Match a material to the stated use by checking the relevant properties. Density, melting point, solubility and conductivity are physical properties; flammability and reactions with acids are chemical properties. A pan base should conduct heat effectively, whereas a handle should conduct it poorly. Use density = mass/volume and keep mass and volume units consistent.
Nanomaterials contain particles with dimensions in the approximate range 1–100 nm; one nanometre is 10−9m. Smaller particles have a larger surface-area-to-volume ratio. For a cube of side L, area is 6L2, volume L3 and their ratio L6. More exposed surface per volume can change a material’s reactivity or other properties; small size does not by itself establish safety.
Example 1
A handle must stay cool. Material A has thermal conductivity 0.20 and B200Wm−1K−1. Which is preferred if other requirements are met?
Choose A: its lower thermal conductivity slows energy transfer along the handle.
Example 2
Compare cubes of sides 2cm and 1cm. Calculate their surface-area-to-volume ratios.
Use L6: the ratios are 3cm−1 and 6cm−1. Halving side length doubles the ratio.
Watch out: Suitability depends on several requirements, including strength, heat resistance, safety and lifetime.