Question

The behavior of trace elements in magmatic systems follows:

• A. Henry's Law
• B. Raoult's Law
• C. Fick's Second Law
• D. First Law of Thermodynamics

Hint:

Always remember: trace element behavior in melts is explained by partition coefficients, which are rooted in Henry's Law. Major element solutions, however, are explained by Raoult's Law.

Answer 1

The Correct Option is A

Step 1: Recall Henry's Law.
Henry's law states that the concentration of a solute in a solvent is proportional to its partial pressure (or activity) in the system.

Step 2: Application to trace elements.
In magmatic systems, trace elements are present in very small concentrations. Their distribution between melt and crystals is governed by partition coefficients, which are derived from Henry's law relations: \[ C_{solid} = K_D \cdot C_{melt} \] where $K_D$ is the distribution coefficient.

Step 3: Why not the others?
- Raoult's Law: Deals with ideal solutions and major element behavior, not trace.
- Fick's Second Law: Describes diffusion, not equilibrium partitioning.
- First Law of Thermodynamics: Energy conservation, unrelated to trace element partitioning.

Final Answer:
\[ \boxed{\text{Henry's Law}} \]