Sulfuric acid and Potassium hydroxide Reaction | H2SO4 + KOH
Sulfuric acid (H2SO4)
reacts with Potassium hydroxide (KOH) gives potassium sulfate (K2SO4)
and water (H2O) as products. Heat is released due to neutralization of a strong acid (H2SO4)
and a strong base (KOH).
One mole of H2SO4 reacts with two moles of KOH. As products, one mole of K2SO4 and two moles of
H2O are given.
Reactants of reaction
Potassium hydroxide (KOH)
Potassium hydroxide is a white solid at room temperature
and readily soluble in water. Aqueous Potassium hydroxide solution is a strong
base because it completely dissociates to K+ and OH- ions in water as below.
Due to strong basic characteristics, aqueous KOH should show pH values much higher than 7.
KOH(aq) → K+(aq) + OH-(aq)
Sulfuric acid (H2SO4)
Sulfuric acid is a strong acid because it completely dissociates to H+ and SO42- ions in water. These sulfuric
acid solutions should show pH values much lower than 7 due to its strong acidic nature.
H2SO4(aq) → 2H+(aq) + SO42-(aq)
Products of reaction
Potassium sulfate (K2SO4
Potassium sulfate is a salt and soluble in water to form a colourless aqueous solution. An aqueous solution which contains only
K2SO4 as a salt, is a neutral solution.
K2SO4(aq) → 2K+(aq) + SO42-(aq)
Heat generation when H2SO4 and KOH are neutralized
When one mole of water is generated due to neutralization of strong acid and strong base, 57.1kJ is released. Because two
moles of water are generated according to the above stoichiometric balanced equation, -114.2 kJ (57.1 kJ mol-1* 2 mol) kJ
is released when H2SO4 is neutralized by KOH.
Potassium's only oxidation state is +1. In both KOH and K2SO4, potassium is at +1 oxidation state.
Sulfur's oxidation number in H2SO4 is +6. And also, on KSO4, oxidation number of sulfur is +6.
Physical and chemical observation of H2SO4 and KOH reaction
Here, we will see some physical observations and chemical properties changes during the reaction.
Colour and physical state changes
Both aqueous H2SO4 and aqueous KOH are colourless aqueous solutions.
K2SO4 which is given as a product is readily soluble in water and give a colourless aqueous solution.
Reactants: KOH is a strong base and show pH value higher than 7 and H2SO4 is strong acid and should show pH value
less than 7.
Products: K2SO4 is a salt. Both K+ and SO42- ions are stable in water and do not
participating in hydrolysis reactions. If all H2SO4 and KOH are completely reacted with each other, pH of final
solution should be 7.
Safety and health hazards possible of H2SO4, KOH and K2SO4
H2SO4: Causes severe skin burns,cause eye damages
KOH: Harmful if swallowed, severe skin burns (skin corrosion and irritation) and eye damage