virtual lab: analysis of sodium compounds in a sample [25 poitns; 5 points / question in purple]

 

This laboratory activity is based on investigation 7 in your AP chemistry lab manual and handout to the in-person lab to determine the % composition of sodium bicarbonate and sodium carbonate in a mixture of these two chemicals based on the change in the mass of the mixture upon heating the mixture. Unfortunately, it provides minimal background / support.

assume that heating a mixture of sodium bicarbonate and sodium carbonate would only affect the former compound and it is described by the following chemical equation:

2 NaHCO3(s)    →   CO2(g) + H2O(g) + Na2CO3(s)    [reaction 1] or

2 NaHCO3(s)   →   Na2O(s) + 2 CO2(g) + H2O(g)     [reaction 2]

questions:

1. while viewing the video 1 (~ 7" duration), record your observations / data. provide observations / calculations to identify which reaction describes the results in the video. hint: video 2 (~ 14" duration)

2. Based on the results of the precding analysis, determine the % NaHCO3 and % Na2CO3 in a 4.622 g mixture of sodium bicarbonate and sodium carbonate, which was heated, where 3.189 g of the mixture remains. ? show your work.

error analysis: assume that reaction 2 does not happen upon heating sodium bicarbonate and what is the basis / rationale of your answer to the following questions:

3. in video 1, it mention that you should repeatively heat the sample and record the data - why ? what is the possible consequence of insufficient heating on your determination of % NaHCO3 and Na2CO3 in your sample ?

4. rather having an initial sample of sodium bicarbonate and sodium carbonate, it was contaminated with sodium chloride. what is the possible consequence on your determination of % sodium carbonate and sodium bicarbonate in your sample ?

5. what is the effect of a sample containing hydrated sodium carbonate (ref ) rather than anhydrous compound (hint: you'll need to know the definition of these terms, so define the term in your answer)