The pH Scale A Way to Quantify Acidity and Basicity

The pH scale is a compact way to specify the acidity of a solution. We define pH as the negative of the log of the hydronium ion concentration  

Notice that we report Ihe pH to two decimal places here. This is because only the numbers to the right of the decimal point are significant in a logarithm. Because our original value for the concentration had two significant figures, the log of that number has two decimal places. 

If the original number had three significant digits, the log would be reported to three decimal places. 

0 is 10 times more acidic than a plum with a pH of 3.0 and 100 times more acidic than a cherry with a pH of 4.0. 

Calculate the pH of each solution at 25 °C and indicate whether the solution is acidic or basic. 

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