surface area

[kenhung123]

Lisachem reckons a solid would decrease in SA with time of a reaction, but it increases right? If the solid gets smaller there is more SA:V ratio?

[ghadz7]

No I think the solid would be consumed in the reaction. The ratio only works for the same amount of solid when comparing powdered substance to lumps.

[/0]

You could try thinking about it in terms of a spherical solid (usually a good approximation)

The surface area is , which decreases as R decreases.

But SA:V ratio is , which increases as R decreases.

[Mao]

Lisachem reckons a solid would decrease in SA with time of a reaction, but it increases right? If the solid gets smaller there is more SA:V ratio?

Yes. The SA:V ratio increases, but SA itself decreases.

[kenhung123]

Ah I get it. I got confused with questions that concern whether a large solid or small solid should be used to increase reaction rate...Thanks guys