Lab 2 Instructor Notes

Lab 2: Density of a Sucrose Solution

Remind Students:

  • Goggles MUST be worn whenever ANY group has chemical at their station.
  • DO NOT throw away waste until the end of lab. If students dispose of material too quickly they may not have enough material for Part D.
  • They need a Mass % assigned that is in the table or they will not be able to perform the percent error calculation. Anything higher than 15% takes a while to dissolve.
  • Remind students HOW to wash glassware.
  • Have students lay the graduated cylinder on its side when moving the bin between the cart and their station.
  • All glassware must be cleaned and dry (in their bin) before leaving lab.

When reviewing the protocol explain:

  • Part A: Tare the scale but record the mass of the beaker and all other steps accurately (read the scale to all decimal spaces).
  • Part B: A graduated cylinder may not be as accurate as what we want. This is the part where we determine if when we read “10.0 mL” if it is in fact 10.0 mL.
    • Tare the beaker.
    • Read exactly to 10.0 mL each time.
    • Transfer water completely (if they spill they need to repeat a trial).
    • They must use Table 1 to find the actual volume of water delivered.
    • Obtain the calibrated volume before moving on.
  • Part C: Calculating Density using Math
    • Here they will read the graduated cylinder at 10.0 mL but will use the CALIBRATED volume from Part B to do the measurement.
    • Quantitative transfers are important here.
  • Part D.
    • Specify what you want in your graph.
    • Do not let them tare the beaker!
    • Read exactly to 10.0 mL each time. Their graph will use some multiple of calibrated volumes.
    • Do not remove solution between trials.
    • Check their graphs before they leave.