The double replacement reaction between calcium nitrate (Ca(NO3)2) and potassium oxide (K2O ) is shown below: Ca(NO3) 2 + K2 O → CaO + KNO3
How many grams of potassium oxide would be needed to produce 5.00 g of potassium nitrate (KNO3) ?

Mass = 2.355 g

Explanation:

Given data:

Mass of K₂O needed = ?

Mass of KNO₃ produced = 5.00 g

Solution:

Chemical equation:

K₂O + Ca(NO₃)₂     →   CaO +  2KNO₃

Number of moles of KNO₃:

Number of moles = mass/molar mass

Number of moles = 5.00 g/ 101.1 g/mol

Number of moles = 0.05 mol

now we will compare the moles of KNO₃ and K₂O.

               KNO₃           :             K₂O

                  2                :               1

                 0.05           :           1/2×0.05 = 0.025 mol

Mass of potassium oxide needed in gram:

Mass =  number of moles × molar mass

Mass = 0.025 mol × 94.2 g/mol

Mass = 2.355 g

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