Mole Basics
How many atoms are in 1 mole of a substance?
6.022 x 1023 atoms
Convert 2 moles of oxygen gas (O2) to grams.
64 g
What is the empirical formula of C6H12O6?
CH2O
What is the percent composition of hydrogen in water (H2O)?
11.2%
What is the molar volume of any gas at STP?
1 mole = 22.4 L
What is the unit for molar mass?
grams/mole (g/mol)
How many moles are in 88 grams of carbon dioxide (CO2)?
2 moles
A compound is found to be 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen. What is its empirical formula?
CH2O
What is the percent by mass of sodium in sodium chloride (NaCl)?
39.3%
Which of the following compounds has the smallest percent of oxygen by mass?
CO2 or SO2
SO2
How do you calculate formula mass?
Add up all of the atomic masses of all the atoms in a formula
Convert 5.36 x 1024 atoms of helium to moles.
8.90 moles
A compound has an empirical formula of CH2 and a molar mass of 42.08 g/mol. What is its molecular formula?
C3H6
Calculate the percent composition of nitrogen in ammonium sulfate (NH4)2SO4.
21.2%
Calculate the mass of 1.00 L of oxygen gas (O2) at STP.
1.43 g
What is the molar mass of water (H2O)?
18.02 g/mol
How many atoms are in 5.00 grams of aluminum oxide (Al2O3)
2.95 x 1022 atoms
Determine the empirical formula of a compound containing 27.3% carbon and 72.7% oxygen by mass.
CO2
A 50 g sample of a compound contains 30 g of oxygen. What is the percent by mass of oxygen in the compound?
60%
If you have 2 moles of sodium chloride (NaCl), how many moles of sodium ions do you have?
2
If you have 2 moles of CO2 how many atoms of oxygen do you have?
4
How many liters of ammonia (NH3) are needed to produce a 10.0 gram sample?
13.2 L
A 10.0 g sample of a compound contains 3.0 g of carbon, 1.0 g of hydrogen, and 6.0 g of oxygen. What is the molecular formula if the molar mass is 60.0 g/mol?
CH4O2
Calculate the percent composition of all elements in glucose (C6H12O6).
C = 40.04%
H = 6.7%
O = 53.3%
A compound contains 85.7% carbon and 14.3% hydrogen. Its molar mass is 42 g/mol. Determine its empirical and molecular formula.
Empirical: CH2
Molecular: C3H6