Chemistry Forum

Hi,

Can anyone explain to me why calcium chloride does not react with nitric acid?

Thanks

The following will occur, in theory:
CaCl2 (aq) + 2 HNO3 (aq) <=> Ca(NO3)2 (aq) + 2 HCl (aq)

However, as all compounds involved are soluble ionic compounds it is not technically recognised as an exchange reaction. All you effectively have is an aqueous solution of Ca²⁺, H⁺, NO3^-, and Cl^- ions.

One of three different product types are required for an exchange reaction to be recognised in an aqueous solution:

• An insoluble ionic compound that precipitates from solution.
• A molecular compound that remains in solution (eg: water from an acid-base neutralisation).
• A gaseous compound that escapes from solution.

The long and short of it is: if no reaction to remove ions from the solution is possible, then no reaction happens when you mix the solutions.

Hi GrahamKemp,

Thank you!
Really appreciate it.

GrahamKemp wrote:The following will occur, in theory:
CaCl2 (aq) + 2 HNO3 (aq) <=> Ca(NO3)2 (aq) + 2 HCl (aq)

However, as all compounds involved are soluble ionic compounds it is not technically recognised as an exchange reaction. All you effectively have is an aqueous solution of Ca²⁺, H⁺, NO3^-, and Cl^- ions.

One of three different product types are required for an exchange reaction to be recognised in an aqueous solution:

• An insoluble ionic compound that precipitates from solution.
• A molecular compound that remains in solution (eg: water from an acid-base neutralisation).
• A gaseous compound that escapes from solution.

The long and short of it is: if no reaction to remove ions from the solution is possible, then no reaction happens when you mix the solutions.

Thanks for the answer buddy.

If one dripped strong HNO₃ on anhydrous CaCl₂, as the reaction with just water due to the exothermic nature of the reaction (the solvation enthalpy of the calcium ion is much greater than the lattice energy) is reported, upon rapid heating, to release some HCl vapors (see p. 162 of "Concise Encyclopedia Chemistry" by DeGruyter), as such, upon working with the anhydrous and mildly preheated (just under 200 C) anhydrous CaCl₂ only, the following reaction:

2 HNO₃ (aq) + CaCl₂ (s) ---> Ca(NO₃)₂ + 2 HCl (g)

to some extent may occur with continuous mild heating. That is, depending on reaction conditions, this may not always necessarily be an ionic reaction.

Now, this point is not necessarily inconsequential, as it does suggest a path to possibly dry, or nearly dry, Ca(NO₃)₂. Interestingly, one of the major application of this salt is dehydration. For example, Cl₂O gas is reputedly prepared by dehydrating conc HOCl with Ca(NO₃)₂ to quote:

"Dichlorine oxide, ClOCl, a brownish yellow gas at room
temperature, is commonly known as chlorine monoxide. This
gas was prepared by Balard in 1834 by drying hypochlorous
acid with anhydrous calcium nitrate but nowadays it is usually
obtained by treating freshly prepared mercuric oxide with
chlorine gas [19]."

Source: Chem. Educator, 2011, 16, 275–278 275
"Chlorine Oxoacids and Structure of Dichlorine Oxides"
by Sandra Luján Quiroga and Luis José Perissinotti.
Link: http://www.academia.edu/1557547/Chlorin ... ine_oxides

Disclaimer: I have not perform this original and largely undocumented path to preparing nearly dry Calcium nitrate, and it is based solely on my speculation/opinion.

property of CaCl₂

Calcium chloride and nitric acid don’t react because they simply coexist as ions in solution without any driving force to initiate a chemical reaction.

Dont answer 8 year old thread .