What does the pH scale measure?

The pH scale specifically measures hydrogen ion concentration in a solution, which is critical for understanding the acidity or alkalinity of that solution. The scale ranges from 0 to 14, with lower values indicating higher acidity (indicating a greater concentration of hydrogen ions) and higher values indicating alkalinity (indicating a lower concentration of hydrogen ions). A pH of 7 is considered neutral.

Understanding pH is paramount in various fields including cosmetology, as it affects the properties and performance of products like shampoos, conditioners, and treatments. For instance, hair and skin have optimal pH levels that help maintain their health, and using products with appropriate pH can prevent damage and promote proper functioning.

While density of solutions, temperature, and acidity of water are all important concepts in chemistry, they do not specifically define what the pH scale measures. Therefore, focusing on hydrogen ion concentration directly relates to the fundamental purpose of the pH scale.