molarity and volume of the M2V2, where Mi and Vi are the molarity concentrated s

Question

molarity and volume of the M2V2, where Mi and Vi are the molarity concentrated solution, respectively, and Mr and V are the and volume of the dilute solution. 3. a. The solution described in problem #2 is placed in the spectrophotometer. Based on the calibration curve shown on the next page, what would you predict the absorbance to be? Note: like the example given in the discussion, the absorbance should be calculated not just estimated from the graph. Notice that the slope and intercept of the calibration curve are provided in the figure on the next page. Absorbance

Explanation / Answer

1. The relation between absorbance and concentration is given by

Absorbance= 2.1033*104* concentration +0.0039

given Absorbance= 0.311, hence 0.311= 2.1033*104* concentration +0.0039

concentration = (0.311-0.0039)/2.1033*104= 1.46*10-5M

there are 1.46*10-5 moles in 1 L or 1000ml

250 ml solution contains (250/1000)*1.46*10-5 moles of Red-40=3.65*10-6 moles

molar mass of Red-40= 496 g/mole

Mass of Red-40 = moles* molar mass= 3.65*10-6*496= 0.00181 gm

Mass % of red-40 in the sample= 100* mass of Red-40/total mass= 100*0.00181/ 0.2548=0.7105%

2) 250 ml of initial solution contains 11.22 gm

50 ml of this solution contains 11.22*50/250= 2.244 gm

2.244 gm of drinks mix will be there in the second 250ml solution.

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.