Science Common Sense

1326 - What is the relationship between the strength of an acid or base and pH value.

The strength of an acid or base, and its pH value, are connected in this way:

• A strong acid has a low pH value (close to 0) because it easily gives away hydrogen ions (H+). The more hydrogen ions it gives away, the stronger the acid is.

• A weak acid has a higher pH value (closer to 7) because it doesn't give away hydrogen ions as easily.

• A strong base has a high pH value (close to 14) because it easily takes in hydrogen ions (H+). The more hydrogen ions it takes in, the stronger the base is.

• A weak base has a lower pH value (closer to 7) because it doesn't take in hydrogen ions as easily.

In short, strong acids are low pH, and strong bases are high pH.