Heating up the Atmosphere
Mars’ atmosphere is much fainter than ours (about 100 times). Its composition is quite different as well. For instance, it has almost no oxygen (0.13% vs. 20% on Earth), and it is mainly made of carbon dioxide (95% vs. 0.04% on Earth). This is a greenhouse gas. In this experiment we will use a chemical reaction to produce carbon dioxide in a bottle. A second i bottle will contain atmospheric air. Check the increase of temperature when exposing them both to solar light or a heat lamp to observe the greenhouse effect.
- Two kitchen thermometers
- Transparent plastic tube (about 3 mm wide and 1 m long)
- Baking soda
- Some soft acid (as that in a kitchen rising agent)
- A small PET bottle (~0.5 L) with cap
- Two large PET bottles (1.5 – 2 L) with caps
- A heating source (e.g., solar light or a filament lamp)
- Understanding (endothermic)chemical reactions
- Understanding greenhouse effect
- Finding out about the compositional differences between the atmospheres of the Earth and Mars
- Linking to and reflecting on climate change on Earth
In the presence of water, baking soda and the acid reacts and carbon dioxide is produced as one of the products. This is a greenhouse gas. The big bottles simulate two planet atmospheres, and one of them is full of carbon dioxide. When both bottles are hit by radiation, the one with the greenhouse gas heats up faster.
Repeat the experiment by using vinegar and baking soda. No water is needed then to produce the CO2. The reaction goes like this:
NaHCO3 + CH3COOH => CH3COO-Na+ + H2O + CO2
- Calculate the mass in grams of vinegar that reacts with 10 grams of sodium bicarbonate.
- Calculate the volume of CO2 produced in the reaction at normal conditions.
Pay attention if using a heater. It may burn your skin, melt the plastic bottles or produce a fire if in contact with some flammable materials.
- Use the scissors to open a small hole (about 3 mm) in the center of the cap of the small bottle.
- Use the scissors to open a small hole (1 mm) in the center of each of the caps of the big bottles, enough for the tip of the termometer to pass through.
- Pass the transparent tube though the hole (2-3 cm of it).
- Pour the acid powder into the small bottle and add about half a glass of water. Alternatively you may use half a glass of vinegar.
- Put the baking soda in a paper napkin and roll it up. Put the napkin into the small bottle and screw the cap immediately.
- Put the other end of the tube into one of the big bottles, touching the bottom.
- Shake the small bottle and wait 1-2 mins. until the reaction ends.
- Take the tube out of the big bottle
- Screw the caps of the two of the big bottles.
- Pass the thermometers through the holes in the caps
- Apply the light source
- Watch the evolution of the temperature. You must see that the one that was filled with the gas of the reaction heats up faster.
Alternatively, you may perform this experiment without the auxiliary small bottle, producing the chemical reaction directly into the big bottle that works as a CO2 atmosphere. For this purpose, just change steps 3 to 8 by these:
- 3b. Pour the acid powder into one of the big bottles and add about half a glass of water.
- 4b. Put the same amount of water in the other bottle.
- 5b. Put the baking soda in a paper napkin and roll it up. Put the napkin into the big bottle containing the acid and screw the cap immediately.
- Then continue with steps 9-12.
Download the instructions for this experiment in Spanish, French and Dutch
26 de agosto de 2022