Chapter 9 Stoichometry

The ions in most ionic compounds are organized into a

crystal

Compared with nonmetals, the number of valence electrons in metals is generally

smaller

According to VSEPR theory, the shape of an AB3 molecule is

trigonal-planar

Name the compound Al2S3.

aluminum sulfide

In a compound, the algebraic sum of the oxidation numbers of all atoms equals

0

What is the formula mass of (NH4)2SO4?

132.16 amu

What is the empirical formula for a compound that is 43.6% phosphorus and 56.4% oxygen?

P2O5

When a solid produced by a chemical reaction separates from the solution it is called

a precipitate

A precipitate may form in a double-displacement reaction when

positive ions combine with negative ions.

The coefficients in a chemical equation represent the

relative numbers of moles of reactants and products.

A chemical equation is balanced when the

same number of each kind of atom appears in the reactants and in the products.

What is the study of the mass relationships of elements in compounds?

composition stoichiometry

For the reaction represented by the equation 2H2 + O2® 2H2O, how many moles of water can be produced from 6.0 mol of oxygen?

12 mol

For the reaction represented by the equation N2 + 3H2 ® 2NH3, how many moles of nitrogen are required to produce 18 mol of ammonia?

9.0 mol

Which branch of chemistry deals with the mass relationships of elements in compounds and the mass relationships among reactants and products in chemical reactions?

stoichiometry

In the reaction represented by the equation C + 2H2 ® CH4, what is the mole ratio of hydrogen to methane?

2:1

If one knows the mole ratio of a reactant and product in a chemical reaction, one can

calculate the mass of the product produced from a known mass of reactant.

What is the study of the mass relationships among reactants and products in a chemical reaction?

reaction stoichiometry

In the reaction represented by the equation N2 + 3H2 ® 2NH3, what is the mole ratio of hydrogen to ammonia?

3:2

In metallic bonds, the mobile electrons surrounding the positive ions are called a(n)

electron sea

What is the formula for the compound formed by calcium ions and chloride ions?

CaCl2

What is the oxidation number of sulfur in SO2?

+4

What is the mass percentage of OH- in Ca(OH)2?

45.9%

Of the following molecular formulas for hydrocarbons, which is an empirical formula?

Ch4

To balance a chemical equation, it may be necessary to adjust the

coefficients.

When sodium chlorate, NaClO3, decomposes, the products are

sodium chloride and oxygen

What can be predicted by using an activity series?

whether a certain chemical reaction will occur

If one knows the mass and molar mass of reactant A and the molar mass of product D in a chemical reaction, one can determine the mass of product D produced by using the

mole ratio of D to A from the chemical equation.

The Haber process for producing ammonia commercially is represented by the equation N2(g) + 3H2(g) ® 2NH3(g). To completely convert 9.0 mol hydrogen gas to ammonia gas, how many moles of nitrogen gas are required?

3.0 mol

Given the equation , the starting mass of A, and its molar mass, and you are asked to determine the moles of C produced, your first step in solving the problem is the multiply the given mass of A by

1 mol A/molar mass A

Which of the following would be investigated in reaction stoichiometry?

the mass of potassium required to produce a known mass of potassium chloride

A balanced chemical equation allows one to determine the

mole ratio of any two substances in the reaction.

Which of the following would not be studied in the branch of chemistry called stoichiometry?

the amount of energy required to break the ionic bonds in calcium fluoride

REVIEW: Which of the following does not describe a direct proportionality between x and y?

xy=k

REVIEW: If two or more compounds are composed of the same two elements, the ratio of the masses of one element that combine with a fixed mass of the other element is a simple whole number. This is a statement of the law of

multiple proportions.

REVIEW: When an electron is acquired by a neutral atom, the energy change is called

electron affinity.

REVIEW: The mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies is called

hybridization

REVIEW: What is the name of Ni(ClO3)2

nickel(II) chlorate

REVIEW: If 0.500 mol of Na+ combines with 0.500 mol of Cl- to form NaCl, how many formula units of NaCl are present?

3.01 1023

REVIEW: If metal X is lower than metal Y in the activity series, then metal X

loses electrons less readily than does metal Y.

REVIEW: For numbers less than 0.1, such as 0.06, the zeros to the right of the decimal point but before the first nonzero digit

show the decimal place of the first digit.

REVIEW: Protons within a nucleus are attracted to each other by

the nuclear force.

In the chemical equation wA + xB ® yC + zD, if one knows the mass of A and the molar masses of A, B, C, and D, one can determine

the mass of any of the reactants or products.

REVIEW: The measurement 0.035550 g rounded off to two significant figures would be

0.036 g.

In the reaction represented by the equation 2Al2O3 ® 4Al + 3O2, what is the mole ratio of aluminum to oxygen?

4:3

Which equation is not balanced?

H2+O2=H2O

REVIEW: Phosphorus-33 (atomic number 15) contains

18 neutrons

REVIEW: Because excited hydrogen atoms always produce the same line-emission spectrum, scientists concluded that hydrogen

released photons of only certain energies.

REVIEW: If n is the principal quantum number of a main energy level, the number of electrons in that energy level is

2n2.

REVIEW: Across a period in the periodic table, atomic radii

gradually decrease.

A determination of the masses and number of moles of sulfur and oxygen in the compound sulfur dioxide would be studied in

composition stoichiometry.

If the percentage yield is equal to 100%, then

the actual yield is equal to the theoretical yield.

What is the maximum possible amount of product obtained in a chemical reaction?

theoretical yield

Which reactant controls the amount of product formed in a chemical reaction?

limiting reactant

REVIEW: The number of atoms in 1 mol of carbon is

6.022 x 10^23

REVIEW: The Bohr model of the atom was an attempt to explain hydrogen's

line-emission spectrum.

REVIEW: A three-dimensional region around a nucleus where an electron may be found is called a(n)

orbital

REVIEW: If the s and p orbitals of the highest main energy level of an atom are filled with electrons, the atom has a(n)

octet

REVIEW: Evidence gathered since Mendeleev's time indicates that a better arrangement than atomic mass for elements in the periodic table is an arrangement by

atomic number.

REVIEW: When an electron is added to a neutral atom, a certain amount of energy is

either released or absorbed.

In the chemical reaction represented by the equation wA + xB ® yC + zD, a comparison of the number of moles of A to the number of moles of C would be a(n)

mole ratio

A chemical reaction involving substances A and B stops when B is completely used. B is the

limiting reactant

A chemist interested in the efficiency of a chemical reaction would calculate the

percentage yield

A chemical reaction involving substances A and B stops when B is completely used. B is the

limiting reactant

In the reaction A+B > C+D if there is an insufficient quantity of B to completely react with all of A then...

B is the limiting reactant

In most chemical reactions the amount of product obtained is...

less than the theoretical yield

The study of mass relationships of elements in compounds is known as...

Composition stoichiometry

The study of mass relationships amount reactants and products in a chemical reaction is know as...

Reaction stoichiometry

What would NOT be studied in the branch of chemistry called stoichiometry?

Anything not pertaining to mole and mass calculations such as the amount of energy required for a reaction.

A balanced chemical equation allows one to determine the what?

Mole ratio of any two substances in the reaction

In solving mass-mass equations the coefficients from the balanced equation are used to find the what?

Mole proportions of chemicals involved

A determination of the masses and number of moles of sulfur and oxygen in the compound sulfur dioxide would be studied in:

composition stoichiometry

Each of the four types of reaction stoichimetry problems requires using

mole ratio

A chemical equation is balanced when the:

same number of each kind of atom appears in the reactants and in the products

If one knows the mole ratio of a reactant and product in a chemical reaction, one can:

calculate the mass of the product produced from a known mass of reactant

When the limiting reactant in the chemical reaction is completely used, the:

reaction stops

To determine the limiting reactant in a chemical reaction, one must know the:

available amount of each reactant

Exothermic

reaction that releases energy, usually in the form of heat

Endothermic

reaction that absorbs energy