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2 years ago

An alkaline battery produces electrical energy according to this balanced equation:

1 answer:

6 0

Considering the reaction stoichiometry and the definition of limiting reagent, the correct answer is option D. MnO₂; 17.2 grams Zn(OH)₂.

The balanced reaction is:

Zn + 2 MnO₂ + H₂O → Zn(OH)₂ + Mn₂O₃

<h3>Reaction stoichiometry</h3>

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Zn: 1 mole
MnO₂: 2 moles
H₂O: 1 mole
Zn(OH)₂: 1 mole
Mn₂O₃: 1 mole

The molar mass of the compounds present in the reaction is:

Zn: 65.37 g/mole
MnO₂: 86.94 g/mole
H₂O: 18 g/mole
Zn(OH)₂: 99.37 g/mole
Mn₂O₃: 157.88 g/mole

Then, by reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of mass of each compound participate in the reaction:

Zn: 1 mole× 65.37 g/mole= 65.37 grams
MnO₂: 2 moles× 86.94 g/mole= 173.88 grams
H₂O: 1 mole× 18 g/mole= 18 grams
Zn(OH)₂: 1 mole× 99.37 g/mole= 99.37 grams
Mn₂O₃: 1 mole× 157.88 g/mole= 157.88 grams

<h3>Limiting reagent</h3>

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

To determine the limiting reagent, it is possible to use a simple rule of three as follows: if by stoichiometry 65.37 grams of Zn reacts with 173.88 grams of MnO₂, 25 grams of Zn reacts with how much mass of MnO₂?

$mass of MnO_{2} =\frac{25 grams of Znx173.88 grams of MnO_{2}}{65.37 grams of Zn}$

<u><em>mass of MnO₂ = 66.498 grams</em></u>

But 66.498 grams of MnO₂ are not available, 30 grams are available. Since you have less mass than you need to react with 25 grams of Zn, MnO₂ will be the limiting reagent.

<h3>Mass of Zn(OH)₂ produced</h3>

Then, it is possible to determine the Mass of Zn(OH)₂ produced by another rule of three, considering the limiting reactant: if by stoichiometry 173.88 grams of MnO₂ produce 99.37 grams of Zn(OH)₂, if 30 grams of MnO₂ react how much mass of Zn(OH)₂ will be formed?

$mass of Zn(OH)_{2}=\frac{30 grams of MnO_{2}x99.37 grams of Zn(OH)_{2} }{173.88 grams of MnO_{2}}$

<u><em>mass of Zn(OH)₂= 17.14 grams≅ 17.2 grams</em></u>

In summary, the mass of Zn(OH)₂ that is produced when 25 grams of Zn react with 30 grams of MnO₂ is 17.2 grams.

<h3>Summary</h3>

In summary, the correct answer is option D. MnO₂; 17.2 grams Zn(OH)₂.

Learn more about reaction stoichiometry:

<u>brainly.com/question/11999193</u>

<u>brainly.com/question/15111313?referrer=searchResults</u>

<u>brainly.com/question/6061451?referrer=searchResults</u>

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