Question

一道化学高考题

过程！

Answer 1

设A, B的摩尔质量分别为a, b g/mol
8g A+17g B的物质的量: 8/a + 17/b mol
2g A+7g B的物质的量: 2/a + 7/b mol
二者之比为体积之比: 8/a + 17/b : 2/a + 7/b = 480:160 = 3:1
8/a + 17/b = 6/a + 21/b
2/a = 4/b
b = 2a
D正确 (CH2O: 30 g/mol; CH3COOH: 60 g/mol)

Answer 2

设A的摩尔质量为ag/mol,B的摩尔质量为bg/mol.
2次气化状态相同,体积比等于摩尔数之比
(8/a+17/b)/(2/a+7/b)=480ml/160ml
8/a+17/b=6/a+21/b
2/a=4/b
a/b=1/2

A C2H4 28g/mol C2H2 26g/mol
B C2H4 28g/mol CH3OH 32g/mol
C C2H2 28g/mol C6H6 78g/mol
D CH2O 30g/mol CH3COOH 60g/mol

只有D的2物质的摩尔质量比是1:2,所以答案选D

Answer 3

1. 依次是 2 5 6 2 5 8
2. 淀粉试剂
3. n(Na2S2O3)=a2*b2/1000
n(KMnO4)=a1*b1/1000
n(H2O2)=n(KMnO4)*(5/2)
n(I2)=1/2n(Na2S2O3)=1/2*a2*b2/1000
n(CH3COOOH)=n(I2)-n(H2O2)
c(CH3COOOH)=n(CH3COOOH)/(b0/1000)=1000[a2b2/2000-a1b1/400]/b0
4. 否