What do we call a solution that has an equal concentration of dissolved solute as the solution to which it is compared?

A solution that has an equal concentration of dissolved solute as the solution to which it is compared is referred to as an isotonic solution. This term comes from the prefix "iso," meaning equal, and "tonic," relating to tension or concentration. In biological contexts, isotonic solutions are significant because they ensure that there is no net movement of water across a semipermeable membrane, such as a cell membrane. This is important for maintaining homeostasis in cells, as an isotonic environment helps prevent cell swelling or shrinking that could occur when cells are placed in solutions that differ in solute concentration.

In contrast, a hypertonic solution has a higher concentration of solute compared to the solution to which it is being compared, leading to water moving out of cells and potentially causing them to shrink. A hypotonic solution, on the other hand, has a lower concentration of solute, causing water to flow into cells, which can result in swelling and potentially bursting. A concentrated solution generally refers to one with a higher amount of solute in a given volume, but it doesn't specify equal concentrations compared to another solution, making it distinct from the concept of isotonicity.