50cm3 of hydrogen is collected over water at 17 degree celsius and 750 mm Hg pressure.Calculate the volume of
dry gas at S.T.P.The water vapour pressure at 17 degree celsius
is 14 mm Hg?
45.6cm^3
45.6cc
To calculate the volume of the dry gas at STP (Standard Temperature and Pressure), we need to follow these steps:
Step 1: Determine the actual pressure of the hydrogen gas.
The given pressure is 750 mmHg, but this includes the vapor pressure of water. To find the actual pressure of the hydrogen gas, we need to subtract the water vapor pressure (14 mmHg) from the given pressure:
Actual Pressure = Given Pressure - Water Vapor Pressure
Actual Pressure = 750 mmHg - 14 mmHg
Actual Pressure = 736 mmHg
Step 2: Convert the actual pressure to atmospheres.
To convert the pressure from mmHg to atmospheres, we divide it by the conversion factor of 760 mmHg/1 atm:
Pressure in atmospheres = Actual Pressure / 760 mmHg/atm
Pressure in atmospheres = 736 mmHg / 760 mmHg/atm
Pressure in atmospheres ≈ 0.97 atm
Step 3: Convert the temperature to Kelvin.
The given temperature is 17 degrees Celsius. To convert it to Kelvin, we need to add 273.15 to the Celsius temperature:
Temperature in Kelvin = Celsius Temperature + 273.15
Temperature in Kelvin = 17°C + 273.15
Temperature in Kelvin ≈ 290.15 K
Step 4: Apply the Ideal Gas Law to find the volume of the dry gas.
We can use the Ideal Gas Law formula (PV = nRT) to find the volume of the dry gas. At STP, the pressure (P) is 1 atmosphere, the volume (V) is unknown, the number of moles (n) is unknown, the gas constant (R) is 0.0821 L.atm/(mol.K), and the temperature (T) is 273.15 K.
1 atm * V = n * 0.0821 L.atm/(mol.K) * 273.15 K
Since we want to find the volume (V), we can rearrange the formula:
V = (n * R * T) / P
Since we have 50 cm³ of hydrogen gas, which is the same as 0.05 L (since 1 L = 1000 cm³), we can substitute these values into the formula and solve for n:
0.05 L = (n * 0.0821 L.atm/(mol.K) * 290.15 K) / 0.97 atm
Simplifying and solving for n:
n = (0.05 L * 0.97 atm) / (0.0821 L.atm/(mol.K) * 290.15 K)
n ≈ 0.00187 moles
Step 5: Substitute the calculated values into the volume formula to find the volume of the dry gas at STP:
V = (n * R * T) / P
V = (0.00187 moles * 0.0821 L.atm/(mol.K) * 273.15 K) / 1 atm
Simplifying and solving for V:
V ≈ 0.0496 L
Therefore, the volume of the dry gas at STP is approximately 0.0496 liters.
Use (P1V1/T1) = (P2V2/T2)
For P1 use 750-14 = ?
V1 = 50 cc
T1 = 273+17 = ?
P2 and T2 ae STP
V2 = solve for this in cc.