Magnesium Oxide Lab

Hey everyone! Today was a really fun day in chemistry because we did the Magnesium Oxide Lab.

At the beginning of class, Mr Lieberman checked in our pre-labs (don't forget that means a data table as well) and we got started on the Magnesium Oxide Lab. We began by massing an empty crucible and lid, and then massing the crucible, lid, and a 25 cm magnesium ribbon together. We recorded these two values in our data tables and then proceeded to place the covered crucible on the clay triangle. We lit the burner and removed the lid every three minutes for a total of fifteen minutes. After the flame had been carefully turned off and the crucible cooled down, we massed the crucible, crucible lid, and magnesium oxide product.

For the post lab:
1. we are first asked to calculate the mass of the magnesium metal and the mass of the product, using the law of conservation of mass to calculate the mass of oxygen that combined with the magnesium. (Law of conservation mass: the mass of substances in a closed system will remain constant, no matter what processes are acting inside the system). This should be done by subtracting the mass of crucible, lid, and ribbon from the mass of the crucible, lid, and magnesium oxide.
2.Then, we are asked to calculate the percent composition of magnesium oxide. To do this, start by calculating the formula mass, and dividing each component mass by the formula mass and multiply by 100.
3. We are then asked to use molar mass to calculate the number of moles for each reactant. (see class notes)
4. calculate the ration between the number of moles of magnesium to the number of moles of oxygen and find the empirical formula of magnesium oxide. Look at Elim's post if you still need help with empirical formulas!
5. convert mass to moles to find theoretical yield (this shouldn't be too complicated)
6. calculate your percent yeild

Hope this helps! Tonight's homework is to complete Avagadro's Crash Activity. If you still need help on empirical formulas I found the following video very helpful http://www.youtube.com/watch?v=r2Log6-voWo! Also, work on the lab (due Thursday), and don't forget to begin studying for Thursday's test! Tomorrow's scribe is Katie I!