Chapter 2 Worksheet
Rubidium has two naturally occurring isotopes with the following masses and natural
abundances. Calculate the average atomic mass of rubidium.
Isotope
Mass (amu)
Abundance (%)
Rb-85
84.9118
72.15
Rb-87
86.9092
Calculate the atomic mass of silicon. The three silicon isotopes have atomic masses and relative
abundances of 27.9769 amu (92.2297%), 28.9765 amu (4.6832%) and 29.9738 amu (3.0872%).
Calculate the atomic mass of lead. The four lead isotopes have atomic masses and relative
abundances of 203.973 amu (1.4%), 205.974 amu (24.1%), 206.976 amu (22.1%) and
207.977 amu (52.4%).
1. How many silver atoms are there in 3.75 moles of silver?
2. If you have 1.42 x 1024 xenon atoms, how many moles do you have?
3. How many argon atoms are contained in 7.66 x 105 mmol of argon?
Chapter 2 Worksheet
4. Which of the following contains the MOST atoms? (Hint: You don't need a calculator,
just a periodic table.)
A) 10.0 g Ne B) 10.0 g He C) 10.0 g Ar D) 10.0 g Kr E) 10.0 g Mg
5. Which of the following contains the FEWEST atoms?
A) 4.0 g Li
B) 4.0 g Na C) 4.0 g K
D) 4.0 g Rb
E) 4.0 g Ca
6. What mass (in g) does 3.99 moles of Kr have?
7. How many mols of potassium are contained in 449 g of potassium?
8. What mass (in kg) does 5.84 mols of titanium have?
9. How many atoms are in 1.1 kg of gold?
10. What is the mass of 3.2 mol of HCl?
11. How many mols of CH4 are in 50g of CH4?
12. How many grams of carbon is in 1.2 mol of CO2?
13. How many grams of oxygen is in 1.2 mol of CO2?
14. How many grams of oxygen is in 25 g of CO2?