You need to make an aqueous solution of 0.201 M iron(II) bromide for an experiment in lab, using a 250 mL volumetric flask. How much solid iron(II) bromide should you add ?

To determine how much solid iron(II) bromide you should add to make a 0.201 M aqueous solution in a 250 mL volumetric flask, you need to follow these steps:

Step 1: Understand the formula for Molarity (M)
Molarity (M) is a unit of concentration that represents the number of moles of a solute dissolved in one liter of solution. Mathematically, Molarity is calculated as:

Molarity (M) = moles of solute / volume of solution (in liters)

Step 2: Convert volume of solution to liters
Given that you have a 250 mL volumetric flask, convert this volume to liters by dividing it by 1000:

Volume of solution (L) = 250 mL / 1000 mL/L = 0.25 L

Step 3: Calculate the moles required
Since the Molarity (M) of the solution is given as 0.201 M, you can use the Molarity formula to calculate the moles of solute required. Rearranging the formula, we get:

moles of solute = Molarity (M) * volume of solution (L)

Substituting the values, we have:

moles of solute = 0.201 M * 0.25 L = 0.05025 moles

Step 4: Determine the molar mass of iron(II) bromide
The molar mass of iron(II) bromide is the sum of the atomic masses of its component elements. Iron (Fe) has a molar mass of 55.845 g/mol, and bromine (Br) has a molar mass of 79.904 g/mol.

So, the molar mass of iron(II) bromide (FeBr2) can be calculated as:

Molar mass of FeBr2 = (Molar mass of Fe) + 2 * (Molar mass of Br)
= 55.845 g/mol + 2 * 79.904 g/mol
= 215.653 g/mol

Step 5: Calculate the mass of solid iron(II) bromide
Using the moles of solute calculated in Step 3 and the molar mass of iron(II) bromide calculated in Step 4, you can calculate the mass of solid iron(II) bromide required:

mass of FeBr2 = moles of solute * molar mass of FeBr2

Substituting the values, we have:

mass of FeBr2 = 0.05025 moles * 215.653 g/mol
= 10.850 g

Therefore, you should add approximately 10.850 grams of solid iron(II) bromide to the flask to make a 0.201 M aqueous solution.