The spectrophometer was used to measure the absorbance of each of a series of [FeSa]+ solutions. A standard curve was construnceted by plotting the absorbance vs. concentration (M). The slope and y-intercept were found to be 1496 M-1 and .003, respectively.

Question

The spectrophometer was used to measure the absorbance of each of a series of [FeSa]+ solutions. A standard curve was construnceted by plotting the absorbance vs. concentration (M). The slope and y-intercept were found to be 1496 M-1 and .003, respectively.

An aspirin sample was prepared following the procedure given in the experiment. A 0.139 g sample of aspirin was hydrolyzed with 5 mL of 1 M NaOH (reaction 1) and diluted with distilled water to 50 mL in a 50 mL volumetric flask, forming solution A. A 1.00 mL aliquot of solution A was diluted to 50.00 mL using .02 M Fe(III), forming solution B (reaction 2). The absorbance of solution B was found to be .396.

1. Use the measured absorbance and the standard curve's slope and y-intercept to calculate the concentration of [FeSa]+ in solution B

Answer 1

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Answer 2

To calculate the concentration of [FeSa]+ in solution B, we can use the equation of a standard curve:

Absorbance = slope * concentration + y-intercept

Given that the absorbance of solution B is 0.396, the slope of the standard curve is 1496 M-1, and the y-intercept is 0.003, we can substitute these values into the equation:

0.396 = 1496 * concentration + 0.003

Now we can solve for the concentration of [FeSa]+:

0.396 - 0.003 = 1496 * concentration
0.393 = 1496 * concentration
concentration = 0.393 / 1496

Using a calculator, we can solve this equation:

concentration ≈ 0.000262 M or 2.62 x 10^-4 M

Therefore, the concentration of [FeSa]+ in solution B is approximately 2.62 x 10^-4 M.

Answer 3

To calculate the concentration of [FeSa]+ in solution B using the measured absorbance and the standard curve's slope and y-intercept, you can use the equation of a line, which is y = mx + b.

In this case, y represents the absorbance, x represents the concentration of [FeSa]+, m represents the slope of the line (1496 M-1), and b represents the y-intercept (.003).

First, rearrange the equation to solve for x: x = (y - b) / m

Now plug in the values:

y = absorbance of solution B = 0.396
b = y-intercept = 0.003
m = slope = 1496 M-1

x = (0.396 - 0.003) / 1496

Calculate the concentration:

x = 0.393 / 1496
x ≈ 0.000263 M

The concentration of [FeSa]+ in solution B is approximately 0.000263 M.