Chem 101 Midterm

Use the standard reaction enthalpies given below to determine ∆H°xn for the following reaction: 2S(s) + 3O2(g) -> 2SO3(g)

-791.4 kJ

Use the ∆H°f and ∆H°rxn information provided to calculate ∆H°f for IF:

-95 kJ/mol

Which of the following represent the Lewis structure for N?

. .N: .

Which of the following represent the Lewis structure for Br-?

.. :Br-: ..

Choose the best Lewis structure for BF3.

.. :F: | B / \ . . :F . . F: .. ..

Determine the concentration of a solution prepared by diluting 25.0 mL of a stock 0.188 M Ca(NO3)2 solution to 150.0 mL

0.0313 M

The titration of 80.0 mL of an unknown concentration H3PO4 solution requires 126 mL of 0.218 M KOH solution. What is the concentration of the H3PO4 solution (in M)?

0.114 M

A sample of gas initially has a volume of 859 mL at 565 K and 2.20 atm. What pressure will the sample have if the volume changes to 268 mL while the temperature is increased to 815 K?

10.2 atm

Consider the following balanced reaction. How many grams of water are required to form 75.9 g of HNO3? Assume that there is excess NO2 present. The molar masses are as follows: H2O = 18.02 g/mol, HNO3 = 63.02 g/mol. 3NO2(g) + H2O(l) = 2HNO3(aq) +NO(g)

10.9 g H2O

Calculate the atomic mass of silver if silver has 2 naturally occurring isotopes with the following masses and natural abundances: Ag-107 106.90509 amu 51.84% Ag-109 108.90476 amu 48.46%

108.19 amu

All of the following has 10 electrons except

10B

How many moles of potassium are contained in 449 g of potassium?

11.5 moles

Determine the density of an object that has a mass of 149.8 g and displaces 12.1 mL of water when placed in a graduated cylinder.

12.4 g/mL

Determine the volume of O2 (at STP) formed when 50.0 g of KClO3 decomposes according to the following reaction. The molar mass for KClO3 is 122.55 g/mol. 2 KClO3(s) = 2 KCl(s) + 3 O2(g)

13.7 L

What answer should be reported, with the correct number of significant figures, for the following calculation?(965.43 x 3.911) + 9413.4136

13189

According to the following reaction, what mass of PbCl2 can form from 235 mL of 0.110 M KCl solution? Assume that there is excess Pb(NO3)2. 2 KCl(aq) + Pb(NO3)2(aq) = PbCl2(s) + 2KNO3 (aq)

3.59 g

How many iron atoms are contained in 354 g of iron?

3.82 x 1024 Fe atoms

What mass (in g) does 3.99 moles of Kr have?

344 g

A 0.465 g sample of an unknown compound occupies 245 mL at 298 K and 1.22 atm. What is the molar mass of the unknown compound?

38.0 g/mol

What pressure will 14.0 g of CO exert in a 3.5 L container at 75°C?

4.1 atm

How many mg does a 433 kg sample contain?

4.33 x 108 mg

How many N2O4 molecules are contained in 76.3 g N2O4? The molar mass of N2O4 is 92.02 g/mol.

4.99 x 1023 N2O4 molecules

Use Lewis theory to determine the chemical formula for the compound formed between Al and O.

Al2O3

Which of the following would most likely form an cation with a 2+ charge?

Ca

Which of the following compounds is soluble in water?

CaS

What element is undergoing oxidation (if any) in the following reaction? Zn(s) + 2 AgNO3(aq) = Zn(NO3)a(aq) + 2 Ag(s)

Zn

Choose the pair of substances that are most likely to form a homogeneous solution.

NH3 and CH3OH

Determine the name for HClO4.

perchloric acid

Consider the following electron configurations to answer the question. (i) 1s22s22p63s23p64s23d104p65s1 (ii) 1s22s22p63s23p5 (iii) 1s22s22p63s23p64s23d8 (iv) 1s22s22p63s23p64s23d104p6 (v) 1s22s22p43s1 An example of a configuration of a transition metal is ________.

(iii)

Determine the oxidation state of Cr in Cr2O3

+3

Draw the best Lewis structure for ClO3 and determine the sum of the formal charges.

-1

A 35.6 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rose from 35.0 to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ/°C, what is the value of ∆H°rxn? The molar mass of ethanol is 46.07 g/mol. C2H5OH(l) + 3O2(g) -> 2CO2(g) + 3H2O(g) DeltaHrxn=?

-1.24 x 103 kJ/mol

Use the standard reaction enthalpies given below to determine ∆H°rxn for the following reaction: 2NO(g) + O2(g) -> 2NO2(g)

-117 kJ

Use the standard reaction enthalpies given below to determine ∆H°rxn for the following reaction: P4(g) + 10Cl2(g) -> 4PCl5(s)

-1835 kJ

Use the data given below to construct a Born-Haber cycle to determine the lattice energy of CaO.

-3414 kJ

Use the information provided to determine ∆H°rxn for the following reaction:

-389 kJ

Use the bond energies provided to estimate ∆H°rxn for the reaction below. PCl3 (g) + Cl2(g) -> PCl5(l)

-419 kJ

A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.0°C and the temperature of the resulting solution was recorded as 37.0°C, determine the ∆H°rxn (in units of kJ/mol NaOH) for the neutralization reaction between aqueous NaOH and HCl. Assume 1) that no heat is lost to the calorimeter or the surroundings, and 2)that the density and the heat capacity of the resulting solution are the same as water.

-55.7 kJ/mol NaOH

Determine the density of NH3 gas at 435 K and 1.00 atm.

0.477 g/L

What mass (in g) of AgCl is formed from the reaction of 75.0 mL of a 0.075 M AgC2H3O2 solution with 55.0 mL of 0.109 M MgCl2 solution? 2 AgC2O3H2(aq) + MgCl2(aq) = 2 AgCl(s) + Mg(C2H3O2) 2(aq)

0.806 g

How many of the following molecules have sp2 hybridization on the central atom? HCN SO2 OCL2 XeCl2

1

How many of the following molecules have sp3 hybridization on the central atom? XeCl4 CH4 SF4 C2H2

1

How many valence electrons do the alkali metals possess?

1

A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.6 atm. What is the partial pressure of Ne?

1.1 atm

Using the following thermochemical equation, determine the amount of heat produced per kg of CO2 formed during the combustion of benzene (C6H6). 2C6H6(l) + 15O2(g) -> 12CO2(g) + 6H2O(g) DeltaHrxn = -6278kj

1.19 x 104 kJ/kg CO2

How many xenon atoms are contained in 2.36 moles of xenon?

1.42 x 1024 xenon atoms

A gas mixture contains CO, Ar and H2. What is the total pressure of the mixture, if the mole fraction of H2 is 0.35 and the pressure of H2 is 0.58 atm?

1.7 atm

Calculate the amount of heat (in kJ) required to raise the temperature of a 79.0 g sample of ethanol from 298 K to 385 K. The specific heat capacity of ethanol is 2.42 J/g°C.

16.6 kJ

According to the following reaction, what amount of Al2S3 remains when 20.00 g of Al2S3 and 2.25 g of H2O are reacted? A few of the molar masses are as follows: Al2S3 = 150.17 g/mol, H2O = 18.02 g/mol. Al2S3(s) + 6 H2O(l) = 2 Al(OH)3(s) + 3 H2S(g)

16.87 g

Choose the orbital diagram that represents the ground state of N.

1s= up/down 2s= up/down 2p = up (x3)

How many of the following molecules have sp hybridization on the central atom? C2Cl2 CO2 O3 H2O

2

How many sublevels are contained in the second shell (n=2) of a given atom?

2

Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Na2CO3 and HCl are mixed.

2 H+(aq) + CO32-(aq) H2O(l) + CO2(g)

Which of the following is a precipitation reaction?

2 LiI(aq) + Hg2(NO3)2(aq) Hg2I2(s) + 2 LiNO3(aq)

Predict the charge that an magnesium ion would have.

2+

Predict the charge that the ion formed from oxygen would have.

2-

Zeatin, a plant hormone, is known to have 5 nitrogen atoms in every molecule. Nitrogen makes up 33.8% of the mass of the molecule. What is the mass of one molecule?

207 amu

Calculate the molar mass for Mg(ClO4)2.

223.21 g/mol

Determine the theoretical yield of HCl if 27.1 g of BCl3 and 37.5 g of H2O are reacted according to the following balanced reaction. A possibly useful molar mass is BCl3 = 117.16 g/mol. BCl3(g) + 3 H2O(l) = H3BO3(s) + 3 HCl(g)

25.3 g HCl

Determine the theoretical yield and the percent yield if 21.8 g of K2CO3 is produced from reacting 27.9 g KO2 with 29.0 L of CO2 (at STP). The molar mass of KO2 = 71.10 g/mol and K2CO3 = 138.21 g/mol. 4 KO2(s) + 2 CO2(g) = 2 K2CO3(s) + 3 O2(g)

27.1 g, 80.4 % yield

Determine the final temperature of a gold nugget (mass = 376 g) that starts at 398 K and loses 4.85 kJ of heat to a snowbank when it is lost. The specific heat capacity of gold is 0.128 J/g°C.

297K

How many different values of l are possible in the third principle level?

3

How many unpaired electrons are present in the ground state P atom?

3

A large balloon is initially filled to a volume of 25.0 L at 353 K and a pressure of 2575 mm Hg. What volume of gas will the balloon contain at 1.35 atm and 253 K?

45.0 L

Choose the valence orbital diagram that represents the ground state of Zn.

4s= up/down 3d= up/down (x5)

Choose the valence orbital diagram that represents the ground state of Se2-.

4s= up/down 4p= up/down (x3)

What is the maximum number of sigma bonds that a central atom with sp3d hybridization can form?

5

How many valence electrons does an atom of S have?

6

When the following equation is balanced, what is the coefficient in front of H2O? ___ Ba(OH)2 + ___ H3PO4 → ___ H2O + ___ Ba3(PO4)2

6

Write balanced complete ionic and net ionic equations for the following reactions: AgNO3(aq) + NaCl(aq) --> AgCl(s) + NaNO3(aq)

Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) --> AgCl(s) + Na+(aq) + NO3-(aq) Ag+(aq) + Cl-(aq) --> AgCl(s)

Choose the compound that exhibits hydrogen bonding as its strongest intermolecular force.

CH3OH

Calculate the mass (in g) of 1.9 x 1024 atoms of Pb.

6.5 x 102 g

A 6.55 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter. If the temperature rose by 32.9°C, use the information below to determine the heat capacity of the calorimeter. 4C6H5NH2(l) + 35O2(g) -> 24CO2(g) + 14H2O(g) + 4NO2(g) DeltaHrxn = -1.28x10^4 kj

6.84 kJ/°C

How many valence electrons do the halogens possess?

7

What is the mass of 9.44 x 1024 molecules of NO2? The molar mass of NO2 is 46.01 g/mol.

721 g

A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 atm. To what temperature must the gas in the syringe be heated/cooled in order to have a volume of 435 mL at 2.50 atm?

721K

If the temperature is 178°F, what is the temperature in degrees celsius?

81.1°C

Determine the percent yield of a reaction that produces 28.65 g of Fe when 50.00 g of Fe2O3 react with excess Al according to the following reaction. A possibly useful molar mass is Fe2O3 = 159.7 g/mol Fe2O3(s) + 2 Al(s) = Al2O3(s) + 2 Fe(s)

81.93 %

If a solution has a temperature of 355 K, what is its temperature in degrees celsius?

82°C

How many grams of CO2 are contained in a 10.0 L tank at 7.53 atm and 485 K?

83.2 g

According to the following reaction, what volume of 0.244 M KCl solution is required to react exactly with 50.0 mL of 0.210 M Pb(NO3)2 solution? 2KCl(aq) + Pb(NO3)2(aq) = PbCl2(s) + 2KNO3 (aq)

86.1 mL

Determine the mass of an object that has a volume of 88.6 mL and a density of 9.77 g/mL.

866 g

What temperature must a balloon, initially at 25C and 2.00 L, be heated in order to have a volume of 6.00 L?

894 K

A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter?

99 J/K

Assign the appropriate labels to the phase diagram shown below.

A = gas, B = solid, C = liquid, D = triple point

Write the formula for barium nitrite.

Ba(NO2)2

A 0.336 g sample of an unknown halogen occupies 48.4 mL at 398 K and 1.41 atm. What is the identity of the halogen?

Br2

Place the following elements in order of increasing atomic radius. P Ba Cl

Cl < P < Ba

Place the following elements in order of decreasing electronegativity. S Cl Se

Cl > S > Se

Place the following elements in order of increasing electronegativity. K Cs P

Cs < K < P

Place the following compounds in order of increasing strength of intermolecular forces. CO2 F2 NH2CH3

F2< CO2 < NH2CH3

Choose the best Lewis structure for NH4.

H + | H-N-H | H

Choose the bond below that is most polar.

H-F

Write a balanced equation to show the reaction of sulfurous acid with lithium hydroxide to form water and lithium sulfite.

H2SO3 (aq) + 2 LiOH (aq) > 2 H2O (l) + Li2SO3 (aq)

Choose the substance with the highest surface tension.

HOCH2CH2OH

Which of the following elements is a noble gas?

He

Which of the following compounds is insoluble in water?

Hg2I2

Choose the substance with the highest boiling point.

Kl

Determine the limiting reactant (LR) and the mass (in g) of nitrogen that can be formed from 50.0 g N2O4 and 45.0 g N2H4. Some possibly useful molar masses are as follows: N2O4 = 92.02 g/mol, N2H4 = 32.05 g/mol. N2O4(l) + 2 N2H4(l) = 3 N2(g) + 4 H2O(g)

LR = N2O4, 45.7 g N2 formed

Determine the reducing agent in the following reaction. 2 Li(s) + Fe(C2H3O2)2(aq) = 2 LiC2H3O2(aq) + Fe(s)

Li

Which of the following elements has properties most similar to K?

Li

Which of the following is an ionic compound?

LiCl

Which of the following represents a physical property?

Mercury is a silver liquid at room temperature.

Which of the following is an oxidation-reduction reaction?

Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)

Which of the following is NOT a strong electrolyte?

MgCO3

A nitrogen oxide is 63.65% by mass nitrogen. The molecular formula could be:

N2O

Determine the empirical formula for a compound that is 36.86% N and 63.14% O by mass.

N2O3

Determine the molecular formula of a compound that has a molar mass of 92.0 g/mol and an empirical formula of NO2.

N2O4

Which of the following is a molecular compound?

P4O10

Determine the empirical formula for a compound that is found to contain 10.15 mg P and 34.85 mg Cl.

PCl3

Place the following in order of increasing dipole moment. I. BCl3 II. BIF2 III. BCIF2

Place the following in order of increasing dipole moment.

Place the following in order of increasing IE1. K Ca Rb

Rb < K < Ca

Choose the molecule or compound that exhibits dipole-dipole forces as its strongest intermolecular force.

SO2

The statement, "In a chemical reaction, matter is neither created nor destroyed." is called

The Law of Conservation of Mass

Which of the following processes is exothermic?

The formation of dew in the morning

Determine the number of protons, neutrons and electrons in the following: 65 x 29

p+ = 29 n = 36 e- = 29

Which of the following processes is endothermic?

The vaporization of rubbing alcohol.

Determine the number of protons, neutrons and electrons in the following: 25 x 12

p+=12 n=13 e- = 12

Choose the ground state electron configuration for Zn2+.

[Ar]3d10

Give the ground state electron configuration for Se.

[Ar]4s23d104p4

Give the ground state electron configuration for Br-.

[Ar]4s23d104p6

Give the ground state electron configuration for Sr.

[Kr]5s2

Choose the homogeneous mixture from the list below.

air

A chemical change

occurs when methane gas is burned.

What is the strongest type of intermolecular force present in H2?

dispersion

Determine the electron geometry, molecular geometry and polarity of N2O (N central).

eg= linear, mg=linear, polar

Determine the electron geometry (eg), molecular geometry (mg), and polarity of SO2.

eg=trigonal planar, mg=bent, polar

Which of the following elements is a halogen?

f

Determine the name for aqueous HBr.

hydrobromic acid

What type of intermolecular force causes the dissolution of NaCl in water?

ion-dipole force

Choose the pure substance from the list below

oxygen

Which processes occur at the triple point?

melting, freezing, vaporization, condensation, sublimation, and deposition

Each of the following sets of quantum numbers is supposed to specify an orbital. Which of the following sets of quantum numbers contains an error?

n = 3, l =3 , ml = -2

Give the set of four quantum numbers that represent the last electron added (using the Aufbau principle) to the Cl atom.

n=3, l=1, ml=0, ms= - 1/2

Which of the following names and formulas are NOT paired correctly?

nitrogen oxide, NO

What is the hybridization of the nitrogen atom in ammonia?

sp3

What is the molecular shape of XeF4?

square planar

Determine the name for H2SO4.

sulfuric acid

A molecule containing a central atom with sp3 hybridization has a(n) __________ electron geometry.

tetrahedral