Chemistry of pH Lab

Objectives of this Lab: The student will be able to recognize an acid and a base on the PH scale. The student will be able to read litmus and PH paper. 2

Common items –vinegar, hand sanitizer, fizzing antacid tablets, apple juice, baking soda, grapefruit juice, Red Litmus Paper Blue Litmus Paper 3 Lab Materials Used:

Procedures for this lab: Label your plastic cups #'s 1-6 Choose one solution and pour a small amount into plas tic cup #1. Write the name of the solution in your data table. Place a drop of the solution onto red and then blue lit mus paper. Record results State whether each solution is an acid or a base. 4

Data: 5 Name of SubstancePH Hypo- thesis Check One Red to Blue Blue to Red No Change AcidBaseNeutral

0-2 Most acidic lemon juice 3-4 apple, vinegar, tomato 5- banana 6- Milk 7-Neutral water 8- blood 8-9 baking soda soap ammonia Most basic drain cleaner 6

How to Understand Litmus Paper Red Litmus Paper Results Red paper turns blue (you are working with a base) Red paper stays red (not a base) *If there is no color change, then you have a neutral substance. Blue Litmus Paper Results Blue paper turns red (you are working with an acid) Blue paper stays blue (not an acid) 7

Analysis Questions 1. Arrange the substances you tested on the pH scale by putting them in order from 0 to When the pH of a substance is taken, what is actually being done? 3. Stomach acid’s ph is between 2 and 3. Is this an acid or a base? 8

pH of Acids and Bases Use the internet or other resources to find the pH of each of the 6 substances. Record the pH of each substance in the second column of your table. 9

How to write your conclusion First paragraph: restate the objectives, materi als, and procedures used in this lab. Second paragraph: discuss the results from the lab (mention all values on the data table). Third paragraph: Describe what the pH scale is and what it is used for. Include as well the common items on the scale. DUE NEXT CLASS NO EXCEPTIONS! 10