Erupting Volcanoes: Science Saturday

We did a few mini-experiments this afternoon to learn more about volcanoes. Unfortunately, I don’t yet have safety goggles for each of the kiddos so I improvised. We may look silly in our snow goggles, but we are safe! 🙂

SHIELD VOLCANOES

When you add baking soda to vinegar, a reaction occurs which makes lots of fizz and foam! What actually happens is this: the acetic acid (CH3COOH, and the thing that makes vinegar sour) reacts with sodium bicarbonate (NaHCO3, or baking soda) to form carbonic acid (H2CO3).

It’s a double replacement reaction, and is also a neutralization reaction. Carbonic acid is unstable, and it immediately falls apart into carbon dioxide (CO2) and water (H2O). The bubbles you see from the reaction come from the carbon dioxide escaping the solution that is left. Carbon dioxide is heavier than air, so, it flows almost like water when it overflows the container. The overall balanced reaction is this:

NaHCO3 + CH3COOH —> CH3COONa + H2O + CO2

COMPOSITE or STRATO VOLCANOES

To do this experiment, you’ll need ammonium dichromate, (NH4)2Cr2O7, an orange crystalline solid at room temperature, which resembles slightly, table sugar. It can be ignited with high heat, such as that from a bunsen burner or a match. As it burns, the dark green solid “fluff” that forms is Cr2O3. The orange, ammonium dichromate, (NH4)2Cr2O7,is decomposed according to the balanced equation below:

(NH4)2Cr2O7(s) —-> Cr2O3(s) + N2(g) + 4H2O(g)