PH Lab

Topics: PH, Acid, Water Pages: 7 (1633 words) Published: November 5, 2013
Lab Report:

Purpose:

The Objective of this lab was to learn how to measure the pH (or acidity) of commonly known fluids, using the correct tools and procedures. To then use that data to document the changes noticed when mixing those same fluids and changing their respective pH levels.

Materials:

In order to conduct this experiment several pieces of equipment and other materials were needed. The first item was a graduated cylinder, which was used in order to measure out the precise amount of fluids needed in the experiment. A 100mL glass beaker was used to house the measured fluids for pH testing as well as for mixing (requiring a stir). An already calibrated pH meter was used to test the levels of pH in each solution. A hammer, paper towel and Rolaid tablet were also provided and used to crush up the antacid tablet. In addition to these few pieces of equipment, specifically measured amounts of the following fluids/substances were used: tap water, distilled water, soda, milk, lemon juice, and dissolved Rolaid solution (mix of an antacid tablet and 50mL of distilled water).

Method:

The subsequent steps were used to preform the pH measuring experiment: My group, comprised of six students, gathered the required equipment from our lab TA – one graduated cylinder, four beakers, hammer, paper towel, Rolaid tablet, a stir and a pH meter. Each of the four beakers and the graduated cylinder were rinsed using tap water before any liquids were poured into them. One group member filled the graduated cylinder with 50mL of tap water and then transferred the liquid into a beaker. This process was repeated for soda, distilled water and milk. The pH meter was turned on, placed in each beaker and remained until the numbers on the tools screen stopped flocculating. Each reading was then documented on the provided data sheets. The beaker containing the tap water was emptied. Using a clean graduate cylinder 10mL of lemon juice and 40mL of water was measured out and added to a beaker. The liquids were combined and measured for their pH level. Next a Rolaid tablet was wrapped in a paper towel, crushed with a hammer and added to the beaker containing distilled water. Each new solution was measured and recorded. The mixed solutions were used for the next portion of our experiment. Using a clean graduated cylinder, 10mL of the antacid solution was added to the soda beaker, mixed and the pH level was measured. This process was repeated twice, adding an additional 10mL each time. Using the beaker containing milk, the same experiment was carried out using the lemon juice mixture. 10mL of lemon juice mixture was measured, added to the milk beaker, mixed and measured for pH levels. This process was repeated twice, once again adding an additional 10 mL of the diluted lemon juice solution each time.

Results:

Liquid
Initial pH

1. Tap Water
7.29
Weakly Basic
2. Distilled Water
5.66
Weakly Acidic
3. Soda
2.23
Strongly Acidic
4. Milk
6.73
Weakly Acidic
5. Dilute (1:5) lemon juice
2.14
Strongly Acidic
6. Dissolved Rolaid solution
7.40
Weakly Basic

The data in the above table is pretty straightforward. Each liquid was measured and recorded in the appropriate section. Tap water had to be measured twice - original recording was excessively acidic.

Antacid – Soda Solution
mL of Antacid Solution
pH

0
2.23
Strongly Acidic
10
2.93
Strongly Acidic
20
4.61
Weakly Acidic
30
5.03
Weakly Acidic

As expected, Rolaid is an Antacid (designed to naturalize acid) and it raises the pH number of an already acidic solution, making it less acidic. The first box represents just the pH level of soda, as identified in the earlier table. As each additional 10mL of antacid solution was added, the level of acidity begins to neutralize or decrease. The changes appear more drastic after the second 10mL is added.

Lemon Juice – Milk Solution
mL of Dilute
pH...
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