Mia and Leo are two high school students who are fascinated by acids and bases. They decide to do some experiments with different substances and indicators to learn more about this concept.
They start by collecting some samples of common acids and bases, such as lemon juice, vinegar, baking soda, ammonia, and soap. They use a pH meter to measure the pH of each substance, which is a measure of how acidic or basic a solution is. They also use some universal indicator paper, which changes color depending on the pH of the solution. They record their results in a table:
| Substance | pH | Indicator color |
|-----------|----|-----------------|
| Lemon juice | 2 | Red |
| Vinegar | 3 | Orange |
| Water | 7 | Green |
| Baking soda | 9 | Blue |
| Ammonia | 11 | Purple |
| Soap | 10 | Violet |
They notice that acids have a low pH, bases have a high pH, and water has a neutral pH. They also notice that the indicator paper changes from red to purple as the pH increases. They wonder what would happen if they mixed acids and bases together. They use a graduated cylinder to measure equal volumes of each substance and mix them in different combinations. They measure the pH and the indicator color of each mixture and record their results in another table:
| Mixture | pH | Indicator color |
|---------|----|-----------------|
| Lemon juice + vinegar | 2 | Red |
| Lemon juice + water | 4 | Yellow |
| Lemon juice + baking soda | 7 | Green |
| Lemon juice + ammonia | 9 | Blue |
| Lemon juice + soap | 8 | Green |
| Vinegar + water | 5 | Yellow |
| Vinegar + baking soda | 7 | Green |
| Vinegar + ammonia | 9 | Blue |
| Vinegar + soap | 8 | Green |
| Water + baking soda | 9 | Blue |
| Water + ammonia | 11 | Purple |
| Water + soap | 10 | Violet |
| Baking soda + ammonia | 11 | Purple |
| Baking soda + soap | 10 | Violet |
| Ammonia + soap | 11 | Purple |
They compare the two tables and realize that mixing acids and bases can change the pH of the solution. They also notice that mixing an acid and a base can produce a neutral solution with a pH of 7. They learn that this is called a neutralization reaction, and that it produces water and a salt as products. They also learn that the amount of acid and base needed to reach the neutral point depends on their concentrations and strengths.
Mia and Leo are happy with their experiments and feel that they have learned a lot about acids and bases. They decide to write some questions and answers based on their findings to test their understanding. Here are some examples:
Q: What is the definition of an acid?
A: An acid is a substance that releases hydrogen ions (H+) in water.
Q: What is the definition of a base?
A: A base is a substance that releases hydroxide ions (OH-) in water.
Q: What is the range of the pH scale?
A: The pH scale ranges from 0 to 14.
Q: What is the pH of a neutral solution?
A: The pH of a neutral solution is 7.
Q: What is the name of the paper that changes color depending on the pH of the solution?
A: Universal indicator paper.
Q: What is the name of the reaction that occurs when an acid and a base are mixed together?
A: Neutralization reaction.
Q: What are the products of a neutralization reaction?
A: Water and a salt.