free response review packet · 2018. 9. 9. · free response review packet 1.base your answer to...

Free Response Review Packet

1. Base your answer to the following question on the information below and on your knowledge ofchemistry.

Illuminated EXIT signs are used in public buildings such as schools. If the word EXIT isgreen, the sign may contain the radioisotope tritium, hydrogen-3. The tritium is a gas sealed inglass tubes. The emissions from the decay of the tritium gas cause a coating on the inside ofthe tubes to glow.

State, in terms of neutrons, how an atom of tritium differs from an atom of hydrogen-1.

Base your answers to questions 2 and 3 on the information below and on your knowledge of chemistry.

A student compares some models of the atom. These models are listed in the table belowin order of development from top to bottom.

2. State one way in which the Bohr model agrees with the Thomson model.

3. Using the conclusion from the Rutherford model, identify the charged subatomic particle that islocated in the nucleus.


4. Base your answer to the following question on the information below and on your knowledge of chemistry.

Chemical concepts are applied in candy making. A recipe for making lollipops is shown below.

Hard-Candy Lollipops Recipe

Ingredients:414 grams of sugar177 grams of water158 milliliters of light corn syrup

Step 1: In a saucepan, mix the sugar and water. Heat this mixture, while stirring, until all of thesugar dissolves.Step 2: Add the corn syrup and heat the mixture until it boils.Step 3: Continue boiling the mixture until the temperature reaches 143°C at standards pressure.Step 4: Remove the pan from the heat and allow it to stand until the bubbling stops. Pour themixture into lollipop molds that have been coated with cooking oil spray.Explain, in terms of the concentration of sugar molecules, why the boiling point of the mixture instep 3 increases as water evaporates from the mixture.


Two very stable compounds, Freon-12 and Freon-14, are used as liquid refrigerants. AFreon-12 molecule consists of one carbon atom, two chlorine atoms, and two fluorine atoms. AFreon-14 molecule consists of one carbon atom and four fluorine atoms.

To which class of organic compounds do Freon-12 and Freon-14 belong?


6. Base your answer to the following question on the information below.The bright-line spectra for three elements and a mixture of elements are shown below.

Explain, in terms of both electrons and energy, how the bright-line spectrum of an element isproduced.

7. Copper has two naturally occurring isotopes. Information about the two isotopes is shown in thetable below.

In the space in your answer booklet, show a numerical setup for calculating the atomic mass ofcopper.

8. In the box below, draw a Lewis electron-dot diagram for an atom of boron.


9. Determine the mass number of the magnesium atom represented by the electron-shell diagram.

10. Write one electron configuration for an atom of silicon in an excited state.


There are six elements in Group 14 on the Periodic Table. One of these elements has thesymbol Uuq, which is a temporary, systematic symbol. This element is now known asflerovium.

Explain, in terms of electron shells, why each successive element in Group 14 has a largeratomic radius, as the elements are considered in order of increasing atomic number.

12. Explain, in terms of atomic structure, why Group 18 elements on the Periodic Table rarely formcompounds.

13. Explain, in terms of electrons, why the radius of a potassium atom is larger than the radius of apotassium ion in the ground state.



Silver-plated utensils were popular before stainless steel became widely used to make eatingutensils. Silver tarnishes when it comes in contact with hydrogen sulfide, , which is found inthe air and in some foods. However, stainless steel does not tarnish when it comes in contactwith hydrogen sulfide.Draw a Lewis electron-dot diagram for the compound that tarnishes silver.


The diagram below represents three elements in Group 13 and three elements in Period 3and their relative positions on the Periodic Table.

Some elements in the solid phase exist in different forms that vary in their physical properties.For example, at room temperature, red phosphorus has a density of 2.16 g/cm3 and whitephosphorus has a density of 1.823 g/cm3.Consider the Period 3 elements in the diagram in order of increasing atomic number. State thetrend in electronegativity for these elements.



Before atomic numbers were known, Mendeleev developed a classification system for the63 elements known in 1872, using oxide formulas and atomic masses. He used an R in theoxide formulas to represent any element in each group. The atomic mass was listed inparentheses after the symbol of each element. A modified version of Mendeleev'sclassification system is shown in the table below.

Based on Mendeleev's oxide formula, what is the number of electrons lost by each atom of theelements in Group III?

17. Base your answer to the following question on the information below. The atomic radius and the ionic radius for some Group 1 and some Group 17elements are given in the tables below.

Explain, in terms of electron shells, why the radius of a K+ ion is greater than the radius of an Na+ ion.


Base your answers to questions 18 through 21 on the information below.

Two sources of copper are cuprite, which has the IUPAC name copper(I) oxide, and malachite,which has the formula Cu2CO3(OH)2. Copper is used in home wiring and electric motorsbecause it has good electrical conductivity. Other uses of copper not related to its electricalconductivity include coins, plumbing, roofing, and cooking pans.Aluminum is also used forcooking pans.At room temperature, the electrical conductivity of a copper wire is 1.6 times greater than analuminum wire with the same length and cross-sectional area. At room temperature, the heatconductivity of copper is 1.8 times greater than the heat conductivity of aluminum. At STP, thedensity of copper is 3.3 times greater than the density of aluminum.

18. Identify one physical property of aluminum that could make it a better choice than copper for acooking pan.

19. Identify one physical property of copper that makes it a good choice for uses that are not relatedto electrical conductivity.

20. Determine the oxidation number of oxygen in the carbonate ion found in malachite.

21. Write the chemical formula of cuprite.

22. Explain, in terms of electron configuration, why selenium and sulfur have similar chemicalproperties.


Base your answers to questions 23 through 25 on the information below and on your knowledge of chemistry.

The formulas and the boiling points at standard pressure for ethane, methane, methanol,and water are shown in the table below.

23. Explain, in terms of molecular polarity, why the solubility of methanol in water is greater than thesolubility of methane in water.

24. State the change in potential energy that takes place in a sample of methane as it boils at–161.5°C.

25. Identify the compound that has the strongest intermolecular forces.



A 1.00-mole sample of glucose, , completely reacts with oxygen, as representedby the balanced equation below.

Using the axes above, complete the potential energy curve for the reaction of glucose withoxygen.


Rubbing alcohol is a product available at most pharmacies and supermarkets. One rubbingalcohol solution contains 2-propanol and water. The boiling point of 2-propanol is 82.3°C atstandard pressure.Explain in terms of electronegativity differences, why a C–O bond is more polar than a C–Hbond.

28. Base your answer to the following question on the information below.

Ammonium chloride is dissolved in water to form a 0.10 M NH4Cl(aq) solution. This dissolvingprocess is represented by the equation below.

Determine the minimum mass of NH4Cl(s) required to produce a saturated solution in 100.grams of water at 40.°C.


Base your answers to questions 29 and 30 on the information below.

In 1864, the Solvay process was developed to make soda ash. One step in the process isrepresented by the balanced equation below.

NaCl + NH3 + CO2 + H2O ®NaHCO3 + NH4Cl29. In the space draw a Lewis electron-dot diagram for the reactant containing nitrogen in the

equation.

30. Write the chemical formula for one compound in the equation that contains both ionic bonds andcovalent bonds.


Carbon has three naturally occurring isotopes, C-12, C-13, and C-14. Diamond andgraphite are familiar forms of solid carbon. Diamond is one of the hardest substances known,while graphite is a very soft substance. Diamond has a rigid network of bonded atoms.Graphite has atoms bonded in thin layers that are held together by weak forces. Recent experiments have produced new forms of solid carbon called fullerenes. Onefullerene, C60, is a spherical, cagelike molecule of carbon.

State, in terms of the arrangement of atoms, the difference in hardness between diamond andgraphite.



Explain why Lewis electron-dot diagrams are generally more suitable than electron-shelldiagrams for illustrating chemical bonding.

Base your answers to questions 33 through 36 on the table below.

33. Explain, in terms of molecular polarity, why hydrogen chloride is more soluble than hydrogen inwater under the same conditions of temperature and pressure.


34. Explain, in terms of intermolecular forces, why hydrogen has a lower boiling point than hydrogenbromide.

35. The density of hydrogen at STP is 0.0899 gram per liter. Express this density to two significantfigures.

36. The volume of 1.00 mole of hydrogen bromide at STP is 22.4 liters. The gram-formula mass ofhydrogen bromide is 80.9 grams per mole. What is the density of hydrogen bromide at STP?


The diagram below represents a cylinder with a movable piston. The cylinder contains 1.0liter of oxygen gas at STP. The movable piston in the cylinder is pushed downward atconstant temperature until the volume of 0 2(g) is 0.50 liter.

37. State the effect on the frequency of gas molecule collisions when the movable piston is pushedfarther downward into the cylinder.

38. Determine the new pressure of O2(g) in the cylinder, in atmospheres.


A few pieces of dry ice, , at are placed in a flask that contains air at .The flask is sealed by placing an uninflated balloon over the mouth of the flask. As the ballooninflates, the dry ice disappears and no liquid is observed in the flask.

39. Write the name of the process that occurs as the dry ice undergoes a phase change in the flask.

40. State the direction of heat flow that occurs between the dry ice and the air in the flask.



Paintball is a popular recreational activity that uses a metal tank of compressed carbondioxide or nitrogen to launch small capsules of paint. A typical tank has a volume of 508 cubiccentimeters. A 340.-gram sample of carbon dioxide is added to the tank before it is used forpaintball. At 20.°C, this tank contains both CO2(g) and CO2( ). After a paintball game, thetank contains only CO2(g).

In the box above, use the key to draw a particle diagram to represent the two phases of CO2 in anewly filled tank. Your response must include at least six molecules of CO2 in each phase.


A student investigated heat transfer using a bottle of water. The student placed the bottle in aroom at 20.5°C. The student measured the temperature of the water in the bottle at 7 a.m. andagain at 3 p.m. The data from the investigation are shown in the table below.

42. Show a numerical setup for calculating the change in the thermal energy of the water in thebottle from 7 a.m. to 3 p.m.

43. State the direction of heat transfer between the surroundings and the water in the bottle from 7a.m. to 3 p.m.



Starting as a gas at 206°C, a sample of a substance is allowed to cool for 16minutes. This process is represented by the cooling curve below.

44. Using the key below, draw two particle diagrams to represent the two phases of the sample atminute 4. Your response must include at least six particles for each diagram.

45. At what time do the particles of this sample have the lowest average kinetic energy?


46. Base your answer to the following question on Heat is added to a sample of liquid water, starting at 80.ºC, until the entire sample is agas at 120.ºC. This process, occurring at standard pressure, is represented by the balancedequation below.

H2O( ) + heat ® H2O(g)On the diagram below, complete the heating curve for this physical change.

47. A liquid boils when the vapor pressure of the liquid equals the atmospheric pressure on thesurface of the liquid. Using Reference Table H, determine the boiling point of water when theatmospheric pressure is 90. kPa.


Many breads are made by adding yeast to dough, causing the dough to rise. Yeast is atype of microorganism that produces the catalyst zymase, which converts glucose, ,to ethanol and carbon dioxide gas. The balanced equation for this reaction is shown below.

Describe how the catalyst, zymase, speeds up this reaction.


The compounds and are soluble in water.Compare the entropy of 30. grams of solid at 20.°C with the entropy of 30. grams of

dissolved in 100. grams of water at 20.°C.



The chemical reaction between methane and oxygen is represented by the potential energydiagram and balanced equation below.

50. Explain, in terms of collision theory, why a lower concentration of oxygen gas decreases the rateof this reaction.

51. Which potential energy interval in the diagram represents the activation energy of theforward reaction?

52. Base your answer to the following question on Propane is a fuel that is sold in rigid, pressurized cylinders. Most of the propane in acylinder is liquid, with gas in the space above the liquid level. When propane is released fromthe cylinder, the propane leaves the cylinder as a gas. Propane gas is

C3H8(g) + 5O2(g) 2CO2(g) + 4H2O( ) + 2219.2kJ

A small amount of methanethiol, which has a distinct odor, is added to the propane to helpconsumers detect a propane leak. In methanethiol, the odor is caused by the thiol functionalgroup (–SH). Methanethiol, CH3SH, has a structure that is very similar to the structure ofmethanol.

Draw a particle diagram to represent propane in a pressurized cylinder. Your response mustinclude at least six molecules of propane in the gas phase and at least six molecules of propanein the liquid phase.


53. Explain, in terms of collision theory, why the rate of a chemical reaction increases with anincrease in temperature.

54. A potential energy diagram for a chemical reaction is shown below. On this diagram, draw acurve to show how the potential energy diagram will change when a catalyst is added to thereaction.


A method used by ancient Egyptians to obtain copper metal from copper(I) sulfide ore washeating the ore in the presence of air. Later, copper was mixed with tin to produce a useful alloycalled bronze.

55. Convert the melting point of the metal obtained from copper(I) sulfide ore to degrees Celsius.

56. Calculate the density of a -gram sample of bronze that has a volume of cubiccentimeters. Your response must include a correct numerical setup and the calculated result.

57. Based on data collected during a laboratory investigation, a student determined an experimentalvalue of 322 joules per gram for the heat of fusion of H2O. Calculate the student's percent error.Your response must include a correct numerical setup and the calculated result.



A student performed an experiment to determine the total amount of energy stored in a peanut.The accepted value for the energy content of a peanut is 30.2 kilojoules per gram. The studentmeasured 100.0 grams of water into a metal can and placed the can on a ring stand, as shown inthe diagram below. The peanut was attached to a wire suspended under the can.The initial temperature of the water was recorded as 22.0° C. The peanut was ignited andallowed to burn. When the peanut finished burning, the final water temperature was recorded as57.0° C. The student's experimental value for the energy content of this peanut was 25.9kilojoules per gram.

58. Determine the student’s percent error for the energy content of this peanut.

59. Calculate the total amount of heat absorbed by the water. Your response must include both acorrect numerical setup and the calculated result.

Answer KeyQuarter II Review

1. –A tritium atom hastwo neutrons and anH-1 atom has noneutrons. –Only thetritium atom hasneutrons. –H-1 has noneutrons.

2. –Atoms haveelectrons. –Atomshave small, negativelycharged particles.–Both models showan internal structure.–Atoms are neutral.

3. –proton –p –p+ –11p –11H –H+

4. –The boiling point ofthe mixture increasesas water evaporatesbecause theconcentration ofdissolved moleculesincreases. –Anincrease in theconcentration of sugarparticles increases theboiling point.

5. –halide –halocarbon6. – When electrons in

an excited state returnto a lower energystate, specific amountsof energy are emitted.These energies areassociated withspecific wavelengthsof light that arecharacteristic of thebright-line spectrumof an element. –Energy is emittedwhen excitedelectrons fall back tolower shells.

7. Acceptable responsesinclude, but are notlimited to: • (62.93u)(0.6917) + (64.93u)(0.3083) or

8.

9. 2310. Examples: - 2–7–4–1 ;

2–7–5 ; 2–8–3–1;1–8–5

11. –The atomic radius ofthese elementsincreases down thegroup because eachsuccessive elementhas one more electronshell. –The number ofshells per atomincreases.

12. Group 18 elementsrarely formcompounds becausetheir atoms havestable electronconfigurations. –Theirvalence shells arecompletely filled. –Allthe elements havemaximum numbers ofvalence electrons.–Atoms of Group 18have a stable octetexcept He, which isstable with twoelectrons.

13. –A potassium atomhas four electronshells and a potassiumion has three electronshells. –A potassiumatom has one moreelectron shell than apotassium ion. –A K+

ion has one fewerelectron than a Katom.

14.

15. – As atomic numberincreases, theelectronegativityincreases. –Electronegativityincreases. – fromlower to higher

16. –three electrons –three–3

17. A K+ ion hasthree electron shellsand an Na+ ion hasonly two. Asodium ion has fewerelectron shells than apotassium ion.

18. –An aluminum panhas less mass than acopper pan of thesame size becausealuminum is lessdense. –Aluminum isless dense thancopper. –A Cu panwould weigh more.

19. Copper is verymalleable or a goodconductor of heat or ahigh melting point

20. –221. Cu2O22. Examples: – An atom

of each element hassix electrons in itsouter shell. – samenumber of valenceelectrons

23. –Methanol and watermolecules are polar,but methane moleculeare nonpolar. –Thecompounds methanoland water have similarpolarities.

24. –As liquid methaneboils, the potentialenergy of the sampleincreases. –Potentialenergy increases.–higher PE

25. H2O/water26.

Answer KeyQuarter II Review

27. – There is a greaterelectronegativitydifference in a CObond than in a CHbond. – The CO bondis more polar becausethe electronegativitydifference for a CObond is 0.8, and theelectronegativitydifference for a CHbond is 0.4. – The CHbond has a smallerdifference. – The COis .8 and the CH is .4

28. 47 g 1 g.29.

30. NaHCO3 or NH4Cl.31. Diamond has atoms

bonded strongly in athree-dimensionalnetwork. Graphite hasatoms that are heldweakly betweenlayers.

32. Lewis electron-dotdiagrams only showvalence electrons,which are involved inbonding.

33. Examples: – HCl'smolecular polarity ismore similar towater's polarity than H2's polarity comparedto water's – HCl andwater both polar, H2 nonpolar, likedissolves like – HClpolarity is moresimilar to water'spolarity

34. Examples: –Hydrogen has weakerintermolecular forcesthan HBr. – hydrogen– weaker forces.

35. 0.090 g/L or 9.0 × 10–2 g/L

36. 3.61 g/L37. –When the piston is

moved farther into thecylinder, thefrequency of collisionbetween the moleculesincreases. –There willbe more collisions persecond. –increasedfrequency

38. 2 atm/2.0 atm39. –sublimation

–subliming40. –Heat flows from the

air in the flask to thedry ice. –air to –to dry ice –from air

41.

42. q = (800. g)(4.18 J/g •ºC)(20.5ºC – 12.5ºC)(800)(4.18)(8)

43. –Heat was transferredfrom the surroundingsto the water in thebottle. –The waterabsorbed energy fromthe surroundings.

44.

45. minute 16 or at 16minutes

46. a line is drawnhorizontally torepresent the phasechange and extendingthe line with a positiveslope to represent thegas phase, only.

47. 97°C ± 1°C.48. –Zymase is a catalyst

that provides analternative pathway,which requires lessenergy. –decreases theactivation energy–changes the reactionmechanism

49. – The entropy of is less than

the entropy of . – The

is moredisordered. – Thesolution is morerandom the solid.

50. Acceptable responsesinclude, but are notlimited to: • A lowerconcentration ofoxygen gas decreasesthe number ofeffective collisionsbetween O2 moleculesand CH4 molecules.

51. B

52.

53. As temperatureincreases, the rate of achemical reactionincreases because thereactant particlesmove faster andcollide more often.

54.

55. Answer: 1084ºC56.

57.332 J/g – 334 J/g ×100 334 J/g Examples: –3.6%; 4%

58. -14% or 14%.59.

free response review packet · 2018. 9. 9. · free response review packet 1.base your answer to...

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