Chemistry Lab Final pre-labs 1-4

21: Assign oxidation numbers to the metal ions in these ionic compounds (enter positive oxidation numbers with a plus sign, and negative oxidation numbers with a minus sign, i.e. +2 or -2): CoS

+2

35: What do we mean by "waste minimization?" We take only the amounts of reagents necessary to complete the experiment. We dispose of waste in proper containers. We do not return excess waste to the reagent bottles. All of the above

All of the Above

10: What are the precautions we need to take when handling ethanol in the Chromatography Experiment? Wear approved splash-proof goggles at all times Wear approved non-latex gloves at all times Avoid skin contact Avoid inhalation Avoid ingestion Tie back long hair Wear appropriate lab attire All of the above. a and b only a-e but not f and g.

All of the above

An analytical balance: Have a smaller total capacity than top-loading balances Have greater precision than top-loading balances. Are in a glass enclosure to minimize the effect of air movement. All of the above Rationale: Please refer to Appendix III of your lab manual. None of the above

All of the above

How would you define density? As an intensive chemical property. As an extensive chemical property. As an intensive physical property. As an extensive physical property.

As an intensive physical property.

23: Name these hydrates: Ba(OH)2• 8H2O

Barium Hydroxide Octahydrate||barium hydroxide octahydrate (correct)

36: Select the chemical formulas for these ternary acids: acetic acid

CH3COOH

28: Refer to Figure 3.4 on page 38 of your lab manual. What components are present in the mixture? A B C D E Components C and D Components A,D, and E Components A, C, and E Components A,B, and E Components B, D, and E Components B, C, and D All components

Components a,b, and e

1: Name these ternary salts:Cu2Cr2O7

Copper(I) Dichromate or copper(I) dichromate or copper(i) dichromate (correct)

28: What graph will we be plotting in this experiment? Density vs. Mass of salt Density vs. % Salt by Mass in Water Density of a Rubber Stopper vs. Trial Density of an Unknown Metal vs. Trial c, d & e none of the above

Density vs. % Salt by Mass in Water

26: You are permitted to bring food or drink into the lab, as long as it's packaged and you don't eat or drink it while in the lab.

False

27: Gloves can be disposed of in the regular trash

False

34: T/F: Your cell-phone is permitted in lab.

False

9: Name these ternary salts: Hg2(CN)2

Mercury (I) cyanide

27: How would you determine the number of significant figures when reading the volume of an aqueous solution in a graduated cylinder? Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit. Read the top of the meniscus and round to the nearest calibration mark. Read the bottom of the meniscus at eye level, and round to the nearest tenth of a milliliter.

Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit.

18: Why is wearing eye protection (full splash-proof goggles) at all times in this laboratory a requirement? Because the instructors think you look funny with them on. To protect your eyes from damage!

To protect your eyes from damage!

1: What hazards are associated with the ethanol being used in the Chromatography Experiment? Flammable vapor Irritant to respiratory tract Carcinogen b and c a, b, and c a, b, and d all of the above

a, b, and c

7: Using a metric ruler subdivided into mm, refer to Figure 3.4 on page 38 of your lab manual. Calculate the Rf for component A.

0.14

21: Using a metric ruler subdivided into mm, refer to Figure 3.4 on page 38 of your lab manual. Calculate the Rf for component C.

0.389

29: Using a metric ruler subdivided into mm, refer to Figure 3.4 on page 38 of your lab manual. Calculate the Rf for component D.

0.516

6: Using a metric ruler subdivided into mm, refer to Figure 3.4 on page 38 of your lab manual. Measure the distance Spot A has moved.

0.65 cm

26: Given the following data for an unknown liquid, compute the mean density for the three trials, (See Appendix I for reference to significant figures, mean and standard deviation.)

0.835 g/mL

Perform a linear fit for the graph Density vs. Mass % Sucrose following data set: Mass % sucrose-Density 10-1.037 20-1.079 30-1.125 40-1.174 50-1.227 What is the value for the correlation?

0.999 (correct)

Trial #- mass- volume 1-3.820-0.744 2- 4.441- 0.869 3- 5.206- 1.016 Compute standard Deviation

1.20x10^-2 g/mL (correct)

31: A block of an unknown metal has a mass of 155.6 kg and a volume of 0.1018 cubic meters. Calculate its density in kg/m3.

1.528x103 kg/m3

What would the mass of 1.563 L of water be at 25 °C? ( the density of water at 25 °C is 0.9982 g/mL)

1.560x10^3 g

25: Using a metric ruler subdivided into mm, refer to Figure 3.4 on page 38 of your lab manual. Measure the distance Spot C has moved.

1.85cm

A block of an unknown metal has a mass of 227.8 kg and a volume of 0.1189 cubic meters. Calculate its density in g/mL.

1.916 g/mL

24: A block of an unknown metal has a mass of 227.8 kg and a volume of 0.1189 cubic meters. Calculate its density in g/L.

1.916x10^3 g/L

When using a balance: Always use a weighing boat or beaker when massing solid or liquid samples Never attempt to move the balance. Always close glass doors on an analytical balance before recording mass. Use a brush to clean any spilled solid reagent. Wait for the balance to stabilize before recording your reading. Try to use the same balance throughout the experiment to eliminate calibration error. Dispose of your weighing boat properly, do not leave it on the bench top. All of the above

All of the above! (correct) Rationale: Students are responsible for maintaining balances. Work carefully and clean up after yourselves! Students are responsible for maintaining balances. Work carefully and clean up after yourselves!

8: Name these hydrates: Ba(NO3)2 • 4H2O

Barium nitrate tetrahydrate

40: Select the chemical formulas for these ternary salts: calcium sulfate dihydrate

CaSO4• 2H2O

5: Name these ionic binary compounds: Cs2S

Cesium Sulfide||cesium sulfide (correct)

33: Name these ternary acids: HClO3

Chloric Acid

33: Which of the following is NOT proper attire for the lab Closed-toe shoes which leave the top of the foot exposed Long sleeved shirt with close-fitting sleeves Long hair that has been pinned back

Closed-toe shoes which leave the top of the foot exposed

24: Name these covalent binary compounds: N2O5

Dinitrogen Pentoxide

28: Name these covalent binary compounds: N2O3

Dinitrogen Trioxide

10: Name these covalent binary compounds: N2O4

Dinitrogen tetraoxide

T/F: Gum chewing is permitted in the lab.

False

39: Select the chemical formulas for these ternary salts: iron(III) nitrate

Fe(NO3)3

12: Assign oxidation numbers to the metal ions in these ionic compounds (enter positive oxidation numbers with a plus sign, and negative oxidation numbers with a minus sign, i.e. +2 or -2): Fe2O3

Fe= +3

41: Select the chemical formulas for these binary covalent compounds: hydrogen sulfide

H2S

13: Select the chemical formulas for these ternary acids: phosphorus acid

H3PO3

18: Select the chemical formulas for these: bromous acid

HBrO2

22: Select the chemical formulas for these ternary acids: perbromic acid

HBrO4

30: Select the chemical formulas for these ternary acids: perchloric acid

HClO4

7: Select the chemical formulas for these ternary acids: iodic acid

HIO3

17: What type of chromatography would be best for separating a mixture of starch and cellulose? High Performance Liquid Chromatography Thin Layer Chromatography Paper Chromatography

High Performance Liquid Chromatography

29: Name these ternary acids: HCN(aq)

Hydrocyanic acid

38: Name these covalent binary compounds: HI(aq)

Hydroiodic Acid

20: Name these ternary acids: HClO

Hypochlorous Acid

14: What physical property of the dyes are we exploiting in order to separate the components of each dye? Reactivity with water Polarity pH Molecular size None of the above

Polarity

11: Assign oxidation numbers to the metal ions in these ionic compounds (enter positive oxidation numbers with a plus sign, and negative oxidation numbers with a minus sign, i.e. +2 or -2): SnF2

Sn= +2

16: Name the following: NaHSO4

Sodium Hydrogen Sulfate

37: Name these ternary salts: Na3PO4

Sodium Phosphate

2: Name these ionic binary compounds: NaCl

Sodium chloride

32: Name these ternary acids: H2SO4

Sulfuric Acid

13: What would be the consequences of the following scenario and what effect would it have on your experimental results? The origin line was marked with pen, and not pencil. We would be unable to determine how far the solvent front traveled, and therefore could not determine the Rf for the components. Too much dye would be spotted, causing large spots that would spread. The chromatogram would be impossible to analyze properly. The solvent could evaporate. If the solvent evaporated before the experiment was complete, we could not accurately determine Rf values. The marks on the origin line would separate and elute, mixing with the dyes. We could not accurately determine Rf values. Too little dye would end up on the chromatogram, making the spots difficult to see and Rf difficult to determine. The solute would be too dilute, which would change pace the solvent eluted, making Rf values inconsistent. The air would not be saturated with solvent, making the chromatograms impossible to analyze. The consequences would be minimal, and would have a negligible effect on the results.

The marks on the origin line would separate and elute, mixing with the dyes. We could not accurately determine Rf values.

A scientist does two sets of experiments with three trials each to determine the density of an unknown solution. The three trials for the first experiment have a standard deviation of 0.0137g/mL. The three trials for the second experiment have a standard deviation of 0.0980g/mL. What can we infer? The measurements from the first experiment were more accurate. The measurements from the first experiment were more precise. The measurements from the second experiment were more accurate. The measurements from the second experiment were more precise. a and b a and d c and d All of the above None of the above.

The measurements from the first experiment were more precise.

12: A scientist does two sets of experiments with three trials each to determine the density of an unknown solution. The three trials for the first experiment have a standard deviation of 0.0980g/mL. The three trials for the second experiment have a standard deviation of 0.0137g/mL. What can we infer? The measurements from the first experiment were more accurate. The measurements from the first experiment were more precise. The measurements from the second experiment were more accurate. The measurements from the second experiment were more precise. a and b a and d c and d All of the above None of the above.

The measurements from the second experiment were more precise.

11: The Dyes Blue 1 and Green 3 have very similar Rf's in most solvents. Why do you think this is? Blue and green are very similar colors The structures of the two dyes are very different, except for the substituent on one aromatic ring. The structures of the two dyes are nearly identical, except for the substituent on one aromatic ring. They both have highly conjugated systems. They're both sodium salts of sulfonic acids.

The structures of the two dyes are nearly identical, except for the substituent on one aromatic ring.

29: Would you expect a small piece of aluminum oxide to have the same density as a large piece? No it wouldn't; density is an intensive chemical property. No it wouldn't; density is an extensive physical property. No it wouldn't; density is an extensive chemical property. Yes it would; density is an intensive physical property. Yes it would; density is an intensive chemical property. Yes it would; density is an extensive physical property. Yes it would; density is an intensive chemical property.

Yes it would; density is an intensive physical property.

31: Are the seven approved FD&C dyes water soluble? Yes, because the molecules are highly conjugated systems. Yes, because all the dyes are edible. Yes, because all the dyes are sodium salts of sulfonic acids. Yes, because all the dyes are sodium salts of sulfonic or carboxylic acids. No, because the molecules are highly conjugated systems. No, because all the dyes are edible. No, because all the dyes are sodium salts of sulfonic acids. No, because all the dyes are sodium salts of sulfonic or carboxylic acids. None of the above.

Yes, because all the dyes are sodium salts of sulfonic or carboxylic acids.

20: Refer to Figure 3.4 on page 38 of your lab manual. Was this a good choice of solvent for the separation? Yes, it yields a result with similar Rf values for each component, giving high resolution. No, it yields a result with similar Rf values for each component, giving high resolution. Yes, it yields a result with significantly different Rf values for each component, giving low resolution. No, it yields a result with significantly different Rf values for each component, giving low resolution. Yes, it yields a result with significantly different Rf values for each component, giving high resolution. No, it yields a result with significantly different Rf values for each component, giving high resolution. Yes, it yields a result with similar Rf values for each component, giving low resolution. No, it yields a result with similar Rf values for each component, giving low resolution. None of the above.

Yes, it yields a result with significantly different Rf values for each component, giving high resolution.

4: How are Parts I and II of the Lab related? The procedures are similar The Rf values determined for each solvent in Part I will help you determine the identity of your unknowns in Part II. The two parts are unrelated. a & b

a&b

What is the difference between mass % and density? Density is an extensive property while mass % is intensive a. Density is mass/volume, where mass % is (mass solute/mass solution) * (100) b. Density is mass/volume, where mass % is mass solute/ mass water c. a & b d. a & c e. none of the above

a. Density is mass/volume, where mass % is (mass solute/mass solution) * (100) (correct)

Which of the following is considered volumetric glassware? a. Erlenmeyer flasks b. Volumetric flasks c. Burets d. Pipets e. Graduated Cylinders

a. Erlenmeyer Flasks

Top loading balances: a. Have a higher capacity than analytical balances. b. Have a lower precision than analytical balances. c. All of the above

c. All of the above

Eye Protection: a. Students are required to bring goggles. b. Goggles must be approved and full splash-proof c. Goggles MUST be worn at all times in the lab d. All of the above

d. All of the above

Which of the following could not be a unit for density: Kg/m3 g/L lb/ft3 g/m kg/dm3

g/m

17: Name these binary ionic compounds: MgI2

magnesium iodide

22: Why do we want the ends to overlap when we roll up our chromatograms? To make the cylinder smaller so it fits in the beaker. To allow the solvent more access to the chromatography paper. To make sure the solvent travels through a uniform thickness of chromatography paper throughout the cylinder. None of the above.

none of the above

Which of the following is a chemical property? color smell reactivity with water freezing point polarity

reactivity with water

14: Select the chemical formulas for these ternary salts: lead(IV) acetate

Pb(C2H3O2)2

If a 0.026366 kg sample of water has a density of 0.9982 g/mL at 25 °C, what would be its volume in mL?

2.641x10^1

25: A block of an unknown metal has a mass of 227.8 kg and a volume of 0.1189 cubic meters. If the object were a sphere, what would be its radius? (The value for pi ~ 3.14159)

30.50cm

A block of an unknown metal has a mass of 155.6 kg and a volume of 0.1018 cubic meters. If the object were a cube, what would be the dimension of one of its sides?

46.69cm

19: How many mixtures of FD&C Dyes will you be spotting on Chromatograms A-D? 0 1 3 4 6 10

6

An 11.65g sample is added to 105.1mL of pure water (density of pure water @25°C is 0.9982g/mL). What is the mass % of the NaCl solution?

9.995% (correct)

30: Which of the following would be an appropriate graduated cylinder in which to measure the volume of an irregularly shaped object with a diameter of 1.75cm? A 50mL graduated cylinder with a diameter of 2cm A 10mL graduated cylinder with a diameter of 1.5cm Any of the above would be appropriate. Both a and c are appropriate.

A 50mL graduated cylinder with a diameter of 2cm

15: Select the chemical formulas for these: silver phosphate

Ag3PO4

30: Required attire in the lab includes: Approved Goggles Non-latex gloves Closed-toe shoes that do not leave the top of the foot exposed Long Pants Lab Coat a, b, c and d are correct All of the above

All of the above

25: Name these ternary acids: HIO2

Iodous Acid

31: Name these ionic binary compounds: Fe2O3

Iron (III) Oxide

16: What hazards are associated with the 0.1% sodium chloride solution being used in the Chromatography Experiment? Toxic Flammable vapor Irritant Carcinogen b and c a, b, and c a, b, and d all of the above

Irritant

3: Select the chemical formulas for these ternary salts: potassium chromate

K2CrO4

27: Name these ternary salts: PbSO4

Lead (II) Sulfate

26: Select the chemical formulas for these ternary salts: lithium hydroxide

LiOH

23: A special receptacle for the disposal of gloves, broken glass and other solid waste is: Located at several places throughout the lab Located in the hall Located at the White Drum Does not exist. These may be discarded in the trash.

Located at several places throughout the lab

6: Name these ternary salts: Hg2SO3

Mercury(I) Sulfite||mercury(I) sulfite||mercury(i) sulfite (correct)

35: Select the chemical formulas for these ternary salts: manganese(II) acetate hexahydrate

Mn(C2H3O2)2• 6H2O

4: Select the chemical formulas for these binary covalent compounds: dinitrogen trioxide

N203

How would you determine the number of significant figures when reading the volume of an aqueous solution in a graduated cylinder? Read the bottom of the meniscus at eye level, and round to the nearest calibration mark on your instrument. Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit. Read the top of the meniscus and round to the nearest calibration mark. Read the bottom of the meniscus at eye level, and round to the nearest tenth of a mL.

Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit.

34: Select the chemical formulas for these binary covalent compounds: sulfur tetrafluoride

SF4

8: What would be the consequences of the following scenario and what effect would it have on your experimental results? A student used a dropper rather than a toothpick to put a small drop of each dye on the chromatography paper. We would be unable to determine how far the solvent front traveled, and therefore could not determine the Rf for the components. Too much dye would be spotted, causing large spots that would spread. The chromatogram would be impossible to analyze properly. The solvent could evaporate. If the solvent evaporated before the experiment was complete, we could not accurately determine Rf values. The marks on the origin line would separate and elute, mixing with the dyes. We could not accurately determine Rf values. Too little dye would end up on the chromatogram, making the spots difficult to see and Rf difficult to determine. The solute would be too dilute, which would change pace the solvent eluted, making Rf values inconsistent. The air would not be saturated with solvent, making the chromatograms impossible to analyze. The consequences would be minimal, and would have a negligible effect on the results.

Too much dye would be spotted, causing large spots that would spread. The chromatogram would be impossible to analyze properly.

5: You find a beaker filled with an unknown clear liquid on your lab bench. What should you do? Pour the liquid down the sink, it's probably water. Taste or smell the liquid to see if it's acidic or basic. Treat the liquid as hazardous; inform your instructor so that you can be notified of the proper disposal technique. Pour the contents into the liquid hazardous waste container. Try combining it with another chemical... maybe the subsequent reaction will help you identify it!

Treat the liquid as hazardous; inform your instructor so that you can be notified of the proper disposal technique.

24: If an instructor asks you what is in a beaker, you will be able to tell them the identity and concentration of the chemical in the beaker.

True

T/F: Gloves worn in the chemistry lab must be latex-free.

True

19: Name the following: H2O

Water

23: What would be the consequences of the following scenario and what effect would it have on your experimental results? The chromatogram was removed from the solvent after the solvent front had reached the top of the chromatogram paper We would be unable to determine how far the solvent front traveled, and therefore could not determine the Rf for the components. Too much dye would be spotted, causing large spots that would spread. The chromatogram would be impossible to analyze properly. The solvent could evaporate. If the solvent evaporated before the experiment was complete, we could not accurately determine Rf values. The marks on the origin line would separate and elute, mixing with the dyes. We could not accurately determine Rf values. The marks on the origin line would separate and elute, mixing with the dyes. We could not accurately determine Rf values. The solute would be too dilute, which would change pace the solvent eluted, making Rf values inconsistent. The air would not be saturated with solvent, making the chromatograms impossible to analyze. The consequences would be minimal, and would have a negligible effect on the results.

We would be unable to determine how far the solvent front traveled, and therefore could not determine the Rf for the components.