Chemistry Lab Report
Finding the empirical formula of Magnesium Oxide























Student Name: Lareen Othman
Class: 9A
Teacher: Juline Daibes



Introduction:
The empirical formula of a chemical compound is the simplest ratio of atoms that are presented in a compound. A simple example of this is the empirical formula of sulfur monoxide which is SO, and the empirical formula of disulfur dioxide, S2O2. Those two formulas are considered the same.
Aim:
The aim of this experiment is to investigate the empirical formula of magnesium oxide.
Hypothesis:
I predict that the empirical formula of magnesium oxide will be MgO as the combustion of magnesium will generate data which can be used to calculate the empirical formula of magnesium oxide. The number of magnesium atoms used in the reaction would need the same number of oxygen atoms to form magnesium oxide.
Variables:
Independent Variable


Amount of Magnesium

Dependent Variable Amount of Magnesium Oxide
Controlled Variable
Heat/ mass of crucible and cover

Equipment & Materials: [List the material & equipment required for the experiment]
• Tools: crucible, cover, heat, tongs, digital balance, stand, and stop watch.
• Materials: Magnesium ribbon, and oxygen.
Procedure:
1. Measure the mass of the crucible and the cover using the digital balance.
2. Add the Magnesium ribbon into the crucible, and measure the mass of the crucible with the cover and the magnesium ribbon.
3. Put the crucible with its cover containing the magnesium ribbon under heat for 10 minutes.
4. Wait until the crucible returns to its normal temperature and measure its mass using the digital balance.
Data Collection and Observations:
**THE FIRST EXPERIEMENT**
Mass of crucible and cover (grams) Mass of crucible and cover and magnesium (grams) Mass of crucible and cover and magnesium oxide (grams)
64.82 64.98 65.06
**THE SECOND EXPERIEMENT**
Mass of crucible and cover (grams) Mass of crucible and cover and magnesium (grams) Mass of crucible and cover and magnesium oxide (grams)
51.33 51.40 51.55

• To find the mass of magnesium :
First experiment: 0.16 grams
Second experiment: 0.07 grams
• To find the mass of oxygen :
First experiment: 0.08 grams
Second experiment: 0.15 grams
• Convert the masses to moles to find the empirical formula:
First experiment:
Mg O
0.16 = 0.0066 0.08 = 0.005
24 0.005 16 0.005

1.32 ≈≈ 1 1

THEREFORE, the empirical formula is MgO

Second experiment:
Mg O
0.07 = 0.002916666 0.15 = 0.009375
24 0.002916666 16 0.002916666

1 0.00558 ≈≈ 1

THEREFORE, the empirical formula is MgO


Result and conclusion:
As mentioned in the hypothesis, the empirical formula of magnesium oxide is MgO. The reaction of magnesium with oxygen needs one atom of magnesium and one atom of oxygen to a create a molecule of magnesium oxide.

Errors and Improvements:

Errors:
• The opening of the cover allows white ashes (MgO) to escape from the crucible.
• Magnesium didn’t burn in the crucible for the right amount of time, some of the magnesium would not have time to react and form magnesium oxide.
• Inaccuracy of measurements, as there is many decimals.
Improvements:
• Quickly close back the cover after allowing some oxygen to enter the crucible
• Leave the magnesium under heat for a longer period of time.
• Repeat the measurements twice to make sure they are accurate.