|Material||pH Value||Acid or Base?|
|Hydrochloric Acid (HCl)||0.0||Acid|
|Battery Acid (H2SO4 sulfuric acid)||1.0||Acid|
|Lemon Juice or Lime||2.2||Acid|
|Wine and Beer||4.0||Acid|
|Pure water (H2O)||7.0||Neutral|
|Baking Soda (Sodium Bicarbonate)||8.3||Base|
|Milk of Magnesia||10.5||Base|
|Lime (Calcium Hydroxide)||12.4||Base|
|Sodium Hydroxide (NaOH)||14.0||Base|
What is the pH Of a Solution?
In chemistry, pH (denoting the “power of hydrogen” or “potential of hydrogen”) is a scale used to measure the acidity or alkalinity of a given aqueous solution. Pure water (H2O) is a non-electrolyte, but at room temperature it contains a very small and equal amount (1.0 × 10-7 M) of both hydronium (H+) and hydroxyl or hydroxide (OH–) ions. Their concentrations are inversely proportional, as determined by the ionic product of water (Kw).
These concentrations play an important role in determining the properties of a solution, and the chemical behaviour of its solutes. If a solution contains an equal concentration of H+ and OH– ions, it is neutral. If it contains a greater concentration of H+ ions, it is acidic in nature. And similarly, if it has a higher concentration of OH– ions, it is basic in nature.
Quantities which span large orders of magnitude and are difficult to express in the standard form are often expressed conveniently on a logarithmic scale. The pH scale is one such widely used scale is based on the p-function, as shown below:
pH = -log [H3O+]
Here, “log” is the base-10 logarithm and “[H3O+]” is the molar concentration of hydronium ions in the solution (H+ ions tend to exist in combination with water molecules, rather than freely in solution). We can obtain the hydronium ion concentration by taking the antilogarithm of the above equation, as shown below:
[H3O+] = 10-pH
Similarly, the hydroxide ion concentration is expressed as the pOH of the solution:
pOH = -log [OH–] or [OH–]=10-pOH
Based on the equilibrium concentrations of H+ and OH– in water, the given relationships hold true for any aqueous solution at 25oC:
pH = −log[H3O+] = −log(1.0 × 10−7) = 7.00
pOH = −log[OH−] = −log(1.0 × 10−7) = 7.00
Kw = [H3O+][OH−]
−logKw = −log([H3O+][OH−]) = −log[H3O+] + −log[OH−]
pKw= pH + pOH = 14
It is important to remember that at temperatures above 25oC, the molarity of H+ and OH– ions increases due to an increase in the dissociation of water molecules, leading to an overall lowering in the pH scale. The reverse holds true for temperatures lower than 25oC. The pH scale plays a very important role in chemistry, biology, medicine, pharmacy, agronomy, water treatment, and even our daily lives.
What is the pH Calculator, and what are its advantages?
As described above, measuring the pH of a solution involves some complicated calculations involving logarithms and antilogarithms. These can be time-consuming and quite vulnerable to human errors. The pH scale is highly sensitive, and even a small calculation mistake can lead to a vast difference. For example, the change of a couple of decimal points in the pH of the blood can potentially kill a person. Similarly, minute differences in the pH can lead to a drug getting inactivated or an enzyme getting denatured.
Therefore, accuracy is extremely important when calculating the pH of a solution. The pH calculator is a helpful online tool designed for this very purpose. It can calculate the pH of a solution in a fast and error-free manner, displaying the result within a few seconds. You do not need to have any prior knowledge of the concerned calculations to use this tool. The pH calculator is programmed with a reliable algorithm to measure the pH with pinpoint precision.
How to Use the pH Calculator?
You can easily measure the pH of a solution using the pH calculator by following the steps given below:
- Open the calculator and enter the name of the chemical solution and its concentration value in the corresponding input fields.
- Click the “Calculate” button.
- Soon, the calculated pH value will be shown in a fresh popup window.
The pH calculator is highly recommended to students, teachers, and professionals alike, particularly in situations where limited time is available for calculations.