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A student reacts steel wool with oxygen by touching the fibers with a 9 volt battery. They begin
with 7.93 g Fe and measure the mass of the final product at 9.50 g.
The balanced equation for the reaction is:
2 Fe + 02 --> 2 FeO
A) The student claims that the percent yield of the reaction was 93.1 %. Support or reject their
claim including a calculation of percent yield as part of your evidence.

Respuesta :

Edufirst

Answer:

  • The claim of the student must be rejected because the percent yield is 77.7%, very far from the 93.1% claimed by the student.

Explanation:

1. Chemical balanced equation (given)

            [tex]2Fe+O_2\rightarrow 2FeO[/tex]

2. Mole ratio

  • 2 moles Fe : 2 moles FeO ⇒ 1 mol Fe : 1 mol FeO

3. Atomic and molar masses

  • Fe: 55.845 g/mol

  • FeO: 71.844 g/mol

4. Theoretical yield

  • number of moles = molar mass / molar mass

  • number of moles of Fe = 7.93g / 55.845 g/mol = 0.142 mol

  • Yield:

As per the theoretical mol ratio, the number of moles of FeO are equal to the number of moles of iron, thus 0.142 mol of FeO is the maximum that could be produced.

  • mass of FeO = number of moles × molar mass = 0.142 moles × 71.844 g/mol = 10.2  g

5. Percent yield, %

% = (actual yield / theoretical yield) × 100 = (7.93g / 10.2g) × 100 = 77.7%

Hence, the percent yield is 77.7%, much lower than the 93.1% claimed by the student.

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