August 2015 Chemistry Regents #51-54

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Questions 51-54 Questions 55-57 Questions 58-59 Questions 60-61 Questions 62-65 Questions 66-68 Questions 69-72 Questions 73-74  Questions 75-76  Questions 77-78  Questions 79-80  Questions 81-82  Questions 83-85

 

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Questions 51-54

 

 

51 Determine the vapor pressure of ethanol at 90.C. [1]

Answer--> 150kPa + or -2kPa

(Table H)

52 Explain, in terms of particle arrangement, why a sample of solid NaCl has less entropy than a sample of aqueous NaCl. [1]

Answer-->)Particle arrangement in NaCl(s) is less random.

53 Determine the molecular formula for a compound that has the empirical formula CH2O and a molar mass of 120. grams per mole. [1]

Answer-->C4H8O4

Work (not required)

CH2O => 12+2+16=30g/mol

120/30= 4......4 x CH2O=C4H8O4

54 A student drew the Lewis electron-dot diagram below to represent sodium chloride.

Explain why this diagram is not an accurate representation for the bonding in NaCl. [1]

Answer-->Ion charges are not shown.

That is a molecular structure and NaCl is ionic.

 

Next-->Questions 55-57

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

Questions 51-54 Questions 55-57 Questions 58-59 Questions 60-61 Questions 62-65 Questions 66-68 Questions 69-72 Questions 73-74  Questions 75-76  Questions 77-78  Questions 79-80  Questions 81-82  Questions 83-85

 

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