need help with all of the following suggest some units for all of the variables

Question

need help with all of the following

suggest some units for all of the variables Beer's Law (Hint: Absorbance is unitless) in The variable in the Beer's Law equation that is dependent upon a constant properties is called the Its value is a for a when it is measured at a given 4. If the absorbance of a solution in a 5 cm cell is 30, what would be the absorbance of a solution of the same solute if the cell path is reduced to 0.5 cm and the concentration is tripled? 5. If the absorbance of the aspirin-iron complex in Figure 14.2 is 150 what is the approximate molarity of the solution? 6. Although aspirin solutions not absorb visible light, we are still able to use do of aspirin. Why? visible light in this experiment to analyze for the purity If you observe that thecolor of is would you estimate the wavelength of the absorbed radiation to be?

Explanation / Answer

2 answer : molar absorptivity are L mol-1 cm-1

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3 answer :

The variable in the Beer's Law equation that is dependent on a molecules structural properties is called the MOLAR ABSORPTIVITY.

It's value is a constant for a solute when it is measured at a given WAVE LENGTH.

A = bc

A = absorption that you read from the spectromoter.

b = path length of the cuvet (or whatever it's in to measure)

c = concentration.

= molar absorptivity

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4 answer :

If the absorbance of a solution in a 5 cm cell is 3.0, what would be the absorbance of a solution of the same solute if the cell pathlength is reduced to 0.5 cm and the concentration is tripled

Set up two conditions:

A1 = b1c1
A2 = b2c2

Because is the smae constant in both, we can rearrange and combine these into

A1/b1c1 = A2/b2c2

We can rearrange this into

(b2c2)/(b1c1) = A2/A1

which is

(b2/b1)*(c2/c1) = A2/A1

For your problem:

A1 = 3.0
b1 = 5 cm
A2 = unknown (what to solve for)
b2 = 0.5 cm
c2 = 3*c1 => c2/c1 = 3

(b2/b1)*(c2/c1) = A2/A1

Everything but A2 is known, so now just plug the numbers in and calculate.

(0.5/5)*(3) = A2/3

A2 =(0.5/5)*(3) *3 =0.9 -answer

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if the absorbance of the aspirin-iron complex in f²igure 14.2 is 1.50 what is the approximate molarity of the solution

.IF the absorbance oF the aspirin-iron complex in figure 14.2 is 1.50, the approximate molarity of the solution can be assumed to be 7.00M.

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6.Although aspirin solutions do no absorb visible light, we are sTll able to use visible light in this experiment to analyze the purity of aspirin. Why?

When iron is added to aspirin, it produces violet tetraaquosalicylatroiron complex, this creates a visible violet color reaction that allows visible light to be used to analyze the purity of aspirin.

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7.If you observe that the color of a solutions is dark red what would you estimate the wavelength of the absorbed radiation to be?

You could estimate the wavelength of the absorbed radiation to be 610-750nm

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