00:01
Hello, and in this question here, we're told that the total mass of uranium in the world's, that is extractable in the earth surface, is equal to 4 .4 times 10 to the power of 9 kilograms.
00:17
Okay? and, well, we want to determine in the first part of the question, the mass of uranium, the amount of uranium 235, okay? so, the mass of uranium of uranium 235, okay? so the mass of, uranium 235 well that is equal to the percentage of uranium that is uranium 235 so that is equal to 0 .007 okay so that's so 0 .7 % is the percentage that is uranium 235 and writing 0 .7 % is a decimal it's equal to 0 .007 okay and we multiply by the total mass of uranium, which is 4 .4 times 10 to the power of 9.
01:08
So this gives the total mass of uranium 235 is equal to 3 .8, 3 .08 times 10 to the power of 10, sorry, times 10 to the power of 7 kilograms.
01:27
And we're asked to calculate the answer in grams.
01:30
So we just, that is equal to 10 to the power of 10 grams.
01:36
And that is the mass of uranium in grams, of uranium 235 in grams.
01:41
Now, in the next part of the question, we're asked to calculate how many moles of uranium this is equal to.
01:47
So one mole, so uranium has a mass of 235.
01:59
04439233u.
02:00
So this means that it has a mass of 235 .0 .04395 grams per mole.
02:09
Okay.
02:11
So we can divide this number here.
02:13
So this is the amount and when meant one mole waste.
02:17
So we can divide the total number of the total mass of uranium.
02:22
So the number of moles, okay, is equal to the mass of uranium 235 divided by the mass of a mole.
02:31
Okay? we can summon these two values, okay? and that gives the number of moles of uranium that's extractable in the earth surface is equal to 1 .3 times 10 to the power of 8 moles...