August 2006 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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41 An unsaturated aqueous solution of NH3 is at 90.C in 100. grams of water. According to Reference Table G, how many grams of NH3 could this unsaturated solution contain?
(1) 5 g     (3) 15 g
(2) 10. g (4) 20. g
1 NH3 would be saturated with 10 grams. Unsaturated is less than 10g.
42 How many total moles of KNO3 must be dissolved in water to make 1.5 liters of a 2.0 M solution?
(1) 0.50 mol (3) 3.0 mol
(2) 2.0 mol (4) 1.3 mol
3 M=mol/L; mol= M/L=2.0/1.5
43 Which statement explains why low temperature and high pressure are required to liquefy chlorine gas?
(1) Chlorine molecules have weak covalent bonds.
(2) Chlorine molecules have strong covalent bonds.
(3) Chlorine molecules have weak intermolecular forces of attraction.
(4) Chlorine molecules have strong intermolecular forces of attraction.
3 Cl2 is nonpolar and have weak intermolecular forces

van der waals

44 Given the balanced equation representing a reaction:
CH4(g) + 2O2(g) --> 2H2O(g) + CO2(g) + heat
Which statement is true about energy in this reaction?
(1) The reaction is exothermic because it releases heat.
(2) The reaction is exothermic because it absorbs heat.
(3) The reaction is endothermic because it releases heat.
(4) The reaction is endothermic because it absorbs heat.
1 heat is on the right of the arrow, it is exothermic and releases heat
45 Given the reaction at equilibrium:
N2(g) + 3H2(g) -->2NH3(g) + 91.8 kJ
What occurs when the concentration of H2(g) is increased?
(1) The rate of the forward reaction increases and the concentration of N2(g) decreases.
(2) The rate of the forward reaction decreases and the concentration of N2(g) increases.
(3) The rate of the forward reaction and the concentration of N2(g) both increase.
(4) The rate of the forward reaction and the concentration of N2(g) both decrease.
1 LeChaterliers Principle, add a reactant it shifts right, reactants decrease [H2] and products increase.
4 Potential Energy Diagrams

Difference in products and reactants is Delta H

Arrow 4

 

47 Based on bond type, which compound has the
highest melting point?
(1) CH3OH     (3) CaCl2
(2) C6H14          (4) CCl4
3 The Ionic One  (Metal and Nonmetals)

the other 3 are covalent (made of all nonmetals)

1 (Mass x %) x (mass x %) / 100%

they distributed the  divide by 100

49 Which list of the phases of H2O is arranged in order of increasing entropy?
(1) ice, steam, and liquid water
(2) ice, liquid water, and steam
(3) steam, liquid water, and ice
(4) steam, ice, and liquid water
2 Entropy is Randomness, increase from

Solid to liquid to gas

50 Solution A has a pH of 3 and solution Z has
a pH of 6. How many times greater is the
hydronium ion concentration in solution A than
the hydronium ion concentration in solution Z?
(1) 100 (3) 3
(2) 2 (4) 1000
4 for each pH value it is 10x's more concentrated

3 pH units 1000 xs

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

 
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