1) If your spectrophotmeter can measure n absorbance up to 1.5, what is the maximum concentration of NADH that you can measure without diluting?
2) If you add 3 mL of water to 1 mL of NADH, mix and get an absorbance of 0.2, what is the concentration of the original NADH solution?
Thanks!
A = 1.5, then %T = 31.6%. But questions 1 and 2 can't be answered without knowing what the graph looks like OR without knowing the absorptivity constant.
there is no graph or absorbancy constant
does anyone has the answer to this?
To answer the first question, you need to understand the relationship between absorbance and concentration in spectrophotometry. The Beer-Lambert Law states that the absorbance of a substance is directly proportional to the concentration of that substance and the path length of the sample. Mathematically, it can be represented as A = εlc, where A is the absorbance, ε is the molar absorptivity or extinction coefficient, l is the path length, and c is the concentration.
In this case, you are given that the spectrophotometer can measure an absorbance up to 1.5. Thus, the maximum absorbance value (A) that can be measured is 1.5. However, this does not directly tell you the maximum concentration (c) that can be measured without dilution.
To determine the maximum concentration without dilution, you need to know the molar absorptivity (ε) and the path length (l) of the spectrophotometer. The molar absorptivity is specific to the substance being measured and can be found in reference sources. The path length is typically a fixed value for the spectrophotometer (e.g., 1 cm or 10 mm).
Once you know the molar absorptivity and the path length, you can rearrange the Beer-Lambert Law equation to solve for the concentration (c). It would be c = A / (εl).
Now let's move on to the second question. You are given that you added 3 mL of water to 1 mL of the NADH solution and obtained an absorbance of 0.2. From this information, you can calculate the concentration of the original NADH solution.
To do this, you need to use the Beer-Lambert Law equation again. Assign the appropriate values to the variables: A = 0.2, ε and l would be the same as in the first question, and solve for c. Rearranging the equation, you would get c = A / (εl).
Remember to make sure your units are consistent. For example, if the molar absorptivity is given in M-1 cm-1 and the path length is measured in cm, the resulting concentration will be in M (molar).
By plugging in the values and solving the equation, you will be able to find the concentration of the original NADH solution.
Hopefully, this explanation helps you understand how to approach and solve both questions. If you have any further questions, feel free to ask!