A metallurgy student investigates how adding small non-metal atoms affects the…
CHEMISTRY · Multi-part · GCSE · Chemistry · Bonding, Structure and the Properties of Matter · Bonding, Structure and the Properties of Matter
Problem
A metallurgy student investigates how adding small non-metal atoms affects the macroscopic properties of iron. Very pure iron samples and samples of steel containing 0.8 mass % carbon are available for comparison.
Answer the following questions about these two solids. Assume room temperature conditions unless otherwise specified.
(a) Describe, at the particulate level, the structural difference between the lattice of pure iron and the lattice of the steel sample containing 0.8 mass % carbon.
(b) Explain why the presence of carbon atoms changes the hardness and malleability of the iron lattice. In your answer, explicitly connect atomic interactions to the observed macroscopic properties.
(c) Predict whether electrical conductivity is significantly altered by the addition of 0.8 mass % carbon. Justify your prediction with reference to electron mobility in the solid.
(d) Steel can be cold-worked (rolled at temperatures below its recrystallization point) to further increase hardness. Provide a brief explanation of why cold-working is generally more effective for the steel sample than for pure iron.