Metal-ligand concepts: a. Draw the Lewis structure of [Co(NH_3)_5(ONO)]^2+. b. W
ID: 506540 • Letter: M
Question
Metal-ligand concepts: a. Draw the Lewis structure of [Co(NH_3)_5(ONO)]^2+. b. What is an isomer? What type of isomers arc the nitrito- and nitro complexes to each other? Given the above chemical equation. a. Calculate the theoretical yield of the nitrito complex if you start with 2.456g of cobal (III) pentaamine trichloride. b. You complete the synthesis reaction and obtain 1.345g of nitrito product, calculate the percent yield. c. If you did not obtain 100% yield provide two possible explanations for experimental error.Explanation / Answer
Ans. 2 [Co(NH3)5Cl]Cl2 + NaNO2 ----------> [Co(NH3)5(ONO)]Cl2 + NaCl
nitrio complex
Stoichiometry: 1 mol cobalt(III) pentaamine trichloride forms 1 mol nitrio complex.
Molar mass of [Co(NH3)5Cl]Cl2 = 250.44 g/ mol
Molar mass of [Co(NH3)5(ONO)]Cl2 = 261.0 g/ mol
#A. Moles of [Co(NH3)5Cl]Cl2 reacted = Mass/ Molar mass
= 2.456 g/ (250.44 g/ mol)
= 0.00980674 moles
According to stoichiometry (theoretical), 1 mol reactant produces 1 mol product.
So,
Theoretical moles of Nitrio complex formed = moles of [Co(NH3)5(ONO)]Cl2 reacted
= 0.00980674 moles
Theoretical mass of nitrio complex formed = Moles x Molar mass
= 0.00980674 moles x (261.0 g/ mol)
= 2.559 g
Thus, theoretical yield of nitrio complex = 2.559 g
#B. % yield = (Experimental yield/ Theoretical yield) x 100
= (1.345 g/ 2.56 g) x 100
= 52.54 %
#C. Two possible experimental errors may be-
I. The reaction was not complete because of insufficient time of reaction, or lowered temperature than the ideal one.
II. NaNO2 must be present in excess for getting a % yield close to 100%. If NaNO2 is the limiting reagent (say, very diluted solution perceived to be sufficient for reaction), the % yield is reduced.