has the formula C3H8NO5P. How many moles of molecules are there in a 783.5-g sample of Roundup? A. 0.2158 B. 5.673 C. 4.634 D. 43.53 E. none of these

C. 4.634

What is the coefficient for water when the following equation is balanced? As(OH)3(s) + H2SO4(aq) → As2(SO4)3(aq) + H2O(l) A. 4 B. 1 C. 6 D. 2 E. 12

C. 6

Balance the following equation for the combustion of benzene: C6H6(l) + O2(g) → H2O(g) + CO2(g) a. C6H6(l) + 9O2(g) → 3H2O(g) + 6CO2(g) b. C6H6(l) + 9O2(g) → 6H2O(g) + 6CO2(g) c. 2C6H6(l) + 15O2(g) → 6H2O(g) + 12CO2(g) d. C6H6(l) + 15O2(g) → 3H2O(g) + 6CO2(g) e. 2C6H6(l) + 9O2(g) → 6H2O(g) + 12CO2(g)

C. C6H6(l) + 15O2(g) → 6H2O(g) + 12CO2(g)

A metal oxide with the formula MO contains 28.53% oxygen. In the box below, type the symbol for the element represented by M.

Ca

The Claus reactions, shown below, are used to generate elemental sulfur from hydrogen sulfide. 2H2S + 3O2 → 2SO2 + 2H2O SO2 + 2H2S → 3S + 2H2O How much sulfur (in grams) is produced from 10.0 grams of O2? A. 45.1 g B. 6.7 g C. 10.0 g D. 20.0 g E. none of these

D. 20.0 g

Consider the following reaction: CH4 + 4Cl2 --> CCl4- + 4HCl What mass of CCl4 is formed by the reaction of 2.15 g of methane with an excess of chlorine? A. 5.2 g B. 0.22 g C. 331 g D. 20.6 g E. none of these

D. 20.6

Hydrocortisone valerate is an ingredient in hydrocortisone cream, prescribed for skin problems. Its molecular formula is C26H38O6. What is the percent by mass of carbon in hydrocortisone valerate? A. 43.6% B. 76.9% C. 60.1% D. 69.9% E. 54.2%

D. 69.9%

In the balanced equation for the reaction: xP4O6(s) + yH2O(l) → zH3PO3(aq) if x equals 2, the coefficient z equals: A.2 B. 4 C. 6 D. 10 E. none of these

E. none of these

True or False: When balancing a chemical equation, it is generally best to start with the least complicated molecules

False

A metal oxide with the formula MO contains 22.55% oxygen. In the box below, type the symbol for the element represented by M.

Mn

A metal oxide with the formula MO2 contains 21.23% oxygen by mass. Type the symbol for the element represented by M in the box below

Sn

A metal oxide with the formula MO contains 15.44% oxygen. In the box below, type the symbol for the element represented by M.

Sr

Oxides of copper include CuO and Cu2O. You heat 1.51 g of one of these copper oxides in the absence of air and obtain 1.21 g of Cu. True or false: You must have had CuO.

True

A metal oxide with the formula MO contains 19.66% oxygen. Type the symbol for the element represented by M in the box below.

Zn

In the reaction of aluminum metal and oxygen gas, aluminum oxide is formed. How many moles of O2 will react with 2.0 moles Al? a. 1.5 moles b. 1.0 moles c. 2.0 moles d. 3.0 moles e. 6.0 moles

a. 1.5 moles

In the reaction of N2 and H2 to produce NH3, how many moles of NH3 can be made from 2.9 moles H2? a. 1.9 b. 5.8 c. 2.9 d. 1.5 e. 4.4

a. 1.9

How many mmol of iron are there in 650 mg of iron? a. 11.6 mmol Fe b. 363.02 mmol Fe c. 55.85 mmol Fe d. 8.95 mmol Fe

a. 11.6 mmol Fe

If the atomic mass of A is 35 and B is 29, what is the molar mass of A6B5? a. 355 b. 75 c. 704 d. 1045 e. 64

a. 355

A compound with a composition of 87.5 % N and 12.5 % H was recently discovered. What is the empirical formula for this compound? a. NH2 b. N2H3 c. NH d. N2H2 e. N2H

a. NH2

Zinc sulfide is 67.1% zinc by mass. What is the mass fraction of sulfur in zinc sulfide? a. 0.671 b. 0.329 c. 67.1% d. 32.9% e. None of these is within 5% of the correct answer

b. 0.329

A 0.100 mole sample of ethane, C2H6, contains which of these? Hint: How many atoms are present in one C2H6 molecule? a. 6.02 x 1024 molecules b. 4.82 x 1023 atoms c. 6.02 x 1022 atoms d. 4.82 x 1022 atoms e. 3.61 x 1024 atoms

b. 4.82 * 10^23 atoms

A 20.0 g sample of CaCO3 was treated with aqueous H2SO4 producing calcium sulfate, water and 3.65 g of CO2(g) according to: CaCO3(s) + H2SO4(aq) -> CaSO4(s) + H2O + CO2(g). What was the percent yield of CO2? a. 33.0 % b. 41.5 % c. 50.7 % d. 83.0 % e. 91.1%

b. 41.5%

In the Haber process nirtrogen reacts with hydrogen to give ammonia. What is the theoretical yield of ammonia in grams that can be prepared from 41.0 g of nitrogen and excess hydrogen? a. 41.0 g b. 49.8 g c. 24.9 g d. 56.6 g e. 63.2 g

b. 49.8 g

In the reaction of aluminum metal and oxygen to make aluminum oxide, how many grams of oxygen gas will react with 2.2 moles aluminum metal? a. 94 b. 53 c. 44 d. 26 e. 1.7

b. 53

What is the mass (in g) of 0.215 mol of H2S? a. 6.31x10^-3 b. 7.33 c. 7.11 d. 3.57x10^-25 e. 1.29x10^23

b. 7.33

Methanol (CH4O) is converted to bromomethane (CH3Br) as follows: CH4O + HBr → CH3Br + H2O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield? a. 40.9% b. 82.6% c. 100.% d. 121% e. 245%

b. 82.6%

Given 6 mol of each reactant, which one would be limiting in the following reaction? 4Au + 8NaCN + O2 + 2H2O => 4NaAu(CN)2 + 4NaOH a. Au b. NaCN c. O2 d. H2O e. There is no limiting reactant.

b. NaCN

What is the empirical formula and empirical formula mass for the following compound? P4O10 a. P4O10 , 283.9 g/mol b. P2O5 , 141.9 g/mol c. PO2.5 , 71.0 g/mol d.P5O2 , 186.9 g/mol e. None of these

b. P2O5 , 141.9 g/mol

In the reaction of Fe3O4 with carbon to form carbon dioxide and iron, the number of moles of carbon required to convert 23 g of Fe3O4 to products is a. 0.05 b. 0.1 c. 0.2 d. 0.3 e. 0.4

c. 0.2

How many grams of H2O (g) are produced when 2.1 grams O2 (g) are consumed? a. 1.2 b. 660 c. 0.64 d. 2.2 e. 0.0020

c. 0.64

In the reaction below, how many grams of H2O(g) are produced when 2.1 grams O2(g) are consumed? C4H6(g) + O2(g) → CO2(g) + H2O(g) a. 1.2 b. 660 c. 0.64 d. 2.2 e. 0.0020

c. 0.64

The combustion of acetaldehyde with oxygen is shown in the equation: CH3CHO + O2 => CO2 + H2O (unbalanced) When properly balanced, the equation indicates that ___ mole(s) of O2 are required for each mole of CH3CHO. a. 1 b. 2 c. 2.5 d. 3 e. none of these

c. 2.5

There are two isotopes of Element X. Their percent abundances and atomic masses are: X-20, 62.96% X-21, 37.04% Calculate the weighted average atomic mass in amu. a. 2037 b. 20.63 c. 20.37 d. 12.59 e. 20.50

c. 20.37

Which of the following is the empirical formula for hexane, C6H14? a. C12H28 b. C6H14 c. C3H7 d. CH2.3 e. C0.43H

c. C3H7

What are the empirical formulas of a) ethylene glycol, a radiator antifreeze, molecular formula C2H6O2 b) peroxodisulfuric acid, a compound used in bleaching agents, molecular formula H2S2O8 a. C2H6O2, H2S2O8 b. C2H3O2, H2S2O4 c. CH3O, HSO4 d. CH3O2, HSO4 e. CH3O, HSO6

c. CH3O, HSO4

If 0.10 mole of SiO2 and 0.20 mole HF are combined in the reaction SiO2 + 4HF => SiF4 + 2H2O which of these statements is FALSE? a. HF is the limiting reactant. b. Some SiO2 will be left over. c. The theoretical yield of SiF4 is 0.10 mole. d. More HF would be needed to ensure that all the reactants are used up. e. The theoretical yield of H2O will be 0.10 mole.

c. The theorectical yield of SiF4 is 0.10 mole.

Iron can react with chlorine to form iron(II) chloride according to: Fe(s) + Cl2(g) => FeCl2(s) If you begin with 10.0 g of iron, a.you will need 10.0 g Cl2 for complete reaction and will produce 20.0 g of FeCl2. b. you will need 20.0 g Cl2 for complete reaction and will produce 30.0 g of FeCl2. c. you will need 12.7 g Cl2 for complete reaction and will produce 22.7 g of FeCl2. d. you will need 12.7 g Cl2 for complete reaction and will produce 20.0 g of FeCl2. e. you will need 25.4 g Cl2 for complete reaction and will produce 35.4 g of FeCl2.

c. you will need 12.7 g Cl2 for complete reaction and will produce 22.7 g of FeCl2.

What is the mass of 5.45 x 10-3 mol of glucose C6H12O6? a. 0.158 g b. 981 g c. 3.03 x 10-5 g d. 0.981 g e. none of the above

d 0.981 g

In the reaction of aluminum metal and oxygen gas to make aluminum oxide, how many moles of aluminum will react with 0.80 grams O2? a. 1.0 b. 19 c. 0.067 d. 0.033 e. 0.10

d. 0.033

Calculate the mass, in grams, of 7.35 mol water. a. 10.7 b. 0.408 c. 25.4 d. 132 e. 18.0

d. 132

What is the mass of one mole of acetylsalicylic acid (aspirin), C9H8O4? a. 29 g b. 108 g c. 196 g d. 180 g e. none of the above

d. 180 g

Balance the following equation: Ca3(PO4)2(s) + SiO2(s) + C(s) → CaSiO3(s) + CO(g) + P4(s) a. Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + P4(s) b. Ca3(PO4)2(s) + 3SiO2(s) + 14C(s) → 3CaSiO3(s) + 14CO(g) + P4(s) c. Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + 2P4(s) d. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + P4(s) e. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + 4P4(s)

d. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + P4(s)

Bromine has two naturally-occurring isotopes. 79Br has a mass of 78.9 amu and accounts for 50.3% of bromine atoms. If the atomic mass of bromine is 79.9 amu, what is the mass of an atom of the second bromine isotope? a. 77.9 amu b. 80.0 amu c. 80.1 amu d. 80.9 amu e. 88.9 amu

d. 80.9 amu

Combustion analysis of a hydrocarbon produces 0.396 g of CO2 and 0.163 g of H2O. Which of the following molecular formulas is consistent with the analysis? a. CH4 b. C2H6 c. C2H2 d. C2H4 e. C3H8

d. C2H4

Magnesium reacts with iron(III) chloride to form magnesium chloride and iron. 3Mg(s) + 2FeCl3(l) → 3MgCl2(s) + 2Fe(s) A mixture of 41.0 g of magnesium (м = 24.31 g/mol) and 175 g of iron(III) chloride (м = 162.2 g/mol) is allowed to react. Identify the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete. a. Limiting reactant is Mg; 67 g of FeCl3 remain. b. Limiting reactant is Mg; 134 g of FeCl3 remain. c. Limiting reactant is Mg; 104 g of FeCl3 remain. d. Limiting reactant is FeCl3; 2 g of Mg remain. e. Limiting reactant is FeCl3; 87 g of Mg remain.

d. Limiting reactant is FeCl3; 2 g of Mg remain.

Hydrazine can be produced by the reaction of chlorine with ammonia, with the unbalanced net reaction shown below. NH3 + Cl2 => N2H4 + NH4Cl When the chemical equation of the reaction is balanced with the smallest set of coefficients, what is the sum of the four coefficients (include a 1 for each/any unwritten coefficients)? a. 4 b. 5 c. 6 d.7 e. 8 f. 9 g. 10 or greater

e. 8

What is the percent yield of PI3, if 58.62 g of I2 are reacted with an excess of phosphorus according to the following equation and 60.75 g are actually obtained? 2 P(s) + 3 I2(s) ---> 2PI3(s) a. 84.97 % b. 1.57 % c. 48.37 % d. 37.6 % e. 95.8 %

e. 95.8%