The pH Scale is a set of numbers from 0 to 14 which is used to indicate whether an aqueous solution is acidic, neutral or alkaline.
All aqueous solutions contain hydrogen ions, H+ and hydroxide ion, OH–. The concentration of these ions differs in solutions of different pH values. Therefore, the pH of a solution is related to the concentration of hydrogen ions or hydroxide ions present in a solution.
It is important to appreciate the formal definition of “pH” in order to master Chemistry. It is formally defined as the “measure of the concentration of the hydrogen ions in a solution”.
Based on the definition above, let’s look at three different sections of the pH Scale:
A) Solution with pH equal to 7
It is NEUTRAL!
This if the pH of pure water i.e. distilled water.
The concentration of hydrogen ions and hydroxide ions is the same.
B) Solution with pH less than 7
It is ACIDIC!
Acids have concentration of hydrogen ions more than the concentration of hydroxide ions.
The lower the pH value, the greater the concentration of hydrogen ions and the lower the concentration of hydroxide ions, which means the more acidic the solution.
C) Solution with pH greater than 7
It is ALKALINE!
Acids have concentration of hydroxide ions more than the concentration of hydrogen ions.
The higher the pH value, the greater the concentration of hydroxide ions and the lower the concentration of hydrogen ions, which means the more alkaline the solution.
Let’s take a look at a Chemistry MCQ question.
Question 1:
An unknown aqueous solution has a pH value of about 2.
Which of the following is correct about the ions present in the solution?
A) Concentration of H+ ions = High & Concentration of OH– ions = None
B) Concentration of H+ ions = High & Concentration of OH– ions = Low
C) Concentration of H+ ions = Low & Concentration of OH– ions = High
D) Concentration of H+ ions = Low & Concentration of OH– ions = None
Work on it and write your answer in the comment section below. See you soon!
PS: Feel free to share this blog post to anyone who might benefit from it.
Ans (B). A substance with a PH value of 2 is an acidic substance. Acidic substances have a high concentration of H+ ions which gives the substance its acidic properties but a Low concentration of OH- ions
I think it is A because any alkaline(OH) would neutralize the acid to give salt and water
B is the answer ph has to do with H+ and OH-
Is there other questions on this site ?Thank you
Answer B
I think the answer is A. If the OH- ions are none please explain why. I seriously suck at chemistry, if only Mr.Chua could help me with his higher knowledge. I have my CIE O levels Exams this May
B/. lower PH greater hydrogen ions and lower hydroxil ions, this concern with acid
Good, you’re right. Chemistry and teaching as well is more attractive and you deal it more when you really love it.
My answer to your question is B.
I think some students may have a misconception that acid does not have any hydroxide ions, and alkali does not have any hydrogen ions.