SCH3U
Zegil
Due May 5th, 2017
Magnesium Oxide Lab
Purpose:
To determine the composition by mass of magnesium oxide, the percentage composition, and the percentage yield.
Hypothesis:
The law of definite proportions states that a chemical compound always contains the same amount of proportions of elements by mass. Based on the law of definite proportions, the percentage composition of magnesium oxide should be 60.3% magnesium and 39.7% oxygen.
Prediction:
Based on the law of definite proportions, the percentage composition of magnesium oxide should be 60.3% magnesium, and 39.7% oxygen.
Materials:
Lab apron
Steel wool
Ring Stand and Clamp
Glass Stirring Rod
1 piece of magnesium ribbon (3 cm)
1 piece of magnesium ribbon (7-8 cm)
Centigram or analytical balance …show more content…
What is the percentage composition by mass of oxide?
The percentage composition by mass of oxide is approximately 60% magnesium and 40% oxygen gas.
Is this percentage constant?
This percentage is pretty constant, but with a few outliers.
What was the percentage yield of the chemical reaction?
The percentage yield of the chemical reaction ranged with the groups, however most of them were over 100%. This was due to errors in the experiment.
What was your limiting reagent?
The limiting reagent was magnesium.
Calculate the percentage yield of the reaction, using your initial mass of magnesium ribbon. Determine what the limiting reagent is.
0.10g Mg x (1 mol / 24.31g) x (2 MgO / 2 Mg) x (40.31g / 1 mol) = 0.166 g of MgO
0.07g O2 x (1 mol / 32.00g) x (2 MgO / 1 O2) x (40.31g / 1 mol) = 0.176 g of MgO
The limiting reagent is Magnesium.
Actual yield: 0.17g
Theoretical Yield: 0.166 g
Percentage Yield MgO = 0.17g / 0.166 g x 100% = 102%
7. How could we alter the experiment to change what element was the limiting reagent?
We could alter the experiment to change what element was the limiting reagent