- Acids are substances that can donate protons (H+ ions) to a solution.
- They are characterized by a sour taste
- the ability to turn blue litmus paper red. (ABR)
- the ability to turn Methyl Orange into red.
- pH value less than 7.
- Examples – hydrochloric acid (HCl), sulfuric acid (H2SO4), acetic acid (CH3COOH), and citric acid (found in citrus fruits).
- proposed by Swedish chemist Svante Arrhenius in 1884.
- According to Arrhenius, acids are substances that, when dissolved in water, release hydrogen ions (H+ ions) into the solution.
- Arrhenius defined bases as substances that, when dissolved in water, release hydroxide ions (OH- ions) into the solution.
- formulated independently by Danish chemist Johannes Brønsted and British chemist Thomas Lowry in 1923.
- According to the Brønsted-Lowry theory, an acid is defined as a substance that can donate a proton (H+ ion) to another substance.
- A base, according to the Brønsted-Lowry theory, is defined as a substance that can accept a proton (H+ ion) from another substance.
- Bases, also known as alkalis, are substances that can accept protons (H+ ions) from a solution.
- They have a bitter taste, a slippery or soapy feel.
- pH value greater than 7.
- Bases turn red litmus paper blue.
- the ability to turn Methyl Orange into Yellow.
- the ability to turn Pheophthalin into Pink.
- used for cleaning and neutralizing acids.
- examples – sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonia (NH3).
- Salts are compounds formed when an acid reacts with a base through a chemical reaction called neutralization.
- In a neutralization reaction, the H+ ions from the acid combine with the OH- ions from the base to form water (H2O), while the remaining ions combine to form a salt.
- Salts can be composed of positively charged ions (cations) and negatively charged ions (anions). The cation comes from the base, and the anion comes from the acid.
- Common table salt, sodium chloride (NaCl), is formed from the neutralization of hydrochloric acid (HCl) and sodium hydroxide (NaOH).
- The pH scale is a logarithmic scale used to measure the acidity or alkalinity (basicity) of a solution.
- It ranges from 0 (strongly acidic) to 14 (strongly alkaline or basic), with 7 being neutral.
- Solutions with a pH less than 7 are acidic, those with a pH greater than 7 are basic, and those with a pH of 7 are neutral (Rain Water).
- The pH of a solution is determined by the concentration of H+ ions.
- Higher H+ ion concentrations result in lower pH values (more acidic).
- while lower H+ ion concentrations result in higher pH values (more basic).
Common Salt Types:
- Sodium chloride (NaCl): Common table salt.
- Calcium carbonate (CaCO3): Found in chalk, limestone, and antacids.
- Sodium bicarbonate (NaHCO3): Baking soda, used in baking and as an antacid.
- Magnesium sulfate (MgSO4): Epsom salt, used for muscle relaxation in baths.
- Potassium nitrate (KNO3): Used in fertilizers and fireworks.
Alkali: bases which are dissolved in water.
A buffer solution is a solution that can resist changes in its pH (acidity or alkalinity) when an acid or base is added to it.