Lewis Structure of Calcium Carbonate and the Reaction with HCl

Calcium carbonate is a wide­spread com­pound found in chalk, lime, mar­ble, and more. This sub­stance is a cru­cial pil­lar of hu­man life – it is used in con­struc­tion, to man­u­fac­ture pa­per and plas­tic, and in many oth­er spheres. It is also pop­u­lar in the food in­dus­try as a nat­u­ral white col­orant.

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.

Cal­ci­um car­bon­ate is a sol­id white sub­stance that won't dis­solve in it com­plete­ly: the wa­ter will turn a mud­dy col­or and a white pre­cip­i­tate will ap­pear. But if the re­ac­tion with wa­ter takes place in the pres­ence of car­bon diox­ide, it yields cal­ci­um hy­dro­gen car­bon­ate, a sol­u­ble acidic salt.

Reaction with HCl

Hy­drochlo­ric acid is a strong monoba­sic acid and is ob­tained via the dis­so­lu­tion of hy­dro­gen chlo­ride HCl in wa­ter. It is a col­or­less liq­uid, al­though in­dus­tri­al acid can have a yel­low tint, of­ten due to a mix­ture of iron. The prop­er­ties of this so­lu­tion de­pend di­rect­ly on the con­cen­tra­tion of hy­dro­gen chlo­ride. The salts of hy­drochlo­ric acid are called chlo­rides.

This sub­stance is very caus­tic and re­quires care­ful han­dling: even a small drop on the skin will cause a se­vere chem­i­cal burn. When work­ing with strong acids, you should al­ways have neu­tral­iz­ers at hand – weak al­ka­line so­lu­tions, sodi­um bi­car­bon­ate (bak­ing soda), etc. 

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

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