What is the concentration of a solution formed by mixing 89.94 grams of cobalt (II)

sulfate in enough water to make 68.6 cL solution?


I keep getting .84 M. Can anyone explain how to get the right answer?

Respuesta :

Answer:

0.47 M

Explanation:

The concentration of the solution can be calculated using the following equation:

[tex] C = \frac{\eta}{V} = \frac{m}{M*V} [/tex]

Where:

V: is the volume of the solution = 68.6x10⁻² L

η: is the moles of cobalt (II)  sulfate

m: is the mass of cobalt (II)  sulfate = 89.94 g

M: is the molar mass of cobalt (II)  sulfate = 281.103 g/mol

The concentration of cobalt (II)  sulfate is:

[tex] C = \frac{m}{M*V} = \frac{89.94 g}{281.103 g/mol*68.6 \cdot 10^{-2} L} = 0.47 mol/L [/tex]

We used the molar mass of the cobalt (II)  sulfate heptahydrate (281.103 g/mol) since it is one of the most common salts of cobalt.

Therefore, the concentration of a solution of cobalt (II)  sulfate is 0.47 M (assuming that the cobalt (II)  sulfate is heptahydrate).

I hope it helps you!

Answer:

[tex]M=0.467M[/tex]

Explanation:

Hello,

In this case, cobalt (II) molar mass is 280.996 g/mol since it is about heptahydrate, so we compute the moles:

[tex]n=89.94g*\frac{1mol}{280.996g}= 0.32mol[/tex]

Then, since we need the volume in litres only:

[tex]V=68.6cL*\frac{1L}{100cL} =0.686L[/tex]

Finally, we compute the molarity:

[tex]M=\frac{0.32mol}{0.686L}\\ \\M=0.467M[/tex]

So your answer should be refined.

Best regards.