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Acid and Base Chart — Table of Acids & Bases

Relative Strength of Acids & Bases

Use this acids and bases chart to find the relative strength of the most common acids and bases. This acid-base chart includes the Ka value for reference along with the chemical's formula and the acid’s conjugate base. The acid and base chart is a reference table designed to make determining the strength of acids and bases simpler. This chart is ideal for use in the lab or in the classroom.

Table of Acid and Base Strength

Acid   Base  
Strength of AcidKaNameFormulaFormulaNameStrength of Base
StrongestLargePerchloric acidHClO4ClO4-Perchlorate
ion
Weakest
 3.2 * 109Hydroiodic acidHII-Iodide 
 1.0 * 109Hydrobromic acidHBrBr-Bromide 
 1.3 * 106Hydrochloric acidHClCl-Chloride 
 1.0 * 103Sulfuric acidH2SO4HSO4-Hydrogen
sulfate ion
 
 2.4 * 101Nitric acidHNO3NO3-Nitrate ion 
 --------Hydronium ionH3O+H2OWater 
 5.4 * 10-2Oxalic acidHO2C2O2HHO2C2O2-Hydrogen
oxalate ion
 
 1.3 * 10-2Sulfurous acidH2SO3HSO3-Hydrogen
sulfite ion
 
 1.0 * 10-2Hydrogen sulfate ionHSO4 -SO4 2-Sulfate ion 
 7.1 * 10-3Phosphoric acidH3PO4H2PO4-Dihydrogen
phosphate ion
 
 7.2 * 10-4Nitrous acidHNO2NO2-Nitrite ion 
 6.6 * 10-4Hydrofluoric acidHFF-Fluoride ion 
 1.8 * 10-4Methanoic acidHCO2HHCO2-Methanoate
ion
 
 6.3 * 10-5Benzoic acidC6H5COOHC6H5COO-Benzoate ion 
Medium5.4 * 10-5Hydrogen oxalate ionHO2C2O2-O2C2O2 2-Oxalate ionMedium
 1.8 * 10-5Ethanoic acidCH3COOHCH3COOEthanoate
(acetate) ion
 
 4.4 * 10-7Carbonic acidH2CO3HCO-Hydrogen
carbonate ion
 
 1.1 * 10-7Hydrosulfuric acidH2SHSO3-Hydrogen
sulfide ion
 
 6.3 * 10-8Dihydrogen phosphate ionH2PO-HPO4 2-Hydrogen
phosphate ion
 
 6.2 * 10-8Hydrogen sulfite ionHS-SO32-Sulfite ion 
 2.9 * 10-8Hypochlorous acidHClOClO-Hypochlorite
ion
 
 6.2 * 10-10Hydrocyanic acidHCNCN-Cyanide ion 
 5.8 * 10-10Ammonium ionNH4 +NH3Ammonia 
 5.8 * 10-10Boric acidH3BO3H2BO3-Dihydrogenborate 
 4.7 * 10-11Hydrogen carbonate ionHCO3 -CO3 2-Carbonate
ion
 
 4.2 * 10-13Hydrogen phosphate ionHPO4 2-PO4 3-Phosphate
ion
 
 1.8 * 10-13Dihydrogen borate ionH2BO3 -HBO3 2-Hydrogen
borate ion
 
 1.3 * 10-13Hydrogen sulfide ionHS-2-Sulfide ion 
 1.6 * 10-14Hydrogen borate ionHBO3 2-BO3 3-Borate ion 
Weakest-WaterH2OOH-HydroxideStrongest

How to Use the Acid & Base Chart

Read these instructions to learn how to use this acids and bases chart. The table lists the Kvalues and the strength of each acid and base.

  1. Strong acids are listed at the top left-hand corner of the table and have Ka values >1
  2. Acids with a Ka value less than one are considered weak and get weaker as we move to the bottom of the table.
  3. The strong bases are listed at the bottom-right of the table and get weaker as we move to the top of the table.

Conjugate Acid-Base Pairs

In this chart, the strongest acids are at the top left, and the weakest bases are at the top right. The conjugate base of a strong acid is a weak base; therefore, the conjugate acid of a strong base is a weak acid.

Acid-Base Pairs and Buffer Chemistry

buffer solution contains a weak acid and its conjugate base or a weak base and its conjugate acid. Buffers work by reacting with a base or acid to control the pH of a solution.

Download the Acid & Base Chart

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