Neutralization reactions happen when an acid reacts with a base to form water and a salt. They matter because they explain everyday processes such as antacid tablets reducing stomach acid, treating acidic spills, and controlling soil or water pH. In a typical reaction, hydrogen ions from the acid combine with hydroxide ions from the base to make liquid water.
The remaining ions stay dissolved or form an ionic salt depending on solubility.
Key Facts
- General reaction: acid + base -> salt + water
- Strong acid and strong base net ionic equation: H+(aq) + OH-(aq) -> H2O(l)
- Example molecular equation: HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)
- Moles in solution: n = M x V, where V is in liters
- At equivalence for a 1:1 acid base reaction: moles H+ = moles OH-
- Heat released: q = m c Delta T, and for the reaction Delta H = -q/n
Vocabulary
- Neutralization
- A chemical reaction in which an acid and a base react to form water and a salt.
- Acid
- A substance that donates H+ ions in water or increases the concentration of hydronium ions.
- Base
- A substance that accepts H+ ions or produces OH- ions in water.
- Salt
- An ionic compound made from the positive ion of a base and the negative ion of an acid.
- Net ionic equation
- An equation that shows only the particles that actually change during a reaction.
Common Mistakes to Avoid
- Writing H2 as a product instead of H2O is wrong because neutralization combines H+ and OH- to make water, not hydrogen gas.
- Forgetting to balance the equation is wrong because mole ratios must match the balanced reaction before doing any stoichiometry.
- Using milliliters directly in n = M x V is wrong because molarity uses liters, so 25.0 mL must be converted to 0.0250 L.
- Calling spectator ions reactants in the net ionic equation is wrong because ions like Na+ and Cl- often remain unchanged in solution.
Practice Questions
- 1 What volume of 0.200 M NaOH is needed to completely neutralize 25.0 mL of 0.100 M HCl?
- 2 50.0 mL of 1.00 M HCl reacts with 50.0 mL of 1.00 M NaOH and the solution temperature rises by 6.8 degrees C. Assuming density is 1.00 g/mL and c = 4.18 J/g degrees C, calculate q released and Delta H per mole of water formed.
- 3 Explain why the net ionic equation for HCl reacting with NaOH is the same as the net ionic equation for HNO3 reacting with KOH, even though the molecular equations are different.