A 0.160-g sample of unknown metal (X) reacts with hydrochloric acid to produce 66.5 mL of "wet" gas at 20 °C and 754 mm Hg. What is the unknown metal (X)? (The vapor pressure of water at 20 °C is 18 mm Hg. Help please?
I'm not sure this has a solution since there is no way to know the mole ratio between H2 produced and mols M consumed. I have assumed +2 metal and 1mol M to 1 mol H2 ratio to make MCl2 but it may not be that at all.
M + 2HCl ==> MCl2 + H2
PV = nRT
P = Ptotal - pH2O = 754-18 = 736
so P = 736/760 = about 0.968 atm.
V is 0.0665L
R you know
T = 20 + 273 = ?
Solve for n and I get approx 0.003.
Then 0.160/0.003 = approx ? You need to redo all of the math.
To determine the unknown metal (X), we can use the ideal gas law equation:
PV = nRT
Where:
P is the pressure of the gas
V is the volume of the gas
n is the number of moles of the gas
R is the ideal gas constant
T is the temperature in Kelvin
First, we need to convert the temperature provided from Celsius to Kelvin:
20 °C + 273.15 = 293.15 K
Next, we need to calculate the partial pressure of the gas produced by the reaction. We will subtract the vapor pressure of water from the total pressure provided:
Partial pressure of "wet" gas = Total pressure - Vapor pressure of water
= 754 mm Hg - 18 mm Hg
= 736 mm Hg
Now, we can rearrange the ideal gas law equation to solve for the number of moles (n):
n = (PV) / (RT)
P = 736 mm Hg (convert to atm by dividing by 760 mm Hg)
V = 66.5 mL (convert to L by dividing by 1000)
R = 0.0821 L·atm/(mol·K) (ideal gas constant)
T = 293.15 K (temperature in Kelvin)
Now, substitute the values into the equation:
n = ((736 mm Hg / 760 mm Hg) * (66.5 mL / 1000 mL)) / (0.0821 L·atm/(mol·K) * 293.15 K)
n = (0.967 * 0.0665 L) / (24.084 L·atm/(mol·K))
n ≈ 0.002663 mol
The number of moles of the unknown metal (X) is approximately 0.002663 mol.
To determine the molar mass of the unknown metal, we need to divide the mass of the sample by the number of moles:
Molar mass of X = Mass of X / Number of moles of X
Mass of X = 0.160 g (given)
Molar mass of X = 0.160 g / 0.002663 mol
Molar mass of X ≈ 60.15 g/mol
Therefore, the molar mass of the unknown metal (X) is approximately 60.15 g/mol. To identify the metal, you would need to compare this molar mass to the molar masses of known metals.