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rature. R Lab Instructor: Date: pe lid. EXPERIMENT 3 ith a v patterin Percentage

ID: 837258 • Letter: R

Question

rature. R Lab Instructor: Date: pe lid. EXPERIMENT 3 ith a v patterin Percentage Composition and Empirical Formula of Magnesium Oxide am of off as am ne odor of Pre-Laboratory Questions roximately l. Calculate the percentage by mass of each element present in the following compounds. headi a. magnesium oxide, Mgo ple rner flame, 5 mg (0.0 o successive b. magnesium nitride, Mg,N2 that was 2. Suppose 2.033 g of magnesium is heated in air. What is the theoretical amount of magnesium oxide he empirical that should be produced? ta. 75 g of thisto are c 2012 Cengage Leaming. All Rights Reserved May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole orin part.

Explanation / Answer

1)

a)

the formula for magnesium oxide is MgO and the molar mass of the compound is 40.3 g/mol.

to find mass percent of Mg, divide the molar mass of Mg by the molar mass of the compound and multiply by 100:

(24.3 g/mol / 40.3 g/mol) * 100 = 60.3%

do the same thing for O, but use the molar mass of O:

(16 g/mol / 40.3 g/mol) * 100 = 39.7%

b)

Molar mass of Mg3N2 = 100.9284 g/mol

2)

No. of moles of Mg = 2.033/24 = 0.0847mol
Since 2Mg + O2 ----> 2MgO
1 mole of Mg will produce 1 mole of MgO

Therefore, no. of moles of MgO = 0.0847mol
Amount of MgO = 0.0847 * (24+16) = 3.388g