What reactions occur when...?

#(i)# #"potassium is added to water..."#

#(ii)# #"potassium chloride is added to water..."#

1 Answer
anor277
Oct 1, 2015

Two chemical reactions occur:
#i. K(s) + H_2O(l) rarr KOH(aq) + 1/2H_2(g)uarr#
#ii. KCl(s) rightleftharpoons K^+(aq) + Cl^(_)(aq)#

Explanation:

Potassium metal undergoes oxidation with water to give hydrogen gas, and potassium hydroxide. Potassium chloride in aqueous solution forms aquated potassium and chloride ions, which do not affect the concentrations of #H_3O^+# or #OH^-# in solution. Reaction (i) is irreversible; reaction (ii) is reversible. Note that potassium chloride does not undergo reaction to form the hydroxide.

Potassium hydroxide is commonly used as a cleaning agent, as an electrolyte in batteries, and (so the internet tells me!) used to remove the horns on calves (ouch!).

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