Which of the following statements best describes what is happening in a water softening unit?
The hard ions are all trapped in the softener, which filets out all the ions.
The ions in the water softener are softened by chemically bonding with sodium.
The sodium is removed from the water, making the water interact less with the soap molecules.
The hard ions in water are exchanged for ions that do not interact as strongly with soaps.
none of the above
The ions in the water softener are softened by chemically bonding with sodium
The statement "The hard ions in water are exchanged for ions that do not interact as strongly with soaps" best describes what is happening in a water softening unit.
To determine which statement best describes what is happening in a water softening unit, we can evaluate each option.
1. "The hard ions are all trapped in the softener, which filters out all the ions."
This statement suggests that the water softener removes all ions, which is not accurate. Water softeners specifically target and remove certain ions that cause water hardness, such as calcium and magnesium. Therefore, this statement is not correct.
2. "The ions in the water softener are softened by chemically bonding with sodium."
Water softeners typically use a process called ion exchange to remove hard ions. In this process, resin beads in the softener are coated with sodium ions. As water passes through the softener, the hard ions in the water (such as calcium and magnesium) are exchanged for sodium ions, effectively softening the water. So, this statement correctly describes the ion exchange process in a water softener.
3. "The sodium is removed from the water, making the water interact less with the soap molecules."
This statement implies that sodium is removed from the water during the softening process. However, in water softeners, sodium ions are actually added to the water during ion exchange, as explained in the previous statement. So, this statement is not accurate.
4. "The hard ions in water are exchanged for ions that do not interact as strongly with soaps."
This statement correctly describes the purpose of a water softener. Hard ions (e.g., calcium and magnesium) are exchanged for ions that do not create soap scum or interfere with the effectiveness of soap. So, this statement is accurate.
Therefore, the statement that best describes what is happening in a water softening unit is: "The hard ions in water are exchanged for ions that do not interact as strongly with soaps."