Question

A series of dye solutions are made by adding water to the stock yellow 5 dye solution. The items below give either the dilution ratio or the final concentration of the dye solution. Arrange the dye solution in order from highest to lowest concentration.

7.0 ml dye, 0 ml water

3.0 ml dye, 1.0 ml water

5.0 ml dye, 5.0 ml water

2.0 ml dye, 6.0 ml water

25 microM dye solution

Answer 1

Yellow 5 dye is also called as Tartrazine whose molar mass is 534.36 g/gmol

The solubility in water is 20g dye in 100ml water.

Therefore concentration of stock solution = (20/534.36)moles / (0.1 lt) = 0.374 g/lt = 0.374M

Given solutions are:

1. 7.0 ml dye in 0 ml water 0.374 M

2. 3.0 ml dye in 1.0 ml water

Concentration = M₁V₁ / (V₁ + V₂) = 0.374 * 3 / (3+1) = 0.28 M

3. 5.0 ml dye in 5.0 ml water

Concentration = M₁V₁ / (V₁ + V₂) = 0.374 * 5 / (5+5) = 0.187 M

4. 2.0 ml dye in 6.0 ml water

Concentration = M₁V₁ / (V₁ + V₂) = 0.374 * 2 / (2+6) = 0.0935M

5. Given concentration is 25*10^-6M

Therefore the list is already arranged in the highest to lowest concentration order.