Calculate the number of mL of hydrogen gas at 27 degrees Celsius and 640 Torr produced by the reaction of 0.520 grams of magnesium with excess hydrochloric acid.
Here is a worked example of a stoichiometry problem. Find moles H2, then use PV = nRT to solve for volume in liters and convert to mL. http://www.jiskha.com/science/chemistry/stoichiometry.html
green liquid + blue lquid
To calculate the number of milliliters (mL) of hydrogen gas produced, we need to use the ideal gas law equation:
PV = nRT
where:
P = pressure (in atmospheres or atm)
V = volume (in liters or L)
n = number of moles
R = ideal gas constant (0.0821 L·atm/mol·K)
T = temperature (in Kelvin or K)
Firstly, we need to convert the given conditions to the appropriate units.
1. Convert 27 degrees Celsius to Kelvin:
T(K) = T(°C) + 273.15
T = 27°C + 273.15 = 300.15 K
2. Convert 640 Torr to atm:
P(atm) = P(Torr) / 760
P = 640 Torr / 760 = 0.8421 atm
Next, we need to determine the number of moles of hydrogen gas produced by the reaction of 0.520 grams of magnesium.
The balanced chemical equation for the reaction between magnesium (Mg) and hydrochloric acid (HCl) is:
Mg + 2HCl -> MgCl2 + H2
From the equation, we can see that 1 mole of magnesium (Mg) reacts with 2 moles of hydrochloric acid (HCl) to produce 1 mole of hydrogen gas (H2).
To calculate the number of moles of magnesium (Mg), divide the given mass (0.520 grams) by the molar mass of magnesium.
The molar mass of magnesium (Mg) is approximately 24.31 g/mol.
Number of moles of Mg = mass of Mg (g) / molar mass of Mg (g/mol)
Number of moles of Mg = 0.520 g / 24.31 g/mol = 0.0214 moles
Since magnesium is in excess, the number of moles of hydrogen gas produced will be equal to the number of moles of magnesium used.
Now, we can rearrange the ideal gas law equation to solve for volume (V):
V = (nRT) / P
Substituting the values:
V = (0.0214 moles) * (0.0821 L·atm/mol·K) * (300.15 K) / (0.8421 atm)
Simplifying:
V ≈ 0.916 L
Finally, we need to convert the volume from liters to milliliters:
1 L = 1000 mL
V(mL) = V(L) * 1000
V(mL) ≈ 0.916 L * 1000 = 916 mL
Therefore, the number of milliliters of hydrogen gas produced by the reaction is approximately 916 mL.