Question

Calculate the concentration of CoCl₄²⁻ if the absorbance of its solution in a 1 cm cell is 0.794. Use the pertinent data from the lab procedures.

Answer 1

Without the molar absorptivity constant and path length, the concentration of CoCl₄²⁻ cannot be determined from the provided absorbance data.

Step-by-step explanation:

To calculate the concentration of CoCl₄²⁻, we need the molar absorptivity constant and the absorbance according to Beer's Law, A = εlc. Unfortunately, the molar absorptivity constant (ε) and the path length (l) are not provided for the specific question about the absorbance of a CoCl₄²⁻ solution. Therefore, without this vital information or additional context from the lab procedures, it's not possible to provide an accurate concentration value.

However, we can show you how to approach a similar problem with provided data:

1. First, use the definition of molarity (moles of solute per liter of solution) to find the molarity. For CoCl₂ the molarity would be the number of moles divided by the volume in liters.
2. Apply Beer's Law with the molar absorptivity constant and the absorbance value to find the concentration.

For example, if the molar absorptivity was given as 14,150 M⁻¹cm⁻¹, and the absorbance was 0.794 in a 1 cm path length cuvette, the concentration would be calculated as 0.794 / (14150 x 1).

Answer 2

Assuming you have the molar absorptivity value
`(\( \varepsilon \))`, you can substitute the given values into the formula to find the concentration
`(\( c \))`:

`\[ c = (0.794)/(\varepsilon \cdot 1) \]`





To calculate the concentration of
`\( \text{CoCl}_4^(2-) \)` in a solution based on its absorbance (\(A\)), you can use the Beer-Lambert Law. The Beer-Lambert Law is expressed as:

`\[ A = \varepsilon \cdot c \cdot l \]`

Where:

- \( A \) is the absorbance of the solution.

-
`\( \varepsilon \)` is the molar absorptivity (extinction coefficient) of the substance.

- \( c \) is the concentration of the substance in solution.

- \( l \) is the path length of the cuvette (in this case, 1 cm).

The formula can be rearranged to solve for concentration
`(\( c \))`:

`\[ c = (A)/(\varepsilon \cdot l) \]`

However, to use this formula, you need to know the molar absorptivity
`(\( \varepsilon \)) for \( \text{CoCl}_4^(2-) \)` at the specific wavelength at which the absorbance is measured. This information is usually provided in the lab procedures or can be found in reference materials.

Assuming you have the molar absorptivity value
`(\( \varepsilon \))`, you can substitute the given values into the formula to find the concentration
`(\( c \))`:

`\[ c = (0.794)/(\varepsilon \cdot 1) \]`

Make sure to check the lab procedures or other provided data for the specific molar absorptivity value at the wavelength used in your experiment. Without that information, you won't be able to calculate the concentration accurately.