Aluminum granules are a component of some drain cleaners because they react with sodium hydroxide to release both energy and gas bubbles to help clear the drain clog. The reaction is:
2NaOH + Al + 6H2O 2NaAl(OH)4 + 3H2
(note: balance the reaction first)
What mass of Aluminum would be needed to produce 4L of hydrogen gas at STP?
2NaOH + 2Al + 6H2O 2NaAl(OH)4 + 3H2
Use PV = nRT and solve for n = mols H2 OR remember at STP 1 mol occupies 22.4L.
Using the coefficients in the balanced equation, convert mols H2 to mols Al
Then mols Al = grams/atomic mass. You know atomic mass and mols, solve for grms.
To determine the mass of aluminum needed to produce 4L of hydrogen gas at STP (Standard Temperature and Pressure), we need to use the stoichiometry of the balanced chemical equation.
The balanced equation is:
2NaOH + 2Al + 6H2O -> 2NaAl(OH)4 + 3H2
Looking at the balanced equation, we can see that the stoichiometric ratio between aluminum (Al) and hydrogen gas (H2) is 2:3. This means that for every 2 moles of aluminum, we get 3 moles of hydrogen gas.
To calculate the mass of aluminum, we need to convert the volume of hydrogen gas (4L) to moles using the ideal gas law at STP (Standard Temperature and Pressure):
PV = nRT
At STP:
Pressure (P) = 1 atm
Volume (V) = 4L
Gas constant (R) = 0.0821 L·atm/(mol·K)
Temperature (T) = 273.15 K
Rearranging the ideal gas law equation, we can calculate the number of moles (n):
n = PV / RT
Substituting the values in:
n = (1 atm) * (4L) / (0.0821 L·atm/(mol·K) * 273.15 K)
n = 0.185 moles of hydrogen gas
Now, we can use the stoichiometric ratio to calculate the moles of aluminum needed:
2 moles Al = 3 moles H2
x moles Al = 0.185 moles H2
Solving for x:
x = (0.185 moles Al) * (2 moles Al / 3 moles H2)
x = 0.123 moles Al
Next, we need to convert moles of aluminum to mass using the molar mass of aluminum, which is 26.98 g/mol.
Mass of aluminum = (0.123 moles Al) * (26.98 g/mol)
Mass of aluminum = 3.32 grams
Therefore, approximately 3.32 grams of aluminum would be needed to produce 4L of hydrogen gas at STP.