When 1.38 g of magnesium is added to 25 mL of 2.0 M hydrochloric acid, hydrogen
gas is released according to the equation below:
Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)
Calculate the volume of the gas formed at STP
1.38g Mg = 0.051 moles
25mL * 2.0 M = 0.05 moles HCl
So it looks like only 0.025 moles of H2 will be released
1 moles occupies 22.4 L, so you will get 0.025 * 22.4 = ___ L of H2
To calculate the volume of the gas formed at STP, we'll need to use the ideal gas law. The ideal gas law equation is:
PV = nRT
Where:
P = pressure (in atm)
V = volume (in liters)
n = moles of gas
R = ideal gas constant (0.0821 L·atm/mol·K)
T = temperature (in Kelvin)
First, we need to determine the moles of H2 gas formed. We can use the stoichiometry of the balanced chemical equation to do this.
From the equation: 1 mole of Mg reacts with 2 moles of HCl to produce 1 mole of H2 gas.
The molar mass of Mg is 24.31 g/mol. Therefore, the moles of Mg can be calculated as:
moles of Mg = mass of Mg / molar mass of Mg
= 1.38 g / 24.31 g/mol
= 0.0568 mol
Since the ratio of Mg to H2 is 1:1, the moles of H2 gas formed will also be 0.0568 mol.
Now, we can use the ideal gas law to calculate the volume at STP.
STP conditions are:
Pressure (P) = 1 atm
Temperature (T) = 273 K
Rearranging the ideal gas law equation to calculate volume, we have:
V = nRT / P
Substituting the values we have:
V = (0.0568 mol) * (0.0821 L·atm/mol·K) * (273 K) / (1 atm)
= 1.23 L
Therefore, the volume of the gas formed at STP is 1.23 liters.
To calculate the volume of gas formed at STP, we need to consider the ideal gas law, which states that the volume of a gas is directly proportional to the number of moles of the gas, as long as the pressure and temperature are constant.
Step 1: Calculate the number of moles of magnesium used.
To do this, we need to convert the mass of magnesium to moles. The molar mass of magnesium (Mg) is 24.31 g/mol.
number of moles = mass / molar mass
number of moles of Mg = 1.38 g / 24.31 g/mol = 0.0568 mol
Step 2: Determine the stoichiometry of the reaction.
From the balanced chemical equation given, we know that one mole of magnesium (Mg) reacts with one mole of hydrogen gas (H2). Therefore, the number of moles of H2 gas produced will also be 0.0568 mol.
Step 3: Apply the ideal gas law formula to find the volume of the gas at STP.
The ideal gas law can be represented as: PV = nRT
where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
At STP (Standard Temperature and Pressure), the pressure is 1 atmosphere (atm), and the temperature is 273 K.
R = 0.0821 L · atm / (mol · K)
Using the ideal gas law formula, we can rearrange it to solve for volume:
V = nRT / P
V = (0.0568 mol) * (0.0821 L · atm / (mol · K)) * (273 K) / (1 atm)
V = 1.31 L
Therefore, the volume of the gas formed at STP is approximately 1.31 liters.