Regents Chemistry Exam Explanations June 2011

June 2011 Chemistry Regents #41-50

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50
Question 51 Questions 52-54 Questions 55-59 Questions 60-61 Questions 62-63 Questions 64-65 Questions 66-68 Questions 69-70 Questions 71-73 Questions 74-76 Questions 77-79 Questions 80-82 Questions 83-85

Questions
Answer Link Explanations
1 Link a physical change is spreading out of the particles
no bonds are formed, no new molecules are made
42 During a laboratory activity to investigate the reaction rate, a student reacts 1.0-gram samples of solid zinc with 10.0-milliliter samples of HCl(aq). The table below shows information about the variables in five experiments the student performs.
Reactions of Zn(s) with HCl(aq)
Experiment Decription of Zinc Sample HCl(aq) Concnetration(M) Temperature (K)
1 lumps 0.10 270.
2 powder 0.10 270.
3 lumps 0.10 290.
4 lumps 1.0 290.
5 powder 1.0 280.
Which two experiements can be used to investigate the effect of the concentration of HCl(aq) on the reaction rate?
(1) 1 and 3 (2) 1 and 5 (3) 4 and 2 (4) 4 and 3
4 Link to investigate a property, all others variables must be held constant
43. Which temperature change would cause a sample of an ideal gas to double in volume while the pressure is held constant?
(1) from 400.K to 200.K
(2) from 200.K to 400.K
(3) from 400.^oC to 200.^oC
(4) from 200.^oC to 400.^oC
2 Link V/T=V/T
to double the volume the kelvin temperature must be doubled
44 A 36-gram sample of water has an initial temperature of 22^oC. After the sample absorbs 1200 joules of heat energy, the final temperature of the sample is
(1) 8.0^oC (2) 14^oC (3) 30.^oC (4) 55^oC
3 Link you add heat the final temperature will be higher
q=mCDT
DT=q/mC=1200J/(36g x 4.18J/gC)= 8^oC
22 + 8=30^oC
45 Which statement explains why Br₂ is a liquid at STP and I₂ is a solid at STP?
(1) Molecules of Br₂ are polar, and molecules of I₂ are nonpolar.
(2) Molecules of I₂ are polar, and molecules of Br₂ are nonpolar.
(3) Molecules of Br₂ have stronger intermolecular forces than molecules of I₂.
(4) Molecules of I₂ have stronger intermolecular forces than molecules of Br₂.
4 Link solids have stronger IMFs than liquids (and gases)
46 Which balanced equation represents an oxidation-reduction reaction?
(1) Ba(NO₃)₂ + Na₂SO₄ ==> BaSO₄ + 2NaNO₃
(2) H₃PO₄ + 3KOH==> K₃PO₄ + 3H₂O
(3) Fe(s) + S(s) ==> FeS(s)
(4) NH₃(aq) + HCl(aq)==> NH₄Cl(s)
3 Link redox reactions have a change in oxidation numbers
look for a free element (ox #=O) and that element in a compound (ox # not 0) on the other side
47 Which solution reacts with LiOH(aq) to produce a salt and water?
(1) KCl(aq) (2) CaO(aq) (3)NaOH(aq) (4)H₂SO₄(aq)
4 Link Neutralization LiOH is a base and must react with an acid to produce salt and water
Acid start with Hydrogen
48 Which volume of 2.0M NaOH(aq) is need to completely neutralize 24 milliliters of 1.0M HCl(aq)?
(1) 6.0mL (2) 12mL (3) 24mL (4) 48mL
2 Link titration MV=MV
2.0M(V)=1.0M(24mL)
V=12mL
49 Which type of reaction releases the greatest amount of energy per mole of reactant?
(1) combustion (2) decomposition (3) nuclear fusion (4) oxidation-reduction
3 Link nuclear reactions release the greatest amounts of energy
50 Which balanced equation represents natural transmutation?

4 Link natural transmutation have only 1 reactant
artificial has 2
transmutation is when 1 element becomes another by changing the number of protons
Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50
Question 51 Questions 52-54 Questions 55-59 Questions 60-61 Questions 62-63 Questions 64-65 Questions 66-68 Questions 69-70 Questions 71-73 Questions 74-76 Questions 77-79 Questions 80-82 Questions 83-85

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