Chem Exam

Which represents the greatest mass?

1.0 mol Zn

Methane, CH4, the major component of natural gas, burns in air to form CO2 and H2O. What mass of water is formed in the complete combustion of 5.00 x 103 g of CH4?

1.00 x 104 g

What is the oxidation state of S in SO32-?

+4

The following reaction occurs in aqueous acid solution: NO3- + I- à IO3- + NO2 The oxidation state of iodine in IO3- is

+5

The oxidation state of nitrogen in NO3- is

+5

The oxidation state of selenium in NaSeO3 is

+5

The oxidation state of chlorine in ClO4- is

+7

The oxidation state of selenium in NaSeO4 is

+7

The oxidation state of an element in its elemental state is

0

For the reaction of C2H4(g) with O2(g) to form CO2(g) and H2O(g), what number of moles of CO2 can be produced by the reaction of 0.480 mol of C2H4 and 1.08 mol of O2?

0.720 mol

The rusting of iron is represented by the equation 4Fe + 3O2 à 2Fe2O3. If you have a 1.50-mol sample of iron, how many moles of Fe2O3 will there be after the iron has rusted completely?

0.75 mol

Sodium and water react according to the reaction 2Na(s) + 2H2O(l) à 2NaOH(aq) + H2(g) What number of moles of H2 will be produced when 4 mol Na is added to 2 mol H2O?

1 mol

Choose the false statement

1 mol = 6.02 x 1023 amu

Calculate the moles of oxygen needed to react with 11.2 g of octane, C8H18, in the following reaction. 2C8H18(g) + 25O2(g) à 16CO2(g) + 18H2O(g)

1.23 mol O2

Calculate the number of moles of water molecules in 25.0 g of water.

1.39 mol

Convert 48 g O2 to mol O2.

1.5 mol

When 1.0 mol of Fe reacts with Cl2 according to the equation 2Fe + 3Cl2 à 2FeCl3 how many moles of Cl2 are required to react with all the iron?

1.5 mol

The mass of 0.80 mol of H2 is

1.6g

Refer to the following unbalanced equation: C6H14 + O2 à CO2 + H2O When balanced in standard form (smallest whole numbers), the coefficient for CO2 is

12

The number of moles in 12.0 g of C2H6O (molar mass = 46.1 g/mol) is calculated as follows:

12.0/46.1

The mass in grams of 6.0 mol of hydrogen gas (contains H2) is

12g

What is the mass of 2.00 moles of Ca(OH)2?

148.2 g

Calculate the theoretical yield of iron in the reaction of 254 g of iron(III) oxide with 25.0 g of carbon, according to the equation 2Fe2O3(s) + 3C(s) à 4Fe(s) + 3CO2(g)

155 g Fe

A sample of metal weighing 2.51 g is combined with oxygen; the metal oxide weighs 3.01 g. The mass percent of oxygen in the compound is

16.6%

What is the mass of 1.48 mol of potassium sulfide?

163 g

The molar mass of Na3PO4 is

164 g/mol

What is the molar mas of K2SO4?

174.26 g/mol

The molar mass of blood sugar, C6H12O6, also known as glucose and dextrose, is

180 g/mol

One mole of water weighs

18g

Answer the following question(s) that refer to the unbalanced reaction shown below as it occurs in acidic solution: _______ Cr2O72- (aq)+ _______ I-(aq)à _______ Cr3+(aq) + _______ I2(s) Determine the coefficient for the Cr3+ ions.

2

How many electrons are transferred in the following oxidation-reduction reaction? Zn(s) + 2AgNO3(aq) à Zn(NO3)2(aq) + 2Ag(s)

2

Of the following four reactions, how many are oxidation-reduction reactions? NaOH + HCl à NaCl + H2O Cu + 2AgNO3 à 2Ag + Cu(NO3)2 Mg(OH)2 à MgO + H2O N2 + 3H2 à 2NH3

2

How many moles of Ca atoms are in 801 g Ca?

20.0 mol

Calculate the mass of 3.50 mol of sulfur dioxide.

224 g

What is the molar mass of nitroglycerin, C3H5(NO3)3?

227 g/mol

What mass of oxygen would be required to completely burn 6.75 g of propane (C3H8) in the following reaction? C3H8(g) + 5O2(g) à 3CO2(g) + 4H2O(g)

24.5 g O2

The mass percent of oxygen in CaO is

28.5%

When the equation Fe2(SO4)3(aq) + Ba(OH)2(aq) à is completed and balanced, a term in the balanced molecular equation is

2Fe(OH)3(s)

When the equation NaOH(aq) + H2SO4(aq) à is completed and balanced in standard form, one of the terms in the balanced equation is

2H2O(l)

When the following reaction is balanced in acidic solution, what is the coefficient of water? Zn(s) + NO3-(aq) à Zn2+(aq) + NH4+(aq)

3

If 18.0 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?

3.68 g

The molar mass of calcium phosphate is

310.18 g/mol

What is the molar mass of H2S?

34.08 g/mol

Calculate the mass of carbon dioxide produced from 11.2 g of octane, C8H18, in the following reaction. 2C8H18(g) + 25O2(g) à 16CO2(g) + 18H2O(g)

34.5 g CO2

A 1.0-mole sample of H2O2 weighs

34g

An excess of Al and 6.0 mol of Br2 are reacted according to the equation 2Al + 3Br2 à 2AlBr3 How many moles of AlBr3 will be formed assuming 100% yield?

4.0 mol

A 3.0-mol sample of KClO3 was decomposed according to the equation 2KClO3(s) à 2KCl(s) + 3O2(g) How many moles of O2 are formed assuming 100% yield?

4.5 mol

For the reaction of C2H4(g) with O2(g) to form CO2(g) and H2O(g), what number of grams of CO2 could be produced from 2.0 g of C2H4 and 5.0 g of O2?

4.6 g

How many moles of O2 are required for the complete reaction of 45 g of C2H4 to form CO2 and H2O?

4.8 mol

What is the percent (by mass) of carbon in glucose, C6H12O6?

40.0%

When the following equation is balanced, what is the coefficient in front of the underlined substance? C2H2(g) + O2(g) à CO2(g) + H2O(l)

5

Which of the following contains the smallest number of molecules?

5.0 g CO2

Which represents the greatest number of atoms?

50.0 g Al

What is the molar mass of NaCl?

58.44 g/mol

Answer the following question(s) that refer to the unbalanced reaction shown below as it occurs in acidic solution: _______ Cr2O72- (aq)+ _______ I-(aq)à _______ Cr3+(aq) + _______ I2(s) Determine the coefficient for the iodide ions.

6

In the balanced equation for the following reaction (in acidic solution) ClO3- + Fe2+ à Cl- + Fe3+ the coefficient of Fe2+ is

6

One mole of oxygen atoms represents

6.02 x 1023 atoms

1.008 g of hydrogen gas contains

6.02 x 1023 hydrogen atoms

Compound X2Y is known to be 60% X by mass. Calculate the percent Y by mass of the compound X2Y2.

60%

Answer the following question(s) that refer to the unbalanced reaction shown below as it occurs in acidic solution: _______ Cr2O72- (aq)+ _______ I-(aq)à _______ Cr3+(aq) + _______ I2(s) Determine the coefficient for water in the balanced equation for the reaction.

7

In the balanced equation for the following redox equation, the sum of the coefficients is Fe3+ + I- à Fe2+ + I2

7

Nitrogen and hydrogen gases are combined at high temperatures and pressures to produce ammonia, NH3. If 100. g of N2 is reacted with excess H2, what number of moles of NH3 will be formed?

7.14 mol

The molar mass of calcium hydroxide is

74.1g

Refer to the following unbalanced equation: C6H14 + O2 à CO2 + H2O What mass of carbon dioxide (CO2) can be produced from 25.0 g of C6H14 and excess oxygen?

76.6 g

What is the molar mass of Al(OH)3?

78.00 g/mol

For the reaction of C2H4(g) with O2(g) to form CO2(g) and H2O(g), what number of moles of CO2 can be produced by the reaction of 5.00 mol C2H4 and 12.0 mol O2?

8.00 mol

Determine the volume of 0.100 M NaOH needed to titrate 20.0 mL of 0.400 M HCl

80.0 mL

A hydrocarbon has the formula C2H4. What is the percent by mass of carbon in the compound?

85.6%

When NH3 is prepared from 28 g N2 and excess H2, the theoretical yield of NH3 is 34 g. When this reaction is carried out in a given experiment, only 30. g is produced. What is the percentage yield?

88%

Refer to the following unbalanced equation: C6H14 + O2 à CO2 + H2O What mass of oxygen (O2) is required to react completely with 25.0 g of C6H14?

88.2g

For the reaction C2H4(g) + 3O2(g) à 2CO2(g) + 2H2O(g) if 6.0 mol of CO2 are produced, how many moles of O2 were reacted?

9.0 mol

The molar mass of MgCl2 is

95.2 g/mol

For the following reactions, identify the solid product Na2S(aq) + AgNO3(aq)

Ag2S

For the following reactions, identify the solid product AgNO3(aq) + BaCl2(aq)

AgCl

When the equation Al(OH)3(s) + H2SO4(aq) is completed and balanced in standard form, one of the terms in the balanced equation is

Al2(SO4)3(aq)

Which of the following reactions does not involve oxidation-reduction?

All are oxidation-reduction reactions.

What is the empirical formula of an oxide of bromine which contains 71.4% bromine?

BrO2

Acetylene gas is 92.3% carbon and 7.7% hydrogen (by mass), and its molar mass is 26 g/mol. What is its molecular formula?

C2H2

Choose the pair of compounds with the same empirical formula

C2H2 and C6H6

The empirical formula for acetic acid is CH2O. Its molar mass is 60 g/mol. The molecular formula is

C2H4O2

Arrange the following compounds in order of increasing percentage of oxygen by mass.

C2H4O2, NO2, CO2, H2O, O2

A compound has a molar mass of 100 g/mol and the percent composition (by mass) of 65.45% C, 5.45% H, and 29.09% O. Determine the empirical formula and the molecular formula.

C3H3O and C6H6O2

The empirical formula of a compound is CH2O, and its mass is 120 amu/molecule. Calculate its molecular formula.

C4H8O4

Calculate the molecular formula of a compound with the empirical formula CH2O and a molar mass of 150 g/mol.

C5H10O5

Which of the following has the empirical formula CH2?

C6H12

Calculate the empirical formula of a compound that is 85.6% C and 14.4% H (by mass).

CH2

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen (by mass). Calculate the empirical formula.

CH2O

Which of the following has the highest mass percent of hydrogen?

CH4

Which of the following has the largest percent by mass of carbon?

CH4

The empirical formula for the compound having the formula H2C2O4 is

CO2H

A compound is analyzed and found to contain 12.1% carbon, 16.2% oxygen, and 71.7% chlorine (by mass). Calculate the empirical formula of this compound.

COCl2

Calcium reacts with fluorine to form

CaF2

Answer the question(s) that refer to the following reaction: TiCl4(l)+ O2(g) à TiO2(s)+ 2Cl2(g) Which species is oxidized?

Cl

0.314 mol of a diatomic molecule has a mass of 22.26 g. Identify the molecule

Cl2

Which statement is true of the following reaction? 2K + CuCl2 à 2KCl + Cu

Copper is reduced.

Consider separate 100.0 g samples of each of the following: NH3, N2O, HCN, N2H4, and HNO3. Which of the samples has the least mass of nitrogen?

HNO3

Which of the following are oxidation-reduction reactions? I. PCl3 + Cl2 à PCl5 II. Cu + 2AgNO3 à Cu(NO3)2 + 2Ag III. CO2 + 2LiOH à Li2CO3 + H2O IV. FeCl2 + 2NaOH à Fe(OH)2 + 2NaCl

I and II

For the redox reaction 2Fe2+ + Cl2 à 2Fe3+ + 2Cl-, which of the following are the correct half-reactions? I. Cl2 + 2e- à 2Cl- II. Cl à Cl- + e- III. Cl2 à 2Cl- + 2e- IV. Fe2+ à Fe3+ + e- V. Fe2+ + e- à Fe3+

I and IV

Which of the following has the highest mass percentage of nitrogen?

N2H4

A certain compound has an empirical formula of NH2O. Its molar mass is between 55 and 65 g/mol. Its molecular formula is

N2H4O2

Which of the following compounds contains chlorine with an oxidation state of +7?

NaClO4

Which gas has the lowest molar mass?

Ne

For the following reactions, identify the solid product KNO3(aq) + BaCl2(aq)

None forms

Consider the reaction 4Fe(s) + 3O2(g) à 2Fe2O3(s) If 12.5 g of iron(III) oxide (rust) is produced from 8.74 g of iron, how many grams of oxygen are needed for this reaction?

None of the above

Refer to the following equation: 4NH3(g) + 7O2(g) à 4NO2(g) + 6H2O(g) How many moles of NH3 will be required to produce 10.0 mol of water?

None of the above

The limiting reactant in a reaction is

None of the above

The limiting reactant is the reactant

None of the above

Answer the question(s) that refer to the following reaction: SiO2(s) + 2C(s) à Si(s) + 2CO(g) Which species is reduced?

Si

Answer the question(s) that refer to the following reaction: SiO2(s) + 2C(s) à Si(s) + 2CO(g) Which species is the oxidizing agent?

SiO2

Which of the following compounds contains the lowest mass percent of oxygen?

SnO

Answer the question(s) that refer to the following reaction: TiCl4(l)+ O2(g) à TiO2(s)+ 2Cl2(g) Which species is the reducing agent?

TiCl4

A chemical mole

contains 6.02 x 1023 particles

Which gas has the lowest mass per mole?

hydrogen

When they react chemically, the alkali metals (Group 1)

lose one electron

The smallest unit of hydrogen fluoride gas is an example of a(n)

molecule

In the reaction 2Ca(s) + O2(g) à 2CaO(s), calcium is ______________.

oxidized

In the reaction C(s) + O2(g) à CO2(g), carbon is ______________.

oxidized

The balanced equation 2Cu(s) + O2(g) à 2CuO(s) tells us that 1 mol of Cu

produces 1 mol of CuO

The balanced equation P4(s) + 6H2(g) à 4PH3(g) tells us that 3 mol H2

produces 2 mol PH3

In the reaction 2Cs(s) + Cl2(g) à 2CsCl(s), the chlorine is ______________.

reduced

Because atoms are so ______________, the standard units of mass are not useful in measurements.

small