Escience 5: qualitative analysis of ions

pre-lab Questions

1. What is one difference between qualitative and quantitative analysis? 

2. Use Table 1 to determine which metal ion would be identified as the reactant if a reaction with ammonia produces a violet complex? Use scientific reasoning to explain your answer. 

3. Use the pH scale to describe an acidic solution and a basic solution. At what pH would a solution be considered neutral? Why?   

experiment 1: qualitative analysis of reactions

Data Sheet

Table 2: Litmus Test Results of OH- and H+ Solution Type
Initial Litmus Color
Final Litmus Color
Acid or Base? Acetic acid 
Purple 
Red 
Acid  Sodium bicarbonate 
Purple 
Blue 
Base Table 3: Test Results Solution Type
Indicator
Observations Initial
Final Carbonate Ion
Bubble formation when an acid is added 
Clear solution 
Bubbles  Sulfate Ion
White precipitates when barium chloride is added to the   solution. 
Clear solution 
White precipitates  Phosphate Ion
Formation of white precipitate 
Clear solution
White precipitate formed  Calcium Ion
Formation of precipitate 
Clear solution 
Precipitate Table 4: Determination of an Unknown Results
Carbonate Ion Test Tube
Sulfate Ion Test Tube
Phosphate Ion Test Tube Observations
No bubbles observed. Solution remained clear 
No precipitate 
White precipitate formed Result: Positive or Negative?
Negative 
Negative 
positive

Post-Lab Questions

1. What ion is contained in the unknown solution? Use your results as evidence. 

2. Imagine that the unknown solution contains aqueous ammonium sulfate, which is commonly used in fertilizer. Write a balanced equation for the precipitation of barium sulfate after mixing aqueous ammonium sulfate and barium chloride.

 3.  Identify and discuss any sources of error for this experiment. How could you mitigate error?