Chemistry 11
MOLE CONVERSIONS
A. CONVERSIONS BETWEEN NUMBERS OF PARTICLES AND MOLES OF PARTICLES
Conversion Factors: 6.022 x 1023 particles or 1 mol______
1 mole 6.022 x 1023 particles
Type 1:Given the number of particles, determine the number of moles that are present.
Ex. How many moles of Carbon atoms are there in 3.01 x 1024 C atoms?
3.01 x 1024 C atoms x ______1mol______= 5.00 mol C
6.022 x 1023 C atoms
Exercise A: Calculate the number of moles present for each of the following. Don’t forget about significant figures.
1. How many moles of Ag are present in 3.0 x 1016 atoms of Silver?
2. How many moles of O2 are present in 5.53 x 1041 molecules of oxygen gas?
3. How many moles of Fe2(CO3)3 are present in 7.49 x 1021 formula units of iron(III) carbonate?
Type 2:Given the number of moles, determine the number of particles that would be present.
Ex. How many CO2 molecules are present in 0.75 mole of CO2?
0.75 mol CO2 x 6.022 x 1023 molecules CO2 = 4.5 x 1023 molecules CO2
1 mole
Exercise B: Calculate the number of particles for each of the following. Remember to use the correct number of significant figures.
1. How many atoms are present in 2 moles of carbon?
2. How many formula units are present in 1.7 moles of AgCl?
3. How many hydrogen atoms are present in 2.6 moles of CH4?
B. CONVERSIONS BETWEEN MASS OF A SUBSTANCE AND MOLES OF PARTICLES
Conversion Factors: X g or 1 mol___
1 mol X g
Type 3:Given the number of moles of a substance, determine how many grams of that substance would be present.
Ex. What is the mass in grams of 0.34 moles of NO2?
Molecular Mass of NO2 = 1 N x 14.0 amu = 14.0 amu
2 O x 16.0 amu = 32.0 amu
46.0 amu
Molar Mass of NO2 = 46.0 g/mol
0.34 mol NO2 x 46.0 g NO2 = 16 g NO2
1 mol NO2
Exercise C: Calculate the mass in grams which are represented by each of the following.
1. What is the mass in grams of 1.41 moles of iron?
2. What is the mass in grams of 5.4 moles of silver hydroxide, AgOH?
3. What is the mass in grams of 3.75 x 10-7 moles of cobalt(II) nitrate, Co(NO3)2?
Type 4:Given the number of grams of a substance, determine how many moles of that substance would be present.
Ex. How many moles are there in 6.28 grams of Magnesium chloride?
Molecular Mass of MgCl = 1 Mg x 24.3 amu = 24.0 amu
1 Cl x 35.5 amu = 35.5 amu
59.8 amu
Molar Mass of MgCl = 59.8 g/mol
6.28 g MgCl x 1 mol MgCl = 0.105 mol MgCl
59.8 g MgCl
Exercise D: Calculate the number of moles present in each of the following.
1. How many moles are there in 92.0 grams of lead?
2. How many moles are there in 0.024 grams of P2O5?
3. How many moles are there in 1.505 grams of NH4OH?
C. CONVERSIONS USING THE MOLAR VOLUME OF A GAS
All gases with the same pressure, temperature and number of particles occupy the same volume!
The volume occupied by a gas under ……
Standard Temperature and Pressure
STP = 0oC (273 K) and 101.3 kPa(1 atm)
Conversion Factor: 22.4 L or 1 mol__
1 mol 22.4 L
Type 5: Given the number of moles, determine how many litres or millilitres of gas it would form.
Ex. What would be the volume, in litres, of 3.5 x 10-2 moles SO3?
3.5 x 10-2 mol SO3 x 22.4 L SO3 = 0.78 L of SO3
1 mol SO3
Exercise E: Calculate the volume of gas present for each of the following.
1. What volume of gas, in L, would be occupied by 2.64 moles of CO2(g)?
2. How many moles of helium gas are contained in a balloon with a volume of 10.0 L at STP?
3. What is the volume occupied by 0.350 moles SO2(g) at STP?
D. CONVERSIONS BETWEEN NUMBERS OF PARTICLES AND MASS OF A SUBSTANCE.
Type 6: Given the number of particles of a substance, determine how many grams of that substance would be present.
Ex. What would be the mass of 8.4 x 1018 SO3 molecules?
Molecular mass of SO3 = 1 S x 32.1 amu = 32.1 amu
3 O x 16.0 amu = 48.0 amu
80.1 amu
Molar mass of SO3 = 80.1 g/mol
8.4 x 1018 molecules SO3 x 1 mol SO3 x 80.1 g SO3 = 1.1 x 10-3 g SO3
6.022 x 1023 molecules SO3 1 mol SO3
Exercise F: Calculate the amount mass in grams which are represented by each of the following.
1. What would be the mass of 7.49 x 1021 atoms of Cobalt?
2. What would be the mass of 6.79 x 1021 molecules of calcium phosphate, Ca3(PO4)2?
3. What would be the mass of 1.8 x 1027 molecules of ammonia, NH3?
4. What is the mass of 4.83 x 1022 molecules of water?
Type 7: Given the number of grams of a substance, determine the number of particles present.
Ex. How many molecules of KMnO4 would be present in 0.24 g of KMnO4?
Formula Unit Mass of KMnO4 = 1 K x 39.1 amu = 39.1 amu
1 Mn x 54.9 amu = 54.9 amu
4 O x 16.0 amu = 64.0 amu
158.0 amu
Molar Mass of KMnO4 = 158.0 g/mol
0.24 g KMnO4 x 1 mol KMnO4 x 6.022 x 1023 molecules KMnO4 = 9.1 x 1020 molec.
158.0 g KMnO4 1 mol KMnO4 KMnO4
Exercise G: Calculate the number of particles present for each of the following.
1. How many atoms of Selenium are there in 0.0092 grams of Selenium?
2. How many molecules of CCl4 are there in 16.8 grams of CCl4?
3. How many formula units of K2C2O4 are there in 48.92 grams of potassium oxalate?
E.COMBINED CONVERSIONS
Exercise H: Calculate the following. Don’t forget about significant figures.
1. How many hydrogen atoms are in 0.268 moles of H3PO4?
2. How many molecules are in 78.54 g of nitrogen dioxide?
3. What volume of gas, in litres, would be occupied by 8.7 x 1020 molecules of methane, CH4?