A chemical plant transitions from using a conventional microcrystalline nickel catalyst with cubic particles of side length 24 nm24\text{ nm}24 nm to a highly active nanocatalyst with cubic particles of side length 3 nm3\text{ nm}3 nm.
By what factor does the surface-area-to-volume ratio (SA/V\text{SA/V}SA/V) of the catalyst particles increase, and how does this change explain the enhanced catalytic properties of the nanomaterial?
The SA/V\text{SA/V}SA/V ratio increases by a factor of 888. This exposes a significantly higher proportion of the transition metal atoms at the surface, providing many more active sites for reactant molecules to bind.
The SA/V\text{SA/V}SA/V ratio increases by a factor of 646464. This increases the surface energy and forces the metal atoms into a more dense, crystalline arrangement that lowers the activation energy.
The SA/V\text{SA/V}SA/V ratio increases by a factor of 888. This increases the total mass and density of the individual catalyst particles, leading to higher kinetic energy during collisions.
The SA/V\text{SA/V}SA/V ratio increases by a factor of 512512512. This exponentially increases the collision frequency by creating highly concentrated localized magnetic fields at the nanoscale.
48 exam-style questions on OCR GCSE Chemistry Properties of materials. Each one has a worked solution and a mark scheme showing where the marks go.