CLASS 10 Science Chapter 2 PH SCALE
Acid Base & Salt
- The pH scale is used to determine the concentration of hydronium ions on a logarithmic scale. By definition, pH of acids and bases is the negative logarithm (with base 10) of activity of hydrogen ion (H+).
- pH scale was devised by Sorenson in 1909.
- The strength of acid solutions as well as basic solutions could be represented by hydrogen ion concentrations in the pH scale.
- The numeric value of the degree of acidity or basicity of a substance can be determined using a pH scale.
- pH stands for ‘potential of hydrogen’.
- The pH of a solution is inversely proportional to the concentration of hydrogen ions in it.
- A pH scale ranges from 0 to 14. 0 indicates the most acidic and 14 indicates the most basic nature of a substance.
- So, we can say that
- Neutral substances have a pH of exactly 7.
- Acids have a pH of less than 7.
- Bases have a pH of more than 7.
- Solutions that have pH value of 7 are known as neutral solutions.
- Solutions having the value of pH equal to 0 are called strongly acidic solutions.
- Solutions with the value of pH equal to 14 are termed as strongly basic solutions.
- Acidity decreases as pH value increases from 0 to 7 and basicity decreases as pH value decreases from 14 to 7.
pH values of some common substances
| Substance | pH | Type |
|---|
| Hydrochloric Acid (HCl) | 0.0 | Acid |
| Battery Acid (H2SO4 sulfuric acid) | 1.0 | Acid |
| Gastric juice | 1.2 | Acid |
| lemon juice | 2.2 | Acid |
| Vinegar | 2.8 | Acid |
| Apples | 3.0 | Acid |
| Soft drinks | 3.0 | Acid |
| Wine and Beer | 4.0 | Acid |
| Tomatoes | 4.5 | Acid |
| Black coffee | 5.0 | Acid |
| Human saliva | 6.4 | Acid |
| Rain water | 6.5 | Acid |
| Milk | 6.8 | Acid |
| Pure water | 7.0 | Neutral |
| Human Blood | 7.4 | Base |
| Tears | 7.4 | Base |
| Egg | 7.8 | Base |
| Baking Soda (Sodium Bicarbonate) | 8.3 | Base |
| Milk of Magnesia | 10.5 | Base |
| Ammonia | 11.0 | Base |
| Lime (Calcium Hydroxide) | 12.4 | Base |
| Sodium Hydroxide (NaOH) | 14.0 | Base |
| Oven cleaner | 13.8 | Base |
List of pH Value of Different Substances:
H
| Substance | pH Value |
| Battery acid | 1.0 |
| Limes | 1.8-2.0 |
| Lemon juice | 2.2-2.4 |
| Fruit jellies | 2.8-3.4 |
| Vinegar | 2.9 |
| Apple juice | 2.9-3.3 |
| Strawberries | 3.0-3.5 |
| Orange juice | 3.7 |
| Tomatoes | 4.0-4.5 |
| Bear | 4.5 |
| Coffee | 5.0 |
| Tea | 5.5 |
| Rainwater | 5.6-6.0 |
| Peas | 5.8-6.4 |
| Urine | 6.0 |
| Corn | 6.0-6.5 |
| Butter | 6.1-6.4 |
| Cow’s milk | 6.4 |
| Maple syrup | 6.5-7.0 |
| Human saliva | 6.5-7.5 |
| Water | 7.0
HOPE U LIKE THE CONTENT .................. |
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