Purpose: The purpose of this
experiment is to discover the
identity of the
element at each lab station by finding the molar
mass of the sample. Although each station represents
one mole of material and thus holds the same number of atoms, the molar
mass of each sample is different. Determine the molar
mass and identify the
element at each of the 12 lab station.
Procedure:
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Go to a station. This is a rotational lab, and you will move to the next station in approximately 4 minutes. Begin by recording the
mass of the empty container. The container
mass has been predetermined and is written on an index card taped to the lab bench. Record this value.
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Next, using the triple beam balance, find the total
mass of the mole and its container. Record this
mass to the nearest 0.05g. WHEN FINISHED,
SLIDE THE RIDERS ON THE BALANCE TO ZERO.
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Calculate the
mass of the mole by subtracting the
mass of the container from the total mass.
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Using a periodic table, determine the
identity of the element.
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Jot down a brief physical description of the element.
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When time is called, advance to the next station. Repeat until all 12 stations have been visited.
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Physical Description
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1
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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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Good lab reports show exactly how a calculation was done. Only one sample of a particular type of calculation needs to be included in the report.
For this lab, show how the molar
mass was determined for station #1. Begin by writing down the formula for the calculation; this is always done, even for simple calculations. Next, substitute
data into the formula and compute the answer.
Pay attention to significant figures. Include units on each number that you write down.
Conclusions:
- State your results.
- Explain whether the hypothesis was valid.
- Think of valid sources of error and explain how the error would affect the outcome.
- What could be done to the procedure to make the results of this experiment better?
Questions:
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Which of the elements were metals? Nonmetals? Metalloids? How do the physical properties of metals differ from the nonmetals?
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How many atoms are in one mole? Did each station represent the same number of atoms? Does each station have the same mass? Define molar mass.
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At the station with silver, there was only one tenth of a mole. How many atoms does this represent? How many atoms would be in one half of a mole of silver, and what would be its mass?