Aluminum carbide powder decomposes in water:

vazorg [7]

Answer:

The given statement shows that the two families knew each other. Some people had left their home due to the war many years ago. Those who had stayed back thought that the ones who had left would never come back. That is why the woman feels surprised to see one of them come back. It also shows that selfishness of human behavior. People care for material things done for human beings. But it can't be said of all human beings. The narrator and her mother were totally different in their nature. They were trusting and loving human beings. Thus the given statement does give some clue about the story.

previously answered by brainly verified user

3 0

3 years ago

A solution of Na2CO3 is added dropwise to a solution that contains 1.15×10−2 M Fe2+ and 0.58×10−2 M Cd2+. What concentration of

castortr0y [4]

The question is incomplete, complete question is;

A solution of $Na_2CO_3$ is added dropwise to a solution that contains $1.15\times 10^{-2} M$ of $Fe^{2+}$ and $0.58\times 10^{-2} M$ and $Cd^{2+}$ .

What concentration of $CO_3^{2-}$ is need to initiate precipitation? Neglect any volume changes during the addition.

$K_{sp}$ value $FeCO_3: 2.10\times 10^{-11}$

$K_{sp}$ value $CdCO_3: 1.80\times 10^{-14}$

What concentration of $CO_3^{2-}$ is need to initiate precipitation of the first ion.

Answer:

Cadmium carbonate will precipitate out first.

Concentration of $CO_3^{2-}$ is need to initiate precipitation of the cadmium (II) ion is $3.103\times 10^{-12} M$ .

Explanation:

1) $FeCO_3\rightleftharpoons Fe^{2+}+CO_3^{2-}$

The expression of an solubility product of iron(II) carbonate :

$K_{sp}=[Fe^{2+}][CO_3^{2-}]$

$2.10\times 10^{-11}=0.58\times 10^{-2} M\times [CO_3^{2-}]$

$[CO_3^{2-}]=\frac{2.10\times 10^{-11}}{1.15\times 10^{-2} M}$

$[CO_3^{2-}]=1.826\times 10^{-9}M$

2) $CdCO_3\rightleftharpoons Cd^{2+}+CO_3^{2-}$

The expression of an solubility product of cadmium(II) carbonate :

$K_{sp}=[Cd^{2+}][CO_3^{2-}]$

$1.80\times 10^{-14}=0.58\times 10^{-2} M\times [CO_3^{2-}]$

$[CO_3^{2-}]=\frac{1.80\times 10^{-14}}{0.58\times 10^{-2} M}$

$[CO_3^{2-}]=3.103\times 10^{-12} M$

On comparing the concentrations of carbonate ions for both metallic ions, we can see that concentration to precipitate out the cadmium (II) carbonate from the solution is less than concentration to precipitate out the iron (II) carbonate from the solution.

So, cadmium carbonate will precipitate out first.

And the concentration of carbonate ions to start the precipitation of cadmium carbonate we will need concentration of carbonate ions greater than the $3.103\times 10^{-12} M$ concentration.

6 0

3 years ago

Which element has an atomic number of 16?<br> a. oxygen (O)<br> b. sulfur (S)<br> c. germanium (Ge)

emmasim [6.3K]

Answer: Sulfur

Explanation:

3 0

3 years ago

Read 2 more answers

I build a fire and burn 3 logs. Apply the Law of Conservation of Matter

photoshop1234 [79]

Capture all of the smoke and weight it. it will weigh exactly the same before and after you burn it but will just be CO2 and H2O gas.

7 0

3 years ago

Mercury may have lost part of its mantle and crust to a _______ leaving it with a large, metal _______.

igomit [66]

<h2>Giant impact and metalcore.</h2>

Explanation :

Mercury has a large core of liquid metal.
The metal core is of iron metal.
The core is surrounded by a mantle which is made up of silica and a solid outer crust.
In the case of Mercury, the total core percentage is 42% of the planet while the Earth's core is only 17% of the planet.
Mercury has lost part of its mantle and crust that left the mercury with a large metal core.

3 0

3 years ago