Re: Of the four, which is most dense? Sugar? Salt? baking soda?or Citric acid?

Jennifer,

     How wonderful that you are having your students answer questions by 
experimentation!  
     I left my copy of the 81st Ed. of the Chemical Rubber Company 
HANDBOOK OF CHEMISTRY AND PHYSICS at school, but from the Cornell 
University Materials Safety Data Sheet (MSDS) site was able to access the 
following density data on the substances you used.  The density of sodium 
chloride (NaCl), A.C.S., reagent grade is 2.163 g/cm3; sodium hydrogen 
carbonate (NaHCO3, AKA: baking soda), A.C.S., reagent grade is 2.159 
g/cm3; sucrose (C12H22O11, AKA: table sugar), A.C.S., reagent grade is 
1.59 g/cm3; and citric acid, anhydrous, U.S.P. grade is 1.54 g/cm3.  So, 
to answer your first question, "Of the four, which is most dense?", the 
answer is sodium chloride.
     As for the solubility, the following data were obtained:  sodium 
chloride, 36g/100gH2O at 0C; sodium hydrogen carbonate, 8.8g/100g H2O, no 
temperature specified (assumed 20-22 C); sucrose, 1g/0.5mL H2O (which is 
1g/0.5g H2O) which is equivalent to 200g/100g H20, no temperature 
specified (assumed 20-22 C); and citric acid, 59.2g/100g H20.  Based on 
the available data the solubility of the four substances, the order from 
least soluble to most soluble is:  sodium hydrogen carbonate, sodium 
chloride, citric acid, and sucrose.
     May I suggest re-designing the experiment so that you have a control 
and controlled variables?  You might want to choose sucrose since it is 
the most soluble.  Set up several containers and add to each of them the 
same volume of water at the same temperature.  To each container add a 
different mass of sucrose and stir until solution is complete.  Then add 
the same egg, in turn, to each until you determine the solution in which 
the egg floats.  Using a hydrometer, measure the density of the solution.