1. As I write this test the sidewalk between my house and garage is covered with
ID: 712913 • Letter: 1
Question
1. As I write this test the sidewalk between my house and garage is covered with at least 6 inches of snow. If I did my math correctly this amounts to about 255 kg of water. How much heat energy will it take to melt 255 kg of snow (solid water) at -18 C to make it liquid water at 5°C? Some constants you may (or may not) need: Specific heat capacity of solid water. 2.108 kJ/kg Specific heat capacity of liquid water: 4187 kJ/kg HFus water: 6.01 kJ/mol AH vap water 40.65 kJ/mol 2. Which of the two liquids has the.... (circle one) Higher boiling point Why? Lower freezing point Why? Lower viscosity CH,CH,CH, or CH,CH2OH CH,CH CH or CF,CF CF CH,OHCHOHCH,OH or CH,CH,CH Why? Higher surface tension CH,COCH, or CH,CH CH2OH Why?Explanation / Answer
Ans 1 . Heat needed = Heat required to bring ice from -18 to 0 + Heat required to convert ice to water at 0 + Heat required to bring water from 0 to 5
= 255*2.108*(0-(-18)) + 255*6.01+255*4.187*5 = 1254815 kJ
Ans 2 a) CH3CH2OH has a higher boiling point because it has hydrogen bonding forces,whereas CH3CH2CH3 has only dispersion forces
b) Ch3Ch2CH3 will have a lower freezing point as force present is only London Dispersion forces while in the latter , ionic forces are present
c) As intermolecular force increases , viscosity increases . So, Ch3Ch2Ch3 has lower viscosity
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