What is the difference in hydrogen ion concentration between a pH of 4 and a pH of 7?

Expert Answers
trophyhunter1 eNotes educator| Certified Educator

The pH scale is a measure of how acidic or basic a substance is. It measures the hydrogen ions in a solution or substance. The scale reads from 1 to 14, with 1 being the strongest acid and 14, the strongest base, with 7 representing neutral distilled water. The ph scale is a logarithmic scale. Therefore, a difference of one pH unit is a tenfold difference in hydrogen ion concentration. A Hydrogen ion concentration of 4 is 1000 times more acidic than a hydrogen ion concentration of 7. That is because a pH of 4 is 10 times more acidic than a pH of 5, 100 times more acidic than a pH of 6 and 1000 times more acidic than a ph of 7. For every number the pH increases, it is a ten-fold increase-10X10X10 in this case or 1000!

jeew-m eNotes educator| Certified Educator

PH is a scale to determine the acidity of solution.

`PH = -log[H^+]`

`[H^+] = 10^(-PH)`


At 25C PH sacle runs to 1-14. When the temperature changes this scale can be changed. At high temperatiures this scale shotens.

When PH = 4

`[H^+]_(PH=4) = 10^(-4)` ----(1)


When PH = 7

`[H^+]_(PH=7) = 10^(-7)` ------(2)



`[H^+]_(PH=4)/[H^+]_(PH=7) =10^(-4)/10^(-7) = 1000`


`[H^+]_(PH=4) = 1000*[H^+]_(PH=7)`


So hydrogen ion concentration at PH=4 is 1000 times greater than hydrogen ions concentration in PH=7.