URGENT! Please help me with #3 ALL PARTS. I ATTACHED NEEDED EQUATIONS... I CAN G

Question

URGENT! Please help me with #3 ALL PARTS. I ATTACHED NEEDED EQUATIONS... I CAN GRAPH JUST CONFUSED ON OTHER STUFF... THANK U

number of drops volume of solution, mL concentration, drops mL (Eq. 6) For example, if the solution you use to determine the spectrum of the food dye, which we shall call "Solution 1," was prepared by adding 1 drop of food dye to 40.0 mL of distilled water, the concentration of the solution is found using Equation 6. 1 drop 40.0 = 2.5 × 10-2 drops mL-1 concentration, drops m -1 More dilute solutions of the food dye are made by mixing measured amounts of Solution 1 and distilled water. The concentrations of such solutions can be calculated using Equation 7. volume of concentration of concentration of diluted solution, drops mL-1 Solution 1, mL) Solution 1, drops mL1 (Eq. 7) total volume of diluted solution, mL

Explanation / Answer

(1) 1 drop of stock solution was added to 50.0 mL water. We will assume that the volume of the drop is insignificant as compared to 50.0 mL and hence, we will treat the final volume of solution 1 as 50.0 mL. The concentration of the food dye in

solution 1 is (1 drop)/(50.0 mL) = 0.02 drop/mL (ans).

The final volume of solutions 2-5 is 10.0 mL. We will use the dilution equation

M1*V1 = M2*V2

Solution 2: (0.02 drops/mL)*(5.0 mL) = M2*(10.0 mL)

M2 = 0.01 drops/mL (ans).

Solution 3: (0.01 drops/mL)*(5.0 mL) = M2*(10.0 mL) (treat solution 2 as the stock solution)

M2 = 0.005 drops/mL (ans).

Solution 4: (0.005 drops/mL)*(5.0 mL) = M2*(10.0 mL) (treat solution 3 as the stock solution)

M2 = 0.0025 drops/mL (ans).

Solution 5: (0.0025 drops/mL)*(5.0 mL) = M2*(10.0 mL) (treat solution 4 as the stock solution)

M2 = 0.00125 drops/mL (ans).

2)

Determine the absorbance of each solution (correct to four decimal places) using the relation

A = 2 – log (%T)

where A = absorbance of the solution; %T = transmittance of the solution.

Concentration

drops/mL

(3) Plot absorbance vs concentration (drops/mL) as below.

The slope of the plot is 62.635 AU/(drops/mL) where AU = absorbance unit.

(4) Plug y = 0.2899 in the regression equation to obtain the concentration of the unknown sample.

0.2899 = 62.635*x + 0.0121

=> 62.635*x = 0.2778

=> x = 0.004435 0.00443

The concentration of the red dye in the unknown sample is 0.00443 drops/mL (ans).

Solution

Concentration

drops/mL

%T A = 2 – log (%T) 1 0.02 5.5 1.2596 2 0.01 22.6 0.6459 3 0.005 46.2 0.3353 4 0.0025 68.4 0.1649 5 0.00125 82.8 0.0820 unknown 51.3 0.2899

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