CHM 2045C Module Two Sample Exam ANSWERS

Module Two: Part G Temperature Conversion     8 points

The general formula for the conversion of temperatures on scale X to temperatures on scale Y is:

oY   =     y units/ x units ( oX - RPx)   +   RPy

convert -196oC to oF

oF  =  9 Funits/ 5 Cunits [ oC – (-40)]  +   (-40)

oF     =  9/5 (-196 + 40) – 40  = 9/5 (-156) – 40   =  - 280.5 -40  = -320.5  oF

convert -196oC to K

K  = oC + 273

K  = oC + 273 = -196 + 273  = 77 K

The Rankin scale uses a Fahrenheit unit, but assumes zero to be absolute zero.  If absolute zero on the Kelvin scale is zero and on Celsius scale is -273oC, calculate absolute zero on the Fahrenheit scale, then estimate the Freezing point of water on the Rankin scale. (The BP water=212 oF=100 oC=373K= ?R)

oF  =  9 Funits/ 5 Cunits [ oC – (-40)]  +   (-40)

oF     =  9/5 (-273 + 40) – 40  = 9/5 (-233) – 40   =  - 419.4 -40  = -459.4  oF

absolute zero on Rankin =  0 R equates to -459.6 oF therefore:

oR  =  1 Runits/ 1 Funits [ oF – (-459.4)]  +   0

oR  =  1 / 1 [  32oF – (-459.4)]  +   0 = 32 + 459.4 = 491.4 oF

Module Two: Part H Density/Specific Gravity Calculations     8 points

A 25.0-mL sample of liquid bromine has a mass of 78.0 g.   What is the density of bromine?

Density = mass/volume = 78.0 g / 25.0 mL = 3.12 g/mL

If a sugar solution weighs 4.678 gram and has a volume of 4.670 ml, calculate the density of the solution.

Density = mass/volume = 4.678 g / 4.670 mL = 1.0017 g/mL = 1.002 g/mL