so, how many moles of Al in 25g?
The equation says you get 3/2 that many moles of H2.
that is how many grams of H2?
The equation says you get 3/2 that many moles of H2.
that is how many grams of H2?
Step 1: Determine the molar mass of aluminum (Al)
Looking at the information given, the atomic mass (AM) of aluminum (Al) is 26.9 g/mol. This means that one mole of aluminum has a mass of 26.9 grams.
Step 2: Convert the mass of aluminum to moles
To find the number of moles of aluminum, we divide the given mass (25 grams) by the molar mass of aluminum (26.9 g/mol):
25 g / 26.9 g/mol = 0.930 moles of aluminum (rounded to three decimal places)
Step 3: Use the balanced chemical equation to determine the stoichiometry
From the balanced chemical equation:
2Al + 6HCl ---> Al2Cl6 + 3H2
We can see that for every 2 moles of aluminum, 3 moles of hydrogen gas are produced.
Step 4: Calculate the moles of hydrogen produced
Since the stoichiometric ratio is 2:3 (aluminum to hydrogen), we can set up a ratio:
0.930 moles Al : x moles H2 = 2 moles Al : 3 moles H2
Using cross-multiplication, we find:
(0.930 moles Al) × (3 moles H2) / (2 moles Al) = 1.395 moles of H2
Step 5: Convert moles of hydrogen to mass
Finally, we can convert the moles of hydrogen gas to grams by multiplying by the molar mass of hydrogen (2.016 g/mol):
1.395 moles H2 × 2.016 g/mol = 2.81 grams of hydrogen gas
Therefore, the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid is approximately 2.81 grams.
Step 1: Find the number of moles of aluminum (Al)
Number of moles = Mass / Molar mass
Given:
Mass of aluminum (Al) = 25 grams
Molar mass of aluminum (Al) = 26.9 g/mol
Number of moles of aluminum (Al) = 25 g / 26.9 g/mol
Step 2: Use the stoichiometry of the balanced equation to determine the number of moles of hydrogen (H2) produced.
From the balanced equation: 2Al + 6HCl -> Al2Cl6 + 3H2
The stoichiometric ratio of Al to H2 is 2:3.
Number of moles of hydrogen (H2) = Number of moles of aluminum (Al) * (3 moles of H2 / 2 moles of Al)
Step 3: Calculate the mass of hydrogen (H2) using the number of moles of hydrogen (H2) and the molar mass of hydrogen (H2).
Molar mass of hydrogen (H2) = 2.0 g/mol
Mass of hydrogen (H2) = Number of moles of hydrogen (H2) * Molar mass of hydrogen (H2)
Now let's plug in the values into the equation:
Number of moles of hydrogen (H2) = (25 g / 26.9 g/mol) * (3 moles of H2 / 2 moles of Al)
Number of moles of hydrogen (H2) = 22.3 g / 26.9 g/mol
Mass of hydrogen (H2) = 22.3 g / 26.9 g/mol * 2.0 g/mol
Mass of hydrogen (H2) = 14.78 grams of hydrogen (H2)
Therefore, the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid is 14.78 grams.