Massing: a Means of Counting

Massing: A Means of Counting

Objectives:

·Measure masses of common compounds, objects, and minerals.

·Calculate moles and atoms from experimental masses.

Introduction:

You can often measure how much of something you have by counting individual objects. For example, you can count the number of pennies you have in your pocket or the number of pencils you have in your book bag. You learned that in chemistry there is a name for a number of atoms, ions, or molecules of that substance. You also learned that you can “count” the number of moles in a substance by massing the substance.

Purpose:

In this lab you will measure the masses of samples of various common compounds like water, salt, and sugar. You will use your results as a means of counting atoms, ions, and molecules in your samples. You will extend your technique to common objects that you can consider to be pure substances, pieces of chalk, and polystyrene peanuts. Finally, you will measure the masses of various mineral samples and use your results to find the number of atoms in each.

Materials:

Sucrose (C12H22O11), sodium chloride, calcium carbonate (chalk), polystyrene peanut (C8H8), and water.

Equipment:

Balance, plastic spoon, and evaporating dish.

Procedure:

1. Mass an evaporating dish.

2. Record mass in data table.

3. Obtain one level teaspoon of sodium chloride.

4. Place in baking cup.

5. Record mass in data table.

6. Repeat steps 3-5 for sucrose & water.

7. Mass a piece of chalk.

8. Record mass in data table.

9. Repeat 7&8 for the polystyrene peanut.

Cleaning Up:

Dump water in the sink. Put the sucrose, sodium chloride, polystyrene peanut, and chalk in appropriate containers. Wash counter tops and equipment.

Name:______Massing: A Means of Counting

Data Table:

Substance / # Atoms of each element / Molar Mass (g/mol) / Mass of Substance +
Evaporating Dish (g) / Mass of Substance (g)
Evaporating dish / / / / 46.12
Sodium Chloride / 51.95
Water / 51.13
Sucrose C12H22O11 / 51.90
Chalk- calcium carbonate / 50.56
Polystyrene peanut C8H8 / 46.21

Calculations:

Calculate the amount of atoms in each sample. Show your work and include the givens in the area provided:

1. Sodium Chloride