Mole Lab J



Mole Lab Name: _____________________________________

[25 points]

Partner(s): __________________________________

Purpose: To evaluate the number of moles and the number of particles in an amount of a given substance.

To gain a better (visual) understanding of the unit that we call the mole.

Materials:

Substance designated at each station

Electronic balance

Calculator

CAUTION

You must show all work to receive credit.

Be sure to report all answers with the appropriate number of significant figures.

Be sure to include units with every answer.

Before leaving a station, be certain that you have recorded all of the required data.

Procedure:

Proceed to each of the stations and answer the questions presented.

Station 1: On a weigh boat, there is a sample of Zinc pellets. Determine the mass of the empty weigh boat at the station.

a) (.5 point) What is the mass of the Zinc?

b) (1 point) How many moles are in this sample of Zinc?

c) (1 point) How many atoms of Zinc does this sample contain?

Station 2: This is a sample of aluminum foil. It measures approximately 8 cm x 8.5 cm,

which = 68 cm2.

a) (.5 point) What is the mass of the Al foil?

b) (1 point) How many moles does this piece of foil contain?

c) (1 point) How many atoms of Al are in this sample of foil?

d) (2 points) Extra Credit: How big would this piece of aluminum foil have to be to contain 1 mole of Al atoms?

Station 3: This station contains 5.00 grams of potassium chlorate.

a) (.5 point) What is the formula for potassium chlorate?

b) (1 point) What is the molar mass (formula mass) of potassium chlorate?

c) (1 point) How many moles are in this sample?

d) (1 point) How many molecules are in this sample?

Station 4: This station contains a weigh boat filled with Cobalt (II) Chloride hexahydrate that has the formula CoCl2 ∙ 6H2O. Determine the mass of the empty weigh boat at this station.

a) (.5 point) What is the mass of this compound?

b) (1 point) What is the molar mass (formula mass) of this compound? (Hint: You must include the mass of the 6 H2O.)

c) (1 point) How many moles are present in the sample?

d) (1 point) How many molecules are present in the sample?

Station 5: This station contains 7.433 x1021 molecules of glucose (C6H12O6).

a) (1 point) What is the molar mass of glucose?

b) (1 point) How many grams does this sample weigh theoretically? (This means that you calculate it.)

c) (1 point) After correcting for the weight of the weigh boat (1.00 g), you determine that the mass of the sample is actually 2.54 grams. What is your percent error?

Percent error = Experimental value – Accepted value x 100% Accepted value

Station 6: This station contains 0.100 moles of ammonium nitrate.

a) (.5 point) What is the formula for ammonium nitrate?

b) (1 point) How many molecules of ammonium nitrate does this sample contain?

c) (1 point) Theoretically, how many grams should this sample weigh? (This means that you calculate it.)

d) (1 point) Weigh the sample and record the value: _______________. If you have 0.00% error, what is the mass of the weigh boat? (Hint: See Percent Error calculation in Station 5c, above.)

Station 7 (or 8): Select a piece of chalk from the beaker.

Record all of the answers for this station in the table below.

Be certain to show all work for any calculations made.

a) (.5 point each) Determine the formula and formula mass of calcium carbonate (chalk).

b) (.5 point) Record the mass of a piece of chalk using the electronic balance.

c) (1 point) Calculate the number of moles of calcium carbonate in your piece of chalk.

d) (1 point) Calculate the number of molecules of calcium carbonate in your chalk.

e) Using your chalk, write your name(s) and the number of moles and molecules of chalk you have on the chalkboard. You want to wear the chalk down…

f) (.5 point) Determine the new mass of your chalk using the same electronic balance.

g) (.5 point) Determine the mass of chalk that you used up in writing.

h) (1 point) Determine the number of moles of calcium carbonate that you used up in writing.

i) (1 point) Determine the number of molecules of calcium carbonate that you used up in writing.

Final Check: Be sure that the table below is complete. Each answer must have units and the correct number of significant figures.

Table:

|Formula of calcium carbonate | |

|Formula mass of calcium carbonate | |

|Original mass of chalk | |

|Original moles of chalk | |

|Original molecules of chalk | |

|New mass of chalk | |

|Mass of chalk used up in writing | |

|Moles of chalk used up in writing | |

|Molecules of chalk used up in writing | |

(2 points) Extra Credit: How many times would you have to repeat your writing to use up 1 mole of chalk? (Show work.)

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