Question

A student wants to prepare a solution of cobalt(II) fluoride with a known molarity.

How many grams of CoF2 must be weighed out to prepare 100. mL of a 0.157 M aqueous solution of the salt?
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Answer 1

`\large \boxed{\text{1.52 g}}`

Step-by-step explanation:

1. Calculate the moles of CoF₂ needed

`n = \text{0.100 L} * \frac{\text{0.157 mol}}{\text{1 L}}  = \text{0.0157 mol}`

2. Calculate the mass of CoF₂

`m = \text{0.0157 mol} * \frac{\text{96.93 g}}{\text{1 mol}}  = \text{1.52 g}\\\\\text{ The student must measure out $\large \boxed{\textbf{1.52 g}}$ of cobalt(II) fluoride}`