Soft solder is an alloy commonly used in electrical wiring and plumbing to join metal components. Which pair of metals constitutes soft solder, and what structural mechanism explains why solder is harder than its pure constituent metals?
- Lead and tin; foreign atoms of different sizes disrupt the regular metallic lattice, making it harder for layers of metal ions to slide past one another.Answer
- BCopper and zinc; foreign atoms release extra delocalized electrons that increase electrostatic repulsion between layers of atoms.
- CCopper and tin; foreign atoms form localized covalent cross-links between metal ions in the crystal lattice.
- DIron and carbon; foreign atoms decrease the density of the metal lattice, causing atoms to pack more loosely.
Answer
Soft solder consists of lead and tin. Alloying introduces atoms of a different atomic size into the metallic lattice, creating distortion that restricts the movement of atomic layers, resulting in enhanced hardness.
Soft solder is an alloy of lead and tin. The addition of foreign atoms of differing atomic radii disrupts the regular, symmetrical arrangement of the pure metal lattice. This lattice distortion prevents atomic layers from sliding easily over one another, rendering the alloy harder than pure lead or pure tin.
Step-by-Step Solution
Key Concept
Composition of solder and structural explanation of enhanced hardness in alloys due to lattice distortion