Question

ou discover that the complex decomposes in water. When 0.1000 g of the complex is dissolved in water with excess NaHg(SCN)4, all of the Co(II) is precipitated as CoHg(SCN)4 (s). After the precipitate is washed and dried, its mass is found to be 0.1102 g. How many grams of cobalt are contained in the original 0.1000 grams of the complex

Answer 1

6.28x10⁻³ g

Step-by-step explanation:

First we convert 0.1102 grams of CoHg(SCN)₄ into moles, using its molar mass:

• 0.1102 g ÷ 491.9 g/mol = 2.24x10⁻⁴ mol CoHg(SCN)₄

There is 1 Co mol per CoHg(SCN)₄ mol, meaning there's also 2.24x10⁻⁴ moles of Co.

We now convert 2.24x10⁻⁴ moles of Co into grams, using its molar mass:

• 2.24x10⁻⁴ mol Co * 28.01 g/mol = 6.28x10⁻³ g