Empirical formula Lab

 

background [prelab assignment (20 points); due at the beginning of the lab]

  1. in this lab, you will be given a hydrated copper chloride compound with the chemical formula:  Cu Cl x * Y H2O.  based upon the below materials, design an experiment to determine X & Y.
  2. define / describe the term, gravimetric analysis
  3. sketch a data table (i.e. not calculations) for this lab containing entries for all required experimental measurements (i.e. review purpose & content of lab report)
  4. MSDS data on silver nitrate

 

purpose

identify the metal in the compound, i.e. Cu+ or Cu++

determine the empirical formula of the sample (a hydrated metal chloride)

 

materials

~ 1.5 g of hydrated copper chloride

balance; watch glass; flask; test tube holder

hot plate

water; 25 mL 1.0 M silver nitrate (forms a precipitate, AgCl, with any chloride containing soluble ionic compound; assume that sliver nitrate is the excess reactant)

filter paper / funnel

 

methods / data analysis

gentle heating of chemical (i.e.  form brownish solid, not blackish liquid); otherwise, could produce chlorine gas

student design

 

 

Content of lab report [30 points]

data analysis  [15 points]

data table of your experimental measurements

determination of the compound's empirical formula - based on your group's data (show your work)

error analysis: no effect ?  underestimate ?  overestimate ?  [15 points]

effect of insufficiently heating the hydrated sample on the determination of the sample's water content.   justify your response.

effect of overheating the hydrated sample on the determination of the samples' chloride content.  justify your response.

effect of copper chloride versus silver nitrate being the limiting reactant on the determination of the sample's chloride content and subsequent determination of its copper content.  justify your response.

effect of insufficient drying the silver chloride on the determination of the sample's chloride content and subsequent determination of its copper content  (assume the filter paper is completely dried)   justify your answer.

the (hydrated copper chloride and / or the dehydrated copper chloride) sample may be "hygroscopic"  - what is the effect on your results ?  be specific & justify your response; include a definition of the term; there are 3 cases to describe. 

resources:

lab activity source (examples):  site 1  [access 4 / 2009]

heat suspension rationale