Question

Find the mass percentages (mass $\% $) of $ Na,\text{ }H,\text{ }C, $ and $ O $ in sodium hydrogen carbonate.

Answer 1

Hint: We know that the mass percentage is one of the ways which is generally used for representing the concentration or molarity of the present element in any compound or the mixture of components. The Law of Conservation of Mass is defined and explained using examples of reacting mass calculations using the law are fully explained with worked out examples using the balanced symbol equation.

Complete step by step answer:
We know that the mass percentage of any element can be determined with the help of their molar mass and the molar mass of the given compound. First we have to calculate the molar mass of sodium hydrogen carbonate or sodium bicarbonate i.e.
 $ (NaHC{{O}_{3}})=\left[ \left( 23 \right)+\left( 1 \right)+\left( 12 \right)+\left( 3\times 16 \right) \right]=\left[ 23+1+12+48 \right]=84g $
Now, the molar mass of sodium is $ 23\text{ }g/mol. $ The molar mass of oxygen is $ 16\text{ }g/mol. $ The molar mass of carbon is $ 12\text{ }g/mol. $ The molar mass of hydrogen is $ 1\text{ }g/mol. $ In the formula of sodium hydrogen carbonate the number of sodium atoms is one, the number of carbon atoms is one and the number of oxygen atoms are three.
The mass percentage of each element can be calculated by using the formula given below.
 $ Mass\text{ }Percentage\text{ }of\text{ }element=\dfrac{Mass\text{ }of\text{ }element}{Mass\text{ }of\text{ }compound}\times \text{100 }\!\!%\!\!\text{ } $
Substitute the respective values in the above equation.
For Sodium: $\text{Mass percentage of element}=\dfrac{23}{84} \times 100=27.36\%$
For Hydrogen: $\text{Mass percentage of element}=\dfrac{1}{84} \times 100=1.20\%$
For Carbon: $\text{Mass percentage of element}=\dfrac{12}{84} \times 100=14.30\%$
For Oxygen: $\text{Mass percentage of element}=\dfrac{48}{84} \times 100=57.14\%$
Hence, the mass percent of sodium is $ 27.36% $ , the mass percentage of hydrogen is $ 1.20% $ , the mass percentage of carbon is $ 14.30% $ and the mass percentage of oxygen is $ 57.14% $ .
Therefore option (B) is the correct answer.

Note:
Remember that the mass percentage of an element can be evaluated by the fraction of element’s mass to the compound’s mass. The overall mass value is multiplied by $ 100%. $ The mass of the entirety of the gases evolved and the mass of the aqueous remains- combined- shall be equivalent to the amount of the mass of the two reactants.