Question

Calculate the mass percent of different elements present in sodium sulphate $\left(N{a}_{2}S{O}_4\right).$

Answer 1

Step 1: Definition and formula of mass percent:

Mass percent is a way of expressing a concentration or describing the component in a particular mixture. The solution composition can be described in mass percentage which shows the mass of solute present in a given mass of solution

Formula of mass percent –

𝑀𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑚𝑒𝑛𝑡$=\frac{\text{mass of that element in the compound}}{\text{molar mass of the compound}}\times 100$

Step 2: Molar mass of an element.

Description:

According to the given question

The molecular formula of sodium sulphate is $\left(N{a}_{2}S{O}_4\right)$

$\text{Therefore, Molar mass = gram atomic mass of sodium + gram atomic mass of Sulphur + gram atomic mass of Oxygen}$

Or, we can write

𝑀𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠

=𝑔𝑟𝑎𝑚 𝑎𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 𝑜𝑓 $Na\left(23\right)+$ 𝑔𝑟𝑎𝑚 𝑎𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 𝑜𝑓 $S\left(32\right)+$ 𝑔𝑟𝑎𝑚 𝑎𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 𝑜𝑓 $O\left(16\right)$

So, Molar mass of $\left(N{a}_{2}S{O}_4\right)$ is

$\Rightarrow \left[\right(2\times 23.0)+(32.066)+4(16.00\left)\right]=142.066gmo{l}^{-1}$

Step 3: Calculate of mass percent of each element presents in sodium sulphate

Description:

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 $=\frac{2\times 23}{142.006}\times 100=32.379\approx 32.4\%$

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑠𝑢𝑙𝑝ℎ𝑢𝑟 $=\frac{32.066}{142.006}\times 100=22.57\approx 22.6\%$

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑜𝑥𝑦𝑔𝑒𝑛 $=\frac{4\times 16}{142.006}\times 100=45.049\approx 45\%$

Final Answer:

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 𝑖𝑛 𝑠𝑜𝑑𝑖𝑢𝑚 𝑠𝑢𝑙𝑝ℎ𝑎𝑡𝑒 $=32.4\%$

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑠𝑢𝑙𝑝ℎ𝑢𝑟 𝑖𝑛 𝑠𝑜𝑑𝑖𝑢𝑚 𝑠𝑢𝑙𝑝ℎ𝑎𝑡𝑒 $=22.6\%$

𝑇ℎ𝑒 𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑜𝑓 𝑜𝑥𝑦𝑔𝑒𝑛 𝑖𝑛 𝑠𝑜𝑑𝑖𝑢𝑚 𝑠𝑢𝑙𝑝ℎ𝑎𝑡𝑒 $=45\%$