Using the following equation: 5 KNO2 + 2 KMnO4 + 3 H2SO4 ------> 5 KNO3 + 2 MnSO4 + K2SO4 + 3 H2O How many moles and how many grams of KMnO4 are needed to carry out this reaction on 11. 4 grams of KNO2?

Respuesta :

  • The number of moles of KMnO₄ needed to carry out the reaction is 0.0536 mole
  • The mass of KMnO₄ needed to carry out the reaction is 8.5 g

Stoichiometry

From the question, we are to determine the number of moles and mass of KMnO₄ needed

From the given balanced chemical equation

5KNO₂ + 2KMnO₄ + 3H₂SO₄ → 5KNO₃ + 2MnSO₄ + K₂SO₄ + 3H₂O

This means 5 moles of KNO₂ is required to react completely with 2 moles of KMnO₄

First, we will determine determine the number of moles of KNO₂ present

From  the given information,

Mass of KNO₂ = 11.4 g

Using the formula,

[tex]Number\ of\ moles = \frac{Mass}{Molar\ mass}[/tex]

Molar mass of KNO₂ = 85.1 g/mol

Therefore,

Number of moles of KNO₂ = [tex]\frac{11.4}{85.1}[/tex]

Number of moles of KNO₂ = 0.13396 mole

Now,

If 5 moles of KNO₂ is required to react completely with 2 moles of KMnO₄

Then,

0.13396 mole of KNO₂ will react completely with [tex]\frac{0.13396 \times 2}{5}[/tex] mole of KMnO₄

[tex]\frac{0.13396 \times 2}{5}[/tex] = 0.053584 mole ≅ 0.0536 mole

Hence, the number of moles of KMnO₄ needed is 0.0536 mole

For the mass of KMnO₄ needed,

Using the formula,

Mass = Number of moles × Molar mass

Molar mass of KMnO₄ = 158.034 g/mol

Therefore,

Mass of KMnO₄ needed = 0.053584 × 158.034

Mass of KMnO₄ needed = 8.468 g

Mass of KMnO₄ needed ≅ 8.5 g

Hence, the mass of KMnO₄ needed to carry out the reaction is 8.5 g

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