Question

How do you determine pH from molarity?

Answer 1

Hint:. pH stands for power of hydrogen and molarity of a solution is denoted by M. to find a relation between them, first we have to understand each term in detail.

Complete step by step answer:
- Molar solution is also known as molarity. Molarity is one of the standard expressions of solution concentration. The molar solution used the gram molecular weight of a solute in calculating molar concentration present in per litre of the solution.
- pH is the scale which is used to specify the acidity and basicity of a solution. The acidic solutions generally have lower pH value while the basic solutions have higher pH value of the pH scale.
The formula for calculation of pH:
$$pH=-\log [H^{+}]$$
- Let’s assume if the molarity of a solution of HCl is 0.1 M. and we know that NaOH or sodium hydroxide is a very strong acid, so it will produce 0.1 moles per litre of $H^{+}$ ions. Hence the pH will be calculated by:
$$pH=-\log (0.1)$$
Similarly, for a base we can calculate the concentration of OH ions using molarity and the calculate pH using the value of pOH.

Note: The pH scale generally ranges from 0 to 14. It helps us to determine how acidic or basic the solution is. If the pH of the solution is less than 7, then it is acidic and if the pH of the solution is more than 7, then it is the basic solution. Similarly, if the pH of the solution of equal to 7, then the solution is neutral.