A sample of dry air at 28 degress celcius in a sealed flask has a pressure of 90kPa. Which is the most likely the partial pressure of Oxygen, O2(g) in the flask?
a) 70kPa
b) 19kPa
c) 3Pa
d) 0.8kPa
Can you explain how you got this answer?
How did you get the mole fraction?
The mole fraction of oxygen molecules in dry air is 0.2095.
Daltons Law:
Po2/90=.2095
Po2=18.8 kPa
To determine the partial pressure of oxygen, we can use Dalton's law of partial pressures. According to this law, the total pressure of a mixture of gases is equal to the sum of the partial pressures of each gas in the mixture.
In this case, we are given the total pressure of the dry air in the sealed flask, which is 90 kPa. We need to find the partial pressure of oxygen, O2(g).
To do this, we need to know the percentage of oxygen in dry air. The approximate percentage of oxygen in dry air is about 21%. Therefore, we can calculate the partial pressure of oxygen as follows:
Partial pressure of oxygen = Total pressure of dry air × Percentage of oxygen in dry air
Partial pressure of oxygen = 90 kPa × 0.21
Partial pressure of oxygen = 18.9 kPa
Therefore, the most likely partial pressure of oxygen in the flask is 18.9 kPa.
Looking at the options given:
a) 70 kPa: This is much higher than the calculated value of 18.9 kPa.
b) 19 kPa: This matches the calculated value of 18.9 kPa, so this could be a likely answer.
c) 3 Pa: This is significantly lower than the calculated value of 18.9 kPa.
d) 0.8 kPa: This is also significantly lower than the calculated value of 18.9 kPa.
Based on the above analysis, the most likely answer is option b) 19 kPa, as it matches the calculated value for the partial pressure of oxygen in the flask.