Question

How much does $1.00$ mole of $Si{O_2}$ substance weigh in grams?

Answer 1

One mole of a compound is defined as the quantity which contains Avogadro’s number i.e.$6.022 \times {10^{23}}mo{l^{ - 1}}$ of molecules of that compound in it. Weight of one mole of a compound in grams $\left( g \right)$ can be calculated by multiplying the molecular mass of the compound with Avogadro’s number.

Complete step-by-step answer: $Si{O_2}$ commonly known as silica is an oxide of silicon, most commonly found in nature as quartz it has a three dimensional network structure however for the sake of our question we just consider one single molecule of silica. Here we can clearly see that one molecule of $Si{O_2}$ contains one atom of Silicon and two atoms of Oxygen thus its molecular mass is approximately equal to the sum of atomic masses of atoms comprising it.
Molecular mass of $Si{O_2}$ $= 28 + 16 + 16 = 60u$(approximately)
$1u = 1.661 \times {10^{ - 24}}g$
Thus, Molar mass of $Si{O_2}$ $= 6.022 \times {10^{23}} \times 60u \times 1.661 \times {10^{ - 24}} = 60g$
Thus,$1$ mole of $Si{O_2}$ weighs $60g$.
Additional information: Silica is the major constituent of sands around the world in the form of quartz, It is highly useful as an electrical insulator in microelectronics and in structural materials, It is also useful in pharmaceutical and food industries. Silica also has other common names like silicic oxide, crystalline silica, pure silica, silicea and silica sand. Silicon in silica is in the $+ 4$ oxidation state where the oxygen atoms are in the $\left( { - 4} \right)$ oxidation state.

Note: In questions requiring the determination of molar mass in grams we first need to estimate its molecular mass accurately and for doing so we must have a rough idea on the atomic number and atomic masses of various commonly used atoms in chemistry, without this basic knowledge estimating molar mass would be nigh impossible.