January 2015 Chemistry Regents #73-75

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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 51-53 Questions 54-55
 Questions 56-58 Questions 59-61 Questions 62-63 Questions 64-65 Questions 66-68 Questions 69-72  Questions 73-75  Questions 76-78  Questions 79-81 Questions 82-85

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Questions

 

  Base your answers to questions 73 through 75 on the information below.

Seawater contains dissolved salts in the form of ions. Some of the ions found in seawater are Ca2+, Mg2+, K+, Na+, Cl-, HCO3-, and SO4 2-. An investigation was conducted to determine the concentration of dissolved salts in seawater at one location. A 300.-gram sample of the seawater was placed in an open container. After a week, all the water had evaporated and 10. grams of solid salts remained in the container.

73 Determine the concentration, expressed as percent by mass, of the dissolved salts in the original sample of seawater. [1] -

Answer==>3.3%

74 At standard pressure, compare the freezing point of seawater to the freezing point of distilled water. [1]

Answer==>Water has a higher freezing point than seawater.

75 Explain why the evaporation that occurred during the investigation is an endothermic process. [1]

Answer==>Energy is required to change liquid water to water vapor.

 

on to Questions 76-78 

 

 
 

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 56-58 Questions 59-61 Questions 62-63 Questions 64-65 Questions 66-68 Questions 69-72  Questions 73-75  Questions 76-78  Questions 79-81 Questions 82-85

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