Molar Mass and Mole Conversions
What is the difference between formula mass and molar mass?
Formula mass is the mass of one particle of a substance (in amu), molar mass is the mass of a mole of that substance (in g/mol)
What is the percent by mass of each element in NaCl?
39.3% Na, 60.7% Cl
A compound is found to contain 63.52 % iron and 36.48% sulfur. Find its empirical formula.
FeS
2 KClO3 --> 2 KCl + 3 O2
How many moles of O2 will be formed from 1.65 moles of KClO3?
2.48 mol O2
2 NaOH + CO2 --> Na2CO3 + H2O
Which reagent is the limiting reactant when 1.85 mol NaOH and 1.00 mol CO2 are allowed to react?
NaOH
What is the molar mass of MgCO3?
84.3 g/mol
What is the % by mass of each element in Ca(OH)2?
54.1% Ca, 43.2% O, 2.7% H
A 170.00 g sample of an unidentified compound contains 29.84 g sodium, 67.49 g chromium, and 72.67 g oxygen. Find the empirical formula.
Na2Cr2O7
__Fe + __O2 --> __Fe2O3
How many grams of Fe2O3 are produced when 0.275 moles of Fe are reacted?
22.0 g Fe2O3
C6H6 + Br2 --> C6H5Br + HBr
What is the theoretical yield of C6H5Br in this reaction when 30.0 g of C6H6 reacts with 65.0 g of Br2?
60.3 g C6H5Br
What is the mass of 4.67 mol of sodium sulfate?
663 g Na2SO4
What is the % by mass of each element in aluminum nitrite?
16.4% Al, 25.4% N, 58.2% O
A sample of a compound with a molar mass of 34.00 g/mol is found to consist of 0.44 g H and 6.92 g O. Find its molecular formula.
H2O2
__C4H10 + __O2 --> __CO2 + __H2O
How many grams of H2O are produced when 5.38 g of O2 are reacted?
2.33 g H2O
__CO + __H2 --> __CH3OH
2.50 g of hydrogen is reacted with 30.0 L of carbon monoxide at STP. What is the limiting reactant? What is the theoretical yield of CH3OH? What is the % yield if 8.25 g of CH3OH are actually formed in this reaction?
H2 is the limiting reactant, theoretical yield = 19.9 g CH3OH, 41.5% yield
How many molecules are in 25 g of dinitrogen tetroxide?
1.6 x 1023 molecules N2O4
What is the % by mass of each element in iron (III) acetate?
24.0% Fe, 30.9% C, 3.9% H, 41.2% O
The molar mass of nicotine is 162.1 g/mol. It contains 74.0% carbon, 8.7% hydrogen, and 17.3% nitrogen. Determine nicotine's empirical formula and molecular formula.
Empirical: C5H7N
Molecular: C10H14N2
__Na2SiO3 + __HF --> __H2SiF6 + __NaF + __H2O
How many formula units of Na2SiO3 can react with 120 L of HF at STP?
4.0 x 1023 formula units Na2SiO3
__NaCl + __Pb(NO3)2 --> __NaNO3 + __PbCl2
How many grams of lead (II) chloride are produced from the reaction of 15.3 g of NaCl and 60.8 g of Pb(NO3)2? What is the limiting reactant? How much excess is left over?
36.4 g PbCl2 is produced, NaCl is the limiting reactant, 17.4 g Pb(NO3)2 will be left over