Answer:
Step-by-step explanation:
The molar mass is the mass of 1 mole of a substance. These values are found on the Periodic Table because they are equal to the atomic masses, but the units are grams per mole instead of atomic mass units.
Aluminum nitrate is made up of 3 elements: aluminum, nitrogen, and oxygen. Look up the molar masses of the individual elements.
- Al: 26.981538 g/mol
- N: 14.007 g/mol
- O: 15.999 g/mol
Let's analyze the chemical formula: Al (NO₃)₃
NO₃ is in parentheses with a subscript of 3 after. This means there are 3 nitrate ions in 1 mole of aluminum nitrate. Find the molar mass of a nitrate ion, multiply by 3, then add aluminum's molar mass.
- NO₃ = 14.007 + 3(15.999) = 14.007+47.997 =62.004 g/mol
- (NO₃)₃ = 3(62.004) =186.012 g/mol
- Al (NO₃)₃ = 26.981538 + 186.012 = 212.993538 g/mol
We can round to the nearest hundredth. The 3 in the thousandth place tells us to leave the 9 in the hundredth place.
The molar mass of aluminum nitrate is approximately 212.99 grams per mole.