Calculează masa de K2Cr207 necesară preparării de 200mL soluție de concentrație 0,1M Se dau:A K=39; A Cr=52; A O=16

Calculate the mass of K2Cr207 required to prepare 200mL of 0.1M solution

There are: A K = 39; A Cr = 52; A O = 16

5.88g

Explanation:

Given parameters:

Volume of K₂Cr₂O₇  = 200mL

Molarity  = 0.1M

Unknown:

Mass of  K₂Cr₂O₇ = ?

Solution:

To solve this problem, let us find the number of moles of  K₂Cr₂O₇ in the solution.

       Number of moles  = molarity x volume

   1000mL = 1L

   200mL = 0.2L

     Number of moles  = 0.1M x 0.2L = 0.02moles

From;

    Mass = number of moles x molar mass

  Molar mass  = 2(39) + 2(52) + 7(16) = 294g/mol

  mass of  K₂Cr₂O₇ = 0.02moles x 294g/mol

                                  = 5.88g

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .