Answer:
Molarity = 0.0428 M = 42.8 mM
Explanation:
Step 1: Data given
Mass of nickel(II) bromide = 1.87 grams
Molar mass of nickel(II) bromide = 218.53 g/mol
Volume = 200 mL = 0.200 L
Step 2: Calculate moles of nickel(II) bromide
Moles nickel (II) bromide = mass / molar mass
Moles nickel (II) bromide = 1.87 grams / 218.53 g/mol
Moles nickel (II) bromide = 0.00856 moles
Step 3: Calculate moles nickel (II) cation
For 1 mol NiBr2 we have 1 mol Ni^2+
For 0.00856 moles NiBr2 we have 0.00856 moles Ni^2+
Step 4: Calculate final molarity of Ni^2+
Molarity = moles / volume
Molarity = 0.00856 moles / 0.200 L
Molarity = 0.0428 M = 42.8 mM