The Absorbance (A) of a coloured substance is measured to be 0.56 at 532 nm in a

Question

The Absorbance (A) of a coloured substance is measured to be 0.56 at 532 nm in a 1 cm path length cel. The substance has a molar absorptivity (E) of 116,000 cm M1. What is the concentration (C) of the substance? Report your answer in exponential form G.e. 0.0023 would be 2.3e-3. Only include the NUMERICAL PORTION of your answer. Answer: The largest nugget of siver mined, weighing 830 kg came from Smuggler's Mine in 1894 near Boulder Colorado. How many moles of silver does this correspond to? Only include the NUMERICAL PORTION of your answer. Answer:

Explanation / Answer

1)

Absorbance = 0.56

molar absorptivity e = 116,000 cm-1 M-1

path length = 1 cm

A = e C l

0.56 = 116000 x C x 1

C = 4.83 x 10^-6 M

concentration = 4.8 x 10^-6 M

2)

mass of silver nugget = 830 kg

moles = mass / molar mass

          = 830 x 10^3 / 107.87

moles of silver = 7694

6)

mass of KOH = 21.0 g

moles = 21.0 / 56.1 = 0.374 mol

concentration = 0.374 / 1.50 = 0.250

concentration = 0.250 M

7)

a = 2 , b = 1 , c = 2 , d = 1

2 NaOH   + CaCl2   -------------> 2 NaCl + Ca (OH)2

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