Certified Ophthalmic Assistant Practice Exam

What term describes the concentration of a chemical in a pharmaceutical solution?

1. Tonicity

2. Viscosity

3. Solubility

4. Density

The correct answer is: Tonicity

The concentration of a chemical in a pharmaceutical solution is referred to as tonicity. Tonicity specifically addresses the osmotic balance between the solution and biological tissues, influencing how the solution will behave when introduced to a biological environment. In ophthalmology, it is crucial to understand tonicity because the tonicity of eye drops can affect how they interact with the eye's surface, potentially causing irritation or influencing the effectiveness of the medication. Viscosity relates to the thickness or flow resistance of a liquid but does not directly indicate the concentration of a chemical. Solubility refers to the ability of a substance to dissolve in a solvent, which is relevant but does not define the concentration in a pharmaceutical context. Density, while related to mass per unit volume, does not specifically describe the concentration of a chemical as it pertains to pharmaceuticals. Hence, tonicity is the appropriate term for describing the concentration of a chemical in a solution in this context.