* Water molecules (H₂O) are polar: The oxygen atom in a water molecule is slightly negatively charged, while the hydrogen atoms are slightly positively charged. This creates a dipole moment, where one end of the molecule is slightly positive and the other slightly negative.
* Ionic bonds: When water dissolves salts or other ionic compounds, the positive and negative ions separate. The positive ions are attracted to the negative end of water molecules, while the negative ions are attracted to the positive end. This process is called hydration.
* Equilibrium: Even in pure water, there is a small amount of ionization, where water molecules break apart into H+ (hydrogen) and OH- (hydroxide) ions. However, these ions exist in equal amounts, maintaining a neutral overall charge.
What can change the charge of water?
* Dissolved ions: If you dissolve more positive ions (like sodium ions from table salt) than negative ions, the water solution will have a net positive charge. The opposite is true if you dissolve more negative ions (like chloride ions).
* pH: The pH of a solution is a measure of its hydrogen ion (H+) concentration. A low pH (acidic) means there are more H+ ions, giving the solution a positive charge. A high pH (alkaline/basic) means there are more OH- ions, giving the solution a negative charge.
Key takeaway: While pure water is neutral, the presence of dissolved ions and changes in pH can affect the overall charge of a water solution.
