Find the mass in grams of a 240 ml sample of dry air at a pressure of 750 mmHg and a temperature of 19 degrees celsius.
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Use PV = nRT as in your other post and solve for n = number of mols. Then n = grams/molar mass. You know n and molar mass, solve for grams.
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how can find mass in gram
To find the mass of dry air, we can use the ideal gas law equation, which states:
PV = nRT
Where:
P = pressure
V = volume
n = number of moles
R = ideal gas constant (0.0821 L.atm/mol.K)
T = temperature
First, we need to convert the given values to the appropriate units:
- Pressure: 750 mmHg = 750/760 atm (since 1 atm = 760 mmHg)
- Volume: 240 ml = 240/1000 L (since 1 L = 1000 ml)
- Temperature: 19 degrees Celsius = 19 + 273 = 292 K
Now, we can plug the values into the equation and solve for the number of moles of air:
(750/760) * (240/1000) = n * 0.0821 * 292
Simplifying the equation:
0.9868 * 0.24 = n * 23.9672
0.236832 = n * 23.9672
n ≈ 0.0098759 moles
Now, we will calculate the molar mass of air, which is the mass of one mole of air. The molar mass of air is approximately 28.97 g/mol.
Finally, we can find the mass of the 0.0098759 moles of air sample by multiplying the number of moles by the molar mass:
mass = 0.0098759 moles * 28.97 g/mol
mass ≈ 0.2859 g (rounded to four decimal places)
Therefore, the mass of the 240 ml sample of dry air is approximately 0.2859 grams.
To find the mass of the air, we need to use the ideal gas law equation:
PV = nRT
Where:
P = pressure
V = volume
n = number of moles
R = gas constant
T = temperature
First, let's convert the given volume from milliliters (ml) to liters (L). Since 1 L = 1000 ml, the volume in liters is:
V = 240 ml / 1000 ml/L = 0.24 L
Next, convert the pressure from millimeters of mercury (mmHg) to atmospheres (atm). Since 1 atm = 760 mmHg, the pressure in atmospheres is:
P = 750 mmHg / 760 mmHg/atm = 0.986 atm
Now, we need to convert the temperature from Celsius to Kelvin. The Kelvin temperature scale starts at absolute zero where 0 Kelvin equals -273.15 degrees Celsius. To convert Celsius to Kelvin, we add 273.15 to the given temperature:
T = 19 degrees Celsius + 273.15 = 292.15 Kelvin
The gas constant (R) is typically given as 0.0821 L atm/(mol K).
Now, we have all the values we need to solve the ideal gas law equation for the number of moles (n):
0.986 atm * 0.24 L = n * 0.0821 L atm/(mol K) * 292.15 K
Simplifying the equation:
0.23664 = n * 23.9595155
Dividing both sides of the equation by 23.9595155:
n = 0.23664 / 23.9595155
n ≈ 0.009864 mol
Finally, to calculate the mass, we use the molar mass of air (approximately 28.97 g/mol):
mass = n * molar mass
mass ≈ 0.009864 mol * 28.97 g/mol
mass ≈ 0.285 g
Therefore, the mass of the given 240 ml sample of dry air at a pressure of 750 mmHg and a temperature of 19 degrees Celsius is approximately 0.285 grams.