When 25.0 g of Zn reacts,how many L of H2 are formed at STP?
1 mol Zn = 1 mol H2.
mols Zn = grams/molar mass = ?
mols H2 = mols Zn
volume H2 @ STP = mols x 22.4L/mol = ?
To determine how many liters of H2 are formed when 25.0 g of Zn reacts at STP (Standard Temperature and Pressure), we need to use stoichiometry to relate the given mass of Zn to the volume of H2 gas.
Step 1: Write the balanced chemical equation for the reaction between Zn and H2:
Zn + H2O -> ZnO + H2 (balanced equation)
Step 2: Calculate the number of moles of Zn:
molar mass of Zn = 65.38 g/mol
moles of Zn = mass of Zn / molar mass of Zn
moles of Zn = 25.0 g / 65.38 g/mol
moles of Zn ≈ 0.3825 mol
Step 3: Use stoichiometry to find the moles of H2 formed:
From the balanced chemical equation, we see that 1 mole of Zn produces 1 mole of H2.
moles of H2 = moles of Zn ≈ 0.3825 mol
Step 4: Calculate the volume of gas using the ideal gas law:
PV = nRT
At STP:
T = 273.15 K
P = 1 atm
R = 0.0821 L·atm/(mol·K)
V = ?
Rearrange the ideal gas law equation to solve for V:
V = nRT / P
V = (0.3825 mol)(0.0821 L·atm/(mol·K))(273.15 K) / 1 atm
V ≈ 8.44 L
Therefore, approximately 8.44 liters of H2 gas are formed when 25.0 g of Zn reacts at STP.
To determine the volume of H2 formed at STP (Standard Temperature and Pressure), we need to use the ideal gas law equation:
PV = nRT
Where:
P = Pressure (in atm)
V = Volume (in liters)
n = Number of moles of gas
R = Ideal Gas Constant (0.0821 L·atm/mol·K)
T = Temperature (in Kelvin)
STP is typically defined as a temperature of 273.15 K and a pressure of 1 atm.
First, we need to find the number of moles of Zn that react, using its molar mass:
Molar mass of Zn = 65.38 g/mol
Number of moles of Zn = Mass of Zn / Molar mass of Zn
= 25.0 g / 65.38 g/mol
≈ 0.382 mol (rounded to 3 decimal places)
According to the balanced chemical equation for the reaction between Zn and H2:
Zn + 2HCl → ZnCl2 + H2
1 mole of Zn reacts to form 1 mole of H2.
Therefore, the number of moles of H2 formed is also 0.382 mol.
Now that we have the number of moles of H2, we can use the ideal gas law equation to find the volume of H2 at STP.
P = 1 atm (STP Pressure)
V = Volume (to be determined)
n = 0.382 mol (number of moles of H2)
R = 0.0821 L·atm/mol·K (Ideal Gas Constant)
T = 273.15 K (STP Temperature)
Rearranging the ideal gas law equation, we have:
V = (nRT) / P
V = (0.382 mol) × (0.0821 L·atm/mol·K) × (273.15 K) / (1 atm)
≈ 8.915 L (rounded to 3 decimal places)
Therefore, approximately 8.915 liters of H2 are formed at STP when 25.0 g of Zn reacts.