17.3: Definitions of Acids and Bases (2023)

Learning Objectives
  • Identify acids, bases, and conjugate acid-base pairs according to the Brønsted-Lowry definition
  • Write equations for acid and base ionization reactions
  • Use the ion-product constant for water to calculate hydronium and hydroxide ion concentrations
  • Describe the acid-base behavior of amphiprotic substances

Acids and bases have been known for a long time. When Robert Boyle characterized them in 1680, he noted that acids dissolve many substances, change the color of certain natural dyes (for example, they change litmus from blue to red), and lose these characteristic properties after coming into contact with alkalis (bases). In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO2), and interact with alkalis to form neutral substances. In 1815, Humphry Davy contributed greatly to the development of the modern acid-base concept by demonstrating that hydrogen is the essential constituent of acids. Around that same time, Joseph Louis Gay-Lussac concluded that acids are substances that can neutralize bases and that these two classes of substances can be defined only in terms of each other. The significance of hydrogen was reemphasized in 1884 when Svante Arrhenius defined an acid as a compound that dissolves in water to yield hydrogen cations (now recognized to be hydronium ions) and a base as a compound that dissolves in water to yield hydroxide anions.

Previously, we defined acids and bases as Arrhenius did: An acid is a compound that dissolves in water to yield hydronium ions (\(H_3O^+\)) and a base as a compound that dissolves in water to yield hydroxide ions (\(\ce{OH-}\)). This definition is not wrong; it is simply limited. We extended the definition of an acid or a base using the more general definition proposed in 1923 by the Danish chemist Johannes Brønsted and the English chemist Thomas Lowry. Their definition centers on the proton, \(\ce{H^+}\). A proton is what remains when a normal hydrogen atom, \(\ce{^1_1H}\), loses an electron. A compound that donates a proton to another compound is called a Brønsted-Lowry acid, and a compound that accepts a proton is called a Brønsted-Lowry base. An acid-base reaction is the transfer of a proton from a proton donor (acid) to a proton acceptor (base). In a subsequent chapter of this text we will introduce the most general model of acid-base behavior introduced by the American chemist G. N. Lewis.

Acids may be compounds such as \(HCl\) or \(H_2SO_4\), organic acids like acetic acid (\(\ce{CH_3COOH}\)) or ascorbic acid (vitamin C), or \(H_2O\). Anions (such as \(\ce{HSO_4^-}\), \(\ce{H_2PO_4^-}\), \(\ce{HS^-}\), and \(\ce{HCO_3^-}\)) and cations (such as \(\ce{H_3O^+}\), \(\ce{NH_4^+}\), and \(\ce{[Al(H_2O)_6]^{3+}}\)) may also act as acids. Bases fall into the same three categories. Bases may be neutral molecules (such as \(\ce{H_2O}\), \(\ce{NH_3}\), and \(\ce{CH_3NH_2}\)), anions (such as \(\ce{OH^-}\), \(\ce{HS^-}\), \(\ce{HCO_3^-}\), \(\ce{CO_3^{2−}}\), \(\ce{F^-}\), and \(\ce{PO_4^{3−}}\)), or cations (such as \(\ce{[Al(H_2O)_5OH]^{2+}}\)). The most familiar bases are ionic compounds such as \(\ce{NaOH}\) and \(\ce{Ca(OH)_2}\), which contain the hydroxide ion, \(\ce{OH^-}\). The hydroxide ion in these compounds accepts a proton from acids to form water:

\[\ce{H^+ + OH^- \rightarrow H_2O} \label{16.2.1} \]

We call the product that remains after an acid donates a proton the conjugate base of the acid. This species is a base because it can accept a proton (to re-form the acid):

\[\text{acid} \rightleftharpoons \text{proton} + \text{conjugate base}\label{16.2.2a} \]

\[\ce{HF \rightleftharpoons H^+ + F^-} \label{16.2.2b} \]

\[\ce{H_2SO_4 \rightleftharpoons H^+ + HSO_4^{−}}\label{16.2.2c} \]

\[\ce{H_2O \rightleftharpoons H^+ + OH^-}\label{16.2.2d} \]

\[\ce{HSO_4^- \rightleftharpoons H^+ + SO_4^{2−}}\label{16.2.2e} \]

\[\ce{NH_4^+ \rightleftharpoons H^+ + NH_3} \label{16.2.2f} \]

We call the product that results when a base accepts a proton the base’s conjugate acid. This species is an acid because it can give up a proton (and thus re-form the base):

\[\text{base} + \text{proton} \rightleftharpoons \text{conjugate acid} \label{16.2.3a} \]

(Video) 17.3 Definitions of Acids & Bases

\[\ce{OH^- +H^+ \rightleftharpoons H2O}\label{16.2.3b} \]

\[\ce{H_2O + H^+ \rightleftharpoons H3O+}\label{16.2.3c} \]

\[\ce{NH_3 +H^+ \rightleftharpoons NH4+}\label{16.2.3d} \]

\[\ce{S^{2-} +H^+ \rightleftharpoons HS-}\label{16.2.3e} \]

\[\ce{CO_3^{2-} +H^+ \rightleftharpoons HCO3-}\label{16.2.3f} \]

\[\ce{F^- +H^+ \rightleftharpoons HF} \label{16.2.3g} \]

In these two sets of equations, the behaviors of acids as proton donors and bases as proton acceptors are represented in isolation. In reality, all acid-base reactions involve the transfer of protons between acids and bases. For example, consider the acid-base reaction that takes place when ammonia is dissolved in water. A water molecule (functioning as an acid) transfers a proton to an ammonia molecule (functioning as a base), yielding the conjugate base of water, \(\ce{OH^-}\), and the conjugate acid of ammonia, \(\ce{NH4+}\):

17.3: Definitions of Acids and Bases (1)

The reaction between a Brønsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:

17.3: Definitions of Acids and Bases (2)

When we add a base to water, a base ionization reaction occurs in which protons are transferred from water molecules to base molecules. For example, adding pyridine to water yields hydroxide ions and pyridinium ions:

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Notice that both these ionization reactions are represented as equilibrium processes. The relative extent to which these acid and base ionization reactions proceed is an important topic treated in a later section of this chapter. In the preceding paragraphs we saw that water can function as either an acid or a base, depending on the nature of the solute dissolved in it. In fact, in pure water or in any aqueous solution, water acts both as an acid and a base. A very small fraction of water molecules donate protons to other water molecules to form hydronium ions and hydroxide ions:

17.3: Definitions of Acids and Bases (5)

This type of reaction, in which a substance ionizes when one molecule of the substance reacts with another molecule of the same substance, is referred to as autoionization. Pure water undergoes autoionization to a very slight extent. Only about two out of every \(10^9\) molecules in a sample of pure water are ionized at 25 °C. The equilibrium constant for the ionization of water is called the ion-product constant for water (Kw):

\[\ce{H_2O}_{(l)}+\ce{H_2O}_{(l)} \rightleftharpoons \ce{H_3O^+}_{(aq)}+H\ce{O^-}_{(aq)}\;\;\; K_\ce{w}=\ce{[H_3O^+][OH^- ]} \label{16.2.4} \]

The slight ionization of pure water is reflected in the small value of the equilibrium constant; at 25 °C, Kw has a value of \(1.0 \times 10^{−14}\). The process is endothermic, and so the extent of ionization and the resulting concentrations of hydronium ion and hydroxide ion increase with temperature. For example, at 100 °C, the value for \(K_\ce{w}\) is approximately \(5.1 \times 10^{−13}\), roughly 100-times larger than the value at 25 °C.

A Video Discussing Conjugate Acid-Base Pairs: Conjugate Acid-Base Pairs [youtu.be]

Example \(\PageIndex{1}\): Ion Concentrations in Pure Water

What are the hydronium ion concentration and the hydroxide ion concentration in pure water at 25 °C?


The autoionization of water yields the same number of hydronium and hydroxide ions. Therefore, in pure water, \(\ce{[H_3O^+]} = \ce{[OH^- ]}\). At 25 °C:

\[K_\ce{w}=\ce{[H_3O^+][OH^- ]}=\ce{[H_3O^+]^2+}=\ce{[OH^- ]^2+}=1.0 \times 10^{−14} \nonumber \]


\[\ce{[H_3O^+]}=\ce{[OH^- ]}=\sqrt{1.0 \times 10^{−14}} =1.0 \times 10^{−7}\; M \nonumber \]

The hydronium ion concentration and the hydroxide ion concentration are the same, and we find that both equal \(1.0 \times 10^{−7}\; M\).

(Video) 17.3 Definitions of Acids & Bases
Exercise \(\PageIndex{1}\)

The ion product of water at 80 °C is \(2.4 \times 10^{−13}\). What are the concentrations of hydronium and hydroxide ions in pure water at 80 °C?


\(\ce{[H_3O^+]} = \ce{[OH^- ]} = 4.9 \times 10^{−7}\; M\)

It is important to realize that the autoionization equilibrium for water is established in all aqueous solutions. Adding an acid or base to water will not change the position of the equilibrium determined by the autoionization reaction but it does shift the relative concentrations of \( \ce{[OH^-]} \) and \(\ce{[H_3O^+]} \). Example 16.2.2 demonstrates the quantitative aspects of this relation between hydronium and hydroxide ion concentrations.

A Video Describing the Self-Ionization of Water (Kw): Self-Ionization of Water (Kw) [youtu.be]

Example \(\PageIndex{2}\): The Inverse Proportionality of \(\ce{[H_3O^+]}\) and \(\ce{[OH^- ]}\)

A solution of carbon dioxide in water has a hydronium ion concentration of \(2.0 \times 10^{−6}\; M\). What is the concentration of hydroxide ion at 25 °C?

(Video) Acid and Base Definitions | Arrhenius, Bronsted-Lowry, and Lewis


We know the value of the ion-product constant for water at 25 °C:

\[\ce{2 H_2O}_{(l)} \rightleftharpoons \ce{H_3O^+}_{(aq)} + \ce{OH^-}_{(aq)} \nonumber \]

\[K_\ce{w}=\ce{[H3O+][OH^- ]}=1.0 \times 10^{−14} \nonumber \]

Thus, we can calculate the missing equilibrium concentration.

Rearrangement of the Kw expression yields that \([\ce{OH^- }]\) is directly proportional to the inverse of [H3O+]:

\[[\ce{OH^- }]=\dfrac{K_{\ce w}}{[\ce{H_3O^+}]}=\dfrac{1.0 \times 10^{−14}}{2.0 \times 10^{−6}}=5.0 \times 10^{−9} \nonumber \]

The hydroxide ion concentration in water is reduced to \(5.0 \times 10^{−9}\: M\) as the hydrogen ion concentration increases to \(2.0 \times 10^{−6}\; M\). This is expected from Le Chatelier’s principle; the autoionization reaction shifts to the left to reduce the stress of the increased hydronium ion concentration and the \(\ce{[OH^- ]}\) is reduced relative to that in pure water.

A check of these concentrations confirms that our arithmetic is correct:

\[K_\ce{w}=\ce{[H_3O^+][OH^- ]}=(2.0 \times 10^{−6})(5.0 \times 10^{−9})=1.0 \times 10^{−14} \nonumber \]

Exercise \(\PageIndex{2}\)

What is the hydronium ion concentration in an aqueous solution with a hydroxide ion concentration of 0.001 M at 25 °C?


\[\ce{[H3O+]} = 1 \times 10^{−11} M \nonumber \]

Amphiprotic Species

Like water, many molecules and ions may either gain or lose a proton under the appropriate conditions. Such species are said to be amphiprotic. Another term used to describe such species is amphoteric, which is a more general term for a species that may act either as an acid or a base by any definition (not just the Brønsted-Lowry one). Consider for example the bicarbonate ion, which may either donate or accept a proton as shown here:

(Video) 17.3 Acid-Base Titrations

\[\ce{HCO^-}_{3(aq)} + \ce{H_2O}_{(l)} \rightleftharpoons \ce{CO^{2-}}_{3(aq)} + \ce{H_3O^+}_{(aq)} \label{16.2.5a} \]

\[ \ce{HCO^-}_{3(aq)} + \ce{H_2O}_{(l)} \rightleftharpoons \ce{H_2CO}_{3(aq)} + \ce{OH^-}_{(aq)} \label{16.2.5b} \]

Example \(\PageIndex{3}\): The Acid-Base Behavior of an Amphoteric Substance

Write separate equations representing the reaction of \(\ce{HSO3-}\)

  1. as an acid with \(\ce{OH^-}\)
  2. as a base with HI
  1. \(HSO_{3(aq)}^- + OH_{(aq)}^- \rightleftharpoons SO_{3(aq)}^{2-} + H_2O_{(l)}\)
  2. \(HSO_{3(aq)}^- + HI_{(aq)} \rightleftharpoons H_2SO_{3(aq)}+ I_{(aq)}^-\)
Example \(\PageIndex{4}\)

Write separate equations representing the reaction of \(\ce{H2PO4-}\)

  1. as a base with HBr
  2. as an acid with \(\ce{OH^-}\)
  1. \(H_2PO_{4(aq)}^- + HBr_{(aq)} \rightleftharpoons H_3PO_{4(aq)} + Br^-_{(aq)}\)
  2. \(H_2PO_{4(aq)}^- + OH^-_{(aq)} \rightleftharpoons HPO_{4(aq)}^{2-} + H_2O_{(l)} \)


A compound that can donate a proton (a hydrogen ion) to another compound is called a Brønsted-Lowry acid. The compound that accepts the proton is called a Brønsted-Lowry base. The species remaining after a Brønsted-Lowry acid has lost a proton is the conjugate base of the acid. The species formed when a Brønsted-Lowry base gains a proton is the conjugate acid of the base. Thus, an acid-base reaction occurs when a proton is transferred from an acid to a base, with formation of the conjugate base of the reactant acid and formation of the conjugate acid of the reactant base. Amphiprotic species can act as both proton donors and proton acceptors. Water is the most important amphiprotic species. It can form both the hydronium ion, H3O+, and the hydroxide ion, \(\ce{OH^-}\) when it undergoes autoionization:

\[\ce{2 H_2O}_{(l)} \rightleftharpoons H_3O^+_{(aq)} + OH^-_{(aq)} \nonumber \]

The ion product of water, Kw is the equilibrium constant for the autoionization reaction:

\[K_\ce{w}=\mathrm{[H_2O^+][OH^- ]=1.0 \times 10^{−14} \; at\; 25°C} \nonumber \]

Key Equations

  • \[K_{\ce w} = \ce{[H3O+][OH^- ]} = 1.0 \times 10^{−14}\textrm{ (at 25 °C)} \nonumber \]


acid ionization
reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid
species that may either gain or lose a proton in a reaction
species that can act as either an acid or a base
reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions
base ionization
reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base
Brønsted-Lowry acid
proton donor
Brønsted-Lowry base
proton acceptor
conjugate acid
substance formed when a base gains a proton
conjugate base
substance formed when an acid loses a proton
ion-product constant for water (Kw)
equilibrium constant for the autoionization of water
(Video) Ch 17 - Defining Acids and Bases

Contributors and Attributions

  • Paul Flowers (University of North Carolina - Pembroke),Klaus Theopold (University of Delaware) andRichard Langley (Stephen F. Austin State University) with contributing authors.Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Download for free at http://cnx.org/contents/[emailprotected]).


How do you define acids and bases? ›

An acid is any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance. A base is a molecule or ion able to accept a hydrogen ion from an acid.

What is a base and acid quizlet? ›

An acid is a substance that releases hydrogen ions into an aqueous solution. A base is a substance that releases hydroxide ions. Bases are caustic and acids are corrosive, giving very similar reactions to organic substances.

What is the main difference between an acid and a base? ›

The main distinguishing characteristic that sets acids and bases apart is their respective pH levels. Acids have pH levels that are below 7, while bases have pH levels that are above 7. This difference can be detected by either using a pH meter or an indicator, such as litmus paper.

What are the 3 theories of acids and bases? ›

In this chapter, we have discussed all the three basic theory of acid-base chemistry-Arrhenius theory, Bronsted-Lowry theory and Lewis acid-base theory.

What is acid short answer? ›

A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals. Acids have a sour taste and turn certain dyes red. Some acids made by the body, such as gastric acid, can help organs work the way they should.

What is acid and base definition with example? ›

(a) Acids are those chemical substances that have a sour taste. Example: Acetic acid and citric acid. Base is a chemical substance that has a bitter taste. Example: Caustic soda and washing soda. (b) Strong bases – Sodium hydroxide (NaOH), potassium hydroxide (KOH).

How bases are defined? ›

(bays) In chemistry, a substance that can accept hydrogen ions in water and can neutralize an acid. Bases feel soapy or slippery on the skin and they can turn certain dyes blue. An example of a base is sodium hydroxide.

What is the function of acid and base? ›

Cells secrete acids and bases to maintain the proper pH for enzymes to do their work. Every time you digest food, acids and bases are at work in your digestive system. Consider the enzyme pepsin, which helps break down proteins in the stomach. Pepsin needs an acidic environment to do its job.

What is pH acids and bases? ›

A pH scale is used to measures how acidic or basic a solution is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic over 7 is a base.

What are 3 differences between an acid and a base? ›

Bases are bitter to taste. (ii) Acids turn blue litmus red. Bases do not change the colour of blue litmus. (iii) Acids do not change the colour of red litmus.

Is acid stronger than a base? ›

Acids have a pH lesser than 7.0 and the lower it is, the stronger the acid becomes. Bases have a pH between 7 and 14. Higher the pH value, stronger will be the base. A pH level of 7 is a neutral substance which is water.

What are 3 properties of an acid? ›

These properties are:
  • Aqueous solutions of acids are electrolytes, meaning that they conduct electrical current. ...
  • Acids have a sour taste. ...
  • Acids change the color of certain acid-base indicates. ...
  • Acids react with active metals to yield hydrogen gas. ...
  • Acids react with bases to produce a salt compound and water.
Apr 30, 2022

What are 5 examples of bases? ›

14.3: Bases: Properties and Examples
  • Learning Objectives.
  • Bases. Warning!
  • Sodium Hydroxide.
  • Potassium Hydroxide.
  • Magnesium Hydroxide.
  • Calcium Hydroxide.
  • Ammonia.
Sep 3, 2019

Which one is strong acid? ›

The common strong acids include: HCl (hydrochloric acid) H2SO4 (sulfuric acid) HNO3 (nitric acid)

What are the uses of acids and bases in our daily life? ›

Benzoic acidIts salt are used to preserve food
Hydrochloric acidTo clean metals before electroplating / household cleaning / leather processing / swimming pool maintenance
Nitric acidProduction of fertilisers, explosives, etching and dissolution of metals (purification and extraction of gold)
4 more rows

What does pH stand for? ›

pH may look like it belongs on the periodic table of elements, but it's actually a unit of measurement. The abbreviation pH stands for potential hydrogen, and it tells us how much hydrogen is in liquids—and how active the hydrogen ion is.

What is the pH of an acid? ›

pHs less than 7 are acidic while pHs greater than 7 are alkaline (basic).

What are the two properties of acid? ›

The properties of acid are as follows: Acids are sour in taste. Acids furnish hydrogen ions in aqueous solution. Acid reacts with metal to form hydrogen gas.

What are 5 types of acids and bases? ›

The five common acids are sulfuric acid, hydrochloric acid, nitric acid, lactic acid, and acetic acid.

What are the 4 uses of bases? ›

  • Sodium hydroxide is used in the manufacture of soap.
  • Calcium hydroxide is used in whitewashing buildings.
  • Magnesium hydroxide is used as a medicine for stomach disorder.
  • Ammonium hydroxide is used to remove grease stains from clothes.

What are the 3 types of acids? ›

Usually acids can be divided into three major types. First one is binary acid, second one is oxyacid, and the last one is carboxylic acid. Binary acids are all written in “H-A” form, which means hydrogen bond to a nonmetal atom.

What is the short definition of base? ›

: a thing or part on which something rests : bottom, foundation. the base of a lamp. : the part of a plant or animal structure by which it is attached to another more central structure. the base of the thumb.

How do acids work? ›

An acid dissociates, or breaks apart, and donates protons, or hydrogen ions, in an aqueous solution, while a base donates hydroxide ions in a solution. Water, for example, is neutral with a pH of 7. When acids are added, they release more hydrogen ions into the solution, and this causes the pH of the solution to drop.

What is the first definition of base? ›

In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form hydroxide ions OH. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction.

What is the relationship between acid and base? ›

An acid increases the concentration of H+ ions. A base is a substance that releases hydroxide (OH-) ions in aqueous solution, donates electrons and accepts protons. An acid is a proton donor. A base accepts a proton.

Is water an acid or base? ›

Pure water is neither acidic or basic; it is neutral. So how does something become acidic or basic? That happens when the hydroniums and the hydroxyls are out of balance.

What are strong acid and base? ›

Strong acids and bases are the ones which dissociate completely in a solution. For, example HCl is a strong acid and dissociates completely into H+ and Cl- ions in the solution. Similarly, NaOH dissociates completely in solution. Also, we can determine the strength by pH, strong acids have pH 0 to 1.

What pH is water? ›

The pH of pure water (H20) is 7 at 25 °C, but when exposed to the carbon dioxide in the atmosphere this equilibrium results in a pH of approximately 5.2 because CO2 in the air dissolves in the water and forms carbonic acid.

What is a basic solution? ›

A basic solution is an aqueous solution that contains more OH-ions than H+ions. In other words, it is an aqueous solution with a pH greater than 7. pH is the hydrogen ion concentration, so the pH range of bases is between 7-14.

Do acids react with metals? ›

Acids react with most metals. When an acid reacts with a metal, the products are a salt and hydrogen.

What is the opposite of an acid? ›

alkaline An adjective that describes a chemical that can accept a proton from another molecule, or donate a pair of electrons. Alkaline solutions are also referred to as basic — as in the opposite of acidic — and have a pH above 7.

How do buffers work? ›

How Buffers Work? Buffers work by neutralizing any added acid (H+ ions) or base (OH- ions) to maintain a moderate pH, making them a weaker acid or base.

What is the reaction between acids and bases called? ›

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.

Is vinegar an acid or base? ›

Vinegar is very acidic, with a pH of 2–3.

What is the weakest acid? ›

Hydrocyanic acid is the weakest acid with the $p{{K}_{a}}$ value of $9.2$ . It partially ionises in water to give hydrogen ion and cyanide ions. The cyanide ion is the strongest conjugate base. The hydrocyanic acid is then represented as $HCN$ .

Is vinegar an alkaline? ›

Vinegar is acidic. Vinegar's pH level varies based upon the type of vinegar it is. White distilled vinegar, the kind best suited for household cleaning, typically has a pH of around 2.5.

Is Milk an acid or a base? ›

Milk — pasteurized, canned, or dry — is an acid-forming food. Its pH level is below neutral at about 6.7 to 6.9. This is because it contains lactic acid. Remember, though, that the exact pH level is less important than whether it's acid-forming or alkaline-forming.

Do bases conduct electricity? ›

Solutions of acids, bases and salts can conduct electricity.

What are 3 characteristics of bases? ›

What are the properties of Bases? Bases are another group of compounds that can be identified by their common properties. A base tastes bitter, feels slippery, and turns red litmus paper blue. The properties of bases are often described as the “opposite” of acids.

Is sugar an acid or a base? ›

Sugar and artificial sweeteners are highly acidic foods, which is one of the reasons the consumption of sweets has recently been linked to so many health ailments. Here is a range of foods from the highly acidic (pH2) to the highly alkaline (ph10). We are aiming to eat foods which are high on the pH scale (above pH6).

Is a salt a base? ›

Salt is not an acid or base. It is a combination of both of them. It may show acidic or basic nature, depending on the strength of the acid or base. While a strong base and strong acid always make neutral salt.

Is Coffee an acid or a base? ›

With an average pH of 4.85 to 5.10, most coffees are considered rather acidic. While this doesn't present a problem for most coffee lovers, the acidity can negatively affect certain health conditions in some people, such as acid reflux and IBS.

Can pH be negative? ›

While the pH scale typically runs from 0 to 14, it is definitely possible to calculate a negative pH. A negative pH occurs when the molarity of hydrogen ions in a strong acid is greater than 1 N (Normality).

What are the 7 weak bases? ›

Some of the example of weak base
  • Al(OH)3 is an aluminium hydroxide.
  • Pb(OH)2 is a kind of lead hydroxide.
  • Fe(OH)3 is a ferric hydroxide.
  • Cu(OH)2 is a copper hydroxide.
  • Zn(OH)2 is a zinc hydroxide.
  • N(CH3)3 trimethylamine.
  • Methylamine is a kind of methylamine (CH3NH2)
  • nitrous oxide (C6H5NH2)

How to calculate pH? ›

To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). The pH is then calculated using the expression: pH = - log [H3O+].

What is the pH of the human body? ›

Life on earth depends on appropriate pH levels in and around living organisms and cells. Human life requires a tightly controlled pH level in the serum of about 7.4 (a slightly alkaline range of 7.35 to 7.45) to survive [1].

What are 10 common household acids? ›

  • Vinegar (contains acetic acid).
  • Lemon Juice (contains citric acid).
  • Vitamin C (aka “ascorbic acid”).
  • Fizzy drinks (contain carbonic acid).
  • Stomach acid (contains hydrochloric acid).
  • Car battery acid (sulphuric acid).
Apr 19, 2023

Is a soap a base? ›

Soaps are slightly basic because they are the salts of strong bases and weak acids. Soap with water shows pH above 7, basic behavior and it also it tastes sour which can be said that base is also having a sour taste.

How do you identify acids bases and salts? ›

Acid:- An acid is defined as a substance whose water solution tastes sour, turns blue litmus red, and neutralizes bases. Base:- A substance is called base if its aqueous solution tastes bitter, turns red litmus blue, or neutralizes acids. Salt:- Salt is a neutral substance whose aqueous solution does not affect litmus.

Is Sugar an acid or a base? ›

Glucose has neither an acidic nor a basic nature. It is considered neutral, and its pH value is $ 7 $ . It does not give off hydrogen ions when dissolved, as most acids do. It also does not donate hydroxyl ions in the same way that the base does.

What is a base in chemistry? ›

(bays) In chemistry, a substance that can accept hydrogen ions in water and can neutralize an acid. Bases feel soapy or slippery on the skin and they can turn certain dyes blue. An example of a base is sodium hydroxide.

What are the properties of acid and base? ›

Acids are chemical substances which are characterized by a sour taste in an aqueous medium. They have the tendency to turn blue litmus red. On the other hand, bases are chemical substances which are characterized by a bitter taste and are slippery to touch. Some bases are soluble in water, while others are not.

How do you identify an acid and base in a reaction example? ›

To determine whether a substance is an acid or base, count the hydrogens before and after the reaction. If the number of hydrogens has decreased, that substance is the acid because it donates hydrogen ions. If the number of hydrogens has increased, that substance is the base since it accepts hydrogen ions.

How do you identify an acid from a base by its name? ›

Step 1: Identify the substance as an Arrhenius acid or base using the following criteria. The names of the acids end in “acid”. Acid formulas have one of these forms: HX(aq) or HaXbOc. (OH-) , carbonate (CO32-) , or hydrogen carbonate (HCO3-) anions are basic.

Is vinegar a base? ›

Vinegar is acidic because of its low PH.

Is coffee acid or base? ›

Most coffee varieties are acidic, with an average pH value of 4.85 to 5.10 ( 2 ).

Is water a base or an acid? ›

Pure water is neither acidic or basic; it is neutral. So how does something become acidic or basic?

What are the 4 strongest acids? ›

What are Strong Acids and their List?
  • Hydrochloric acid (denoted by the chemical formula HCl)
  • Hydrobromic acid (denoted by the chemical formula HBr)
  • Hydroiodic acid or hydriodic acid (denoted by the chemical formula HI)
  • Sulfuric acid (denoted by the chemical formula H2SO4)

What is a base called? ›

A base is a substance that can neutralize the acid by reacting with hydrogen ions. Most bases are minerals that react with acids to form water and salts. Bases include the oxides, hydroxides and carbonates of metals. The soluble bases are called alkalis. Sodium hydroxide is an alkali.

Where are bases found? ›

Bases are less common as foods, but they are nonetheless present in many household products. Many cleaners contain ammonia, a base. Sodium hydroxide is found in drain cleaner. Antacids, which combat excess stomach acid, are comprised of bases such as magnesium hydroxide or sodium hydrogen carbonate.


1. 17.3 acid base titrations
2. 16.1+2 acids and bases definitions
3. 16.3 Definitions of Acids & Bases
(Chemistry with Mrs. K)
4. 17.3 Titrations
(Roxi Hulet)
5. AP Chem - Section 17.3 - Titrations
6. 17.3 Part 1 - Acid-Base Titrations
(Chemistry - Ohio State - Loza)
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