Name: ___Charis Betts_________ Date: ________________ !Biology 12 Unit 1 Assignment 1: pH Virtual Lab !

Instructions: Please complete the pH Virtual Lab . External Link: http://www.glencoe.com/sites/common_assets/science/virtual_labs/E22/E22.html !Read the information and procedures provided in the lab and complete both the table and journal questions (provided below). Please note you should be answering your questions in detail, by providing support in the form of data values (external or from the lab) and scientific information/research to explain your statements. !Table/Graph Section: !Table 1: ___Predictions and Actual pH Values of Common Items___ !

!!Journal Questions: !

1. What facts did you us to predict the pH values of the solutions? How did you predict pH values for each of the common solutions compare with the actual pH values for those solutions?

To predict the Ph values of the solutions I thought about what I knew about each solution. Battery acid and stomach acid have the words acid in them, so I knew they would be on the acidic side of the scale. However, I knew that battery acid would be more acidic than stomach acid because stomach acid exists inside our body while battery acid is a corrosive substance, so I chose to estimate battery acid slightly more acidic than stomach acid. I know that vinegar in an acid, and while also ingestible, is not as acidic as stomach acid, but based on it’s sour taste I decided to estimate a pH somewhat close to stomach acid. I knew, based on the name, that

Solutions Predicted pH Value Actual pH Value Type of Solution

Battery Acid 3 1 Acid

Antacid 10 10 Base

Vinegar 6 3 Acid

Stomach Acid 4 2 Acid

Soft Drinks 6 3 Acid

Shampoo 9 5 Acid

antacid is a base because it’s “against” acid, and is used as a medicine to counteract stomach acid, so I knew it must be quite basic. I estimated correctly a pH level of 10. Because soft drinks go inside our body and aren’t used as a kind of medicine, I thought they would be quite a weak acid, so I estimated 6. In fact, soft drinks have a pH of 3, making them much more acidic than I thought. I guessed that shampoo was a base, but it’s actually an acid with a pH level of 5. In general, my estimates were mainly correct when referring to acids V. bases, however I was quite far off in the precise levels of pH for each substance. !

2. Of the six solutions you tested, which one was the most acidic? Which one the most basic? Which one was the closest to neutral? Of the six solutions I tested, the battery acid was the most acidic at a pH of 1, antacid was the most basic at a pH of 10, and shampoo was the closest to neutral at a pH of 5. !

3. Milk of magnesia is sometimes used as a remedy for an acid stomach. Would you expect the pH of milk of magnesia to be less than 7, more than 7, or 7? Why? I would expect the pH of milk of magnesia to be more than 7 because the presence of stomach acid cannot be fixed by adding more acid, so it must be a base. !

4. What are some real-world applications in which pH is an important factor? !pH is an important factor in oceans and lakes. Most living organisms underneath depend on water to survive, therefore if the pH were to change, it would affect the overall health of said organisms, because a change in pH would occur inside their systems, rendering them sick. !pH is importance in our stomachs. If the pH changes, enzymes that normally break down ingested foods would denature, therefore they will not be able to function and thus we wouldn’t be able to digest food properly and could become ill. !The normal pH of human blood is slightly basic at 7.4. If an individual is having trouble breathing, carbon dioxide builds up in the blood stream and changes the pH, leading to acidosis(blood becomes too acidic), thus rendering the person very sick.