Calculate the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid. (AM of Al= 26.9g/mol) 2Al + 6HCl ----> Al2Cl6 + 3H2
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?
To calculate the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid, we need to follow a few steps.
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.
To calculate the mass of hydrogen formed when 25 grams of aluminum reacts with excess hydrochloric acid, we need to determine the number of moles of aluminum and then use the stoichiometry of the balanced equation to find the number of moles of hydrogen.
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.