1.0g鎂條在空氣中完全燃燒後，生成1.604g固體，已知只有氧化鎂及氮化鎂生成。計算產物中MgO的質量。
唔識點計，但已知ans是1.3298g
20分！急！中七化學題（計量學）
2009-11-07 6:04 am
回答 (2)
2009-11-07 6:40 am
✔ 最佳答案
2Mg + O2 --------->2MgO3Mg + N2 ---------> Mg3N2
設有x g的MgO生成,(1.604-x)g的Mg3N2生成
由於mole ratio of Mg:MgO=1:1 , Mg:Mg3N2=3:1
1g鎂=1/24.3 mol
x/(24.3+16) + (1.604-x)/(24.3*3+14*2)=1/24.3
x=1.329g
2009-11-08 19:33:00 補充：
是,的確我打錯了,應該是
x/(24.3+16) + [(1.604-x)*3]/(24.3*3+14*2)=1/24.3
x=1.329g
2009-11-07 6:54 am
No. of mole of Mg in the 1g ribon = 1/24.3 = 0.0412 mol
The molar mass of MgO = 24.3 +16 =40.3 g
The molar mass of Mg3N2 =3*24.3 +14*2 =100.9 g
Let x be no. of mole of MgO formed and (0.0412 - x)/3 be no. of Mg3N2 formed.
40.3x +100.9(0.0412 - x)/3 = 1.604
120.9x + 4.15708 - 100.9x = 4.812
20x = 0.65492
x = 0.033 mol
Mass of MgO formed = 0.033*40.3 = 1.3299 g
The molar mass of MgO = 24.3 +16 =40.3 g
The molar mass of Mg3N2 =3*24.3 +14*2 =100.9 g
Let x be no. of mole of MgO formed and (0.0412 - x)/3 be no. of Mg3N2 formed.
40.3x +100.9(0.0412 - x)/3 = 1.604
120.9x + 4.15708 - 100.9x = 4.812
20x = 0.65492
x = 0.033 mol
Mass of MgO formed = 0.033*40.3 = 1.3299 g
參考: ME
收錄日期: 2021-04-13 16:55:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20091106000051KK01492