Question

A sample of wine was diluted 1:10 and analyzed for alcohol content. A calibration curve was created from a set of standard solutions producing a plot of absorbance vs. percent alcohol. The calibration curve had a slope of 8.07 x 10-2 with an intercept of 6.02 x 10-3. Keeping in mind that the wine sample was diluted by a factor of ten, what is the percent, by volume, of alcohol in your sample if the absorbance of your sample was 0.606?

Answer 1

Given:

We are given absorbance , slope and intercept. We also know the dilution is done in 10 times 10 fold.

Solution :

We have to find the volume percent of the alcohol in the original sample of the alcohol.

Lets use the equation of line and then we relate the absorbance with the volume percent.

We know , the absorbance is directly proportional to the concentration.

So the concentration in terms of the volume percent will be the variable and absorbance is the function of this volume percent.

y = m x + c

let, y is absorbance = 0.606 , m is slope = 8.07 E-2 , c (intercept) = 6.02E-3 , x is concentration in terms of volume percent.

Let plug these value in order to get volume percent.

0.606 = 8.07 E-2 x Vol percent + 6.02 E-3

Vol percent = 7.43 V %

Now we have already diluted it 10 times

Let x be its initial volume percent. Lets find x

x = 7.43 V % / (1/10 ) = 74.3 %

So the volume percent = 74.3 %