Chemistry Exam 2

Chapter 8-13

The process of using a chemical equation to calculate the absolute masses of reactants and products involved in a reaction is called stoichiometry. Is this statement true or false?

False

True or false? The calorie is defined as the amount of energy (heat) required to raise the temperature of one gram of water by one degree Celsius.

True

The greenhouse effect occurs only on the planet Earth. Is this statement true or false?

False

Which of the following devices is used to determine heat associated with a chemical reaction?

Calorimeter

Going down the periodic table, in a group of non-metals, which property decreases in value?

reactivity

The number of electrons in the third sublevel of an iron atom is

6

The number of unpaired electrons in a carbon atom is

2

Consider the following representation of a 2p orbital: 8
Which of the following statements best describes the movement of electrons in a p orbital?

The electron movement cannot be exactly determined.

The element with the electron configuration [Kr] 5s2,4d10,5p2 is

Sn

A d sublevel can hold a maximum of

10 electrons

How many unpaired electrons does the element cobalt (Co) have in its lowest energy state?

3

The number of d orbitals in the second principal energy level is

none of these

Strontium reacts with chlorine to form

SrCl2

For which of the following stable ions is 1s22s22p6 the correct electron configuration?

The oxygen ion?

Which of the following ions has the same electron configuration as an argon atom?

K+

True or false? The greater the difference in electronegativity between two bonded atoms, the more polar the bond.

True

In a phosphorous-nitrogen bond, the bond is
\__________ and the \_________ atoms bears \_______ charge

polar, P, a partial positive

Which of the following violates the octet rule?

BF3

Consider the drawings below:
H-F:
H-Ñ-H o\=C\=0;

Which of the following statements are true?
I. The electrons in each molecule tend to be attracted to the most electronegative element
II. Each molecular drawing follows the localized electron model.
IlI. Both HF and CO2 are linear molecules and therefore nonpolar.
IV. The bond angles of NH, are slightly less than 109.5° because the lone pair compresses the angles between the bonding pairs.

I, II, IV

Which of the following statements is true about the kinetic molecular theory?

Pressure is due to the collisions of the gas particles with the walls of the container.

In ionic bonding

a noble gas configuration is formed for each element or ion.

Which of the following has the highest percent of oxygen (by mass)?
Sodium carbonate
• Calcium phosphate
• Copper(II) oxide
• Diboron trioxide
• Cobalt(III) nitrate

Diboron trioxide

A mole ratio is used to convert the moles of a starting substance to the moles of a desired substance. Is this statement true or false?

true

\_______ is a flow of energy due to a temperature difference.

Heat

A gas absorbs 75 kJ of heat and does 40 kJ of work. Calculate Delta E.

35 kj

Which of the following statements is/are true?
I. q (heat) is a state function because Delta H is a state function and q \= Delata H.
II. When 50.0 g of aluminum at 20.0°C is placed in 50.0 mL of water at 30.0°C, the H20 will undergo a smaller temperature change than the aluminum. (density of H20 \= 1.0 g/ml, specific heat capacity of H20 \= 4.18 J/g. °C, specific heat capacity of aluminum \= 0.89 J/g. °C)
IlI. When a gas is compressed, the work is negative since the surroundings is doing work on the system and energy flows out of the system.
IV. For the reaction (at constant pressure) 2N2(g) + 502(g) -\> 2NzOg(g), the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps.

II, IV

Which of the following processes is exothermic?

Reacting hydrogen and oxygen gases to make water

True or false? Enthalpy is not a state function.

False

The electron configuration for vanadium is

\[Ar) 4s2,3d3

What is the expected ground-state electron configuration for Te2-?

\[Kr] 5s2,4d10,5p6

Going down the periodic table in a group of metals, which property decreases in value?

ionization energy

Which of the following atoms has the smallest atomic radius?
P, Sb, Bi, As, N

N

True or false? The frequency of the wave is the distance between two consecutive wave peaks.

False

Arrange the elements Se, Br, and CI in order of increasing ionization energy.

Se < Br < CI

A given set of f orbitals consists of \__________ orbitals(s).

7

Which of the following elements has the electron configuration 1s2,2s2,2p6,3s2,3p6,4s2,3d7?

Co

Which species is larger in each pair?
i) O2- or S2-
ii) K+ or K
iiii) Cl or CI-

S2-, K, Cl-

Choose the member of each set that best matches the label.
More covalent N2O, Na2O
Highest electronegativity O, S, Br

N2O, O

Which of the following species would be expected to have the lowest ionization energy?

Rb+

Which of the following bonds does not have a dipole moment?

H-H

Which of these has more than one reasonable resonance structure?

NO2-

The least electronegative element of those listed is

Ba

What does R represent in the equation PV \= nRT?

universal gas constant

Perform the following conversion of pressure units
1.092 atm \= \___torr

829.9

Which of the following is the empirical formula of terephthalic acid, C8H6O4?

C4H3O2

How many moles of oxygen will be produced by the decomposition of 7 moles of water?

3.5 moles

Which of the following statements is always true concerning a reaction represented by the balanced chemical equation below?
2C2H6(g) +7O2(g) \> 4CO2(g) + 6H2O(g)

If we have extra mass of ethane, then oxygen must be the limiting reactant.

The quantity of heat required to change the temperature of 1 g of a substance by 1°C is defined as

specific heat capacity

In the equation Delta E \= q + w, q represents

heat

Which of the following statements about energy is false?

Energy can be defined as whatever is required to oppose a natural tendency.

Which of the following elements of Group 1A has the highest ionization energy?

Li

\____________is a phenomenon that may be caused by the burning of fossil fuels, which increases the carbon dioxide content in the earth's atmosphere.

The greenhouse effect

Aluminum has how many electrons in its outermost principle energy level?

3

The Group 3A elements through the Group 8A elements form an area of the periodic table where the electron sublevels being filled are

p orbitals

Which of the following is the highest energy orbital for a silicon atom?

3p

Which of the following elements are ranked in order of the largest to the smallest atomic radius?

Cs \> V \> Ga \> P \> O

Rank the following bonds from least polar to most polar: Si-Cl, P-Cl, Mg-Cl, and S-Cl

S-CI < P-CI < Si-CI < Mg-CI

The electron configuration for the bromide ion is identical to that of

Kr

Which has a bent structure?

H2O

Which of the following molecules has nonpolar bonds?

I2

Which pair has the same structure?

PH3 and BF3

Which of the following statements are true of real gases?

The particles collide with the walls of its container and exert pressure.

There are two balloons that are both the same size and temperature. One balloon contains hydrogen and the other balloon contains carbon dioxide. The hydrogen balloon floats, and the carbon dioxide balloon sinks in the air. Which balloon contains a greater number of molecules?

Both balloons contain the same number of molecules.

What is the volume of a helium balloon that contains 2.91 mol helium at 27 °C and 1.10 atm?

65.1 L

Convert 9.01 x 102 torr to psi.

17.4 psi

The largest a party balloon can get before bursting is 9.31 L at 25°C and 1.00 atm.
Supposing you fill the balloon only with oxygen gas, how many grams of oxygen can be added to the balloon before it pops? Assume you have not yet added any gas to the balloon at all (so essentially the balloon is flat).

12.2 g O2

Which conditions of P and T are most ideal for a gas?

Low P and High T

A chloride of rhenium contains 63.6% rhenium. What is the empirical formula of this compound?

ReCl3

Vinegar contains carbon, hydrogen, and oxygen with percent masses of 40.01% C and 6.70% H. If the molar mass of vinegar is about 60 g/mol, what is its molecular formula?

C2H4O2

The balanced equation 2Cu(s) + O2(g) -\> 2CuO(s) tells us that 8.0 mol of Cu

produces 8.0 mol of CuO

Consider the following unbalanced equation: Na2SiF6(s) + Na(s) -\> Si(s) + NaF(s)
If 3.80 moles of Si were produced, how many moles of NaF were also created?

22.8 mol

Consider the following unbalanced equation:
C2H5OH(g) + O2(g) -\> CO2(g) + H2O(l)
If 2.45 g of ethanol reacts with 10.7 g of oxygen, how many moles of water are produced?

0.160 mol

Equal masses (in grams) of hydrogen gas and oxygen gas are reacted to form water. Which substance is limiting?

Oxygen gas is limiting.

Consider the equation: A + 3B -› 2C. The molar mass of B is 50.0 g/mol. Which of the following statements is true when equal masses of A and B are reacted?

If the molar mass of A is less than the molar mass of B, then B must determine how much C is produced.

Heat is typically measured in

Joules

Potential energy of an object is energy due to the motion of the object, whereas kinetic energy is energy due to position or composition. Is this statement true or false?

False

True or false? The law of conservation of energy states that energy can be converted from one form to another but can be neither created nor destroyed.

True

When moving down a group (family) in the periodic table, the number of valence electrons \_________.

remains constant

Which of the following elements has the electron configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p2

Pb

Which of the following colors of visible light has the least amount of energy per photon?

Red

Order the elements Al, CI, and F in terms of increasing atomic radius.

AI, CI, F

Which element has the fewest electrons in its valence shell?

Cs

For which of the following stable ions is 1s2 2s2 2p6 the correct electron configuration?

The sodium ion

True or false? Ionic bonding occurs between atoms with small differences in electronegativities.

False

Which of the following compounds is the product of the reaction Mg + O2?

MgO

Which species is larger in each of the following pairs?
i) O2- or S2-
ii) Fe2+ or Fe3+ and
iii)Cl or CI-

S2-, Fe2+, Cl-

Which of the following element or ion has the electron configuration 1s2 2s2 2p6 3s2 3p6

Ca2+

You are playing with a helium balloon on a typically warm California day. Suddenly, the Celsius temperature doubles. Which of the following is true?

The volume of the balloon will slightly increase.

Which of the following would represent the greatest pressure?
21.8 in Hg
12.2 psi
65465 Pa
0.662 atm
265 mm Hg

12.2 psi

A specified quantity of an unknown gas has the volume of 14.1 mL at 22°C and 659 torr.
Calculate the volume at STP.

11.3 mL

A sample of an ideal gas containing 0.561 mol is collected at 742 torr pressure and 31°C.
Calculate the volume.

14.3 L

Which of the following gives a graph with a straight line and a y-intercept of 0?

Volume vs. temperature (K)

Convert: 2.16 mol PCI5 \= \________molecules PCI5

1.30x10^24

What is the molar mass of H2CO?

30.03 g/mol

Consider the following reaction: 2A + B -› 3C+ D
3.38 mol of A and 2.00 mol of B react to form 4.00 mol of C. What is the percent yield of this reaction?

78.9%

\_______is a measure of disorder or randomness.

Entropy

Which of the following is a valid unit for specific heat (or specific heat capacity)?

cal/g.°C

6.60 kcal of energy is equivalent to how many joules?

2.76 × 10^4 J

True or false? The energy gained by the surroundings must be equal to the energy lost by the system.

True

The maximum number of electrons in the second principal energy level of an atom is

8