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Hello.
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In this question it has been given that a sample of air contains at stp 0 .039 moles of nitrogen, right? and oxygen is 0 .010 moles and 0 .0010 moles of air.
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Right.
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So this is given here.
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These values are given here.
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We have to find and we assume that there is no other gas present.
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Right.
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So first thing we have to find is find the partial pressure of oxygen.
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So we have to find the partial pressure of oxygen.
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And next is what is the volume of the container? now we remember this, we already know this, that partial pressure is equal to n into total pressure at stp, where n is the mole fraction, right? and total pressure at stp is equal to one atmosphere.
00:49
So what we do is first we will try to find the number of total number of moles.
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So we have been given these number of moles.
00:57
So these are the numbers we have been given.
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So we will add up all these numbers.
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This will give us the total number of moles.
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So when we add up, we get 0 .05 as the total number of moles.
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Now what we do? we calculate the mole fraction of oxygen, right? so mole fraction of oxygen will be fraction of oxygen divided by the total number of moles.
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So we see that the number of moles of oxygen is 0 .010...