Old Lab Quizzes

Quizlet 1A Spring, 1998

1 - Please round the following to three sig. figs.

a) 0.002265 grams

b) 3.0046 grams

2 - How many sig. figs. are there in

a) 0.0020 meters

b) 16 people

3 - Express the answer in scientific notation, and to the correct number of sig. figs.

a) 99.42 kilograms + 821.0 grams =

b) 0.00220 frumps/(0.9972 frumps/grunchwald) =

4 - A cube of gold has an edge length of exactly 103 cm.

a) Calculate the edge length, in nanometers.

b) Calculate the volume of the cube, in liters.

c) If the density of gold is 17.3 g/cm3, calculate the mass of the cube, in kilograms.

(If you couldn't find the volume above, assume the volume was 1.50x108 liters.)

d) According to yesterday's Bee, gold was being traded for \$298.90 per troy ounce. If there are 37.799 grams in one troy ounce, what's the price of our cube?

(Again, if you couldn't do (c), assume the mass was, oh, 2.5x106 kg.)

Second Quizlet (Quiz 1b)

1 - Calculate the following, and express the result in scientific notation.

a) log(1.60x10-19) = b) ln(5280) =

c) e-4.414 = d) antilog(-6.20) =

2 - If ln(P2/P1) = - DH{1/T2 - 1/T1}/R

and DH = 40,700 J/mole, R = 8.315 J/mole-K, P1 = 23.8 torr, T2 = 298K and T1 = 353K, calculate P2.

3 - a) Please write the formula for chromium(III) oxide.

b) What is the name of K3N?

c) Please write the formula of ammonium sulfide.

d) What is the name of B(CN)3?

4 - 3.214x10-5 meters minus 0.217x10-2 cm is how many nanometers? Express your answer to the correct number of significant figures, and in scientific notation.

5 - How many neutrons are there in

a) one ammonia molecule?

b) 5.00 grams of HCl?

SECOND QUIZ

1- Consider exactly five grams of sodium chloride.

a-How many protons are there?

b-How many neutrons are there?

c-Calculate the mass of the sample, in atomic mass units.

2 - a) Balance the following equation for the combustion of propanol

C3H8O + O2 = CO2 + H2O

b) If 3.000 grams of sugar (C12H22O11) decomposes, how many grams of water will be produced? The reaction is

C12H22O11 = 12 C + 11 H2O

3 - Please write the formula of

a) ammonium chlorite

b) magnesium iodate

a) Fe(OH)2

b) BaSO3

c) NO2

5- a- Name, and give the location of, every safety device that can be used for fire protection.

b- What is the minimum time a student should wash his/her eyes after getting acid in them?

Quiz No. 3

1 - Please name the following compounds:

a) K2SO5

b) SO2

2 - What are the formulas of

a) ammonium nitrite

b) hydrobromic acid

3 - In each case, write the formula of the principal solute species that actually exists in each solution, and the equation for the net ionic reaction that would occur when the solutions were mixed.

Solution A Solution B Net Ionic Reaction

a) ammonium nitrate potassium hydroxide

b) iron(III) sulfate barium acetate

c) sulfuric acid sodium bicarbonate

4 - Consider the reaction:

3 Ag+(aq) + PO34-(aq) = Ag3PO4(s)

If 10.0 grams of Ag2SO4 are added to 100.0 mL of 0.250 molar Na3PO4, calculate

a) the number of moles of each reactant.

b) the limiting reactant. Show your work.

c) the mass of silver phosphate produced.

Quiz Number 4

1 - Write the formula of the solute species that actually exist in each solution and the equation for the net ionic reaction that would occur when the solutions were mixed.

Solution A Solution B Net Ionic Reaction

a) iron(II) sulfate potassium carbonate

b) hydrofluoric acid barium hydroxide

2 - Consider the reaction

Mg(s) + 2 H+(aq) = Mg2+(aq) + H2(g) DHrxn = -105 kcal/mol (of Mg)

If 0.200 grams of solid magnesium reacts with excess hydrochloric acid in a coffee cup calorimeter containing 100 mL of aqueous solution, we're going to calculate the final temperature if the initial temperature is 22.5oC. Assume the density and specific heat of the solution are the same as those of water. (I'll sell you the values, if you need them.)

i) First, calculate Qrxn, the actual heat of reaction.

ii) Now, calculate Qsolution, the heat change of the aqueous solution.

iii) Finally, calculate the final temperature.

3 - Now, we're going to use the heat of reaction I gave you in the previous question to calculate the molar heat of formation of magnesium ion. If the standard heat of formation of the hydrogen ion in water is 10.2 kcal/mole, calculate the heat of formation of Mg2+(aq).

4 - Write the equation for the Formation Reaction of CuSO4.5H2O(s).

Quiz Number 5

R = 0.0821 L-atm/mole K; R = 8.315 J/mole K

1- Vessel A contains CO2 gas at 20oC and 0.8 atm. Vessel B contains HCl gas at 40oC and 1 atm. The two vessels have the same volume.

a) Which vessel contains more molecules?

b) Which vessel contains more mass?

c) In which vessel is the average kinetic energy of the molecules higher?

d) In which vessel is the average speed of the molecules higher?

2 - A glass bulb having a volume of 4.00 L contains air (mole fraction of nitrogen = 0.80, mole fraction of oxygen = 0.20) at a total pressure of 765 torr. If the mass of air in the bulb is 5.00 grams, what is the temperature? (Hint: find the average molecular weight of air. If you can't do that, estimate the MW of air.)

Quiz Number 5 Fall, 1997

1 - a) Assume the average velocity of an oxygen molecule is 1050 miles/hour at 30 oC. If the average velocity of another gaseous molecule is 900 miles/hour at the same temperature, calculate the molecular weight of this molecule.

b) Calculate the average velocity of the unknown molecule at 60 oC.

2 - a) Derive the equation that relates the density of an ideal gas to its pressure, temperature, and molecular weight.

b) If the density of dry air is 1.193 g/L at 23 oC and 760 torr, calculate the average molecular weight of air. R = 0.0821 L-atm/mol-K.

3 - If it takes 28 seconds for 1.0 L of oxygen gas to diffuse through a small pinhole, and 72 seconds for 1.0 L an unknown gas to diffuse through the same pinhole under the same experimental conditions, caluclate the molecular weight of the unknown gas.

Quiz #6

1- The equation for the energy of a one electron atom or ion is

E = -Z2RH/n2, where RH = 2.18x10-18 joules, and Z is the atomic number,

a) Calculate the energy of a Li2+ ion in its ground state.

b) Calculate the energy of a Li2+ ion in its second excited state.

c) How much energy is required to excite a ground state electron on Li2+ to the second excited state? Show your work.

d) Calculate the wavelength, in nanometers, of the photon that would cause the transition in c). h = 6.63x10-34 J-sec; c = 3.00x108 m/sec. (If you couldn't do (c), calculate the wavelength of a photon with an energy of 1.00x10-18 Joules)

2 - The equation for the DeBroglie wavelength of a particle is lambda = h/mv. It turns out that a 1s electron on a hydrogen atom has a kinetic energy equal to RH (from problem 1). If the mass of an electron is 9.11x10-28 grams, calculate the DeBroglie wavelength of a 1s electon in a hydrogen atom.

Quiz Number 6

1 - As you undoubtedly would have guessed, the equation for the energy of a hydrogenlike atom with Z protons is

E = - Z2RH/n2, where RH = 2.18x10-18 J

a) Calculate the wavelength, in nm, of a photon with an energy of 2.0x10-17 J. Planck's constant is 6.63x10-34 J-sec, and the speed of light is 3.00x108 m/sec.

b) Calculate the energy required to excite a 1s electron in 3Li2+ to the 3p orbital.

c) Would the photon in a) accomplish the change in b)? Why or why not?

Quiz No. 7 Section ____

1-Write the electron configuration of

a) 42Mo2+

b) 79Au

c) Is Mo2+ diamagnetic or paramagnetic? Why?

2- Assign a possible set of quantum numbers for each electron in the highest energy occupied subshell in the Mo2+ ion.

3- Which atom in the periodic table has

b) the largest ionization energy?

c) the most negative electron affinity?

4- Of 11Na+, 10Ne, or 9F-, (all of which have a 2s22p6 electron configuration)

a) which has the largest radius? Why?

b) which has the largest ionization energy? Why?

c) which has the most negative electron affinity? Why?

Quiz No. 7

1 - Write the electron configuration of

a) 72Hf

b) Hf2+

2 - How many electrons on Hf have l = 1?

3- Which atom in the periodic table has

b) the smallest ionization energy?

c) the most positive electron affinity?

R = 0.0821 L-atm/mol-K; R = 8.315 J/mol-K; h = 6.63x10-34 J-sec; c = 3.00x108 m/sec

1 - If the average velocity of a gaseous ammonia molecule is 1400 miles/hour at 10oC, a) Calculate the average velocity of an HCl molecule at the same temperature.

b) Calculate the average velocity of an ammonia molecule at 50 oC.

2- a) Calculate the energy of a photon with a wavelength of 2.0x10-5 cm.

b) In which region of the spectrum is the photon in a)?

c) Assume the energy of the highest energy electron of a hypothetical molecule is given by the equation:

En = -A/n, where A = 2.00x10-19 Joules, and n = 1,2,3,....

i) If a ground state atom absorbs a photon having an energy of 1.33x10-19 joules,

what would be the final energy of the atom?

ii) What value of the quantum number, n, would the atom in i) have?

3 - a) Please write the electron configuration of

i) Fe

ii) Hg2+

b) Is Hg2+ diamagnetic or paramagnetic? Why?

4 - a) Which of the following has the lowest ionization energy?

Mg Al Si

b) Which of the above has the largest radius?

c) Which of the following has the most negative electron affinity?

Cl Br Se

d) Which of the above (Cl, Br, or Se) has the largest electronegativity?

Quiz Number 8

1 - a) Draw the Lewis Dot Structure of

i) H3CNO2

ii) PCl3

b) What is the size of the

i) O-N-O angle in i) above?

ii) Cl-P-Cl angle in ii)?

c) Is PCl3 polar or nonpolar? Show why, using a diagram of the molecule.

d) Calculate the formal charge on each atom in i).

e) Do either of the molecules exhibit resonance? If so, draw all resonance structures.

Sample Questions for Quiz number 9

1- If 5.00 grams of ice at a temperature of 0.00 oC are added to 25.00 grams of water at 27.40oC, calculate the final temperature if the heat of fusion of ice is 80.0 cal/gram.

2 - Which compound has the higher

a) heat of vaporization: H3COH or H3CCl? Why?

b) vapor pressure: I2(s) or CaCl2(s)? Why?

1- If 52.42 grams of water, at 23.2oC, are added to a coffee cup calorimeter, and steam is bubbled through the water until the calorimeter contains 55.81 grams of water at 60.1oC,

a) calculate the mass of steam that condensed.

b) calculate the heat of vaporization of water, in calories per mole.

2- Consider the phase diagram.

a- What phase(s) is/are stable

i- at point A?

ii- at point B?

b- What is the vapor pressure at

c- Predict the normal boiling point

of the substance. (Show your work.)

1 (a) Which of CH3OH or CH3F should have stronger intermolecular forces?

Why?

(b) Of CH3OH or CH3F, which has the higher

i) Heat of vaporization?

ii) Vapor Pressure (at the same temperature)?

iii) Normal Boiling Point?

1 - In each case, answer the question, and justify your choice.

a) Which would have the larger vapor pressure (at the same temperature), CF4 or CCl4? Why?

b) Which would have the higher normal melting point, K2SO4 or I2? Why?

c) Which would have the larger heat of vaporization, HF or HCl? Why?

d) Which would have the larger heat of vaporization, MgO or NaF? Why?

e) Which would have the higher normal boiling point, Br2 or ICl? Why?

f) Which has the larger magnitude of lattice energy, NaCl(s) or CsI(s)? Why?

The Penultimate Quiz! (Quiz 10)

1- In terms of the energetics of the solution process discussed in lecture, explain which of the following solutes should be more soluble in the given solvent.

CaCl2(s) or H2O(l), dissolved in CCl4(l)

2- Consider a 5.00% solution of NaCl in water, at 25oC. The solution has a density of 1.056 grams/ml.

a) If the vapor pressure of pure water is 23.76 torr at this temperature, calculate the vapor pressure of the solution.

b) If the boiling point elevation constant for water is 0.52oC/molal solution, calculate the normal boiling point of the solution.

c) If R = 0.0821 L-atm/mole K, calculate the osmotic pressure of the solution.

4(12)- Consider the reaction: N2O4(g) = 2 NO2(g) DHrxn = 57.2 kJ/mol

a) In order to increase the yield of NO2, should the pressure be increased or decreased (at constant temperature)? Explain.

b) How should the temperature be changed (at constant pressure) to increase the yield of NO2? Explain.

6(16) - Consider the reaction: A + B = 2 C

Run [A], mol/L [B], Mol/L rate, mol/L-minute

1 0.100 0.100 2.1x10-6

2 0.300 0.100 2.0x10-5

3 0.300 0.250 5.1x10-5

(8) a) Calculate the order with respect to each reactant.

(4) b) Calculate the rate constant, including the units.

(4) c) Propose a possible rate determining step for the reaction.

Also, questions on a phase diagram (including a Clausius-Clapeyron Equation question) and a question that has them determine the molecular weight from a colligative property measurement (Pv, Tv, Tf, or pi) would be good.

The Very Last Quiz! (Samples)

[A] = [A]0 - k0t ln[A] = ln[A]0 - k1t 1/[A] = 1/[A]0 + k2t

1 - Consider the reaction: A = B + C, for which the following data have been obtained.

time, minutes 0 10 20 30 40 50 60 70 80

[A], moles/L 0.25 0.18 0.14 0.11 0.096 0.083 0.074 0.066 0.060

a) Estimate the initial half-life.

b) Estimate the half-life, starting with a concentration of 0.14 moles/L.

c) Guess the order of the reaction, based on your first two answers. Explain.

d) Confirm your answer in c) by calculating the rate constant for two different pairs of data.

e) Using the second order rate equation, predict the concentration after 100 minutes have elapsed.

f) Predict a possible rate determining step for the reaction.

[A] = [A]o - kot ln([A]/[A]o) = -k1t 1/[A] -1/[A]o = k2t

1 - The following concentration data were obtained for the reaction of selenide ion with perchlorate ion in aqueous solution:

[Se2-] (M): 0.175 0.122 0.093 0.064 0.048

t (s): 0 100 200 400 600

(a) Estimate the first and second half-lives.

(b) Is the reaction first order or second order? Explain your reasoning.

(c) Calculate the rate constant for the reaction.

(d) How long will will it take for [Se2-] to fall to 0.010 M?

2 - Fluorine reacts with nitrogen dioxide according to the following net reaction:

2 NO2 (g) + F2 (g) = 2 FNO2 (g)

The net reaction occurs by a two-step mechanism, outlined below:

(1) NO2 (g) + F2 (g) = FNO2 (g) + F (g)

(2) F (g) + NO2 (g) = FNO2 (g)

The observed rate law for the net reaction is

net rate = k[NO2][F2]

What is the Rate Determining Step for the reaction? Explain your reasoning.