In the reaction of colorless solutions of cobalt(III)

Question

In the reaction of colorless solutions of cobalt(III) chloride and ethylenediamine
(C2H8N2) a dark orange solution is formed.
The reaction proceeds:
CoCl3 + 3NH2CH2CH2NH2 → 2HCl + Co(NH2CH2CH2NH2)3Cl3
If the reaction takes place by mixing 10 mL of 0.01 M solution of CoCl3 and 10
mL of 0.06 M solution of C2H8N2, determine:
a) The number of moles of CoCl3
b) The number of moles of C2H8N2
c) The limiting reactant
d) The theoretical yield of Co(NH2CH2CH2NH2)3Cl3

Answer 1

You're given the concentrations and volumes of the two solutions.

(concentration) = (moles)/(volume)

 

So for a), you have 0.01M CoCl₃ = n / (0.010 L) and can solve for n

For b), you have 0.06M C₂H₈N₂ = n / (0.010 L) and again can solve for n

 

1CoCl₃ + 3NH₂CH₂CH₂NH₂ → 2HCl + 1Co(NH₂CH₂CH₂NH₂)₃Cl₃

 

The chemical equation you're given states that you need the ratio of 1 mol CoCl₃ to 3 mol C₂H₈N₂ to make the products. Check your answers for a) and b). Triple a) and compare that to b). If 3*a) is more than b), then b) runs out first, and it's the limiting reactant. If 3*a) is less than b), then a) runs out first, and is the limiting reactant.

 

Take your limiting reactant, and use the equation to determine how much of the product is formed. CoCl3 forms the product at a 1:1 rate. C2H8N2 forms the product at a 3:1 rate.

Answer 2

M=# moles/V  then # moles= M*V (Volume should be expressed in L)

 

a) # moles of CoCl3= 0.01 M * 0.01 L = 0.001 moles of CoCl3

 

b) # moles of C2H8N2= 0.06 M* 0.01 L=  0.0006 moles of C2H8N2

 

c) The limiting reagent is C2H8N2 because the reaction takes place in a proportion of 1 mole of CoCl3/ 3 moles (0.33 proportion) of C2H8N2 and in the previous calculation we found that we have  0.001 moles of CoCl3/ 0.0006 moles of C2H8N2 (1.66 proportion), in other words we have more CoCl3 than the needed for this reaction. 

 

d) The theoretical yield will be 0.0002 moles of Co(NH2CH2CH2NH2)3Cl3, because the proportion between the limiting reagent C2H8N2/Co(NH2CH2CH2NH2)3Cl3= 3 then 0.0006 moles/3= 0.0002 moles