On which type of graph paper is percent transmittance plotted against concentration?

• A. Semilogarithmic Paper
• B. Linear Graph Paper
• C. Polar Coordinates Paper
• D. Log-Log Paper

Answer: (A)

Percent transmittance follows an exponential decrease with concentration according to T = 10^(-εlc). If you take the logarithm of percent transmittance, log(T%), you get log(T%) = log(100) - εlc, which is a straight line when plotted against concentration. Using semilogarithmic paper, where we place concentration on a linear axis and percent transmittance on a logarithmic axis (i.e., plotting log(T%) versus c), yields a clean straight line. This makes it easy to determine the slope and thus εl from the data. On linear paper, the curve would be curved; on other papers like log-log or polar coordinates, the standard linear relation isn’t accomplished in the same straightforward way.