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A chunk of zinc metal reacts with an excess of hydrochloric acid solution. What is the percentage yield if a 7.23g piece of zinc produces 2.16L of hydrogen gas at StP?
Begin with a balances equation ​

1 Answer

3 votes

Answer:

87.02%

Step-by-step explanation:

Percent yield of a product in a chemical equation is the ratio of actual or experimental yield to theoretical yield expressed as percentage.

In this case we are given;

Mass of Zinc as 7.23 g

Actual volume of Hydrogen gas produced as 2.16 L

We are required to calculate the percentage yield of Hydrogen gas;

Step 1: Write a balanced equation for the reaction

The balanced equation for the reaction between Zinc metal and Hydrochloric acid is given by;

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

Step 2: Moles of Zinc metal that reacted

Moles are given by dividing mass with molar mass

Moles = Mass ÷ Molar mass

Molar mass of Zinc = 65.38 g/mol

Therefore;

Number of moles = 7.23 g ÷ 65.38 g/mol

= 0.1106 moles

Step 3: Calculate the number of moles of Hydrogen gas produced

From the equation 1 mole of Zinc results in the formation of 1 mole of Hydrogen gas.

Therefore, Moles of hydrogen gas = Moles of Zinc × 1

= 0.1106 moles × 1

= 0.1106 moles

Step 4: Calculate the theoretical volume of Hydrogen gas produced.

At STP, 1 mole of a gas occupies 22.4 Liters

Therefore;

Volume of Hydrogen = Number of moles × 22.4 L

= 0.1106 mole × 22.4 L

= 2.477 L

Step 5: Calculate the percent yield

Percent yield = (Actual yield ÷ Theoretical Yield) × 100%

= (2.16 L ÷ 2.477 L)× 100%

= 87.20%

Thus, the percent yield of hydrogen gas produced is 87.02%

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