January 2017 Chemistry Regents #69-72

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 #69-72
  

A solution of ethylene glycol and water can be used as the coolant in an engine-cooling system. The ethylene glycol concentration in a coolant solution is often given as percent by volume. For example, 100. mL of a coolant solution that is 40.% ethylene glycol by volume contains 40. mL of ethylene glycol diluted with enough water to produce a total volume of 100. mL. The graph below shows the freezing point of coolants that have different ethylene glycol concentrations.

69 Explain, in terms of particle distribution, why a coolant solution is a homogeneous mixture. [1]

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All particles are uniformly dispersed.

70 Explain, in terms of the molecular polarity, why ethylene glycol dissolves in water to form a solution. [1]

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Water molecules and ethylene glycol molecules are both polar

71 Identify the percent by volume of ethylene glycol in a solution that freezes at -10.C. [1]

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any answer from 21 to 23%

72 One engine-cooling system has a volume of 6400 mL. Determine the volume of ethylene glycol in the completely filled engine-cooling system when the concentration of ethylene glycol is 50.% by volume. [1]

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3200mL
  

on to Questions 73-77

  

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 51-53 Questions 54-55
 Questions 56-57 Questions 58-59 Questions 60-61 Questions 62-65  Questions 66-68  Questions 69-72  Questions 73-77 Questions 78-79 Questions 80-82 Questions 83-85