Question

Which metal bicarbonates do not exist in solid state?
(i) \[LiHC{O_3}\] (ii) \[Ca{(HC{O_3})_2}\] (iii) \[Zn{(HC{O_3})_2}\] (iv) \[AgHC{O_3}\]
A. I, ii, iii, iv
B. I, ii, iii
C. I, ii, iv
D. ii, iii, iv

Answer 1

Hint: In inorganic chemistry, bicarbonate, also known as hydrogen carbonate is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula \[HC{O^ - }\]
Complete Step-by-Step answer:
Before we move towards the solution of this particular problem, we must understand certain trends that are observed when metal bicarbonates are concerned on the basis of the metal bicarbonates given to us in the options:
 \[LiHC{O_3}\] : \[LiHC{O_3}\] or lithium bicarbonate, is a bicarbonate compound of lithium. Lithium is a metal which belongs to the first group in the periodic table. Because of the small size of the lithium ion, it has very high hydration enthalpy. This makes lithium bicarbonate more stable in aqueous state, than in a solid state.
 \[Ca{(HC{O_3})_2}\] : \[Ca{(HC{O_3})_2}\] or calcium bicarbonate is a compound that is widely used in the cement industry. The thermodynamic properties of calcium bicarbonate render it unstable at ambient conditions of temperature and pressure. But it finds thermodynamic stability when it exists in aqueous solutions.
 \[Zn{(HC{O_3})_2}\] : \[Zn{(HC{O_3})_2}\] or zinc bicarbonate also faces the same issues of thermodynamic stability as calcium bicarbonate. Hence, it too exists only in aqueous media.
 \[AgHC{O_3}\] : \[AgHC{O_3}\] or silver bicarbonate is also thermodynamically unstable in solid state. The stability in the compound can be restored only when it is aqueous state of matter.
Hence, none of the above-mentioned metal bicarbonates exist in the solid state

Hence, Option A is the correct option.

Note: The only metal to form a thermodynamically stable bicarbonate at ambient conditions of temperature and pressure is sodium bicarbonate or \[NaHC{O_3}\]. This compound is also commonly known as baking soda.