What is the mass percent of chlorine in hydrochloric acid?

Understand the Problem

The question is asking for the mass percent of chlorine in hydrochloric acid (HCl). This involves calculating the mass of chlorine in the compound and then dividing it by the total molar mass of hydrochloric acid and multiplying by 100 to get the percentage.

Answer

$97.26\%$

Steps to Solve

Determine the molar mass of hydrochloric acid (HCl) First, we need to calculate the molar mass of HCl. The molar mass is the sum of the atomic masses of hydrogen (H) and chlorine (Cl).

Atomic mass of H = 1 g/mol
Atomic mass of Cl = 35.5 g/mol

So, the molar mass of HCl is: $$ \text{Molar mass of HCl} = 1 \text{ g/mol} + 35.5 \text{ g/mol} = 36.5 \text{ g/mol} $$

Calculate the mass of chlorine in hydrochloric acid The mass of chlorine in one mole of HCl is equal to the atomic mass of chlorine, which we've already identified.

Mass of Cl = 35.5 g/mol

Calculate the mass percent of chlorine in HCl To find the mass percent of chlorine, divide the mass of chlorine by the total molar mass of HCl and multiply by 100 to convert to a percentage: $$ \text{Mass percent of Cl} = \left( \frac{\text{Mass of Cl}}{\text{Molar mass of HCl}} \right) \times 100 $$

Substituting the values we found: $$ \text{Mass percent of Cl} = \left( \frac{35.5}{36.5} \right) \times 100 $$

Perform the calculation Now we will divide and multiply to find the percentage: $$ \text{Mass percent of Cl} \approx 97.26% $$

The mass percent of chlorine in hydrochloric acid (HCl) is approximately $97.26%$.

More Information

Chlorine is a key component of hydrochloric acid, and understanding its mass percent is important in chemistry for various applications, including titration and reaction stoichiometry.

Tips

Miscalculating the atomic masses can lead to incorrect results. Always refer to a reliable periodic table.
Forgetting to multiply by 100 when calculating the percentage is a common error. Ensure this step is included.

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