chemistry

NAME: ______________________________________________ LAB SECTION: _____________

NAME: Wenjia Zhang

HOMEWORK #4

MOLE CALCULATIONS – Mass, Moles, and Atoms

Show all of your steps and include units in every calculation.

1. (2.5 points) How many atoms are there in 5.4 moles of magnesium?

2. (2.5 points) How many moles are there in 7.8245 x 1026 calcium atoms?

3. (2.5 points) In 18.0 moles of C3H6, how many moles of C atoms are there?

4. (2.5 points) How many grams of hydrogen are there in 532.7 moles of CH4?

5. (2.5 points) How many electrons are there in 1.8 moles of carbon?

6. (2.5 points) About 65% of an adult human’s body weight comes from water. This means that a person who weighs 56 kg (123.5 pounds) has about 36,400 g of water in their body. How many moles of water are there in 36,400 g of water?

7. (6 points) Calculate the molar mass of these chemicals. Remember to include units and show all of your work to earn full credit.

Chemical	Molar Mass	Space for your calculations
HNO3
CH2O
C2Cl3F3
H2SO4

8. (4 points) A sample of Geranium (Ge) from outer space has an unusual mixture of isotopes. Based on the data for this mixture (in the table below), what is the atomic mass of Ge in this sample from outer space?

Isotope	70Ge	71Ge	72Ge	73Ge
Mass	69.9242 amu	70.9250 amu	71.9221 amu	72.9235 amu
Abundance	0%	12%	74%	14%

· Show all of your work

· Include units in your calculation

· Your answer should be different from the atomic mass on the periodic table.

· See your Lecture 12 notes for a similar problem with C

Fall 2020 – CHEM 1001 – Homework #4

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