June 2014 Chemistry Regents #16-20

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Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Question 51-54 Questions 55-56 Questions 57-58 Questions 59-61 Questions 62-65 Questions 66-69 Questions 70-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

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Questions

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Explanations

16 Which change results in the formation of different substances?

(1) burning of propane

(2) melting of NaCl (s)

(3) deposition of CO2(g)

(4) solidification of water

1 link phases changes do not result in a different substance.

Chemical reactions do.

17  Which substance can not be broken down by a chemical change?

(1) ammonia      (3) propanal

(2) ethanol        (4) zirconium

4 link definition of an element

zirconium is an element

18 According to Table I, which equation represents a change resulting in the greatest quantity of energy released?

(1 ) 2C(s) + 3H2 (g) C2H6(g)

(2) 2C(s) + 2 H2 (g) C2H4(g)

(3) N2 (g) + 3 H2 (g) 2NH3(g)

(4) N2 (g) + O2(g) 2NO(g)

3 link release is exothermic

so DH is negative

and has the largest number

 

19 Which clement is a liquid at STP?

(1) bromine (3) francium

(2) cesium (4) iodine

1 link bromine is a liquid

see the melting point on table S

20  Which statement describes a reversible reaction at equilibrium?

(1) The activation energy of the forward reaction must equal the activation energy of the reverse reaction.

(2) The rate of the forward reaction must equal the rate of the reverse reaction.

(3) The concentration of the reactants must equal the concentration of the products.

(4) The potential energy of the reactants must equal the potential energy of the products.

2 link at equilibrium concentrations are constant and rates are equal

Con Con REqual

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Question 51-54 Questions 55-56 Questions 57-58 Questions 59-61 Questions 62-65 Questions 66-69 Questions 70-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

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