Determining the Amount of Zinc Required to Produce 1 Liter of Hydrogen Gas from Hydrochloric Acid

Understanding the chemical reaction between zinc and hydrochloric acid can be crucial for various industrial and educational purposes. In this article, we will explore how to calculate the exact amount of zinc needed to produce 1 liter of hydrogen gas when reacting with hydrochloric acid. This process involves several steps, including writing a balanced chemical equation, determining the moles of hydrogen gas produced, relating moles of zinc to moles of hydrogen, and finally calculating the mass of zinc required.

Step-by-Step Guide

Step 1: Write the Balanced Chemical Equation

The reaction between zinc (Zn) and hydrochloric acid (HCl) can be represented as:

( text{Zn} 2text{HCl} rightarrow text{ZnCl}_2 text{H}_2 )

Step 2: Determine the Moles of Hydrogen Gas Produced

Under standard temperature and pressure (STP) conditions, 1 mole of any ideal gas occupies 22.4 liters. To find the number of moles of hydrogen gas (H2) in 1 liter:

Moles of H2 ( frac{1 text{ L}}{22.4 text{ L/mol}} ) ≈ 0.04464 mol

Step 3: Relate Moles of Zn to Moles of H2

From the balanced equation, we observe that 1 mole of Zn produces 1 mole of H2. Therefore, the moles of Zn required are equal to the moles of H2 produced:

Moles of Zn required 0.04464 mol

Step 4: Calculate the Mass of Zn Required

The molar mass of zinc (Zn) is approximately 65.38 g/mol. With the moles of Zn required, we can now calculate the mass:

Mass of Zn moles of Zn x molar mass of Zn in g/mol

Mass of Zn 0.04464 mol x 65.38 g/mol ≈ 2.92 g

Conclusion

Therefore, you would need approximately 2.92 grams of zinc to react with hydrochloric acid and produce 1 liter of hydrogen gas at standard temperature and pressure. This calculation is based on the ideal behavior of gases under STP conditions.

Additional Information

Note that hydrochloric acid behaves as an ideal solution at low temperatures. The molar mass of Zn is 65.38 g/mol. The balanced equation is:

( text{Zn} 2text{HCl} rightarrow text{ZnCl}_2 text{H}_2 )

At STP, 1 mole of an ideal gas occupies a volume of 22.71 liters (this value was updated from 22.4 L with the IUPAC change).

The number of moles of H2 in 1 liter can be calculated as:

Moles of H2 1 L x ( frac{1 text{ mol}}{22.71 text{ L}} ) 0.044 mol

The mole ratio of H2 to Zn is 1:1, indicating that 1 mole of H2 is produced from 1 mole of Zn. Therefore, the moles of Zn required are equal to the moles of H2 produced, which results in 0.044 mol of Zn. The mass of Zn in 0.044 mol is calculated as:

Mass of Zn moles of Zn x molar mass of Zn in g/mol 0.044 mol x 65.38 g/mol ≈ 2.88 g or approx. 2.9 g

Thus, 2.9 grams of zinc is required to react with hydrochloric acid to produce 1 liter of hydrogen gas.