The burning of the magnesium becomes uncontrolled (it burn brightly. Oops! How will this procedural error affect the reported mole ratio of magnesium to oxygen in the analysis? Explain.
4 answers
You haven't described the procedure you have used in detail but from what I know about the usual procedure, if the ribbon of Mg catches fire and burns brightly the chances are good that convection currents associated with the brightly burning Mg ribbon will carry away some of the oxide that is formed; thus, the true weight of the MgO will not be measured when the product is weighed.
In a hurry to complete the experiment, Josh did not allow all the magnesium to react. Will his reported magnesium to oxygen ration be reported too high or too low? Explain
Part of the Mg burns to MgO but part of the Mg stays in the original state. That means the final product contains a mixture of MgO and Mg but Josh THINKS it is all Mg and O combined.
mass oxide - mass initial mg will be too low (since not all of the Mg has combined with O) so the Mg to O ratio will be too high. That is, the experimental result will be mg2O, Mg3O, or something like that. The way to do this yourself is to assume you had 24 g Mg and it combined with 16 g Oxygen to form 40 g MgO. Then back up and say, "ok, only 12 g Mg combined, so the final product will be 12 g Mg and 12+8 g MgO so you have a mass of 32 g which you think is the oxide. Experimentally, 32-24 = 8 g oxygen combined, 8 g is 0.5 mole, 24 g Mg is 1 mole so we have MgO1/2 and that is a ratio of Mg2O in small whole numbers. So the ratio Mg to O will be too high? Check my thinking.
mass oxide - mass initial mg will be too low (since not all of the Mg has combined with O) so the Mg to O ratio will be too high. That is, the experimental result will be mg2O, Mg3O, or something like that. The way to do this yourself is to assume you had 24 g Mg and it combined with 16 g Oxygen to form 40 g MgO. Then back up and say, "ok, only 12 g Mg combined, so the final product will be 12 g Mg and 12+8 g MgO so you have a mass of 32 g which you think is the oxide. Experimentally, 32-24 = 8 g oxygen combined, 8 g is 0.5 mole, 24 g Mg is 1 mole so we have MgO1/2 and that is a ratio of Mg2O in small whole numbers. So the ratio Mg to O will be too high? Check my thinking.
John forgot to add the few drops of water resulting in the presence of some Mg3N2 in the final solid product. Will her reported magnesium to oxygen mole ratio be reported too high or too low? Explain. Hint: The Mg: N mass ratio is 1:0.38, and the Mg:O mass ratio is 1:0.66.
3 answers