An 7.50 mL aliquot of a 125 ppm stock Red 40 dye solution was diluted to a final volume of 25.0 mL with deionized water. What is the concentration of the dilute Red 40 dye solution (in ppm)?

The concentration is equal to 37.5 ppm

Explanation:

This exercise is about dilutions. We have the following data:

V1 = aliquot volume = 7.5 mL

C1= aliquot concentration  = 125 ppm

V2 = final volume = 25 mL

C2 = final concentration of Red 40 dye = unknown

the formula is as follows:

V1xC1 = V2xC2

Clearing C2:

C2 = V1xC1/V2 = (7.5 mL x 125 ppm)/25 mL = 37.5 ppm

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explanation:

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o