Vocab
What is the mass of an element measured in amu?
Atomic Mass
What is the mass (in amu) of 75 S atoms?
2404.5 amu
How many copper atoms are in 1.60 mol of Cu?
9.63 x 1023 Cu atoms
What is the molar mass of Al2(CO3)3?
233.99 g Al2(CO3)3
What is the mass of a substance measured in grams?
Molar Mass
How many Cu atoms have a mass of 2.500 x 107 amu?
393391 Cu atoms
How many molecules of NH3 are present in 5.5 moles of ammonia?
3.31 x 1024 molecules of NH3
How many grams are in 5.00 moles of aluminum?
134.9 g Al
What is the mass of each element per 100 mass units of a compound?
Percent Composition
What is the mass (in amu) of 95 silver atoms?
10247.7 amu
How many sodium ions are in 12.00 moles of Na2O?
1.44 x 1025 ions of sodium
How many hydrogen atoms are in 30.1 g of C3H8?
3.29 x 1024 Hydrogen atoms
What is the “actual” number of each atom of each element present in a compound? It is a multiple of the empirical (simplest) formula.
Molecular Formula
How many gold atoms have a mass of 1.65 x 104 amu?
83.8 Au atoms
How many molecules are in 12.0 g of H2O?
4.01 x 1023 H2O molecules
How many formula units of O are there in 312 grams of Cu(NO3)2?
6.01 x 1024 formula units of O
What is the relationship between the number of moles of a particular element and a mole of the compound containing that element?
Mole Ratio
What is the formula mass of Mg(CO3)?
84.32 amu
How many grams are present in 3 x 107 molecules of C6H10S?
5.69 x 10-15 g C6H10S
Aspirin is 60.0% C, 4.5% H and 35.5% O. What is the empirical (simplest) formula? (Assume total mass of 100.0 g).
C9H8O4
A compound contains C 24.27%, H 4.07%, and Cl 71.65%. The molar mass is about 99 g. What are the empirical and molecular formulas?
CH2Cl = empirical
C2H4Cl2 = molecular