Tag: percentage composition and empirical formula

Questions Related to percentage composition and empirical formula

Calculate the percent composition of carbon in $C _6H _{12}O _6$ :

chemistry introduction to analytical chemistry percent composition water of crystallisation percentage composition and empirical formula

  1. $50%$

  2. $40%$

  3. $35.3%$

  4. $22.1%$

Show answer
Correct Option: B
Explanation:

Molar mass of compound $: 6(12.0)+12(1.01)+6(16.0)=180g/mol$
Mass due to carbon $=6(12.0)=72.06g/mol$
$%$ composition of $C=72/180\times 100=40%$

The formula for % composition of a compound is:

chemistry introduction to analytical chemistry percent composition water of crystallisation percentage composition and empirical formula

  1. molar mass of a compound/mass due to specific component $\times$ 100

  2. mass due to specific component $\times$ 100

  3. mass due to specific component/molar mass of a compound $\times$ 100

  4. molar mass of a specific component/temperature $\times$ 100

Show answer
Correct Option: C
Explanation:

To calculate the per cent composition of a component in a compound: Find the molar mass of the compound by adding up the masses of each atom in the compound using the periodic table or a molecular mass calculator. Calculate the mass due to the component in the compound you are for which you are solving by adding up the mass of these atoms. Divide the mass due to the component by the total molar mass of the compound and multiply by 100.

% $\text{composition of a compound}=\cfrac{\text{ Mass due to specific component}}{\text{molar mass of a compound}}\times 100$

Hence, the correct option is $\text{C}$

% composition requires ................ of the compound :

chemistry introduction to analytical chemistry percent composition water of crystallisation percentage composition and empirical formula

  1. molar mass

  2. temperature

  3. atmospheric pressure

  4. both a and b

Show answer
Correct Option: A
Explanation:

The present composition (by mass) of a compound can be calculated by dividing the mass of each element by the total mass of the compound. i.e. by calculating the $molar$ $mass$ of the compound.