Date:
Class:

## Homework: Moles

Show work for all calculations!

1. The number under an atomic symbol in the periodic table has two meanings:
1. If you consider just one atom of that element, what does that number mean and what are the correct units for it?
2. If you consider a mole of atoms of that element, what does that number mean and what are the correct units for it?
2. Consider the list of units below. Write each unit in the box that corresponds to the category for that unit.
 CommonUnits g                  mL     g/mL          mol g/mol          m m2                sec Used for MeasuringAmounts of Materials Characteristics of Materialswhich Can be Used as Conversions

#### Moles: Numbers and Masses

##### Molar Masses

For each of the following elements or compounds calculate the mass of 1 mole of particles of that substance. Express answers in units of g/mol. Use at least five significant figures for the mass of each element when calculating molar masses.

1. CO2
2. Ba3(PO4)2
1. C6H12O6
2. AgNO3
##### Putting Molar Masses to Work

For each of the masses, convert to number of moles. For each quantity given in moles, convert to mass in grams. Express each answer with the correct number of significant figures.

1. 5.9 mol CO2
2. 3.8 × 10-3 mol Ba3(PO4)2
1. 1.2 kg C6H12O6
2. 37.98 g AgNO3

page break

##### Comparing Moles

Compare the following pairs of samples on the basis of the number of particles (the number of moles, not the mass). Which one has more particles? Circle the sample that has the larger number of particles.

 116.89 g NaCl      117.56 g Ca(OH)2 49.542 g H2O      116.695 g BaSO4

##### Big Numbers

For each of the following amounts of materials, calculate the number of molecules given that [6.02 × 1023 molecules = 1 mol].

1. 1.2 mol H2O
2. 0.50 mol NH3
1. 36 g H2O
2. 8.5 g NH3
1. You have been given a container which weighs 49.87 g. You place a sample of glucose (C6H12O6) into it and weigh it and now it weighs 92.54 g. How many molecules of glucose are in the container?
2. Chloral hydrate (C2H3Cl3O2) is a drug formerly used as a sedative and hypnotic. It is the compound used to make “Mickey Finns” in detective stories.
1. Calculate the molar mass of chloral hydrate.
2. How many moles of C2H3Cl3O2 molecules are in 500.0 g of chloral hydrate?
3. What is the mass in grams of 2.0 × 10-2 mol chloral hydrate?
4. How many chlorine atoms are in 5.0 g of chloral hydrate?
5. What mass of chloral hydrate would contain 1.0 g Cl?
6. What is the mass of exactly 500 molecules of chloral hydrate?
This homework belongs with the Moles Group Activity.
Moles Practice Calculations
Last updated: Apr 25, 2024       Home