How can geologists use acid to confirm that the rock towers are made of limestone?
Answer (3)
Limestone is a composite of calcite and dolomite. The chemical formula of calcite is CaCO3. Geologists can use an acid such as HCl for the following reaction. CaCO3 + 2H(+) + 2Cl(-) ⇒ Ca(2+) + 2Cl(-) + H2CO3 The H2CO3, however, immediately decomposes into H2O and CO2, so by determining that gas is being emitted, aka it is bubbling, they can determine that it is limestone.
limestone has the chemical formula "CaCO3". The acid contains Hydrogen ions with a positive charge. Two hydrogen ions bond with an oxygen atom to form a water molecule. The remaining two oxygen atoms and the carbon atom break away to form carbon dioxide gas which is why bubbles are observed when this reaction takes place. If the acid used was Hydrochloric acid "HCl" the chloride ion bonds with Calcium to form calcium chloride. The geologist can then carry out tests to see what is produced when the acid and the sample of rock are mixed. If the compounds produced are the ones stated above they know that the rock tested is limestone.
Geologists can confirm rock towers are made of limestone by applying dilute hydrochloric acid to a rock sample. If it fizzes, that indicates the presence of calcite, confirming the rock is limestone. If no fizz is observed, grinding the rock into powder and testing again can confirm if it contains dolomite.
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