Calcium carbonate is a wide-spread com-pound found in chalk, lime, mar-ble, and more. This sub-stance is a cru-cial pil-lar of hu-man life – it is used in con-struc-tion, to man-u-fac-ture pa-per and plas-tic, and in many oth-er spheres. It is also pop-u-lar in the food in-dus-try as a nat-u-ral white col-orant.

Lewis Structure

The Lewis structures for Calcium Carbonate (CaCO3) consist of a Calcium ion (Ca^(2+)) bonded to a carbonate ion (CO3^(2-)). The carbonate ion exhibits three resonance structures with one double bond and one single bond between Carbon and Oxygen atoms, and formal charges of -1 on two Oxygen atoms.

Cal-ci-um car-bon-ate is a sol-id white sub-stance that won't dis-solve in it com-plete-ly: the wa-ter will turn a mud-dy col-or and a white pre-cip-i-tate will ap-pear. But if the re-ac-tion with wa-ter takes place in the pres-ence of car-bon diox-ide, it yields cal-ci-um hy-dro-gen car-bon-ate, a sol-u-ble acidic salt.

Reaction with HCl

Hy-drochlo-ric acid is a strong monoba-sic acid and is ob-tained via the dis-so-lu-tion of hy-dro-gen chlo-ride HCl in wa-ter. It is a col-or-less liq-uid, al-though in-dus-tri-al acid can have a yel-low tint, of-ten due to a mix-ture of iron. The prop-er-ties of this so-lu-tion de-pend di-rect-ly on the con-cen-tra-tion of hy-dro-gen chlo-ride. The salts of hy-drochlo-ric acid are called chlo-rides.

This sub-stance is very caus-tic and re-quires care-ful han-dling: even a small drop on the skin will cause a se-vere chem-i-cal burn. When work-ing with strong acids, you should al-ways have neu-tral-iz-ers at hand – weak al-ka-line so-lu-tions, sodi-um bi-car-bon-ate (bak-ing soda), etc. 

When calcium carbonate (CaCO3) reacts with hydrochloric acid (HCl), itproduces calcium chloride (CaCl2), carbon dioxide (CO2), and water (H2O).