Question

How do you determine the formula and molar mass of Silver Cyanide?

Answer 1

Chemical Formula:

1. A substance's chemical formula is a symbolic representation of its chemical constituents. It defines the ratios in which their atoms combine to form molecules.
2. The electronic configuration of Silver is$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^{6}4{\mathrm{d}}^{10}5{\mathrm{s}}^1$. It will form a stable d-orbital configuration after removing one electron from its s-orbital.
3. The valency of an element is defined as the combining capacity of the element to form compounds with another, since silver loses one electron to form a stable configuration, its valency is $+1$.
4. Cyanide ion has a charge of $-1$ according to the lewis structure hence, it has a valency of $-1$.
5. 
6. For writing the molecular formula, we will use the criss-cross method i.e. exchange the valencies of ions, we get ${\mathrm{Ag}}_1{\mathrm{CN}}_1$ or simply $\mathrm{AgCN}$.
7. Hence, the formula for silver cyanide is $\mathrm{AgCN}$.

Molar mass:

1. It is the sum of the atomic mass of all the atoms in the molecule.
2. The atomic mass of silver$=107.87\mathrm{u}$, the atomic mass of carbon$=12.01\mathrm{u}$, and the atomic mass of nitrogen$=14.01\mathrm{u}$
3. The molar mass of silver cyanide$=$ Atomic mass of silver $+$Atomic mass of carbon $+$atomic mass of nitrogen$\Rightarrow 107.87+12.01+14.01$
4. The molar mass of silver cyanide $=133.89\mathrm{g}{\mathrm{mol}}^{-1}$