In UV-Vis spectrophotometry, absorbance is defined as $A=-{\log }_{10}T$, where $T$ is the fraction transmittance. Which expression correctly gives percent transmittance ($\%T$) from absorbance $A$?

• A. $\%T=100\times {10}^{-A}$
• B. $\%T=100\times {10}^A$
• C. $\%T=100\times A$
• D. $\%T=100÷A$

Answer: (A)

Verified step by step guidance

1. Recall the definition of absorbance in UV-Vis spectrophotometry: \(A = -\log_{10}(T)\), where \(T\) is the fraction transmittance (a value between 0 and 1).
2. To find the fraction transmittance \(T\) from absorbance \(A\), rearrange the equation by taking the inverse logarithm (antilog) of both sides: \(T = 10^{-A}\).
3. Percent transmittance (%T) is the fraction transmittance multiplied by 100 to convert it into a percentage: \(\%T = 100 \times T\).
4. Substitute the expression for \(T\) into the percent transmittance formula: \(\%T = 100 \times 10^{-A}\).
5. Thus, the correct expression for percent transmittance in terms of absorbance is \(\%T = 100 \times 10^{-A}\).