June 2017 Chemistry Regents #72-76

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Question 51-53 Questions 54-57 Questions 58-60 Questions 61-63 Questions 64-65 Questions 66-68 Questions 69-71 Questions 72-76  Questions 77-80  Questions 81-82  Questions 83-85 

 

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Question 72-76

 

 

Base your answers to questions 72 through 76 on the information below and on your knowledge of chemistry.

Fruit growers in Florida protect oranges when the temperature is near freezing by spraying water on them. It is the freezing of the water that protects the oranges from frost damage. When H2O(l) at 0°C changes to H2O(s) at 0°C, heat energy is released. This energy helps to prevent the temperature inside the orange from dropping below freezing, which could damage the fruit. After harvesting, oranges can be exposed to ethene gas, C2H4, to improve their color.

72 Write the empirical formula for ethene. [1]

Answer-->  CH2

73 Explain, in terms of bonding, why the hydrocarbon ethene is classified as unsaturated. [1]

Answer-->  there is a carbon to carbon double bond   or not all single bonds present

74 Determine the gram-formula mass of ethene. [1]

Answer-->  28

75 Explain, in terms of particle arrangement, why the entropy of the water decreases when the water freezes. [1]

Answer-->  liquids are more random than solids

76 Determine the quantity of heat released when 2.00 grams of H2O(l) freezes at 0°C.[1]

Answer-->  Q=mHf=200g x 334J/g=  668J

on to Questions 77-80

 

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 54-57 Questions 58-60 Questions 61-63 Questions 64-65 Questions 66-68 Questions 69-71 Questions 72-76  Questions 77-80  Questions 81-82  Questions 83-85 
 

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