What is strong acid and weak acid?

4 Answers

samhouston's profile pic

samhouston | Middle School Teacher | (Level 1) Associate Educator

Posted on

The pH scale is used to measure how acidic or basic a substance is.  The scale goes from 0 to 14.  A substance with a pH of 0 through 6 is considered an acid, while a substance with a pH of 8 through 14 is considered a base.  A pH of 7 is neutral.  Uncontaminated, pure water is neutral.  The closer the number is to 7, the weaker the substance is.  The farther the number is from 7, the stronger the substance is. 

A substance with a pH of 1 or 2 would be a strong acid.  A substance with a pH of 5 or 6 would be a weak acid.

A substance with a pH of 13 or 15 would be a strong base.  A substance with a pH of 8 or 9 would be a weak base.

An example of a strong acid is vinegar.  The pH of vinegar is 2.4.  An example of a weak acid is citric acid.  The pH of citric acid is 4.8.

User Comments

element-water's profile pic

element-water | Student, Grade 6 | (Level 1) Salutatorian

Posted on

A strong acid is an acid that is totally ionised in a solution. There aren't many strong acids in the world. Some examples of strong acids are sulphuric acids, hydrochloric acid, hydrobromic acid and nitric acid.

A weak acid is an acid that is only partially ionised in a solution. Anything that is not in the strong acid list is classified as a weak acid.

phangsingsheen's profile pic

phangsingsheen | Student, College Freshman | (Level 1) eNoter

Posted on

strong acid are acid that dissociate completely when dissolve in water.the degree of dissciation is 1.

weak acid are acid that dissociate partially when dissolve in water..there will be H atom left in the acid and does not dissociate.

jackmacc2000's profile pic

jackmacc2000 | Student, Grade 11 | (Level 1) eNoter

Posted on

A strong acid is an acid where the pH is lower than, generally, 3. These acids are in very high concentration of H+ ions (an acid of pH 3 has 0.001 moles per liter of H+), while a weak acid’s pH ranges from 3 to 7. These acids still have higher H+ concentration than OH-, however not a lot. Stronger acids tend to be more harmful to the human body than weak acids, so treat strong acids with caution!