Chemistry T.e.w. Practice Test 2

Front 1

Choose the appropriate answer:
A: Law of Definite Composition
B: High dielectric constant
C: van der Waals forces
D: Graham's Law of Diffusion (Effusion)
E: Triple point

At a particular temperature and pressure, three states of a compound coexist.

Back 1

E: Triple point

Hint 1

The triple point of a phase diagram shows that all three states can exist at this point.

Front 2

Choose the appropriate answer:
A: Law of Definite Composition
B: High dielectric constant
C: van der Waals forces
D: Graham's Law of Diffusion (Effusion)
E: Triple point

Water is a good solvent.

Back 2

B: High dielectric constant

Hint 2

The high dielectric constant of waters
is due to the polar nature of the water molecules.

It is this property that is largely responsible for
the ability of water to dissolve so many solutes.

Front 3

Choose the appropriate answer:
A: Law of Definite Composition
B: High dielectric constant
C: van der Waals forces
D: Graham's Law of Diffusion (Effusion)
E: Triple point

The rate of movement of hydrogen gas compared to oxygen gas is 4:1.

Back 3

D: Graham's Law of Gaseous Diffusion (or Effusion)

Hint 3

According to Graham's Law of Gaseous Diffusion (or Effusion),
the rate of diffusion is inversely proportional
to the square root of the molecular weight.

Front 4

Choose the appropriate answer:
A: Law of Definite Composition
B: High dielectric constant
C: van der Waals forces
D: Graham's Law of Diffusion (Effusion)
E: Triple point

The molecules of nitrous oxide and nitrogen dioxide
differ by a multiple of the mass of one oxygen.

Back 4

A: Law of Definite Composition

Hint 4

The Law of Definite Composition states that when compounds form,
they always form in a ratio of 1:8 of hydrogen to oxygen by mass.

For nitrous oxide (NO) and nitrogen dioxide (NO2),
the difference in molecular mass is one atomic mass of oxygen.

Front 5

Choose the most appropriate answer:
A. Hydrogen bond
B. Ionic bond
C. Polar covalent bond
D. Pure covalent bond
E. Metallic bond

The type of bond between atoms of K and Cl
in crystal of KCl is:

Back 5

B: Ionic bond

Hint 5

Potassium and cholorine have a large enough difference
in their electronegativities to form ionic bonds.

The respective positions of these two elements
in the periodic chart
also are indicative of the large difference in their electronegativity values.

Front 6

Choose the most appropriate answer:
A. Hydrogen bond
B. Ionic bond
C. Polar covalent bond
D. Pure covalent bond
E. Metallic bond

The type of bond between the atoms in a nitrogen molecule is:

Back 6

D: Pure covalent bond

Hint 6

Two atoms of an element that forms a diatomic molecule ALWAYS
have a pure covalent bond between them since the electron attraction or electronegativity of each atom is the same.

Front 7

Choose the most appropriate answer:
A. Hydrogen bond
B. Ionic bond
C. Polar covalent bond
D. Pure covalent bond
E. Metallic bond

The type of bond between the atoms in a molecule of CO2
(electonegativity difference = 1) is:

Back 7

C: Polar covalent bond

Hint 7

Electronegativity differences between 0.5 and 1.7 are usually
indicative of polar covalent bonds
since the bonds are symmetrical in the molecule.

Front 8

Choose the most appropriate answer:
A. Hydrogen bond
B. Ionic bond
C. Polar covalent bond
D. Pure covalent bond
E. Metallic bond

The type of bond between the atoms of calcium in a crystal of calcium is:

Back 8

E: Metallic bond

Hint 8

Calcium is a metal
and forms a metallic bond between atoms.

Front 9

True or False?

The structure of SO3 is shown by using more than one structural formula.

Back 9

True

Hint 9

Sulfur trioxide is shown by three structural formulas
because each bond is a "hybrid"
of a single and a double bond.

Front 10

True or False?

The structure of SO3 is shown by using more than one structural formula
BECAUSE SO3 is very unstable
and resonates between these possible structures.

Back 10

False

Hint 10

Resonance in chemistry does NOT mean
that the bonds resonate between the structures
shown in the structural drawing.

Front 11

True or False?

Boric acid is a strong acid.

Back 11

False

Hint 11

Boric acid is a WEAK acid, because it ionizes only SLIGHTLY.

Front 12

True or False?

Boric acid cannot be kept in a glass bottle.

Back 12

False

Hint 12

Hydrofluoric acid is the acid that reacts with glass.

Front 13

True or False?

The elements in the upper right portions of the periodic chart are mostly nonmetal.

Back 13

True

Front 14

True or False?

Nonmetallic elements have close to filled outer energy levels.

Back 14

True

Hint 14

Nonmetal:
an element whose oxide reacts with water to form an acid and
that takes on electrons and acquires a negative valence.

Front 15

True or False?

Hydrosulfuric acid is often used in qualitative tests because it is a weak acid.

Back 15

False

Hint 15

Hydrosulfuric acid is a weak acid, but is used in qualitative tests
because of the distinctly colored precipitates of sulfides
that it forms with many metallic ions.

Front 16

True or False?

Molecules of sodium chloride go into solution in water as ions.

Back 16

False

Hint 16

Sodium chloride is an ionic crystal, not a molecule.

Front 17

True or False?

In sodium chloride,
the sodium has a +1 charge and the chloride has a -1 charge
and they are hydrated by the water molecules.

Back 17

True

Hint 17

Sodium chloride's ions are hydrated by the polar water molecules.

Front 18

True or False?

In an equilibrium reaction,
if the concentration of the reactants is increased,
the reaction will increase its forward rate
BECAUSE when a stress is applied to a reaction in equilibrium,
the equilibrium shifts in the direction that opposes the stress.

Back 18

True

Hint 18

Le Chatelier's Principle:
If stress is placed on a system in equilibrium,
the system will react in the direction that relieves the stress.

Front 19

The ^H reaction of a particular reaction can be arrived at by
the summation of the ^H reaction values of two or more reactions that,
added together, give the ^H reaction of the particular reaction
BECAUSE the First Law of Thermodynamics states that
the total energy of the universe is a constant.

Back 19

True

Hint 19

First Law of Thermodynamics:
total energy of the universe is constant and cannot be created or destroyed.

Front 20

In a reaction that has both a forward and a reverse reaction,
A+B<>AB,
when only A and B are introduced into a reacting vessel,
the forward reaction rate is the highest at the beginning
and begins to decrease from that point until equilibrium is reached.

Back 20

True

Front 21

At equilibrium,
the forward reaction and reverse reaction stop
BECAUSE the reactants and product have reached the equilibrium concentrations.

Back 21

False

Hint 21

The forward and reverse reactions are occurring at equal rates when equilibrium is reached.
The reactions do NOT stop.
The concentrations remain the same at this point.

Front 22

The hybrid orbital form of carbon in acetylene is believed to be the "sp" form
BECAUSE it is a linear compound with a triple bond betwen the carbons.`

Back 22

True

Hint 22

Since acetylene is known to be a linear molecule with a triple bond between the two carbons, the "sp" orbitals along the central axis with the hydrogens bonded on either end fit the experimental evidence.

Front 23

The weakest of the bonds between molecules are coordinate covalent bonds
BECAUSE they represent the weak attractive force of the electrons of one molecule
for the positively charged nucleus of another.

Back 23

False

Hint 23

The weakest bonds between molecules are called van der Waals forces.

Front 24

Define van der Waals forces.

Back 24

Weak attractive forces existing between molecules.

Front 25

A saturated solution is not necessarily concentrated
BECAUSE dilute and concentrated are terms that relate only to the relative amount of sollute dissolved in the solvent.

Back 25

True

Hint 25

The terms dilute and concentrated merely indicate
a relatively large amount of solvent and a small amount of solvent, respectively.
You can have a dilute saturated solution if the solute is only SLIGHTLY soluble.

Front 26

Lithium is the most active metal in the first group of the periodic chart
BECAUSE it has only one electron in the outer energy level.

Back 26

False

Hint 26

Caesium (Cs) is the most active Group 1 metal
BECAUSE it has the largest atomic radius,
thus making it easier to lose its outer energy level electron.

the intermediate electrons help screen the positive attraction of the nucleus,
also increasing the ease with which the outer electron is lost.

Front 27

The anions migrate to the cathode in an electrochemical reaction
BECAUSE positively charged ions are attracted to the negatively charged cathode.

Back 27

False

Hint 27

the cations are positively charged ions and migrate to the cathode,
while the anions are negatively charged
and migrate to the anode.

Front 28

The combining of a saturated hydrocarbon with an unsaturated hydrocarbon is known as:

Back 28

alkylation.

Front 29

A process by which hydrogen is made to combine with another substance, usually organic, in the presence of a catalyst is known as:

Back 29

hydrogenation.

Front 30

The separation of the components in a mixture of liquids having different boiling points by vaporization is known as:

Back 30

fractional distillation.

Front 31

The process of combining several molecules to form one large molecule (polymer)
is known as:

Back 31

polymerization.

Front 32

The reaction of two molecules by loss of a molecule of water is known as:

Back 32

condensation polymerization.

Front 33

Name four types of reactions.

Back 33

1. combination (synthesis)
2. decomposition (analysis)
3. single replacement
4. double replacement

Front 34

Define combination reaction (synthesis).

Back 34

Formation of a compound from the union of its elements.

Front 35

Define decomposition reaction (analysis).

Back 35

Breakdown of a compound to release its components
as individual elements or other compounds.

Front 36

Define single replacement (simgle displacement) reaction.

Back 36

One substance is displacing another substance.

Front 37

Define double replacement (double displacement) reaction.

Back 37

The actual exchange of "partners" to form new compounds.

Front 38

Define Heat of Combustion (combination reaction).

Back 38

The heat evolved when one mol of a substance is completely oxidized.

^H

Front 39

The opposite of neutralization reactions is known as:

Back 39

hydrolysis reactions.

Front 40

The salt and water react to form an acid and a base (solution is neutral).
This is known as:

Back 40

hydrolysis.

Front 41

The measure of the randomness that exists in a system is known as:

Back 41

entropy.

Front 42

Heat content is known as:

Back 42

enthalpy.

Front 43

^H (heat content) for endothermic reaction =

Back 43

positive kcals (kilocalories).

Front 44

^H (heat content) for exothermic reaction =

Back 44

negative kcals (kilocalories).

Front 45

Name the law that states: the heat of reaction is the algebraic sum of two or more other reactions.

Back 45

Law of Heat Summations

Front 46

Name the law that states:
the total energy of the universe is constant and cannot be created or destroyed.

Back 46

First Law of Thermodynamics

Front 47

What is the Standard State Condition for reporting heat data?

Back 47

25 degrees Celcius
and
one ATM pressure

Front 48

All of the following involve a chemical change EXCEPT:

A. the formation of HCl from H2 and Cl2.
B. the color change when NO is exposed to air.
C. the formation of steam from brning H2 and O2.
D. the solidification of Crisco at low temperatures.
E. the odor of NH3 when NH4Cl is rubbed together with Ca(OH)2 powder.

Back 48

D. the solidification of Crisco at low temperatures.

Hint 48

The solidification of Crisco is merely a physical change
just like the formation of ice from liquid water at lower temperatures.
All the others involve actual recombinations of the atoms
and, thus, are chemical changes.

Front 49

When most fuels burn, the products include carbon dioxide and:

A. hydrocarbons
B. hydrogen
C. water
D. hydroxide
E. hydrogen peroxide

Back 49

C. water

Hint 49

Water is formed because most common fuels contain hydrogen in their structure.

Front 50

In the metric system, the prefix "kilo" means:

A. 10 to the zero power
B. 10 to the negative one power
C. 10 to the negative two power
D. ten to the second power
E. ten to the third power

Back 50

E. 10 to the third power

Hint 50

The other choices, in order, would be: 1, 1/10 or deci, 1/100 or centi, and 100.

Front 51

How many atoms are in 1 mol of water?

A. 3
B. 54
C. 6.02 x 10 to the 23rd power
D. 2(6.02 x 10 to the 23rd power)
E. 3(6.02 x 10 to the 23rd power)

Back 51

E. 3(6.02 x 10 to the 23rd power)

Hint 51

One mole of any substance contains (6.02 x 10 to the 23rd power) molecules.
Since each water molecule is TRIATOMIC,
there would be 3(6.02 x 10 to the 23rd power) atoms present.

Front 52

Which of the following atoms normally forms monoatomic molecules?

A. Cl
B. H
C. O
D. N
E. He

Back 52

E. He

Hint 52

The noble gases are ALL monoatomic
because of their complete outer energy level.
A rule to help you remember diatomic gases is:
Gases ending in "-gen" or "-ine" usually form DIATOMIC molecules.

Front 53

Which method is often employed in the separation of the hydrocarbons found in petroleum?

A. alkylation
B. hydrogenation
C. catalytic cracking
D. fractional distillation
E. polymerization

Back 53

D. fractional distillation

Hint 53

Fractional distillation separates the hydrocarbons by taking advantage of the difference in boiling points.
All other processes mentioned are used to modify the molecular structure of the hydrocarbons.

Front 54

The complete loss of an electron of one atom to another atom with the consequent formation of electrostatic charges is said to be:

A. a covalent bond
B. a polar covalent bond
C. an ionic bond
D. a coordinate covalent bond
E. a pi bond between p orbitals

Back 54

C. an ionic bond

Hint 54

The complete loss and gain of electrons is an ionic bond.
All other bonds indicated are "sharing of electrons" type bonds
or some form of covalent bonding.

Front 55

In the electrolysis of water, the cathode reaction is:

A. 2H2O(l) + 2e- >>> H2(g) + 2OH- + O2(g)
B. 2H2O(l) >>> ½ O2(g) + 2H+ + 2e-
C. 2OH- + 2e- >>> O2(g) H2(g)
D. 2H+ + 2e- >>> H2(g)
E. 2H2O(l) + 4e- >>> O2(g) + 2H2(g)

Back 55

D. 2H+ + 2e- >>> H2(g)

Hint 55

The cathode reaction releases ONLY H2 gas.
The half-reaction is a given in reaction D.

Front 56

The polarity of water is useful in explaining which of the following?

I. the solution process
II. the ionization process
III. the high conductivity of distilled water

A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III

Back 56

C. I and II only

Hint 56

Only I and II are true.
Distilled water does NOT significantly conduct an electric current.
The polarity of the water molecule is helpful in ionization
and in causing substances to go into solution.

Front 57

When sulfur dioxide is bubbled through water,
the sulution will contain:

A. sulfurous acid
B. sulfuric acid
C. hyposulfuric acid
D. persulfuric acid
E. anhydrous sulfuric acid

Back 57

A. sulfurous acid

Hint 57

SO2 is the acid anhydride of H2SO3 (sulfurous acid).
H2O + SO2 >>> H2SO3.

Front 58

Which fraction would be used to correct a given volume of gas at 30 degrees Celsius
to its new volume when it is heated to 60 degrees Celsius
and the pressure is kept constant?

A. 30/60
B. 60/30
C. 273/333
D. 303/333
E. 333/303

Back 58

E. 333/303

Hint 58

Since the temperature (in kelvins) increases from 303 to 333 K, the volume of the gas should increase with the pressure held constant.
The correct fraction is 333/303.

Front 59

What would be the predicted freezing point of a solution that has 684 g of sugar (1 mol = 342 g) dissolved in 1500 g of water?

A. 1.86 degrees C
B. -0.93 degrees C
C. -1.39 degrees C
D. -2.48 degrees C
E. -2.79 degrees C

Back 59

D. -2.48 degrees C

Hint 59

One mole of dissoved substance (which does not ionize)
causes a 1.86 drop (Celsius) in the freezing point of a 1 M solution.
Since 1500 g of water was used, the solution has 684/342 or 2 mol in 1500 g of water.
Then:
2mol/1500 = x moles/1000 g
x=2000/1500 = 1.33 mol/1000 g
So the freezing point is depressed 1.33 x -1.86 degrees = -2.48 degrees Celsius

Front 60

What is the approximate pH of a 0.003 M solution of H2SO4?

A. 1
B. 2
C. 5
D. 9
E. 13

Back 60

B. 2

Hint 60

The pH is -log[H+].
A 0.003 M solution of H2SO4 ionizes in a dilute solution to release two H+ ions per molecule of H2SO4.
Therefore, the molar concentration of H+ ion is 2 x 0.003 mol/L or 0.006 mol/L.
Substituting this in the formula gives: pH = -log[0.006] = -log [6 x 10 to the negative 3 power].
The log of a number is the exponent to which the base 10 is raised to express that number in exponential form:
1 = 10 to the zero power and so long 1 = 0
and 10 = 10 to the first power and so log 10=1.
The log of 6 must be 10 to a decimal exponent less than 1 and probably close to 0.7.

Front 61

How many grams of NaOH are needed to make 100 g of a 5% solution?

A. 2
B. 5
C. 20
D. 40
E. 95

Back 61

B. 5

Hint 61

If the solution is to be 5% sodium hydroxide,
then 5% of 100 g is 5g.
Percent is always by weight unless otherwise specified.

Front 62

For the Haber process, N1 + 3H2 >>> 2NH3 + heat (at equilibrium),
which statement concerning the reaction rate is true?

A. The reaction to the right will decrease when more N2 is added.
B. The reaction to the right will decrease when the pressure is increased.
C. The reaction to the right will decrease when the pressure is increased.
D. The reaction to the right will decrease when more H2 is added.
E. The reaction to the right will decrease when NH3 is removed.

Back 62

C. The reaction to the right will decrease when the pressure is increased.

Hint 62

Since this equation is exothermic, higher temperatures will decrease the reaction to the right and increase the reaction to the left.

Front 63

In general, when metal oxides react with water,
they form solutions that are:

Back 63

basic.

Hint 63

Metal oxides are generally basic anhydrides.

Front 64

Isotopes of an element are related because which of the followin is (are) the same in these isotopes?

I. atomic mass
II. atomic number
III. arrangement of orbital elemets

A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III

Back 64

D. II and III only

Hint 64

The atomic number and the arrangement of orbital electrons are identical.
Isotopes differ only in the number of neutrons in the nucleus,
and this affects only the atomic mass.

Front 65

Which of the following particles has the least mass?

A. alpha particle
B. beta particle
C. proton
D. neutron
E. gamma ray

Back 65

B. beta particle

Hint 65

The beta particle is a high-speed electron and
has the smallest mass of the first four choices.
Gamma rays are electromagnetic waves.

Front 66

Which emission from a radioactive source is an electromagenetic wave
and is not affected by an electric field?

A. alpha particle
B. beta particle
C. proton
D. neutron
E. gamma ray

Back 66

E. gamma ray

Hint 66

A gamma ray is not affected by an electric field
because it is an electromagnetic wave.

Front 67

Which of the following will cause the volume of a gas to increase?

I. Decrease the pressure with the temperature held constant.
II. Increase the pressure with a temperature decrease.
III. Increase the temperature with a pressure increase.

A. I only
B. II only
C. I and III only
D. II and III only
E. I, II, and III

Back 67

A. I only

Hint 67

Accordingto the gas laws, only I will cause an increase in the volume of a confined gas.