June 2010 Chemistry Regents #59-61

Highlight to reveal answers and explanations

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

Questions

Base your answers to questions 59 through 61 on the information below.

Heat is added to a 200.-gram sample of H2O(s) to melt the sample at 0°C. Then the resulting H2O() is heated to a final temperature of 65°C.

59 Determine the total amount of heat required to completely melt the sample. [1]

 ANSWER= 66 800 J   or   6.68 × 104 J NOTE=the question was only asking for the energy to melt Q=mHf Q=200g(334J/g)

60 In the space in your answer booklet, show a numerical setup for calculating the total amount of heat required to raise the temperature of the H2O() from 0°C to its final temperature. [1]

 Just the setup (DON'T ANSWER IT) Q=mCDT q = (200. g)(4.18 J/g•°C)(65°C) (200)(4.18)(65)

61 Compare the amount of heat required to vaporize a 200.-gram sample of H2O() at its boiling point to the amount of heat required to melt a 200.-gram sample of H2O(s) at its melting point. [1]