Analysis of Acids, Bases, Ph and Salt

Billy Kong
Chem&163
Lab Report 1
Analysis of Acids, Bases, pH and Salt

Purpose:
Explore various methods for determining the characteristics of acid/base solution. The goal of this experiment include the investigation of various acid/base indicators, calculating the change of pH with concentration, change of pH due to the addition of salt and different between strong and weak acids/bases.

Safety and Disposal:
Use extreme caution when handling concentrated acids and bases. Dispose of all solutions as directed by the instructor. Wear goggles at all times.

Part 1 observation:
In part 1, we obtain 10mL of each of the solutions. First, we test each solution with the pH meter. We found that the acidic solution has a lower pH value than the water, which is lower than 6.23 and the based solution has a higher pH value than the water, which is around 7.75 and higher. After that, we tested the solution with the Red and Blue Litmus paper. With acidic solution, the Red litmus paper will remain no change, and the Blue litmus paper will change from blue to red. With based solution, the Red litmus paper will change from red to blue; however, the Blue litmus paper will remain unchanged. We also used the pH paper to test the solutions. With acidic solution, the pH value is low and the colors are properly around pink and red. On the other hand, the based solution has a high pH value and the color is usually purple. Next, we added PHEN indicator to the solutions. The acidic solutions will remain no changed but the based solutions will change from colorless to pink. Finally, we added BTB indicator to the solutions. The acidic solutions will change from colorless to yellow, and the based solutions will remain unchanged.

Table 1:
|Solution |pH level from pH |Color from Red |Color from Blue |pH paper color |Color change with|Color change with|
| |meter |Litmus |Litmus |AND pH level |PHEN indicator |BTB indicator |
|H2O |6.23 |No change |No change |Orange 7 |No change |Colorless to |
| | | | | | |Green |
|HNO3 |1.53 |No change |Blue to Red |Pink 1 |No change |Colorless to |
| | | | | | |yellow |
|NaOH |7.75 |Red to Blue |No change |Purple 11 |Colorless to pink|Colorless to blue|
|KHP |3.93 |No change |Blue to Red |Orange 4 |No change |Colorless to |
| | | | | | |yellow |
|NH4OH |10.75 |Red to Blue |No change |Purple 11 |Colorless to pink|Colorless to blue|
|HC2H3O2 |1.58 |No change |Blue to Red |Red 2 |No change |Colorless to |
| | | | | | |yellow |
|HCl |1.31 |No change |Blue to Red |Pink 1 |No change |Colorless to |
| | | | | | |yellow |
|H2SO4 |2.22 |No change |Blue to Red |Red 2 |No change |Colorless to |
| | | | | | |yellow |
|KOH |12.43 |Red to Blue |No change |Purple 12 |Colorless to pink|Colorless to blue|
|Ca(OH)2 |10.88 |Red to Blue |No change |Purple 11 |Colorless to pink|Colorless to blue|
|H2C2O4 |1.41 |No change |Blue to Red |Pink 1 |No change |Colorless to |
| | | | | | |yellow |

Part 2 observation:

Table 2:
|Solution |pH paper color AND pH |pH level from pH meter |[H+] |Ka |
| |value | | | |
|#1 (0.1M) |3 Orange |3.43 | | |
|#2 (0.01M) |3 Orange |3.65 | | |
|#3 (0.001M) |3 Orange |3.8 | | |
|#4 (0.0001M) |4 Orange |4.01 | | |
|#5 (0.1M with 0.05g |4 Orange |4.91 | | |
|salt) | | | | |
|#5 (0.1M with 0.2g salt)|5 Orange |5.4 | | |

Part 3 observation:

Table 3:
|Salt |pH paper color AND pH level |pH level from pH meter |[H+] |
|Calcium acetate |8 Green |8.43 | |
|Ammonium Chloride |5 Orange |5.28 | |
|Sodium Bromide |4 Orange |3.88 | |
|Sodium Carbonate |12 Purple |12.11 | |
|Sodium Chloride |4 Orange |4.53 | |
|Potassium Chloride |10 Blue green |10.55 | |

Questions:

Problems & Errors:
Observation of pH paper color may not exactly accurate.
The pH level from pH meter may have a bit not accurate because of not washing the sensor clearly.

Learning:
Learn the color change in different solution, the various acid/base indicators, calculating the change of pH with concentration, change of pH due to the addition of salt and different between strong and weak acids/bases.