The concentration of copper(II) sulfate in one brand of soluble plant fertilizer is 0.07% by mass. If a 20 g sample of this fertilizer is dissolved in 2.0 L of solution, what is the molarity of Cu2+?

Respuesta :

Answer: The molarity of [tex]Cu^{2+}[/tex] ions in the given amount of sample is [tex]4.38\times 10^{-5}M[/tex]

Explanation:

We are given:

Mass of sample = 20 g

0.07 % (m/m) of copper (II) sulfate in plant fertilizer

This means that, in 100 g of plant fertilizer, 0.07 g of copper (II) sulfate is present

So, in 20 g of plant fertilizer, =[tex]\frac{0.07}{100}\times 20}=0.014g[/tex] of copper (II) sulfate is present.

To calculate the molarity of solution, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}[/tex]

We are given:

Mass of solute (copper (II) sulfate) = 0.014 g

Molar mass of copper (II) sulfate = 159.6 g/mol

Volume of solution = 2.0 L

Putting values in above equation, we get:

[tex]\text{Molarity of solution}=\frac{0.014g}{159.6g/mol\times 2.0L}\\\\\text{Molarity of solution}=4.38\times 10^{-5}M[/tex]

The chemical equation for the ionization of copper (II) sulfate follows:

[tex]CuSO_4\rightarrow Cu^{2+}+SO_4^{2-}[/tex]

1 mole of copper (II) sulfate produces 1 mole of copper (II) ions and sulfate ions

Molarity of copper (II) ions = [tex]4.38\times 10^{-5}M[/tex]

Hence, the molarity of [tex]Cu^{2+}[/tex] ions in the given amount of sample is [tex]4.38\times 10^{-5}M[/tex]