August 2010 Chemistry Regents #41-50

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 

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AnswerExplanations
41 A cylinder with a movable piston contains a sample of gas having a volume of 6.0 liters at 293 K and 1.0 atmosphere. What is the volume of the sample after the gas is heated to 303 K, while the pressure is held at 1.0 atmosphere?
(1) 9.0 L   (3) 5.8 L
(2) 6.2 L   (4) 4.0 L		2V/T=V/T  higher temp the volume goes up. Only 10K so the increase is small
42 What is the minimum amount of heat required to completely melt 20.0 grams of ice at its melting point?
(1) 20.0 J    (3) 6680 J
(2) 83.6 J    (4) 45 200 J		3Melt is fusion

q=mHf= 20.0g x 334J/g

43 As the temperature of a chemical reaction in the gas phase is increased, the rate of the reaction increases because
(1) fewer particle collisions occur
(2) more effective particle collisions occur
(3) the required activation energy increases
(4) the concentration of the reactants increases		2reactions occur because of effective collisions
44 The entropy of a sample of CO2 increases as the CO2 changes from
(1) gas to liquid    (3) liquid to solid
(2) gas to solid     (4) solid to gas		4entropy is randomness. 

solids least random

gases the most

45 Which two factors must be equal when a chemical reaction reaches equilibrium?
(1) the concentration of the reactants and the concentration of the products
(2) the number of reactant particles and the number of product particles
(3) the rate of the forward reaction and the rate of the reverse reaction
(4) the mass of the reactants and the mass of the products		3equilibrium=con con Requal

concentrations constant

rates are equal

46 Which formula represents an unsaturated hydrocarbon?
(1) C5H12 (3) C7H16
(2) C6H14 (4) C8H14		4NOT an ALKANE

unsaturated no all single bonds (double or triple)

hydrocarbon (hydrogen and carbon only)

 use general formulas on table Q

47 The reaction between an organic acid and an alcohol produces
(1) an aldehyde   (3) an ether
(2) a ketone        (4) an ester		4acid and alcohol makes an ester and water
4redox= charge changes

look for the reaction with a free element

Mg or H2 in this case

49 A solution with a pH of 2.0 has a hydronium ion concentration ten times greater than a solution with a pH of
(1) 1.0      (3) 3.0
(2) 0.20    (4) 20.		310 time greater has 1 zero, the pH differs by 1

2 is more acidic than 3

50 Which isotope is used to treat cancer?
(1) C-14      (3) Co-60
(2) U-238    (4) Pb-206		3Co-60 just memorize it

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 
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