You are provided with five vials (labelled A, B, C, D or E) that could contain 0.5 M solutions of ca — Qualitative Analysis Chemistry Question
Problem Context
You are provided with five vials (labelled A, B, C, D or E) that could contain 0.5 M solutions of calcium chloride, sodium carbonate, sodium chloride, sodium hydroxide, or sulfuric acid. Determine which solution is in which vial.
Give a brief description of your experimental plan.
Model Answer
- A systematic plan to mix the solutions together to see if a reaction occurs
- Indication of observations to look for (i.e. precipitation, heat evolution, bubbling, or no change)
Record your data and other observations.
Model Answer
- Clear table indicating the mixtures created and the observations made.
- Solutions should be mixed systematically together.
Sample Data
The identification of the solutions in the vials is:
Solution A ___________________________________________
Solution B ___________________________________________
Solution C ___________________________________________
Solution D ___________________________________________
Solution E ___________________________________________
Model Answer
1 points for each correct identification.
Solution A ____sodium chloride_________________________
Solution B ____calcium chloride_________________________
Solution C ___sodium carbonate__________________________
Solution D ___sulfuric acid__________________________
Solution E ___sodium hydroxide_________________________
Write appropriate net ionic equations for reactions that you utilized to identify the solutions in the vials.
Model Answer
Ca2+ (aq) + CO3 2- (aq) → CaCO3 (s)
Ca2+ (aq) + 2 OH- (aq) → Ca(OH)2 (s)
CO3 2- (aq) + 2 H+ (aq) → CO2 (g) + H2O (l)
H+ (aq) + OH- (aq) → H2O (l) + heat
Precipitation reactions to form insoluble carbonate and hydroxide
* CaCl2 (aq) + Na2CO3 (aq) → CaCO3 (s) + 2NaCl (aq)
* CaCl2 (aq) + 2 NaOH (aq) → Ca(OH)2 (s) + 2 NaCl (aq)
* No reactions with NaCl as chlorides are soluble except for AgCl, PbBr2, and Hg2Cl2
* No precipitation reactions with H2SO4 as most sulfates are soluble except BaSO4, PbSO4, Ag2SO4 and SrSO4
Acid-base reactions
* Neutralization reactions between H+ and OH- do not exhibit a visible change, except possible detection of heat, that can be noted without an indicator
* Na2CO3 reacting with an acid would result in the evolution of carbon dioxide – fizzing
Na2CO3 (aq) + H2SO4 (aq) → Na2SO4 (aq) + CO2 (g) + H2O (l)