Question 1

Gadolinium oxide,a colorless powder which absorbs carbon dioxide from the air,contains 86.76 mass % Gd.Determine its empirical formula.

Accepted Answer

A) Gd2O3 
B) Gd3O2 
C) Gd3O4 
D) Gd4O3 
E) GdO 
A) Gd2O3 
B) Gd3O2 
C) Gd3O4 
D) Gd4O3 
E) GdO

Question 2

In 0.20 mole of phosphoric acid,H3PO4,
a.how many H atoms are there?
b.what is the total number of atoms?
c.how many moles of O atoms are there?

Accepted Answer

a.3.61 @#LAT-DLM& 10²³

Question 3

Calcium fluoride,CaF2,is a source of fluorine and is used to fluoridate drinking water.Calculate its molar mass.

Accepted Answer

A) 118.15 g/mol 
B) 99.15 g/mol 
C) 78.07 g/mol 
D) 59.08 g/mol 
E) 50.01 g/mol 
A) 118.15 g/mol 
B) 99.15 g/mol 
C) 78.07 g/mol 
D) 59.08 g/mol 
E) 50.01 g/mol

Question 4

a.A solution of common salt,NaCl,in water has a concentration of 0.0921 M.Calculate the number of moles of HCl contained in 50.0 mL of this solution.
b.If,instead,an NaCl solution is prepared by dissolving 10.0 g of solid NaCl in enough water to make 250.mL of solution,what is the molarity?

Accepted Answer

a.0.00461

Question 5

Lead(II)sulfide was once used in glazing earthenware.It will also react with hydrogen peroxide to form lead(II)sulfate and water.How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II)sulfide?

Accepted Answer

A) 151 g 
B) 123 g 
C) 50.3 g 
D) 37.7 g 
E) 9.41 g 
A) 151 g 
B) 123 g 
C) 50.3 g 
D) 37.7 g 
E) 9.41 g

Question 6

Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain.Calculate the mass in grams of 3.65 $\times$ 1020 molecules of SO3.

Accepted Answer

A) 6.06 $\times$ 10-4 g 
B) 2.91 $\times$ 10-2 g 
C) 4.85 $\times$ 10-2 g 
D) 20.6 g 
E) 1650 g 
A) 6.06 $\times$ 10-4 g 
B) 2.91 $\times$ 10-2 g 
C) 4.85 $\times$ 10-2 g 
D) 20.6 g 
E) 1650 g

Question 7

What volume,in L,of 10.0 M HCl is needed to make 2.00 L of 2.00 M HCl solution by dilution with water?

Accepted Answer

A) 0.800 L 
B) 0.400 L 
C) 0.200 L 
D) 0.100 L 
E) None of these choices is correct. 
A) 0.800 L 
B) 0.400 L 
C) 0.200 L 
D) 0.100 L 
E) None of these choices is correct.

Question 8

Alkanes are compounds of carbon and hydrogen with the general formula CnH2n+2.An alkane component of gasoline has a molar mass of between 125 and 130 g/mol.What is the value of n for this alkane?

Accepted Answer

A) 4 
B) 9 
C) 10 
D) 13 
E) 14 
A) 4 
B) 9 
C) 10 
D) 13 
E) 14

Question 9

When a solution is diluted with water,the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Accepted Answer

A) True 
 B)False

Question 10

Sodium hydroxide,also known as caustic soda,is used to neutralize acids and to treat cellulose in making of cellophane.Calculate the number of moles of solute in 1.875 L of 1.356 M NaOH solution.

Accepted Answer

A) 2.543 mol 
B) 1.383 mol 
C) 0.7232 mol 
D) 0.3932 mol 
E) 0.001383 mol 
A) 2.543 mol 
B) 1.383 mol 
C) 0.7232 mol 
D) 0.3932 mol 
E) 0.001383 mol

Question 11

The number of hydrogen atoms in 0.050 mol of C3H8O3 is

Accepted Answer

A) 3.0 $\times$ 1022 H atoms 
B) 1.2 $\times$ 1023 H atoms 
C) 2.4 $\times$ 1023 H atoms 
D) 4.8 $\times$ 1023 H atoms 
E) none of these choices is correct 
A) 3.0 $\times$ 1022 H atoms 
B) 1.2 $\times$ 1023 H atoms 
C) 2.4 $\times$ 1023 H atoms 
D) 4.8 $\times$ 1023 H atoms 
E) none of these choices is correct

Question 12

Phosphine,an extremely poisonous and highly reactive gas,will react with oxygen to form tetraphosphorus decaoxide and water.
PH3(g)+ O2(g) $\to$ P4O10(s)+ H2O(g)[unbalanced]
Calculate the mass of P4O10(s)formed when 225 g of PH3 reacts with excess oxygen.

Accepted Answer

A) 1880 g 
B) 940.g 
C) 900.g 
D) 470 g 
E) 56.3 g 
A) 1880 g 
B) 940.g 
C) 900.g 
D) 470 g 
E) 56.3 g

Question 13

Magnesium reacts with iron(III)chloride to form magnesium chloride (which can be used in fireproofing wood and in disinfectants)and iron.
3Mg(s)+ 2FeCl3(s) $\to$ 3MgCl2(s)+ 2Fe(s)
A mixture of 41.0 g of magnesium (  
= 24.31 g/mol)and 175 g of iron(III)chloride (  
= 162.2 g/mol)is allowed to react.What mass of magnesium chloride = 95.21 g/mol)is formed?

Accepted Answer

A) 68.5 g MgCl2 
B) 77.0 g MgCl2 
C) 71.4 g MgCl2 
D) 107 g MgCl2 
E) 154 g MgCl2 
A) 68.5 g MgCl2 
B) 77.0 g MgCl2 
C) 71.4 g MgCl2 
D) 107 g MgCl2 
E) 154 g MgCl2

Question 14

Balance the following equation:
B2O3(s)+ HF(l) $\to$ BF3(g)+ H2O(l)

Accepted Answer

A) B2O3(s)+ 6HF(l) $\to$ 2BF3(g)+ 3H2O(l) 
B) B2O3(s)+ H6F6(l) $\to$ B2F6(g)+ H6O3(l) 
C) B2O3(s)+ 2HF(l) $\to$ 2BF3(g)+ H2O(l) 
D) B2O3(s)+ 3HF(l) $\to$ 2BF3(g)+ 3H2O(l) 
E) B2O3(s)+ 6HF(l) $\to$ 2BF3(g)+ 6H2O(l) 
A) B2O3(s)+ 6HF(l) $\to$ 2BF3(g)+ 3H2O(l) 
B) B2O3(s)+ H6F6(l) $\to$ B2F6(g)+ H6O3(l) 
C) B2O3(s)+ 2HF(l) $\to$ 2BF3(g)+ H2O(l) 
D) B2O3(s)+ 3HF(l) $\to$ 2BF3(g)+ 3H2O(l) 
E) B2O3(s)+ 6HF(l) $\to$ 2BF3(g)+ 6H2O(l)

Question 15

Gaseous methanol (CH4O)reacts with oxygen gas to produce carbon dioxide gas and liquid water.Write a balanced equation for this process.

Accepted Answer

2CH₄O(g)+

Question 16

When 2.61 g of solid Na2CO3 is dissolved in sufficient water to make 250 mL of solution,the concentration of Na2CO3 is:

Accepted Answer

A) 0.0246 M 
B) 10.4 M 
C) 0.205 M 
D) 0.0985 M 
E) 0.141 M 
A) 0.0246 M 
B) 10.4 M 
C) 0.205 M 
D) 0.0985 M 
E) 0.141 M

Question 17

What will be the final volume of a solution prepared by diluting 25 mL of 8.25 M sodium hydroxide to a concentration of 2.40 M?

Accepted Answer

A) 330 mL 
B) 210 mL 
C) 86 mL 
D) 60 mL 
E) 7.3 mL 
A) 330 mL 
B) 210 mL 
C) 86 mL 
D) 60 mL 
E) 7.3 mL

Question 18

Magnesium fluoride is used in the ceramics and glass industry.What is the mass of 1.72 mol of magnesium fluoride?

Accepted Answer

A) 43.3 g 
B) 62.3 g 
C) 74.5 g 
D) 92.9 g 
E) 107 g 
A) 43.3 g 
B) 62.3 g 
C) 74.5 g 
D) 92.9 g 
E) 107 g

Question 19

How many mL of concentrated nitric acid (HNO3,16.0 M)should be diluted with water in order to make 2.00 L of 2.00 M solution?

Accepted Answer

A) 32.0 mL 
B) 62.5 mL 
C) 125 mL 
D) 250.mL 
E) 500.mL 
A) 32.0 mL 
B) 62.5 mL 
C) 125 mL 
D) 250.mL 
E) 500.mL

Question 20

Aluminum oxide,Al2O3,is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators.Calculate the number of moles in 47.51 g of Al2O3.

Accepted Answer

A) 2.377 mol 
B) 2.146 mol 
C) 1.105 mol 
D) 0.4660 mol 
E) 0.4207 mol 
A) 2.377 mol 
B) 2.146 mol 
C) 1.105 mol 
D) 0.4660 mol 
E) 0.4207 mol

Exam 3: Stoichiometry of Formulas and Equations

Gadolinium oxide,a colorless powder which absorbs carbon dioxide from the air,contains 86.76 mass % Gd.Determine its empirical formula.

In 0.20 mole of phosphoric acid,H3PO4, a.how many H atoms are there? b.what is the total number of atoms? c.how many moles of O atoms are there?

Calcium fluoride,CaF2,is a source of fluorine and is used to fluoridate drinking water.Calculate its molar mass.

a.A solution of common salt,NaCl,in water has a concentration of 0.0921 M.Calculate the number of moles of HCl contained in 50.0 mL of this solution. b.If,instead,an NaCl solution is prepared by dissolving 10.0 g of solid NaCl in enough water to make 250.mL of solution,what is the molarity?

Lead(II)sulfide was once used in glazing earthenware.It will also react with hydrogen peroxide to form lead(II)sulfate and water.How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II)sulfide?

Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain.Calculate the mass in grams of 3.65 ×\times× 1020 molecules of SO3.

What volume,in L,of 10.0 M HCl is needed to make 2.00 L of 2.00 M HCl solution by dilution with water?

Alkanes are compounds of carbon and hydrogen with the general formula CnH2n+2.An alkane component of gasoline has a molar mass of between 125 and 130 g/mol.What is the value of n for this alkane?

When a solution is diluted with water,the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Sodium hydroxide,also known as caustic soda,is used to neutralize acids and to treat cellulose in making of cellophane.Calculate the number of moles of solute in 1.875 L of 1.356 M NaOH solution.

The number of hydrogen atoms in 0.050 mol of C3H8O3 is

Phosphine,an extremely poisonous and highly reactive gas,will react with oxygen to form tetraphosphorus decaoxide and water. PH3(g)+ O2(g) →\to→ P4O10(s)+ H2O(g)[unbalanced] Calculate the mass of P4O10(s)formed when 225 g of PH3 reacts with excess oxygen.

Balance the following equation: B2O3(s)+ HF(l) →\to→ BF3(g)+ H2O(l)

Gaseous methanol (CH4O)reacts with oxygen gas to produce carbon dioxide gas and liquid water.Write a balanced equation for this process.

When 2.61 g of solid Na2CO3 is dissolved in sufficient water to make 250 mL of solution,the concentration of Na2CO3 is:

What will be the final volume of a solution prepared by diluting 25 mL of 8.25 M sodium hydroxide to a concentration of 2.40 M?

Magnesium fluoride is used in the ceramics and glass industry.What is the mass of 1.72 mol of magnesium fluoride?

How many mL of concentrated nitric acid (HNO3,16.0 M)should be diluted with water in order to make 2.00 L of 2.00 M solution?

Aluminum oxide,Al2O3,is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators.Calculate the number of moles in 47.51 g of Al2O3.

Keys to the Study of Chemistry

The Components of Matter

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids,solids,and Phase Changes

The Properties of Solutions

The Main-Group Elements: Applying Principles of Bonding and Structure

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Acid-Base Equilibria

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

In 0.20 mole of phosphoric acid,H₃PO₄, a.how many H atoms are there? b.what is the total number of atoms? c.how many moles of O atoms are there?

Calcium fluoride,CaF₂,is a source of fluorine and is used to fluoridate drinking water.Calculate its molar mass.

Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain.Calculate the mass in grams of 3.65 $\times$ 10²⁰ molecules of SO₃.

Alkanes are compounds of carbon and hydrogen with the general formula C_nH₂_n₊₂.An alkane component of gasoline has a molar mass of between 125 and 130 g/mol.What is the value of n for this alkane?

The number of hydrogen atoms in 0.050 mol of C₃H₈O₃ is

Phosphine,an extremely poisonous and highly reactive gas,will react with oxygen to form tetraphosphorus decaoxide and water. PH₃(g)+ O₂(g) $\to$ P₄O₁₀(s)+ H₂O(g)[unbalanced] Calculate the mass of P₄O₁₀(s)formed when 225 g of PH₃ reacts with excess oxygen.

Balance the following equation: B₂O₃(s)+ HF(l) $\to$ BF₃(g)+ H₂O(l)

Gaseous methanol (CH₄O)reacts with oxygen gas to produce carbon dioxide gas and liquid water.Write a balanced equation for this process.

When 2.61 g of solid Na₂CO₃ is dissolved in sufficient water to make 250 mL of solution,the concentration of Na₂CO₃ is:

How many mL of concentrated nitric acid (HNO₃,16.0 M)should be diluted with water in order to make 2.00 L of 2.00 M solution?

Aluminum oxide,Al₂O₃,is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators.Calculate the number of moles in 47.51 g of Al₂O₃.