Middle School

How many grams of O\(_2\) are required to produce 36.9 grams of ZnO?

\[ \text{2Zn} + \text{O}_2 \rightarrow \text{2ZnO} \]

Answer :

Answer:

Mass = 7.2 g

Explanation:

Given data:

Mass of ZnO = 36.9 g

Mass of oxygen needed = ?

Solution:

Chemical equation:

2Zn + O₂ → 2ZnO

Number of moles of ZnO:

Number of moles = Mass/ molar mass

Number of moles = 36.9 g/81.38 g/mol

Number of moles = 0.45 mol

Now we will compare the moles of ZnO with oxygen:

ZnO : O₂

2 : 1

0.45 : 1/2 × 0.45 = 0.225

Mass of oxygen:

Mass = number of moles × molar mass

Mass = 0.225 mol × 32 g/mol

Mass = 7.2 g

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