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Chapter 10 NOTES. PRACTICE PROBLEMS. Try it on your own!. A compound is formed when 9.03 g Mg combines completely with 3.48 g N. What is the percent composition of this compound? Known Mass of Mg = 9.03g Mass of N = 3.48 g Total mass of cmpd . = 12.51 g (9.03g + 3.48g) Unknown % Mg = ?
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Chapter 10 NOTES PRACTICE PROBLEMS
Try it on your own! • A compound is formed when 9.03 g Mg combines completely with 3.48 g N. What is the percent composition of this compound? Known • Mass of Mg = 9.03g • Mass of N = 3.48 g • Total mass of cmpd. = 12.51 g (9.03g + 3.48g) Unknown • % Mg = ? • % N = ?
Solve • % Mg = 9.03 g x 100% = 72% 12.51 g • % N = 3.48 g x 100% = 28% 12.51g
Try it on your own! • When a 14.2-g sample of mercury(II) oxide is decomposed into its elements by heating, 13.2 g Hg is obtained. What is the percent composition of the compound? Known • Mass of cmpd = 14.2g • Mass of Hg = 13.2 g • Mass of O = 1.0 g (14.2g – 13.2g) Unknown • % Hg = ? • % O = ?
Solve % Hg = 13.2g x 100% = 93% 14.2g % O = 1.0g x 100% = 7% 14.2g
Try it on your own! • Calculate the percent composition of ethane (C2H6). • Know: mass of C in 1 mol ethane= 2X12=24g • Mass of H in 1 mol ethane=1X6=6g • Unknown: Percent C? • Percent H? • Molar mass= 24g+6g= 30g
Solve • %C= 24g X 100 = 80% 30g %H= 6g X 100= 20% 30g % equals 100!
Try it on your own • Calculate the percent nitrogen in NH₄NO₃ • Know: mass of N in 1 mol NH₄NO₃= 14X2=28g • Know: molar mass NH₄NO₃= (14X2)+(4X1)+(3X16)= 28g • Unknown: percent N?
Solve • % N = 28g X 100 = 35% 80g This is correct because: %H= 4g X100 = 5% 80g %O = 48g X 100= 60% 80g