Question

KF combines with HF to form $KH{F_2}$the compound contains the species:
A. ${K^ + },{F^ - }\;and\; {H^ + }$
B. ${K^ + },{F^ - }\;and\;HF$
C. ${K^ + }\;and\;{[H{F_2}]^ - }$
D. ${[KHF]^ + }\;and\;{F_2}$

Answer 1

Hint: We know that the reaction of a transition metal with a halogen involves a high activation energy and therefore requires a high temperature for initiation. This is why transition metals react with halogens at high temperature to form halides. The halides of transition metals in higher oxidation states exhibit a greater tendency for hydrides.

Complete step by step answer:
We know that potassium fluoride is the chemical compound with the chemical formula KF. After hydrogen fluoride, KF is the only primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide and occurs naturally as the rare mineral carobbite. The solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective.
We have to remember that the potassium fluoride is prepared by dissolving potassium carbonate in hydrofluoric acid. Evaporation of the solution forms crystals of potassium bifluoride. The bifluoride on heating yields potassium fluoride:
${K_2}C{O_3} + 4HF \to 2KH{F_2} + C{O_2} + {H_2}O$
$KH{F_2} \to KF + HF$
From the above reaction we can see that $KH{F_2}$ yields ${K^ + }\;and\;{[H{F_2}]^ - }$.
Platinum or heat resistant plastic containers are often used for these operations. Potassium chloride converts to KF upon treatment with hydrogen fluoride. In this way, potassium fluoride is recyclable.

So, the correct answer is Option C.

Note: Now we can discuss about the uses of potassium fluoride in various field:
The preparation of silver soldering flux used by crafters and metal workers.
Increasing the rate of chemical reactions as a catalyst in organic synthesis.
Etching and frosting glass because of the synthesis of soluble fluorosilicates.
Making disinfectants, insecticides, and pesticides
Salt fluoridation as a means of community-based fluoridation through the addition of KF to iodized salt.