Identify unknown substances #2

Chemistry Level 2

The table below is the result of testing 3 unknown substances $X, Y, Z$ with other substances (by mixing them together):

Substance	Substances used to test	Phenomenal (Chemical reaction)
$X$	$Cu(OH)_2$	The solution turns blue.
$Y$	$AgNO_3$ solution in $NH_3$	A new precipitate is formed

Z

Neutral (Purple) litmus

The litmus turns blue.

Identify $X, Y, Z$ . Choose the best answer (in order: X, Y and Z)

P/s: I can't find a way to modify the table. Please edit it if you can and tell me how to do it properly.

Glucose, ethyl acetate and triolein Sucrose, methyl formate and methylamine, Ethanol, glucose and ethylamine. Glucose, acetylene and aniline.

1 solution

Anh Khoa Nguyễn Ngọc
Apr 16, 2020

First, when adding $Cu(OH)_{2}$ to $X$ , the solution turns blue, meaning that $X$ can dissolve $Cu(OH)_{2}$ (in some way). So answer $C$ is wrong. Then, since $Z$ can turn neutral litmus from purple to blue, that means $Z$ is a base. So answer B is correct.

Note that although aniline is also an amine, it does not dissolve very well in water and has $pK_{a} = 4.82$ , which is out of the litmus indicating range (turns red when $pH < 4.5$ and turns blue when $pH > 8.3$ ), it wouldn't change the litmus's color.

Identify unknown substances #2

1 solution

0 pending reports