If you want to make 0.5 L of a 0.01 M solution of bromine (Br2) in water, how much bromine would you need? A. 0.8 grams. . B. 0.8 moles. . C. 1.6 grams. . D. 1.6 moles.
The atomic mass of bromine is: A(Br) = 80 The molecule Br₂ consists of 2 Br atoms. Thus, the molecular mass of bromine is: Mr(Br₂) = 2*A(Br) = 2*80 = 160 This means there are 160 grams/l of Br₂ in 1 M.
Let's write a proportion. If 160 grams/l of Br₂ are present in 1 M, how much of Br₂ will be in 0.01 M: 160 g/l : 1 M = x : 0.01 M After crossing the products: x = 80 * 0.01 = 1.6 g/l
Let's write another proportion. If there are 1.6 g of Br₂ in 1 liter, how many of Br₂ will be present in 0.5 liter: 1.6 g : 1 l = x : 0.5 After crossing the products: x = 1.6 * 0.5 = 0.8 g
