Homeschool Space Unit Study: Venus C02 Science Experiments

Our homeschool Space Unit Study is our newest project! If your kids are interested in the solar system or astronomy, you will LOVE what we have been working on!

Today's homeschool space themed science experiments also double as a chemistry lesson!

We are working our way through the solar system with these fun, hands-on space themed science experiments! This is our 2nd Venus themed can see our first one (carbon dioxide and clouds on Venus) here!

Anyway, this experiment shows several things:

1- Carbon dioxide (CO2) is a byproduct of human (and all other animal) metabolism--the air you breathe out is about 5% carbon dioxide.

2- CO2 is acidic.

3- The pH scale is a base 10 (or logorithmic) scale.

4- Indicators (like bromothymol blue) show the pH of a solution.

5- Side note: lemon juice is more acidic than carbon dioxide.

First, a few Venus Fun Facts! (You can see more here!) Venus...

* has an average surface temperature over 800 degrees Farhenheit!
* was named after the Roman goddess of love and beauty!
* has at least 1600 volcanoes--more than any other planet!
* is a planet where a day lasts longer than a year!
* has air pressure 90 times Earth's air pressure--about the same as the water pressure 1/2 a mile under the ocean!
* has an atomosphere made of 96% carbon dioxide.

Venus CO2 Science Experiment: 


* test tube and holder (Amazon affiliate link: I used the test tube in this set.)
* straw
* bromothymol blue & its pH color chart (Amazon affiliate link: You can get it here.)

Step by Step:

1- Discuss carbon dioxide. What is it? Where is it found? What do your kids know about it already? Key points: carbon dioxide is a gas. Less than 1/2% of our atmosphere is carbon dioxide. It is also the gas used to carbonate drinks, the gas released when you mix vinegar and baking soda, and about 5% of the air we breathe out. 

Do they remember any of this from the first lesson on Venus and carbon dioxide? If so, it's a great chance for them to teach you! If not, it's a great chance to review!

2- Discuss the planet Venus. What do your kids know about it already? Key point: More than 96% of Venus's atmosphere is carbon dioxide. This traps a TON of heat, making Venus THE HOTTEST planet in our solar system (over 800 degrees Farhenheit on the surface--hot enough to melt lead!). It also makes some fantastic toxic clouds that prevented us from getting a good look at the planet until the Magellan probe in 1990 and the Venus Express in 2006!

3- Let's see what the 5% carbon dioxide in our breath can do! 

Start by filling your test tube about 1/3 full of water and adding 5-10 drops of bromothymol blue. Use the color chart to figure out what its pH is. (hint: most tap water is around a 7)

Ask your kids how they think blowing their breath into the water will change its pH. Start blowing and see what happens! (hint: it took us about 15 seconds to get enough CO2 into the test tube to change its pH down to 6.)

What pH are you at now? The pH scale is logorithmic (or base 10), so every time you move down 1 number on it (like from a 7 to a 6), you have made the solution 10 times more acidic. (Sidenote for advanced kids: technically, some of your carbon dioxide combines with water molecules to form carbonic acid, a weak acid that lowers the pH of your water/breath solution.)

My kids really wanted to see another change in pH, so we pulled out some lemon juice...

It turned a nice, bright pink!

Discuss: Your breath is only 5% carbon dioxide. The air around you is less than 0.5% carbon dioxide. The air on Venus is more than 95% carbon dioxide. What would that kind of air feel like on your skin? On your eyes? What kind of complications would it create for designing a robot to visit the planet and gather statistics about it?

Just for fun, here is a picture an artist drew of a balloon, dropped from a space ship, bringing a robot to Venus to take measurements:

Click HERE to see a real picture of Venus (scroll down to the bottom).

In your lab journal, discuss some of the following:

1- What steps did you go through for your experiment?
2- What did you learn today?
3- Make up a story about a spaceship (manned or robotic) landing on Venus. What does it find? What does it do? What challenges does it have?
4- Research what missions (and what from which countries) have actually been to Venus.

Be sure to check out the other experiments I have in the Homeschool Space Science Unit Study! I hope you have a great time with them!

And if you're looking for more homeschool unit studies, be sure to check out our growing collection here!

Happy Educating,
Carla & the kids who don't sit still!