finding quite tricky help me plsssss
You can use the molar mass of oxygen gas (O_{2}) and Avogadro's number as conversion factors in this problem. The molar mass is good for "g→mol" or "mol→g" conversions. Avogadro's number is good for "molecules→moles" or "moles→molecules" conversions.
Avogadro's number is the number of things (6.022 x 10^{23}) in a mole of things (e.g., there are 6.022 x 10^{23} molecules of O_{2} in one mole of O_{2}).
Molar masses are found on the periodic table. The molar mass of an element is the mass, in grams, of a mole of atoms for each element. It is 16.00 g/mol for O. Because there are two O atoms in O_{2}, the molar mass for O_{2} is 32.00 g/mol.
The calculation can be planned out like this, because we have conversion factors for each of the two steps.
grams O_{2} → mol O_{2} → molecules O_{2}
And the calculation steps are set up this way:
250 g O_{2} x (1 mol O_{2} / 32.00 g O_{2}) x (6.022 x 10^{23} molecules O_{2} / 1 mol O_{2})
= 4.7 x 10^{24} molecules
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