The hydronium concentration, often represented as [H3O+], is the measure of the amount of hydronium ions in a solution. It's used to determine the acidity or alkalinity (pH) of a solution.
A substance that donates protons (or hydrogen ions) when dissolved in water, increasing the hydronium ion concentration.
A substance that accepts protons (or hydrogen ions) when dissolved in water, decreasing the hydronium ion concentration.
A logarithmic scale used to specify the acidity or basicity/alkalinity of an aqueous solution. It measures how much H3O+ is present.