(a)
(b)
What does pH scale measure ?
Write its range.
State the significance of highest and lowest values of pH scale.
Answers
pH values of some common substances
Acids and bases
Acid Acid–base reaction Acid strength Acidity function Amphoterism Base Buffer solutions Dissociation constant Equilibrium chemistry Extraction Hammett acidity function pH Proton affinity Self-ionization of water Titration Lewis acid catalysis Frustrated Lewis pair Chiral Lewis acid
Acid types
Brønsted–Lowry Lewis Acceptor Mineral Organic Strong Superacids Weak Solid
Base types
Brønsted–Lowry Lewis Donor Organic Strong Superbases Non-nucleophilic Weak
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In chemistry, pH (/piːˈeɪtʃ/) is a scale used to specify how acidic or basic a water-based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH. At room temperature (25°C or 77°F), pure water is neither acidic nor basic and has a pH of 7.
The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution (a lower pH indicates a higher concentration of hydrogen ions). This is because the formula used to calculate pH approximates the negative of the base 10 logarithm of the molar concentration[a] of hydrogen ions in the solution. More precisely, pH is the negative of the base 10 logarithm of the activity of the hydrogen ion.[1]
At 25 °C, solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic. The neutral value of the pH depends on the temperature, being lower than 7 if the temperature increases. The pH value can be less than 0 for very strong acids, or greater than 14 for very strong bases.[2]
The pH scale is traceable to a set of standard solutions whose pH is established by international agreement.[3] Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator. Measurements of pH are important in chemistry, agronomy, medicine, water treatment, and many other applications
Answer:
pH is a measure of the acidic or basic (alkaline) nature of a solution (concentration of the hydrogen ion [H+] activity in a solution determines the pH). The pH scale ranges from 0 to 14, which is the most acidic, a pH of 7 is neutral, and 14 is the most alkaline.