Escience: Qualitative Analysis of Ions

  

pre-lab Questions

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

Answer. Qualitative and quantitative analysis differ in that qualitative analysis is based on the properties and attributes of an item while quantitative analysis is based on computable values of an item or individual. 

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. 

Answer. The metal ion is Nickel ion. This is because the reaction between nickel ion and ammonia produces a violet color of transition of nickel complex.

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

Answer. An acidic solution has a PH of below 7 in a PH scale while a basic solution i has a PH above 7. A neutral solution has a PH of 7. This is because at a PH of 7, a solution cannot be regarded as either acidic or basic. 

  

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?