CHM113 - lab final (prelab quiz)

A 10.0 gram piece of metal is placed in an insulated calorimeter containing 250.0 grams of water initially at 20.0°C. If the final temperature of the mixture is 25.0°C, what is the heat change of piece of metal? 5230 J −5230 J 209 J −209 J 5440 J

-5230 J

When you read the label on a chemical container, what are the 3 most important pieces of information? (Choose three answers.) -the concentration -the volume -the chemical name -any hazard warnings -the manufacturer

-the concentration -the chemical name -any hazard warnings

If the partial pressure of a gas produced in a reaction was determined to be 0.35 atm in a 161.0 mL container at a temperature of 25.0°C, how many moles of gas were produced? (Hint: Use the ideal gas law and convert temperature to Kelvin, and volume to Liters.) 0.0023 mol 2.3 mol 27 mol 0.027 mol 0.19 mol

0.0023 mol

When sodium metal is added to water, the following reaction occurs:2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)What is the theoretical number of moles of hydrogen gas should be produced when 0.068 mol of sodium metal reacts? 1.0 mol H2 0.14 mol H2 0.068 mol H2 0.034 mol H2

0.034 mol H2

Upon heating a sample of NiCl2•6H2O, a sample originally weighing 3.5 g yields an anhydrous salt residue weighing 2.1g. How many moles of water were in the sample? 0.194 mol H2O 0.117 mol H2O 237.69 mol H2O 0.0777 mol H2O 18.02 mol H2O

0.0777 mol H2O

If 2.0 mL of water is added to 8.0 mL of a 0.30 M solution to make a new solution with a total volume of 10.0 mL, what is the concentration of the new solution? 0.060M 0.24M 1.21.6M

0.24M

After the completion of a gas forming reaction, the column of water remaining in the collection flask was measured to me 55mm high, the vapor pressure of water is 0.0313atm at 25oC, and the atmospheric pressure that day was measured as 0.950 atm, what is the partial pressure of the gas produced by the reaction? 1mmHg=13.595mm H2O and 1atm=760mmHg (see sample calculation found in prelab slides.) 0.913 atm 2.39 atm 1.5 atm 0.66 atm

0.913 atm

If a student determined that the volume of a sample of water is 11.4 mL, and its mass is 10.98 g, what should the student record as the experimental density of the water sample, with the correct number of significant figures? 1.038g/mL 1.04g/mL 0.963g/mL 0.96g/mL 125g/mL

0.963g/mL

What is the molar mass of anhydrous nickel(II) chloride hexahydrate, NiCl2•6H2O? 147.62 g/mol 129.60 g/mol 21411.12 g/mol 108.10 g/mol 237.69 g/mol

129.60 g/mol

A mixture of helium, neon and argon gases have a total pressure of 790 mmHg. If there is 118.5 mmHg of argon, 474 mmHg of helium, what is the partial pressure of the neon gas? 790 mmHg 760 mmHg 197.5 mmHg 200 mmHg

197.5 mmHg

What is the molar mass of nickel(II) chloride hexahydrate, NiCl2•6H2O? 237.69 g/mol 129.60 g/mol 147.62 g/mol 21411.12 g/mol 108.10 g/mol

237.69 g/mol

In most experiments, what is the least number of measurements (trials) when you are making quantitative measurements in lab? -1 -2 -3

3

What is the percent of hydrogen peroxide in the solution when 5.02g of H2O2 solution reacts to produce 0.153g of H2O2? 2H2O2 (l) → 2H2O (l) + O2 (g) Mass percent = (mass of solute/mass of solution)*100 3% 5% 30% 50%

3%

The figure shows a liquid measurement using a 50 mL graduated cylinder. First determine the value of each increment, and then read the volume of the liquid. Which of the following is closest to what you would record for this measurement, to the correct number of significant figures?

36.5 (lowest part of meniscus and can add one number)

What is the specific heat of liquid water, written with correct units? Refer to the Appendix in your textbook, or your lecture notes. 2.027 J 2.027 J/(g°C) 2.015°C 4.184 J 4.184 J/(g°C)

4.184 J/(g°C)

Upon heating a sample of NiCl2•6H2O, a sample originally weighing 3.5 g yields an anhydrous salt residue weighing 2.1g. What is the percent by mass of water in the hydrate? 80% 40 % 60% 20% 30%

40%

After determining the density of three samples of water, each at 22.0 degrees celsius, Anna calculated an average density for the three trials to be 1.048 g/mL. Use the following link: http://jupiter.plymouth.edu/~jsduncan/courses/2012_Spring/Techniques/Exams/DensityOfWater-vs-Temp.pdf to find the accepted density value of water at this temperature, and calculate the percent error for her average density result. 3.197% 1.050% 5.034% 9.521% 0.9521%

5.034%

A 10.0 gram piece of metal is placed in an insulated calorimeter containing 250.0 g of water initially at 20.0°C. If the final temperature of the mixture is 25.0°C, what is the heat change of water? 5230 J −5230 J 209 J −209 J 5440 J

5230 J

A student determines the mass of a sample of water by determining the mass of an empty container (99.20 g) and the mass of the container including the sample of water (108.23 g). Use significant rules (for subtracting) to determine the mass of the water sample alone, to the correct number of significant figures. 9g 9.0g 9.03g 9.030g 9.0300g

9.03g

In a Synthesis or Combination: In this type of reaction two or more substances (reactants) react to produce one product. Combination reactions are exothermic (heat is released). AB → A + B A + BC → B + AC AB + CD → AD + CB A + B → AB

A + B → AB

Using known solutions of a specific dye color, assigned to your group , you will construct a graph of: Absorbance vs Concentration Concentration vs Absorbance Concentration vs %T %T vs Concentration

Absorbance vs Concentration

Should you add concentrated acid to water or add water to concentrated acid? -Add acid to water with constant stirring -Add water to acid with constant stirring. -It doesn't matter. -You should pour both acid and water into a separate container at the same time.

Add acid to water with constant stirring

Which of the following best describes what is in an aqueous solution of silver nitrate, AgNO3(aq)? Ag+, N3−, and O2− ions Ag+ and NO3− ions Ag2+ and NO32+ ions Ag, N2, and O2 molecules AgNO3 molecules

Ag+ and NO3− ions

When collecting the mass of the crucible, which of the following is true? -All of the above are true. -Place your hand near the crucible to determine how hot it is before picking it with the crucible tongs. -Use the same balance for each mass measurement. -Hit the Tare button each time before you collect a mass measurement. -Do not touch the crucible with your bare hands because your fingerprints have mass.

All of the above are trueThe mass percent of water in a hydrate of MnCl2 is 36.41%. What is the empirical formula of the hydrate?

Which of the following should help to prevent error in your colorimetric measurements? -Ensuring that finger prints are not on the cuvette sample holders -Washing the cuvette with sample solution after washing with water and before filling the cuvette with that solution. -Making careful and precise volume measurements from the same known solution. -Making sure you don't spill any liquid in the colorimeter and that the cuvette is always inserted in the proper orientation. -All of these.

All of these

When is it important to wear safety goggles in the laboratory? -When using liquid chemicals in the lab. -When I start pouring or transferring chemicals at the lab bench. -Any time there are chemicals or laboratory equipment present in the lab. -Only when my lab TA tells me to. -As soon as my lab partners put on their goggles.

Any time there are chemicals or laboratory equipment present in the lab.

Match the incident with the most appropriate action. -There is a small, isolated fire on the lab bench

Attempt to smother the fire by putting a container on top of the flames.

Which piece of volumetric glassware in the figure is a volumetric pipet?

C

Which one of the following substances has London dispersion forces as its only intermolecular force? (No hydrogen bonding, no dipole-dipole forces.) CH3 OH NH3 H2S CH4

CH4

Before hooking a Bunsen burner to the gas line, what should you do? -Strike the match to light the burner. -Remove all items from the lab bench. -Ask the lab TA to light the burner for your group. -Open the gas stopcock to make sure there's sufficient gas pressure. -Check to make sure there are no cracks or holes in the connecting hose.

Check to make sure there are no cracks or holes in the connecting hose

How can you protect your hands when working with corrosive chemicals? -Ask my lab partner to do it. -Always work with corrosive chemicals using screw-top containers. -Cover your hands using appropriate gloves provided by my lab TA. -Neutralize the corrosive chemicals before working with them. -Rub SPF-50 sunblock into my hands.

Cover your hands using appropriate gloves provided by my lab TA.

Which piece of volumetric glassware in the figure is a graduated cylinder?

D

When calibrating the colorimeter, what should you use as your blank to set the reading for 100% T or 0 Absorbance? Tap water De-ionized water The undiluted dye solution Ethanol

De-ionized water

What should you do with chemicals leftover after an experiment? -Return any unused chemicals to their original containers. -Flush all chemicals down the sink with plenty of water. -Store the unused chemicals in beakers inside your lab drawer in case you'll need them in a future experiment and dump the used chemicals down the sink. -Dispose of any used or unused chemicals in the proper waste containers. -Take the unused chemicals home for use as insecticides in your apartment/home.

Dispose of any used or unused chemicals in the proper waste containers.

In lab, temperature changes caused by ________________ of liquids will be related to the strength of intermolecular forces. Evaporation Mass Density pH

Evaporation

True or False. It is safe to heat flammable liquids with a Bunsen burner

False

What is the driving force for the reaction of HCl(aq) and NaOH(aq)? -Formation of a precipitate -Formation of a gas -Formation of ions -Formation of H2O(l) -Formation of NaCl(aq)

Formation of H2O(l)

Which of the following is characteristic of a solution containing an acid? H+(aq) OH−(aq)

H+ (aq)

What are the three main types of intermolecular forces that will be explored in lab? H-bonding, Dipole-Dipole forces, and London dispersion forces Viscosity, Surface tension, Vapor pressure Ethanol, Acetone, and Hexane None of the above

H-bonding, Dipole-Dipole forces, and London dispersion forces

Which of the following molecules is nonpolar? H2 HF HCl HI HBr

H2

Which of the following molecules is polar? H2O CO2 CH4 N2 None of the above

H2O

Which of the following molecules can participate in Hydrogen bonding? HF CO2 CH4 H2S

HF

What types of shoes are appropriate for the lab? -Hard shoes with tops and closed toes. -Flip-flops -Heels -Rollerblades -Pink

Hard shoes with tops and closed toes.

Match the incident with the most appropriate action. -My lab partner completely severs his/her hand

Immediately call 911, then tell my TA

What intermolecular force is responsible for the attraction between an ion and a polar molecule? Dipole-dipole interaction Hydrogen bonding Ion-dipole interaction London dispersion forces

Ion-dipole forces

When is it appropriate to taste a chemical or solution? -Only when it looks good. -Only after heating the chemical to 180°C for 30 min to kill any pathogenic bacteria. -Only when my lab partner double-dares me. -Only when my TA is not looking. -Lab chemicals should never be tasted.

Lab chemicals should never be tasted.

Use solubility rules provided in your student handout (procedure) within CANVAS to determine which of the following compounds is insoluble (not soluble) in water. KNO3 Ca(NO3)2 KOH Mg(OH)2 NH4Cl

Mg(OH)2

The mass percent of water in a hydrate of MnCl2 is 36.41%. What is the empirical formula of the hydrate? MnCl2•3H2O MnCl2•5H2O MnCl2•2H2O MnCl2•H2O MnCl2•4H2O

MnCl2•4H2O

Using the ideal gas law, PV=nRT, what variable are we solving for in this investigation? Moles (n) Volume (V) Temperature (T) Pressure (P)

Moles (n)

When is it safe to use glassware that has cracks or stars? -Always -Never -Only when the defect is on the side of the glass container. -Only when the defect is very small. -Only when the glassware is used for powdered chemicals.

Never

A 140.5 g sample of NiSO4•XH2O was heated until no further mass decrease was noted. The remaining sample was assumed to be anhydrous NiSO4 with a mass of 77.5 g. First determine the moles of anhydrous NiSO4 and moles of H2O lost. What is the mole ratio of NiSO4 to water? NiSO4•5H2O NiSO4•4H2O NiSO4•7H2O NiSO4•3H2O NiSO4•6H2O

NiSO4•7H2O

Which gas is produced in the decomposition reaction of H2O2? O2 H2 CO2 CO Cl2

O2

Where should you keep your personal belongings that you bring to lab? -In my lab drawer. -Off the floor, out of the way, preferably on a shelf on the side of the room. -On the lab bench top. -On the floor. -I can keep my belongings with me as long as I keep everything in my backpack and wear the backpack during lab.

Off the floor, out of the way, preferably on a shelf on the side of the room.

When aqueous solutions of lead(II) nitrate and potassium iodide are mixed, what is the formula for the insoluble solid (precipitate) that forms? KNO3(s) PbI(s) PbI2(s) Pb(NO3)2(s) PbIO3(s)

PbI2(s)

How can you make sure that all of the water of hydration is removed? -When the sample turns black and starts smoking, it is done. -Touch the powder with your finger to see if it feels wet. -Perform a heating, cooling, weighing cycle until duplicate masses are obtained between weighing cycles. -Heat the sample 5 minutes longer than the lab recommends. -It is dry when it changes color.

Perform a heating, cooling, weighing cycle until duplicate masses are obtained between weighing cycles.

What is the proper method to smell a chemical if required in lab? -Pour the chemical onto a watchglass to increase the vaporization. -Stick your nose as close to the chemical as possible. -Rub a small amount of the chemical between your thumb and forefinger and then sniff your hands. -Place your nose away from the mouth of the container and gently waft the odor toward your nose. -Stick a straw up your nose and then put the other end of the straw in the chemical.

Place your nose away from the mouth of the container and gently waft the odor toward your nose.

The Beer-Lambert law tells us that concentration and absorbance are: -Proportionally related (as one increases, the other increases) -Inversely related (as one increases, the other decreases)

Proportionally related (as one increases, the other increases)

What is another name for a colorimeter? Styrofoam cup Thermometer Spectrophotometer Calorimeter Microscope

Spectrophotometer

Match the incident with the most appropriate action. -My shirt catches on fire

Stop, drop, and roll or use the fire blanket/safety shower if immediately available

Match the incident with the most appropriate action. -A larger fire occurs

Tell my TA and move away from the fire

Match the incident with the most appropriate action. -Any injury occurs to me in the lab

Tell my TA. Fill out the appropriate accident report form stating I deny medical treatment or leave lab to seek medical treatment

If you spill a liquid chemical, what is the first thing you should do? -Wipe up the spilled chemical with paper towels. -Tell your teacher about the spill. -Dilute the spilled chemical with water. -Hide the spill by placing your lab partner's backpack on top of the liquid. -Use the proper absorbent material to clean up the spill.

Tell your teacher about the spill

The dots on the figure represent the points hit by a set of 6 darts when trying to hit the target in the very center. Which diagram represents the greatest accuracy for the grouping of target hits?

The one on the left (holes are closer to the center)

What can we say about the temperature change of a sample of water when the value of q is negative? -The temperature of the water increased. -The temperature of the water decreased. -It depends on whether mass and specific heat values are positive or negative.

The temperature of the water decreased.

Which statement about intermolecular forces is true? Only occur in ionic bonds. They have to be overcome to decompose a substance. These forces hold atoms together in a molecule. They are responsible for the physical properties of matter.

They are responsible for the physical properties of matter

Which of the following statements is true about the number of significant figures in the following measurements? 0.01000 L and 40.00 g. -They both have 4 significant figures -They both have 1 significant figure -They have different significant figures

They both have 4 significant figures

True or False. A hot plate is used for heating the hydrate in a crucible at least 2 times for 10-15 minutes at medium-high setting.

True

True or False. All liquid, precipitate, and solid metal waste will be placed in a glass bottle WASTE container in the fume hood. However, matches, wooden splints, pH paper, etc must be placed in red bucket in the fume hood.

True

True or False. Although chemicals aren't used in this investigation, glassware will be used, so PPE is required.

True

True or False. Figures 1 and 2 show the most efficient way to tie each of your paper towels with with string.

True

True or False. In this investigation an OPEN FLAME may be present, KEEP PAPERS and OTHER FLAMMABLES DISTANT.

True

True or False. It is never appropriate/safe to eat, drink or put on makeup in the laboratory.

True

True or False. Most of the substances used in this investigation are extremely volatile (easily evaporate) and should be used with care in a fume hood.

True

True or False. PPE is required at all times chemicals and glassware are used.

True

True or False. Part 1 of this investigation should be completed individually as a proposal, prior to lab.

True

True or False. The thermometer used for this investigation only reaches a temperature of ~40 degrees celsius, so the objective is to mathematically determine the initial temperature of hot water. The picture below shows the set-up for the calorimeter apparatus that will be used for this investigation.

True

True or False: A separation technique that can be used for this investigation is centrifugation.

True

When using a gas burner in the lab, what should you do if the flame sputters, goes out, or you smell gas in the room? -Turn up the gas volume to increase the size of the flame. -Turn off the gas source by closing the stopcock. -Try relighting the burner. -Open the lab door to let in fresh air. -Reconnect the burner gas line to another stopcock.

Turn off the gas source by closing the stopcock.

Match the incident with the most appropriate action. -Chemicals splash in my eye(s)

Wash my eyes thoroughly in the wash-fountain

How should you protect your eyes from chemicals and glass shards in the lab? -Look away when working with chemicals or glassware. -Use glasses with shatter-proof lenses. -Don't come to lab. -Wear my shades in lab. -Wear proper fitting goggles with side shields.

Wear proper fitting goggles with side shields.

How often do you need to calibrate the colorimeter? -Once, before you start reading %T of your samples -Whenever the wavelength is changed -Never

Whenever the wavelength is changed

What is the proper way to carry/move a heated object? -Using folded paper towels to protect your hands. -Using a book as a tray to carry the heated object. -Never carry/move a heated object. -With the proper tongs/test tube holder or with hot mitts. -Ask my TA to carry it for me.

With the proper tongs/test tube holder or with hot mitts.

In the ideal gas law, PV=nRT, what units should pressure (P) be in if the R constant is 0.08206 L∙atm/(mol∙K)? atm Liters moles Kelvin mm Hg

atm

An everyday example of a hydrate is -flour -sawdust -concrete -brownies -moss

concrete

A _______________________, as shown in the image above, will be filled 3/4 of the way with solution and placed in the colorimeter (spectrophotometer) to be analyzed. crucible evaporating dish test tube cuvette

cuvette

When the surroundings absorbs heat, is the heat change of the system (qsystem) positive or negative? positive (> 0) negative (< 0)

negative

When the surroundings absorbs heat, is the heat change (qsurroundings) positive or negative? positive (> 0) negative (< 0)

positive

In the Beer-Lambert Law equation, what does the "b" represent? -Concentration -Absorption -thickness of solution -y-intercept

thickness of solution

In a calorimetry experiment, it was determined that a 92.0 gram piece of copper metal released 1860 J of heat to the surrounding water in the calorimeter (qcopper = −1860 J). If the final temperature of the copper metal-water mixture was 25.00°C, what was the initial temperature of the copper metal? The specific heat of copper is 0.377 J/(g°C). Tinitial = 28.6°C Tinitial = −28.6°C Tinitial = 78.6°C Tinitial = 92.6°C Tinitial = 53.6°C

tinitial = 78.6 C

What does anhydrous mean? -absorber of hydrogen -enemies of the comic book criminal organization HYDRA -without water -without hydrogen -absorber of water

without water

In a calorimetry experiment, it was determined that the heat change of the surroundings, qsurroudings, was 4482 J. What is the heat change of the system, qsystem? 4482 J −4482 J 2241 J −2241 J

−4482 J