Common acids include:
Common alkalis include:
Alkalis produce hydroxide ions, OH-, when they dissolve in water.
During the reaction, hydrogen ions from the acid react with hydroxide ions from the alkali to form water:
H+(aq) + OH-(aq) H2O(l)
When an acid reacts with a metal hydroxide, a salt and water are produced:
acid + metal hydroxide salt + water
The name of a salt has two parts:
|Hydrochloric acid||Sulfuric acid||Nitric acid|
|Potassium hydroxide||Potassium chloride||Potassium sulfate||Potassium nitrate|
|Sodium hydroxide||Sodium chloride||Sodium sulfate||Sodium nitrate|
|Calcium hydroxide||Calcium chloride||Calcium sulfate||Calcium nitrate|
Write a word equation to describe the reaction between hydrochloric acid and sodium hydroxide.
hydrochloric acid + sodium hydroxide sodium chloride + water
To work out the formula of a salt you must know the charges of the ions involved.
|Common cations||Charge||Common anions||Charge|
|Hydrogen ion, H+||+1||Group 7 ions, eg Cl-||-1|
|Ammonium ion, NH4+||+1||Hydroxide ion, OH-||-1|
|Group 1 ions, eg K+, Na+||+1||Nitrate ion, NO3-||-1|
|Group 2 ions, eg Mg2+, Ca2+||+2||Oxide ion, O2-||-2|
|Copper(II), Cu2+||+2||Carbonate ion, CO32-||-2|
|Iron(II), Fe2+||+2||Sulfate ion, SO42-||-2|
Transition metals can form ions with different charges, eg iron can form Fe2+ ions and Fe3+ ions. Their charges are shown in the name of the compound, eg iron(II) oxide and iron(III) oxide.
The formula for a compound must produce no overall charge. For example:
What is the formula of sodium sulfate?
Na2SO4 (two positive charges and two negative charges)
To write a balanced chemical equation first write the word equation. Replace the name of each compound with the correct formula.
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
Write a balanced chemical equation for the reaction of dilute sulfuric acid with sodium hydroxide solution.
H2SO4(aq) + 2NaOH(aq) Na2SO4(aq) + 2H2O(l)