Magnesium Strip

Chemistry Internal Assessment 8
Lee Dong Hun (16) 5.12 Proverbs

Table 1 : Mass of Magnesium Strip Mass of Magnesium Strip and Weighing bottle /g (± 0.001g) | 3.585 | Mass of Weighing bottle /g (± 0.001g) | 3.460 | Mass of Magnesium Strip /g (± 0.002g) | 0.125 |

Table 2 : Mass of Crucible and lid Mass of Crucible /g (± 0.001g) | 15.147 | Mass of Lid /g (± 0.001g) | 9.670 |

Table 3 : Mass of Magnesium Oxide Mass of Magnesium Oxide and Crucible and Lid /g (± 0.001g) | 24.985 | Mass of Crucible and Lid /g (± 0.002g) | 24.817 | Mass of Magnesium Oxide /g (± 0.003g) | 0.168 |

Mass of Oxygen reacted with Magnesium
= 0.168 - 0.125
= 0.042g ± 0.005g
Both the crucible and the lid are in good condition, with some stains.
The magnesium strip was polished to reveal a grey solid.
When burning in air, the magnesium strip glows.
After complete reaction, a black powder was observed within the crucible.

Processing of Data | Processing of Uncertainties | No of moles of Mg in reaction= 0.12524.31= 0.00514 mol (to 3sf)No of moles of Oxygen in reaction= 0.04216.00= 0.00263 mol (to 3sf)No of moles of Mg : No of moles of O= 2:1 ∴ Empirical formula of the compound = Mg2O | Percentage Uncertainty of No of moles of Mg in reaction= 0.0020.125 ×100%= 1.60% (to 3sf)Absolute uncertainty of No of moles of Mg in reaction= 0.00514 × 1.60100= 0.00008 mol (to 5dp)Percentage Uncertainty of No of moles of O in reaction= 100% × 0.0050.042= 11.9%Absolute Uncertainty of No of moles of O= 11.9100 ×0.00263= 0.00032 mol (to 5dp) |

There had been a presence of a systematic error, as the experiment setup could not stop the fumes of Magnesium oxide from escaping from the crucible, which led to the amount of oxygen being observed as much lesser than the value that it should have