3.5g of zinc react with excess dilute hydrochloric acid to produce hydrogen gas at STP,calculate mas of hydrogen gas produced
divide the mass of the zinc by its molar mass (65.4 g) to find the number of moles
each mole of zinc will produce a mole of hydrogen gas (diatomic)
multiply the moles by the molar mass of Hâ‚‚ (2.02 g)
To calculate the mass of the hydrogen gas produced, we need to use stoichiometry. The balanced chemical equation for the reaction between zinc (Zn) and hydrochloric acid (HCl) is:
Zn + 2HCl → ZnCl2 + H2
From the equation, we can see that for every 1 mole of zinc, 1 mole of hydrogen gas is produced. We need to convert the mass of zinc given (3.5g) to moles, and then use the mole ratio to find the mass of hydrogen gas.
Step 1: Calculate the moles of zinc (Zn)
Molar mass of zinc (Zn) = 65.38 g/mol
moles of zinc = mass of zinc / molar mass of zinc
moles of zinc = 3.5g / 65.38 g/mol
Step 2: Calculate the moles of hydrogen gas (H2)
Using the mole ratio from the balanced equation, we know that 1 mole of Zn produces 1 mole of H2.
moles of hydrogen gas (H2) = moles of zinc
Step 3: Calculate the mass of hydrogen gas (H2)
Molar mass of hydrogen gas (H2) = 2.016 g/mol
mass of hydrogen gas (H2) = moles of hydrogen gas * molar mass of hydrogen gas
Now let's calculate the values:
moles of zinc = 3.5g / 65.38 g/mol = 0.053 moles (rounded to 3 decimal places)
moles of hydrogen gas (H2) = 0.053 moles
mass of hydrogen gas (H2) = 0.053 moles * 2.016 g/mol = 0.107 g (rounded to 3 decimal places)
Therefore, approximately 0.107 grams of hydrogen gas will be produced in the reaction.