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Law of Definite Proportions Lab Procedure

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This is the procedure for the Honors Chemistry lab "Law of Definite Proportions".

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Alright, this is the law of definite proportions lab and as you see here we have our crucible and lid and 20 cm of loosely coiled magnesium ribbon. First step is to weigh the crucible with lid and that will be the first data point in your table and we have a weight of about 25.37 grams. Second data point you do the crucible, lid, and magnesium ribbon so we put the magnesium in the crucible weigh that and put this is in your lab notebook as 25.64 grams. Now we have our crucible set up on our clay triangle ready to heat and react the magnesium ribbon which will turn into magnesium oxide place to lid on top allowing a slight amount of oxygen in.  Go ahead and light the Bunsen burner. [heat with lid slightly open to let oxygen in] [heat with lid slightly open to let oxygen in] We're going to heat this until we see reaction start to form and white magnesium oxide form inside of the crucible. So, now we're about 5 minutes into heating this and the magnesium ribbon is starting to combine with oxygen in the air to form magnesium oxide. As you can see inside of the crucible it's turning a whitish powder and it's also starting to glow red. We don't want it to to fully ignite in a white flame because you lose some the magnesium oxide out into the air. So let this finish heating and we'll come back when it's done. So the magnesium is finish reacting.  We're going to shut this flame off and look at our magnesium oxide product. Inside the crucible you see that white magnesium oxide. During the reaction you don't want a lot of white smoke to come out because that's actually magnesium oxide you'll be losing to the air. So right now we're going to take the crucible off the clay triangle and allow it to cool so we can weigh it. Now that we have our magnesium oxide nice and cool. We're going to put the lid back on and get a weight on it. Our new weight is 25.78 grams of the directions call for you to add water to magnesium oxide and then reheat it this is to make sure that any remaining magnesium gets reacted so add couple drops of water and start the process over again. When you go to heat the magnesium with the water we want to make sure the lids on so we don't lose any of that product. [heat crucible with lid fully on during 2nd and 3rd heating] [heat crucible with lid fully on during 2nd and 3rd heating] [heat crucible with lid fully on during 2nd and 3rd heating] Now we're weighing our magnesium oxide for the second time after we heated it with the couple drops distilled water. You can see the weight is still 25.78 the only...only reason we did this is because if your weight had increased by more than 0.03 grams, you would want to use that second weight, just make sure all the magnesium has fully reacted. But it was and that's your lab.

Uploaded by Nathaniel Pettinato.

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Law of Definite Proportions Lab Procedure

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