June 2009 Chemistry Regents #41-50

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

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Questions

Answer Explanations
41 Given the balanced equation representing a reaction:
2HCl(aq) + Na2S2O3(aq)--> S(s) + H2SO3(aq) + 2NaCl(aq)
Decreasing the concentration of Na2S2O3(aq) decreases the rate of reaction
because the
(1) activation energy decreases
(2) activation energy increases
(3) frequency of effective collisions decreases
(4) frequency of effective collisions increases
3 reaction=effective collision
42 Given the equation representing a reaction at equilibrium:
H2(g) + I2(g) + heat--> 2HI(g)
Which change favors the reverse reaction?
(1) decreasing the concentration of HI(g)
(2) decreasing the temperature
(3) increasing the concentration of I2(g)
(4) increasing the pressure
2 decreasing a reactant replaces the reactant

temp can be considered "heat"

4 but means 4 carbons

-ene  a double bond

2- the double bond is on the second carbon

44 Given the balanced equation representing a reaction:
Fe2O3 + 2Al--> Al2O3 + 2Fe
During this reaction, the oxidation number of Fe changes from
(1) +2 to 0 as electrons are transferred
(2) +2 to 0 as protons are transferred
(3) +3 to 0 as electrons are transferred
(4) +3 to 0 as protons are transferred
3 redox electrons are transferred
45 Which reaction occurs spontaneously?
(1) Cl2(g) + 2NaBr(aq)-->Br2(l) + 2NaCl(aq)
(2) Cl2(g) + 2NaF(aq)--> F2(g) + 2NaCl(aq)
(3) I2(s) + 2NaBr(aq)--> Br2(l) + 2NaI(aq)
(4) I2(s) + 2NaF(aq)--> F2(g) + 2NaI(aq)
1 Using TABLE J

Cl2 can replace Br2

46 Which sample of HCl(aq) contains the greatest number of moles of solute particles?
(1) 1.0 L of 2.0 M HCl(aq)
(2) 2.0 L of 2.0 M HCl(aq)
(3) 3.0 L of 0.50 M HCl(aq)
(4) 4.0 L of 0.50 M HCl(aq)
2 multiply Molarity and Liters to get moles

 

M=mol/Liters

47 Which change in pH represents a hundredfold increase in the concentration of hydronium ions in a solution?
(1) pH 1 to pH 2     (3) pH 2 to pH 1
(2) pH 1 to pH 3     (4) pH 3 to pH 1
4 Hydronium is H3O+ more acidic pH decreases

100 has 2 zeros pH changes by 2

48 Which indicator would best distinguish between a solution with a pH of 3.5 and a solution with a pH of 5.5?
(1) bromthymol blue     (3) litmus
(2) bromcresol green    (4) thymol blue
2 Table M
49 Given the equation:
HCl(g) + H2O(l)--> X(aq) + Cl--(aq)
Which ion is represented by X?
(1) hydroxide     (3) hypochlorite
(2) hydronium    (4) perchlorate
2 Hydronium is H3O+
50 Which nuclide is used to investigate human
thyroid gland disorders?
(1) carbon-14          (3) cobalt-60
(2) potassium-37     (4) iodine-131
4 Iodide =Thyroid Just memorize it

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

Questions 51-53 Questions 54-57 Questions 58-59 Questions 60-62 Questions 63-65 Questions 66-67 Questions 68-70 Questions 71-73 Questions 74-76 Questions 77-78 Questions 79-83

 
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