The Molar Mass Lab
Background and Directions
Discussion: At each lab station is a sample of a different element. After weighing a container, record its mass. Next record the mass of the empty container (written on container) and the moles of the substance (also written on container). The mole is a very important unit of measurement in chemistry. In this lab you will learn how the mass of an element is related to this unit. Avogadro called it the mole.
DO NOT OPEN ANY OF THE CONTAINERS! When your teacher tells you to begin, go to any scale and record the scale number as your lab group number. You may choose your station. Be sure to “zero” your balance before starting.
In the chart on the front of your printed lab sheet record the first 3 columns of data for your container: (a) the mass of the bottle with the element inside of it you measure on your balance in grams; (b) mass of the empty bottle printed on the container; and, (c) # of moles printed on the container. On the back of your lab sheet number 1-12 leaving spaces for your observations of the physical characteristics of your sample to help you with the identification – color; shiny or dull; powder or solid (if solid, its shape) or liquid; and anything else you might notice about the sample. After recording these four things pass your sample bottle on to the group immediately to your right. If you have extra time (you are waiting for the group on your left to hand you the next bottle) you may start your calculations to find the mass of the element, and the mass of one mole of the element.
If you have calculated the mass
of one mole correctly, you can identify your element by using your periodic
table. Chemists often identify elements from their physical properties. Good luck in learning the identities of the
elements. May the mole be with you!
Name: __________________________
Date: ____________ Period: _______
Lab Group # (scale #): ________
Molar Mass Lab Std 3e
Directions: Using this chart below as a guide, figure out what element is in each bottle.
On the back of this paper, number 1-12 and write a brief description
of each element.
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bottle num. |
Mass
of container + elmnt in grams (balance) |
Mass
of bottle in
grams (given) |
Moles of element (given) |
Mass of element in grams (calc.) |
g/mole (molar mass of element) (calc.) |
Name of element |
Metal, non-metal,
metalloid |
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2 |
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3 |
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4 |
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5 |
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6 |
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7 |
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8 |
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9 |
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10 |
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11 |
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12 |
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Post Lab Questions
1. Which element (s) did you already know by its physical properties?
2. Which element(s) did you learn the appearance of from the mole calculation?
3. Do you think that you have identified any of the elements incorrectly? Which and why?
4. Write at least 3 sentences about what you think you learned from doing this lab.