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