Question

1.

The crucible is not fired, as the procedure suggests. The mass of the dirty crucible is recorded. However, the impurities are burned off in the experiment. Will the reported mass of the final product be too high, too low, or unchanged as a result of this technique error?

• Too high

• Too low

• Unaffected

2.

If you put more water than is needed for reaction 3, and then did not dry out this excess water, what effect (if any) would this have on the calculated ratio of oxygen?

• Too high

• Too low

• Unaffected

3.

A student forgot to polish the magnesium metal. Will the reported mole ratio of magnesium to oxygen be too high or too low as a result of this error?

• Too high

• Too low

• Unaffected

4.

If a significant amount of the dense white smoke escaped from the crucible during the burning, what effect (if any) would this have on the calculated ratio of magnesium?

• Too high

• Too low

• Unaffected

5.

Based on your knowledge of nomenclature, what is the empirical formula of magnesium oxide?

• Mg₂O

• MgO

• MgO₂

• Mg₂O₂

6.

In a hurry to complete the assignment, a student did not allow all of the magnesium to react. Will the reported magnesium to oxygen ratio be reported as too high or too low?

• Unaffected

• Too low

• Too high

Answer 1

1. If there is dirt left over on the crucible from the last experiment, it has retained some impurities from this previous use. The “dirty” pass is recorded, and the impurities are burned off. The mass of the final product will be too high do to not firing off the impurities before weighing.

3.The mole ratio of magnesium to oxygen would be too low. The magnesium unpolished is actually covered in a protective layer of Oxygen, being MgO, so its heavier. The calculated mole value would be higher. A bigger denominator the O2/Mg ratio will give smaller ratio.

4.The loss of magnesium oxide will result in the loss of an equal amount of both magnesium and oxygen atoms. As a result , the magnesium to oxygen ratio will remian unchanged.

5. Emperical formulae- MgO

6.If not all of the magnesium is reacted and oxidized, there will be more magnesium present in the end result, then the Mg:O ratio will be too high. His reported ratio will be too high.