Answer:
0.280 moles
Step-by-step explanation:
We can convert from grams to moles through molar mass.
Stoichiometry
Stoichiometry is the study of the relationship between quantities of substances. Part of stoichiometry is converting between different quantity measurements such as grams (g) and moles (mols).
One way to convert between g and mols is molar mass. Molar mass is the number of grams in one mole of a substance. Molar mass is a constant that can be found on periodic tables.
Conversion
First, we need to look at a periodic table and find that the molar mass of Argon (Ar) is 39.948 g/mol. To convert between units, set up a multiplication problem where the unwanted units (grams in this case) are in the numerator at one point and then in the denominator. Having the units in opposite positions allows the units to cancel out.
So, there are 0.280 moles of Argon in 11.2 grams. Note that this answer has been rounded according to significant figures rules.