Qualitative Analysis Of Cations Lab Report

CH 204 - Introduction to Chemical Practice
Experiment 2 - Qualitative Analysis of Cations

Petra Hsia
Stefi Hsia
TA: Joey Gurrentz
February 8, 2018

RESULTS & DISCUSSION
In Part A of the experiment, the presence of silver was confirmed by the "Unknown 4" substance. It was discovered with two rounds of testing. In the first round, two drops of 6M acetic acid and 4 drops of 1M K2CrO4 was added to the "Step 6" test tube, the solution turned a yellow-orange color. Because there was no formation of yellow precipitate, it was confirmed that lead was not present in the solution. Since lead was not present, the "Part A" test tube, which contained precipitate from the "Unknown 4" substance, was now to be tested for the presence of silver. The "Part A" test tube 's precipitate was first washed with deionized water to remove any contaminants. When 2 mL of 6M NH4OH was added, white precipitate deposited at the bottom of the test tube. After centrifuging the "Part A" test tube, the liquid was poured into a clean

KCl was discovered by dipping a wooden stick into the "Unknown 4" solution and then held in a fire. The stick with the solution let off a flame that was colored. The result was reasonable and expected because the color of the flame let off by the "Unknown 4" solution was lavender in color, which is color that is let off in the presence of KCl. These flame tests were used to identify the cations present in different solutions. Each cation gave off a very distinct color, which helped identify the presence of a cation in each solution. However, the main restriction in using a cation flame test is that if there were to be multiple cations in one solution, the color of the flame may be muddled up, which makes it hard to determine which specific cations are present in the solution.

Table 1. Colors given off by each cation during the flame test
Flame Test
Solution: Color of