Have you ever tasted lemon juice and scrounged up your face, because it was too sour? Or enjoyed a refreshing drink of water and wondered why these two liquids are different? You can use this pH Explorer set to test different solutions in your home and learn about liquid chemistry.
What you'll need:
All of the things in our world are made from small particles called atoms. There are many different types of atoms (see Periodic table of elements to learn more), and sometimes they combine with other atoms to make molecules. It is similar to different ingredients combining to create various foods. Water is a molecule made from two Hydrogen atoms and one Oxygen atom (H2O). In certain conditions a Hydrogen atom separates from a water molecule, resulting in two ions, or charged atoms/molecules. Hydrogen will maintain a positive charge (H+), while the remaining molecule (OH-) carries a negative charge. The activity of H+ ions is measured on a pH scale, generally measured in a range of 1-14. A pH < 7 is considered acidic, pH = 7 is neutral, and a pH ˃ 7 is considered basic/alkaline.
Do all of the experiment with a parent present. Some of the household solutions may be dangerous. Make sure you perform the experiment where spills can be easily contained and cleaned up.
- Gather your materials. You will need the provided beakers, litmus paper strips, and the solutions you want to test. Suggested solutions are: water, orange/lemon juice, milk, coffee, vinegar, baking soda (dissolved in water), soap solution, soda/pop, rubbing alcohol.
- Predict which solutions will be acidic and which will be basic.
- Draw a line with a scale from 0-14 on a large piece of paper. Predict where your solutions will fit on this scale and label their names along this scale.
- Pour a little bit of each solution in a beaker and test it with the litmus test strips. Red litmus test paper will turn blue in basic/alkaline solution. The deeper blue color indicates that the solution is more basic. (If you are using blue Litmus paper keep in mind that it will turn red in acidic solutions. The deeper red it turns the more acidic your solution). Keep track of your litmus paper results by taping the papers next to the correct label.
- If you are re-using the beakers, clean and dry the beakers thoroughly for accurate results.
- On a new piece of paper, draw a corrected scale reflecting your results. Were your predictions accurate? Was there a result that surprised you?
- Explore other questions with this activity: How does the temperature of the solutions change their pH? What happens when you combine acidic and basic solutions?
pH is an important characteristic of chemicals. Not only it is interesting to study, but living organisms need specific pH environment to survive. For example, acidification of the oceans affects the ocean animals.