Magnesium Oxide Lab Report
Percentage Composition of Magnesium Oxide
Aleshia Otieno
Mr. Taylor
SCH3U-01
Lab #4
Monday, November 17, 2014
Introduction Percentage composition is the percentage of a formula mass represented by each element. Percentage composition compares the mass of one part of a substance to the mass of the whole. The law of definite proportions states that a specific compound always contains the same amount of elements in fixed proportions by mass. By finding the percent composition of magnesium oxide one will essentially be proving this law to be true.
Purpose The purpose of this lab is to determine the percent composition of magnesium oxide and determine whether the percentage is consistent.
Hypothesis Based …show more content…
Observation tables were to be copied into lab books in order to record data.
2. Equipment was assembled as shown in diagram. (See figure 1.1 on page 2)
3. Welder’s goggles were used to protect the eyes when the magnesium was burning.
4. An 8cm long strip of magnesium was stripped of possible oxidation with a piece of sandpaper or steel wool. A piece of dry paper towel was used to remove any possible residue.
5. Based on the observation table the mass of the crucible with lid was recorded. A piece of magnesium was placed into the crucible with a lid and that mass was recorded as well.
6. With the lid off the crucible and the piece of magnesium strip inside, the crucible was placed onto the clay triangle. A Bunsen burner was lit to a high temperature (blue flame) with a flint lighter and placed directly under the crucible. Crucible tongs were then used to balance the lid on an angle allowing the crucible to mainly be closed while allowing little bit of oxygen into the crucible. Once the magnesium ignited the lid was placed on the crucible for a minute.
7. Crucible tongs were use to lift the side of the crucible lid in order to let in more oxygen.
8. Once the magnesium stopped igniting when exposed to oxygen Bunsen burner was turned off and crucible was left to …show more content…
Would the Mg:O ratio have increased, decreased, or remained unchanged?
Mg will remain the same.
The amount of oxygen is determined by subtracting the mass of crucible, lid and magnesium from the mass of the crucible, lid and magnesium oxide.
33.304g-33.192g= 0.112g is the amount of oxygen produced. If some of the MgO was lost as smoke during the experiment and the amount of oxygen s less than 0.112g then the overall mass would be lighter because it would be oxygen leaving the crucible. Therefore the ratio will have more magnesium and less oxygen than it should have been. So one could say there has been an increase in the M:O ratio.
How would the value you calculated for the percentage composition of magnesium oxide have been affected if all the magnesium in the crucible had not reacted?
Using magnesium and oxygen’s mass on the periodic table let’s say only half of the Mg reacted you would have 12.15g of Mg that did not react with 12.15g+8g= 20.15g of MgO making the total mass that you weigh 32.30 (20.15+12.15). Which is less then the expected 40.3g for the mass of MgO.
The mass is going to be less due to the fact that no oxygen mixed with the unreacted
Aleshia Otieno
Mr. Taylor
SCH3U-01
Lab #4
Monday, November 17, 2014
Introduction Percentage composition is the percentage of a formula mass represented by each element. Percentage composition compares the mass of one part of a substance to the mass of the whole. The law of definite proportions states that a specific compound always contains the same amount of elements in fixed proportions by mass. By finding the percent composition of magnesium oxide one will essentially be proving this law to be true.
Purpose The purpose of this lab is to determine the percent composition of magnesium oxide and determine whether the percentage is consistent.
Hypothesis Based …show more content…
Observation tables were to be copied into lab books in order to record data.
2. Equipment was assembled as shown in diagram. (See figure 1.1 on page 2)
3. Welder’s goggles were used to protect the eyes when the magnesium was burning.
4. An 8cm long strip of magnesium was stripped of possible oxidation with a piece of sandpaper or steel wool. A piece of dry paper towel was used to remove any possible residue.
5. Based on the observation table the mass of the crucible with lid was recorded. A piece of magnesium was placed into the crucible with a lid and that mass was recorded as well.
6. With the lid off the crucible and the piece of magnesium strip inside, the crucible was placed onto the clay triangle. A Bunsen burner was lit to a high temperature (blue flame) with a flint lighter and placed directly under the crucible. Crucible tongs were then used to balance the lid on an angle allowing the crucible to mainly be closed while allowing little bit of oxygen into the crucible. Once the magnesium ignited the lid was placed on the crucible for a minute.
7. Crucible tongs were use to lift the side of the crucible lid in order to let in more oxygen.
8. Once the magnesium stopped igniting when exposed to oxygen Bunsen burner was turned off and crucible was left to …show more content…
Would the Mg:O ratio have increased, decreased, or remained unchanged?
Mg will remain the same.
The amount of oxygen is determined by subtracting the mass of crucible, lid and magnesium from the mass of the crucible, lid and magnesium oxide.
33.304g-33.192g= 0.112g is the amount of oxygen produced. If some of the MgO was lost as smoke during the experiment and the amount of oxygen s less than 0.112g then the overall mass would be lighter because it would be oxygen leaving the crucible. Therefore the ratio will have more magnesium and less oxygen than it should have been. So one could say there has been an increase in the M:O ratio.
How would the value you calculated for the percentage composition of magnesium oxide have been affected if all the magnesium in the crucible had not reacted?
Using magnesium and oxygen’s mass on the periodic table let’s say only half of the Mg reacted you would have 12.15g of Mg that did not react with 12.15g+8g= 20.15g of MgO making the total mass that you weigh 32.30 (20.15+12.15). Which is less then the expected 40.3g for the mass of MgO.
The mass is going to be less due to the fact that no oxygen mixed with the unreacted