What do you think of when you hear the word reaction?
A response based on a previous situation or event?
None of these thoughts are wrong, but today, we are talking about acid-base reactions. Check out the link below to define exactly what an acid-base reaction is.
- What is an acid-base reaction?
- Why do acids and bases react and what happens when acids and bases react with one another?
- What compound is created from an acid-base reaction?
- Use a Venn Diagram to compare and contrast acids and bases.
Learn more about Acid-Base reactions in this Crash Course video by Hank Green!
Make sure you do this experiment in the kitchen (or other easily cleanable area) or outside, if weather permits.
YOU WILL NEED:
- Baking soda
- Ziplock bag
- One square of paper towel
- Measuring spoons
- Measuring cups
Predict: What do you think will happen when you mix baking soda and vinegar in a sealed plastic bag?
YOU WILL DO
- Double check that your Ziplock bag has no holes. To test this out, fill it up with water and zip it up. If you see a leak, get a new bag.
- Create a “time-release” packet of baking soda.
- Place your paper towel on a flat surface.
- Measure 1.5 Tablespoons of baking soda and dump it in the center of the paper towel.
- Fold the paper towel into a small square so that the baking soda is enclosed and will not leak out the sides.
- Measure 1/2 cup vinegar and 1/4 cup warm water, then pour both into the plastic bag.
- Now, you will need to move quickly! You may need a partner to help you out. You will need to hold your Ziplock bag open and place the time-release packet into the bag. The tricky part is that you need to zip the bag shut immediately after inserting the time-release packet. If you have a partner, have them put the packet in so you can focus on zipping the bag shut.
- Shake the bag up for a few seconds and then place it in the sink (or on the ground, if you’re outside).
- Record your observations!
What exactly happened and why?
Baking soda is a base and vinegar is an acid. When the two mixed together, there was an acid-base reaction! When the reaction occurred, it created carbon dioxide, which is a gas. The gas is what created those bubbles that blew up your Ziplock bag.
Now that you have seen an acid-base reaction first-hand, you are going to try another one. This one will take a little longer to occur, so you won’t be able to watch the whole process.
YOU WILL NEED
- Two eggs
- Two glasses
- Saran wrap
- A soup spoon
YOU WILL DO
- Place one egg carefully inside each glass.
- Pour enough vinegar to cover both of the eggs. You should see bubbles form on the eggs’ shells. Why?
- Cover both glasses with saran wrap and put them in the refrigerator.
- Wait 24 hours.
Predict: What might the vinegar do to your eggs?
- Use a soup spoon to CAREFULLY scoop the eggs out of the glass. What do they look like so far?
- Dump the vinegar into the sink and then place the eggs back into the glasses.
- Fill the glasses with enough fresh vinegar to cover the eggs, and place them back in the fridge for 24 more hours.
- Once again, use a soup spoon to carefully remove the eggs from the glasses.
- What do the eggs look like now?!
The eggshell is made up of calcium carbonate, which is a base. Referring to the experiment you already did with baking soda and vinegar, what do you think happened when you put the eggs into vinegar? Why? How was this experiment similar or different from the one above?
Extension: Learn about Osmosis!
Now that you have two shell-less eggs, let’s try a new experiment with them as an introduction to osmosis.
FIRST: What is osmosis?
An isotonic solution is “at peace.” It has an equal amount of solute outside the cell than inside the cell.
What is solute and what is a solution?
An example of a solution is sugar water. The solute (substance to be dissolved) is the sugar and the solvent (the substance doing the dissolving) is the water.
Basically, a cell within a hypertonic solution will shrink, as the movement of water goes from the cell to the solution. A cell within a hypotonic solution will swell, as the movement of water goes from the solution to the cell. A cell within an isotonic solution will stay the same, as the water moves in and out of the cell equally.
Check this science rap to help you remember these osmosis terms and learn more about where osmosis occurs in real life!
Goal: See what happens when you put an egg in a hypertonic solution versus a hypotonic solution.
YOU WILL NEED
- Two glasses
- Two naked (shell-less) eggs
- Corn syrup
- Soup spoon
CHECK FOR UNDERSTANDING
- Is the corn syrup hypotonic or hypertonic?
- Is water hypotonic or hypertonic?
Predict: How will your two eggs differ after hours?
Here's what to do!
- Place each egg in a clear glass.
- Fill one glass with enough water to cover the egg.
- Fill the second glass with enough corn syrup to cover the egg.
- Place both glasses in the refrigerator for 24 hours.
- Take both glasses out and record your observations.
What do your eggs look like? How do they differ? Why did this happen?
What do you think would happen if you now placed the eggs in opposite solutions? Try it out!
- Put the corn syrup egg in a glass of water and the water egg in a glass of corn syrup.
- Place in the refrigerator. What do they look like after 24 hours?
- Record your final results.
CrashCourse, 2013. Acid-Base Reactions in Solution: Crash Course Chemistry #8. Uploaded from Youtube on 8/15/2016. https://www.youtube.com/watch?v=ANi709MYnWg&feature=youtu.be
Openstax, 2016. The process of osmosis over a semi-permeable membrane, the blue dots represent particles driving the osmotic gradient. Image uploaded from Wikimedia Commons on 8/15/2016.
https://upload.wikimedia.org/wikipedia/commons/6/62/0307_Osmosis.jpg File used in accordance with the Creative Commons Attribution-Share Alike 4.0 International license. No changes were made.
LadyofHats, 2007. Effect of different solutions on blood cells]]. Image uploaded from Wikimedia Commons on 8/15/2016.
https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Osmotic_pressure_on_blood_cells_diagram.svg/553px-Osmotic_pressure_on_blood_cells_diagram.svg.png File released into the Public Domain.
Sciencemusicvideos, 2013. Osmosis! Rap science music video. Uploaded from Youtube on 8/14/2016. https://youtu.be/HqKlLm2MjkI