Sapling Learning 100 q/mol is dissolved in a 10-mL An unknown amount of a compou

Question

Sapling Learning 100 q/mol is dissolved in a 10-mL An unknown amount of a compound with a molecular mass of 259.02 volumetric flask. A 1.00-mL aliquo water is added to dilute to the mark. The absorbance of this diluted solution at 329 nm is 0.505 in a 1.000- cm cuvette. The molar absorptivity for this compound at 329 nm is 329 6255 M1cm-1 t of this solution is transferred to a 25-mL volumetric flask and enough is the concentration of the compound in the cuvette? Number (b) What is the concentration of the compound in the 10-mL flask? at Number 0 He (c) How many milligrams of compound were used to make the 10-mL solution? Number Web 0 O Tech 0

Explanation / Answer

a)

0.505 = 6255 M-1cm-1 * c* 1 cm

or, C =8.07*10-5 M ( answer)

b) initial concentration * initial volume ( 1 ml) = final concentration ( 8.07*10-5 M ) * final volume ( 25 ml)

hence, initial concentration = 201.75*10-5 M

c)201.75*10-5 M = 201.75*10-5 mole /liter

number of moles in 10 ml solution = 201.75*10-5 mole /lit * 0.01 L =20175*10-5 mole  

molecular weight = 259.02 gm /mole

weight of 20175*10-5 mole = 20175*10-5 mole * 259.02 gm /mole = 0.0522 mg

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