General Midterm and Final Exam Review and Sample Questions for C125

Midterm Exam. Test will have 40 multiple choice questions. Choose the best answer in each. Listed below are the topics for the exam with a sample question that might represent the type of content expected. Some unit conversions and physical constants will be provided as well as an activity series. Bring the periodic table provided in lecture (ask your instructor if you do not have a periodic table) as it is the only allowed version.

Final Exam. The Final Exam will have 50 multiple choice questions. You will choose the best answer in each with no penalty for incorrect guesses. Listed below are the topics for the exam with a sample question that might represent the type of content expected. Some unit conversions and physical constants will be provided as well as an activity series. Bring the periodic table provided in lecture (ask your instructor if you do not have a periodic table) as it is the only allowed version. Remember this handout is just a study guide, and additional questions will likely be on both the midterm and final exams.

• Safety issues and hazards, general lab procedures, protocol, glassware, equipment

1. Identify the following picture:

(pictures of glassware or equipment used)

2. Which of the following substances is highly corrosive?

sodium bicarbonate H₂SO₄

carbon monoxide potassium iodide

3. One can generally increase the rate of dissolution of a solid in a liquid by

pulverizing solid first stirring while mixing

warming the solution all of the above

4. A tared filter paper weighs 0.2366 g. After an aqueous precipitate was filtered using this paper, the sample was left to dry overnight. The paper and precipitate were weighed again and found to be 2.4455 g. This sample was now placed in a drying oven for a period and weighed and found to be 2.4422 g. Further time in the drying oven did not alter this final result. The most likely reason for the change in mass between overnight drying and time in the oven was

decomposition of the product more alcohol evaporated in oven

product oxidized in oven sample not completely dry after overnight

5. What is the weight of the pure precipitate?

• Significant digits in calculations, unit conversions

1. Calculate the result of the following ensuring the result has the correct number of significant digits:

2.0001 ´ [26.999 – (2.0010´13.492)]

How many significant digits are in the result?

0 1 2 3 4 5

2. Convert 2.50 g/cm³ to lbs/ft³.

• Use of formulas from data: mean, standard deviation (formula provided), percent error (formula provided)

1. Calculate the mean of the data below (with correct number of significant digits):

24.50, 26.00, 25.55, 25.60

2. Calculate the standard deviation of the data below:

24.50, 26.00, 25.55, 25.60

• Proper graphing: elements of a good graph, e.g. labels, axis ranges, units, etc. regression analysis and curve (line) fitting, straight line: y = mx + b. Using uncertainties in calculations.

1. Experimental data is fit to the equation of a straight line, y = mx + b. The slope of the line is given by

y m b m/b b/m

2. Use the fit line to the data below to estimate the value of P when V = 250. mL.

25 atm 100 atm 250 atm estimate not possible

3. Find the maximal pressure that could be achieved from the following set of data (considering proper significant digits):

n = 1.2 mol

T = 300. K

V = 1.2 ± 0.1 atm

24.6 atm 22.4 atm 22. atm 22.7 atm 23. atm

• Empirical formula from data

1. A binary compound of phosphorus and chlorine contains only 14.874% phosphorus. What is its empirical formula?

PCl PCl₂ P₂Cl PCl₃ PCl₅

2. A 3.55 g sample of iron sulfide (with an unknown formula) contains 1.91 g of iron. What is its empirical formula?

FeS Fe₂S FeS₂ Fe₂S₃ Fe₃S₂

• Chemical reactions: types, precipitates, net ionic equations, spectator ions, solubility rules, activity series (series provided but you will need to apply the concept to potential reactions)

1. Write the net ionic equation when Pb(NO₃)₂ solution is mixed with KIO₃ solution.

2. Which of the following pairs of solutions forms a precipitate when mixed?

sodium nitrate, potassium iodate silver nitrate, lithium bromide

ammonium chlorate, chromium acetate cesium nitrate, sodium chloride

3. Which of the following can be added to a solution of potassium bromide and produce bromine?

KI KCl iodine solution chlorine water

• Observations in chemical reactions (visual, gas liberated, precipitate formed, color change, dissolution of solid, heat evolved, etc.)

1. Which of the following will liberate a gas, and if do, which gas?

zinc + HCl, liberates Cl₂ zinc + H₂SO₄, liberates H₂

copper + HCl, liberates H₂ Sn + H₂O, liberates H₂

• Atomic spectra: light, wavelength, frequency, energy of light, sequence of colors in spectrum

1. Arrange the following in order of increasing wavelength:

violet red green yellow blue

• Hydrogen and hydrogen-like spectra: use of E = R [1/n₁² – 1/n₂²]

1. Which of the following is the most energetic transition in a hydrogen atom transition?

n = 1 to n = 3 n = 5 to n = 8

n = 10 to n = 100 n = 10 to n = ¥

• Calibration curves: reading data

1. A power supply had an arbitrary scale from 0 to 8 (scale in tenths). The measured voltages are given by the calibration curve below. The curve is the best fit through the data. Estimate the scale value that would supply an output voltage of .5 V.

.5 1.0 2.0 2.3 3.0

• Construction of calibration curves: measurements using an internal device-scale vs accepted values for that measurement, standards vs unknowns

(see above)

• Interpolation of a scale

• Thermochemistry, heat capacity

1. Write an equation whose heat of reaction is the heat of neutralization.

2. Write the chemical reaction whose heat is the heat of formation of N₂O₅(s).

3. Describe a calorimeter.

• Visible Absorption Spectroscopy/Beer-Lambert Law

1. If the concentration of a solution sample is increased, which of the following increases?

absorbance transmittance cell path molar absorptivity

2. The following is a calibration curve from a series of standards. Find the concentration of the unknown solution given its percent transmittance is 40.0%. Remember that absorbance = log(100/percent transmittance).

• Data Handling and Reduction

1. Given the data in the table below, find the maximum value of the molar mass of the unknown possible considering the errors in the readings.

	instrument reading	error
P, atm	1.1	±0.1
V, L	6.422 L	±0.002
T, K	299.2	±0.2
Mass, g	4.402	±0.001

2. Find the minimum value of the molar mass possible for the unknown above, considering the errors in the readings.

3. Read the thermometer below considering the optimum choice of the uncertain digit.

• Vocabulary and descriptive chemistry

1. “Clear” in describing a solution implies

a. colorless d. suspension

b. no precipitate e. not cloudy

c. white

2. Epsom salt is a hydrate of

a. sodium carbonate d. potassium chloride

b. magnesium sulfate e. sodium chloride

c. lead iodate

3. Baking soda added to a common household liquid below evolves the indicated gas.

a. bleach, CO₂ d. vinegar, H₂

b. lemon juice, H₂ e. vinegar, CO₂

c. liquid detergent, Cl₂

4. An unknown metal is added to dilute HCl. A gas is evolved. The metal could be

a. zinc d. aluminum

b. lithium e. all of the above

c. calcium

5. Which of the following is most flammable under ordinary conditions?

a. CO₂ d. CH₄

b. CCl₄ e. NaHCO₃

c. O₂

6. Define the following terms:

ligand transmittance absorbance bidentate partial pressure

7. Lead iodate recovered in your laboratory was

a. black. d. orange.

b. white. e. red.

c. green.

8. CuCl₂(aq) is

a. colorless and clear. d. red opaque solid.

b. blue and clear. e. orange opaque solid.

c. green and cloudy.

9. The precipitate obtained from mixing silver nitrate with a chloride ion solution is

a. black. d. white.

b. green. e. blue.

c. red.

• Coordination chemistry

1. The complex K₃[Fe(C₂O₄)₃]·3H₂O was prepared in lab. What is the oxidation state of the iron in the coordination complex?

2. Find the percent oxalate in the above complex, K₃[Fe(C₂O₄)₃]·3H₂O.