Question

(e) The %mass ratio of Cl(heated) to Cunheated) obtained from the analysis of the Co-complex we synthesized in the lab was found to be 1.5/1. Express this as a ratio of integers 1.5 What information does this ratio provides regarding both the amount and location of chloride in the Co-complex? Cl) amount Clu (m) location number coordinated and number not coordinated () In Co-analysis lab a sample of the cobalt compound weighing 1.1427 gram was heated until color change occurred followed by the addition of 10.0 mL of water, and 1.0 mL of sulfuric acid. The solution was transferred quantitatively to a 100.00 ml Volumetric flask, shaken and tied to the mark with water. A sample of this solution gave a percent transmittance reading of 59.3% when put in a spectrophotometer. The absorbance of this sample is = 00) Use the least squares line (Trendline) from the Beer's Law plot below to determine the concentration of cobaltion in the diluted solution. The concentrations are in the same units as in the experiment you performed Excel Trendline: y = 4.990[x) - 2.400 x 10 (1) The cobalt concentration, (Coj= Mand (iv) The percentage cobalt in the Co coordination compound analyzed V) Assuming that the above determinations of %CI and % Co are accurate within t.1%, the amount of %NHs present in this cobalt coordination compounds

it only gives the ratio and expects us to answer the question from there.

Answer 1

(e)

(i) 1.5 / 1 expressed as ratio of integers would be 3 / 2

The answer you have filled(1.5) is wrong. Remember that integers are numbers like 0,1,2,3,4,5...............Also 1.5 is not an integer.

(ii) amount of Cl = 3

This obtained when complex is heated. When you heat, all the Cl will come out (including coordinated and uncoordinated)

(iii)Location

number coordinated = 1

number uncoordinated = 2

when you are not heating, only uncoordinated one will come out, which is equal to 2.

The rest out of 3 (which is = 1) coordinated = 2

(f)

(i) Absorbance = -log(% transmittance / 100)

Given

% transmittance = 59.3 %

Absorbance = -log(59.3 / 100) = 0.227

Absorbance of this smaple = 0.227

(ii) and (iii)

Given

y = 4.990*x - 2.400*10-3

Comparing this to Beer-Lambert Law, we can say that y denotes Absorbance and x denote Concentration

We found the absorbance to be equal to 0.227

hence y=0.227

Finding x will give us the concentration.

y = 4.990*x - 2.400*10-3

Rearranging the equation, we can write:

x = (y + 2.400*10-3) / 4.990

putting y=0.227, we get

x = (0.227 + 2.400*10-3) / 4.990

x = 0.2294 / 4.990 = 0.04597 M

The cobalt ion concentration [Co] = 0.04597 M