在标准状况下,将NO2和氧气按体积之比3:2混合后充入一支干燥管中,将试管倒立于水中,充分反应后试管中溶液的物质量浓度是
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3NO2 + H2O = 2HNO3 + NO.(1)

2NO + O2 = NO2.(2)

(1)x2+(2)x1：4NO2 + O2 + 2H2O = 4HNO3

4 1 4

3体积 2体积 3体积

2/3 > 1/4,说明氧气过量,应以NO2的量计算生成物HNO3的量.

设试管的容积为V,V(NO2) = V x 3/5 n(NO2) = V/Vm x 3/5 = n(HNO3)

剩余氧气体积：V x ( 2 - 3/4)/5 = V/4 V[HNO3(aq)] = V x3/4

c(HNO3) = n(HNO3)/V[HNO3(aq)] =(V/Vm x 3/5)/(V x 3/4) = 4/(5 x 22.4L/mol) = 0.036 mol/L

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