an alloy contain 50% copper and 50% silver. when the alloy is heated with excess concentrated nitric acid ,which of the following is observed?
a. part of the alloy dissolves ,leaving a slivery solid and blue solution
b. part of the alloy dissoves ,leaving a reddish brown solid and colourless solution
c.the alloy dissolve competely to form a colourless solution
d. the alloy dissolve competely to form a blue solution
我揀左A, 左答案係D,
但ECS中排序係:
Cu2+ ----> Cu
NO3- -----> NO2
Ag+ ---->Ag
甘唔係靜係Cu 同 NO3- react 到咩?
MC OF REDOX
2011-08-26 10:54 pm
回答 (2)
2011-08-27 3:29 am
✔ 最佳答案
Because the nitric acid used is concentrated.And, it is heated.
So, it reacts with both Cu and Ag.
Cu and Ag can redeuce concentrated nitric acid to NO2.
4Ag + 6HNO3 ---> NO + NO2 + 4AgNO3 + 3H2O
Cu + 4HNO3 ----> Cu(NO3)2 + 2NO2 + 2H2O
The ions are Ag(+) , NO3(-) , Cu(2+)
The first two ions are colourless while Cu(2+) is blue
So, the answer should be D.
黑白灰_唯物主義者_魑魅魍魎
參考: 黑白灰_唯物主義者_魑魅魍魎
2011-08-29 5:34 am
Although the position of NO3- -----> NO2 is slightly higher than Ag+ ---->Ag,
Ag can still be oxidized. This is an exceptional case.
Ag can still be oxidized. This is an exceptional case.
收錄日期: 2021-04-16 13:14:52
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