# 10: Acids and Bases


Acids and bases are common substances found in many every day items, from fruit juices and soft drinks to soap. In this unit we'll examine what the properties are of acids and bases, and learn about the chemical nature of these important compounds. You'll learn what pH is and how to calculate the pH of a solution.

• 10.1: Acids- Properties and Examples
Acids are very common in some of the foods that we eat. Citrus fruits such as oranges and lemons contain citric acid and ascorbic acid, which is better known as vitamin C. Carbonated sodas contain phosphoric acid. Vinegar contains acetic acid. Your own stomach utilizes hydrochloric acid to digest food. Acids are a distinct class of compounds because of the properties of their aqueous solutions.
• 10.2: Bases- Properties and Examples
A base is thought of as a substance which can accept protons or any chemical compound that yields hydroxide ions (OH-) in solution. It is also commonly referred to as any substance that can react with an acid to decrease or neutralize its acidic properties, change the color of indicators (e.g. turn red litmus paper blue), feel slippery to the touch when in solution, taste bitter, react with acids to form salts, and promote certain chemical reactions (e.g. base catalysis).
• 10.3: Molecular Definitions of Acids and Bases
Although the properties of acids and bases had been recognized for a long time, it was Svante Arrhenius in the 1880's who determined that: the properties of acids were due to the presence of hydrogen ions, and the properties of bases were due to the presence of hydroxide ions.
• 10.4: Strong and Weak Acids and Bases
Acids are classified as either strong or weak, based on their ionization in water. A strong acid is an acid which is completely ionized in an aqueous solution. A weak acid is an acid that ionizes only slightly in an aqueous solution. Acetic acid (found in vinegar) is a very common weak acid.
• 10.5: Water - Acid and Base in One
Water is an interesting compound in many respects. Here, we will consider its ability to behave as an acid or a base. In some circumstances, a water molecule will accept a proton and thus act as a Brønsted-Lowry base.
• 10.6: Autoionization of Water
In any aqueous solution at room temperature, the product of $$[H^+]$$ and $$[OH^−]$$ equals $$1.0 \times 10^{−14}$$.
• 10.7: The pH Scale
pH is a logarithmic function of [H+]. [H+] can be calculated directly from pH. pOH is related to pH and can be easily calculated from pH.

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