Today is 15 July 2009 -- We learned how to write a lab report

We made lab notebooklets in which to write up the report on the first experiment, "Combustion of Magnesium and associated reactions."  Students were provided with a data page that identified what they were to look for.  The data page is:

COMBUSTION OF MAGNESIUM RIBBON AND ALLIED EXPERIMENTS

1.  Weigh a portion of magnesium ribbon.  About 0.5g is enough.  Record the weight.

2.  Weigh a clean beaker.  Record the weight.

3.  Hold the magnesium with tongs.

4.  Ignite the ribbon over a burner; hold it over the beaker to catch the residue of combustion.

5.  What is the chemical equation that describes the combustion?  Write and balance the equation.

5a. How many moles of magnesium did you start with and how many moles of magnesium oxide resulted? 

6.  Weigh the beaker and combustion product.  This is the "gross weight."  Subtract the weight of the beaker (the "tare weight") from the gross.  This gives the "net weight."  The net weight is mass of the magnesium oxide collected.

7.  Based on the reaction equation, how many grams of magnesium oxide did you expect?  How much did you actually obtain?  What is the percentage recovery?

8.  Write and balance the equation showing the reaction of magnesium oxide with hydrochloric acid to produce magnesium chloride and water. 

8a.  What is the mole ratio of magnesium oxide to hydrochloric acid?

8b.  Based on the amount of magnesium oxide recovered, how much hydrochloric acid do you need to react with it?

9.  Hydrochloric acid is hydrogen chloride dissolved in water.  The concentration of hydrochloric acid that you will work with is 3.7%, the rest being water.  How many milliliters of the dilute acid will you need to react with the magnesium oxide?

10.  Add the acid to the magnesium oxide and stir or swirl to react.  Use a glass stirring rod, if necessary.

11.  When the reaction is complete, the solution should be clear.  If you have undissolved residue, carefully add more dilute acid.  Measure EXACTLY how much you are adding. 

12.  Using a hot plate or burner with wire gauze, warm the solution and evaporate to dryness.   The result should be magnesium chloride crystals. 

13.  Cool and reweigh.  Subtract the beaker tare from the gross weight to find the number of grams of magnesium chloride.

14.  How many moles of magnesium chloride were recovered?  How much was expected? How much magnesium was present in the material recovered?  Compare the amount of magnesium recovered to the amount you started with as magnesium ribbon.