If you collect hydrogen gas over water at a temperature of 85*C, what is the volume of just the water if the pressure of hydrogen is 1.23 atm and the grams of hydrogen was 2.6
This problem is a bit confusing to me. If you've collected the H2 over water and you calculate V H2 from PV = nRT why won't the volume of the H2O be the same as the volume of H2 gas? I plugged in the numbers and obtained abou4 31 L for volume H2. Seems to me any other gas will occupy the same volume.
To calculate the volume of just the water in this scenario, we need to use the gas laws, specifically the combined gas law formula. The combined gas law formula allows us to relate the initial conditions of a gas (in this case, hydrogen) to its final conditions, taking into account changes in temperature, pressure, and volume.
The formula for the combined gas law is:
(P1 * V1) / (T1) = (P2 * V2) / (T2)
Where:
P1 and P2 are the initial and final pressures, respectively,
V1 and V2 are the initial and final volumes, respectively,
T1 and T2 are the initial and final temperatures in Kelvin.
Given information:
P1 (pressure of hydrogen) = 1.23 atm,
V1 (volume of hydrogen) = unknown,
T1 (temperature) = 85°C
To use the combined gas law formula, we need to convert the temperature from Celsius to Kelvin:
T1 (temperature) = 85°C + 273.15 = 358.15 K
Now we can rearrange the formula and solve for V1 (volume of hydrogen):
V1 = (P2 * V2 * T1) / (P1 * T2)
Since we are interested in the volume of just the water (V_water), we need to subtract the volume of hydrogen (V_hydrogen) from the total volume (V_total) measured.
V_water = V_total - V_hydrogen
The volume of hydrogen can be determined using the ideal gas law formula:
PV = nRT
Where:
P is the pressure of the gas (in atm),
V is the volume of the gas (in liters),
n is the number of moles of the gas,
R is the ideal gas constant (0.0821 L*atm/mol*K),
T is the temperature of the gas (in Kelvin).
To calculate the volume of hydrogen (V_hydrogen), we first need to determine the number of moles of hydrogen (n_hydrogen):
n_hydrogen = mass of hydrogen (grams) / molar mass of hydrogen
The molar mass of hydrogen is approximately 2 g/mol.
Once we have the number of moles of hydrogen, we can use the ideal gas law to find its volume (V_hydrogen).
It's important to note that water vapor is also present in the system. Since it's collected over water, we need to account for the water vapor pressure at the given temperature. The vapor pressure of water can be found in a reference table or determined using a vapor pressure chart.
After finding the water vapor pressure (P_water), we subtract it from the total pressure (P_total) to obtain the pressure of hydrogen (P_hydrogen) alone:
P_hydrogen = P_total - P_water
By applying the formulas and equations described above, we can determine the volume of just the water in the given scenario.