1.) How many moles of Fe 3+ can be reduced by 1 mL of 0.421 M hydroxylamine solu

Question

1.) How many moles of Fe3+ can be reduced by 1 mL of 0.421 M hydroxylamine solution?

2.) The trendline equation calculated from a calibration curve of absorbance vs iron concentration in g dL-1 is y = 0.00076x + 0.00801. If a sample analyzed using the same assay gives an absorbance of 0.145, what is the iron concentration of the unknown sample in g dL-1?

3.) As part of this laboratory, you may have to remove iron from a solution. If you have 50 mL of a solution that contains 195 g dL-1, how many g of iron must be removed to reach a concentration of 150 g dL-1?

For the first one I didn't know if it just using simple molarity converting and for the second, do I plug in the absorbance for x?

If someone could show me how to do these questions please that would be a lot of help!

Explanation / Answer

Solution :-

Q1) Using the balance reaction equation need to use the mole ratio of the hydroxyl amine and Fe^3+ and then from the mole ratio calculate the moles of the Fe^3+ that can be reduced by the given volume and molarity of the hydroxylamine,

Q2) caliberation curve plot as absorbance vs concnetration

therefore inthe stright line equation

Y= absorbance and X= cocnnetration

straight line equation is y = 0.00076x + 0.00801

so lets put the value of the absorbance in the equation and solve for the x

0.145 = 0.00076x + 0.00801

0.145-0.00801 / 0.00076 = x

180.25 ug /dl =x

so the concnetration of the iron = 180.25 ug/dl

Q3)

50 ml * 195 ug / 100 ml = 97.5 ug

we want the concnetration 150 ug/dl

so

150 ug * 50 ml / 100 ml = 75 ug

So now lets find the difference in the mass of the iron

97.5 ug - 75 ug = 22.5 ug

So we need to remove 22.5 ug of the iron.

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