CHEM 101 Study Guide - Spatula, Molar Mass

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blushbadger787

17 Nov 2014

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Purpose: the purpose of this lab is to dehydrate a hydrated salt and determine its percent composition of water. Hypothesis: if the hydrated salt is heated and dehydrated, then the water molecules present in the compound will be released, making it will possible to determine the hydrate"s percent composition of water. Materials: hydrated salt, clean crucible, crucible lid, crucible tongs, bunsen burner, balance, clean spatula, ring stand, clay triangle, asbestos pad, 5-10 ml of water. Mass of crucible, lid, and hydrated salt (before) Mass of crucible, lid, and anhydrous salt (after) Analysis questions: (see all work on attached paper: calculate the mass of the original hydrated compound. The mass of the original hydrated compound is 6. 80 grams: calculate the mass of the final dehydrated salt. The mass of the final dehydrated salt is 3. 77 grams: calculate the mass of the water that was removed.

Part I: What is the complete formula (Salt · x H2O) for the hydrate you will be given in lab?

(25 points)

General Procedural guidelines for this lab:

From the very beginning of this experiment, only handle the crucible or evaporating dish with crucible tongs. SAFETY: The crucible will be very hot! Never touch the crucible while it could be hot. Use crucible tongs.
Use the same scale throughout this lab.
Do all of your calculations with proper sig figs.
For additions and subtractions, keep the fewest number of decimal places.
For multiplication and division keep the fewest number of significant figures.
While things are heating and cooling, work on Part II of this task.

Procedure: Watch this video, read along with the following procedure, and take notes: https://www.youtube.com/watch?v=k2s-YG15eIA

Wash out a crucible and flame dry. Heat the crucible with a Bunsen burner for 5 minutes on high and let it cool for 10 minutes.

Zero the balance.
Mass the crucible and record the mass (with units). __________

Fill the crucible about ¾ full with the hydrate.

Mass the crucible with the hydrate and record this mass. __________

Record the color of the hydrate (before heating). __________

Heat the crucible with the until all water is driven off. What is left in the crucible is the anhydrate.

Record the color of the anhydrate (after heating). __________

Let the crucible cool for a few minutes (at least 10). Then mass the anhydrate and crucible and

record this mass. __________

Complete the calculations to determine the (i) % mass of water in the hydrate and (ii) the value for x for your hydrate. Show all of your calculations. The calculations for the % mass of water in the hydrate are outlined in the video. You will have to do the calculations for x by yourself. Show all of your calculations on this page or another page.

MAKE A DATA TABLE HERE FOR ALL OF YOUR DATA:

MAKE A RESULTS TABLE HERE FOR THE RESULTS OF YOUR CALCULATIONS:

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CHEM 101 Study Guide - Spatula, Molar Mass

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Related Questions

Part I: What is the complete formula (Salt · x H2O) for the hydrate you will be given in lab?

(25 points)