Most stone is made over millions of years, cooked in the core of our planet. That stone then erodes over time due to wind, acids found in rain and groundwater, and other natural weatherings. Chalk is a type of limestone formed by the shells of microscopic marine organisms.
The process of erosion can produce beautiful features in earth’s crust, like arches, stacks, and caves. This process usually takes tens of thousands of years.
But we can make a limestone cave in just a matter of minutes. All you need for this DIY chalk cave is a block of chalk and vinegar.
2CH3CO2H(aq) + CaCO3(s) > 2Ca(CH3CO2)2(aq) + CO2(g) + H2O(l)
The vinegar, a weak acid, reacts with the calcium compound, dissolving it. It then forms carbon dioxide gas, water, and an aqueous calcium solution. This same process takes place for real caves, but the acid in rain and ground water is much more diluted, therefore taking much much longer to see the results.
Written by: Mimi Garai