Name two visualization techniques for viewing colorless compounds on a TLC plate

Question

Name two visualization techniques for viewing colorless compounds on a TLC plate. An aqueous concentrated H_2 O_2 solution is 30% by mass and has a density of 1.11 g/mI (a) Determine the amount of the concentrated H_2 O_2 solution required to prepare 100 g aqueous solution of 3.0% mass/mass of H_2 O_2. Show work. (b) Calculate the molarity of concentrated H_2 O_2. Show work. Give the product of the following reaction. Which class of compounds will most likely give a fragment ion of M.^-18? (a) aldehydes (b) ethers (c) carboxylic acids (d)

Explanation / Answer

A)

visualization technique:

- Iodine vapor --> will color yellow

- UV light --> will show traces

Q2.

H2O2 solutino is 30% by mass, D = 1.11 g/mL

a)

H2O2 required for 100 g of aqueouis solution of 3% by mass

so

C1M1 = C2M2

0.3*M1 = 0.03*100

M1 = 0.03/3*100 = 1 g of original mix

b)

Molartiy = mol / volume

assume a basis of 100 mL of mix, 0.1 L

100 mL --> 1.11*100 = 111 g of mix

30% by mass so, 111*0.3 = 33.3 g of H2O2

mol = mass/MW = 33.3/34 = 0.9794

then

M = 0.9794/0.1

M = 9.794 M of H2O2

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