The number of moles of H₂ formed when 2.97 g sample of Mg reacts with excess HCl is 0.122 moles
To determine the number of moles of H₂ that can be formed if 2.97 g sample of Mg reacts with excess HCl,
First, we will write a balanced chemical equation for the reaction
Mg + 2HCl → MgCl₂ + H₂
From the reaction above,
It means that 1 mole of Mg will react with 2 moles of HCl to produce 1 mole of MgCl₂ and 1 mole of H₂
Now, we will determine the number of moles of Mg present in the given sample.
From the question,
Mass of Mg = 2.97 g
Using the formula
[tex]Number \ of \ moles = \frac{Mass}{Molar \ mass}[/tex]
Molar mass of Mg = 24.305 g/mol
∴ [tex]Number \ moles \ of \ Mg = \frac{2.97}{24.305}[/tex]
Number of moles of Mg in the sample = 0.122 moles
Since, 1 mole of Mg will react with 2 moles of HCl to produce 1 mole of MgCl₂ and 1 mole of H₂
∴ 0.122 moles of Mg will react with excess HCl to produce 0.122 moles of H₂
Hence, the number of moles of H₂ formed when 2.97 g sample of Mg reacts with excess HCl is 0.122 moles
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