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The emperical formula of MgO

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Introduction

The Empirical Formula of Magnesium Oxide Data collection: This table shows the mass of different chemicals: Chemicals Mass/g + 0.01 crucible lid 38.12 crucible lid+ Magnesium 38.30 crucible lid + contents after heating 38.40 Table (1): Raw data Uncertainties: 1. balance +/-0.01 Data processing and presentation: Quantity Mass+ the uncertainty Magnesium 38.30- 38.12=0.18+0.1 oxygen 38.40- 38.30=0.10+0.1 number of moles of Mg 0.18/24.31=0.00699 number of moles of oxygen 0.10/16=0.00625 Table (2) Mass of Mg= (the mass of crucible lid +Mg) - (the mass of crucible lid) = 38.30- 38.12= 0.18 Mass of Oxygen= (the mass of crucible lid + contents after heating) - (the Mass of crucible lid+ Magnesium) =38.40- 38.30=0.10 -3 Number of moles of Mg=0.18/24.31= 6.7 X10 moles Number of moles of oxygen= 0.10/16.00 = 6.3 X10 moles Ratio Mg/O =0.00699/ 0.00625 =1.11+0.1 The actual value of Mg/O=1.00 The experimental empirical formula Mg O 6.7 X10 6.3 X10 6.3 X10 6.3 X10 Mg O 1.1 1 Magnesium oxide is made up of a ratio by mass of approximately 1:1 Magnesium to Oxygen, giving up an empirical formula of MgO. ...read more.

Middle

The theoretical empirical formula for Magnesium Oxide was Mg2.4O while the experimental empirical formula was MgO. Because the theoretical mole ratio differed from the experimental mole ratio, there is a mole ratio percent error. To find the mole ratio percent error, the Oxide as 2 magnesium atoms per 2 oxygen atoms. This theoretical ratio is 2:2which equals 1:1. From the Experimental empirical formula, the experimental percent composition was determined to be 65.2% magnesium in the magnesium oxide and 34.5%oxygen in the magnesium oxide. These numbers differ from the theoretical percent composition, as the theoretical percent composition was 60.3% magnesium and 39.7%oxgyen. The percent error in the experimental percent compositions for both magnesium and oxygen were calculated using the theoretical percent compositions for magnesium and oxygen, and the experimental percent compositions for these elements, and then plugging these numbers into the percent error formula. The percent error for magnesium was 8.6%, with the percent error of the oxygen being 13.1 %.( Refer to percent error under results for complete calculations) ...read more.

Conclusion

Also, although the crucible was taken off the flame only when the magnesium inside looked fully oxidized, and therefore altered the ratio of magnesium to oxygen in the resulting magnesium oxide, because of the amount of magnesium which was not chemically combined with oxygen. Improvements may be made to the lab to lessen the margin for error. The shape of the metal could be standardized to lessen the possibility for leftover unoxidized magnesium. If the magnesium was in smaller particles, the greater surface area might allow a more complete oxidation process since there would be more surface area for the oxygen to chemically react with. Also a way to ensure complete oxidation of the magnesium would be beneficial. Although stirring the magnesium oxide to check for any unoxidized magnesium would probably remove some magnesium oxide on the stirring instrument, maybe the crucible could simply be left on the flame for an additional period of time to lessen the chance for unoxidized magnesium. ...read more.

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