1.The oxide of an element with formular X2O5 contains 34.78% oxygen by mass. Find the atomic mass of X.
2.A compound has formula MSO4.XH2O. 14.35g of the compound is heated until all the of crystallisation is removed. The mass remaining is 8.05g. Calculate
a)the percentage by mass of water of crystallisation,
b)the atomic mass of M and the value of X.(Given that:the formular mass of MSO4 is 161)
Chemistry mass
2011-11-11 5:58 am
回答 (1)
2011-11-11 7:21 am
✔ 最佳答案
1.Let M be the atomic mass of X.
Percentage by mass of O in X2O5 :
(16*5)/(2M + 16*5) = 34.78%
80/(2M + 80) = 0.3478
0.6956M + 27.824 = 80
M = 75.01
The atomic mass of X = 75.01
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2.
a)
The percentage by mass of water of crystallization
= [(14.35 - 8.05)/14.35] * 100%
= 43.9%
b)
The atomic mass of M
= 161 - (32 + 16*4)
= 65
The value of X
= 161 * [(14.35 - 8.05)/8.05] / (1*2 + 16)
= 7
參考: andrew
收錄日期: 2021-04-13 18:22:06
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