Video Transcript
In which of the following examples of a solution is the physical state of the solute
and solvent the same? (A) Saltwater, (B) air, (C) carbonated drinks, (D) mercury silver dental amalgam, (E)
H2 in palladium.
A solution is a homogeneous mixture that consists of one or more solutes dissolved in
a solvent. Solutes are minor components, while the solvent is the major component. The solute or solutes are the substances that are dissolved, while the solvent is the
substance that does the dissolving. For example, saltwater is a homogeneous solution. When salt, the solute, is added to water, the solvent, and complete mixing occurs,
where the two components are no longer distinguishable from one another, we say
dissolving occurs, salt water is the result. And we call it the solution.
The salt water solution is a liquid mixture made from a liquid solvent and a solid
solute. Notice the solute and solvent in this example are not in the same physical state. In fact, the solute, solvent, and solution of any homogeneous mixture can potentially
be in any physical state. The table shows that a solute and a solvent might be in the same physical state or a
different physical state.
Air is an example of a solution where the solute and solvent are both in the same
state. The major component of air is nitrogen gas. And so nitrogen is the solvent. All other gases in air are the solutes. The question asked us to identify a solution where the physical state of the solute
and solvent is the same. We can see that this is true for air.
An ethanol water mixture has both a liquid solvent and a liquid solute. Some alloys such as brass are examples of solid solutions where both the solute and
the solvent are in the solid state. Brass is composed of zinc dissolved in copper. Don’t get confused. The zinc and copper have to first be melted down to mix, and then they cool and
solidify.
This diagonal line on the table are examples of solutions where the physical state of
the solute and solvent is the same. Soft drinks contain dissolved gas particles in liquid. Therefore, we can rule out answer option (C), carbonated drinks.
Salt water is an example of a solution where the solute, salt, is in the solid phase
and the solvent, water, is in the liquid phase. We can rule out answer option (A), saltwater.
Dental amalgam is composed of liquid mercury dispersed throughout solid silver. Mercury is the solute and silver, the solvent. Because mercury and silver are in different physical states, we can rule out answer
option (D), mercury silver dental amalgam.
It is uncommon to find a solid solute dissolved in a gas or liquid solute particles
dissolved in a gas. Finally, an example of a gas solute dissolved in a solid solvent are the hydrogen gas
particles dissolved in solid palladium or platinum and other catalysts in
hydrogenation reactions. We can rule out answer option (E), H2 in palladium.
Finally, in which of the following examples of a solution is the physical state of
the solute and solvent the same? The answer is (B), air.
