How do you investigate the effect of surface area on reaction rates?

You investigate the effect of surface area on reaction rates by conducting experiments with varying sizes of reactant particles.

To understand the effect of surface area on reaction rates, you need to conduct a series of experiments. These experiments should involve the same reactant but in different physical forms, such as a solid block, small chunks, or a powder. The idea is to keep the mass of the reactant constant while changing its surface area.

For instance, you could use calcium carbonate (marble) reacting with hydrochloric acid. You could use a large piece of marble, smaller chunks, and marble powder, each with the same mass. You would then add a fixed volume of hydrochloric acid to each sample and measure the time taken for the reaction to complete. This could be done by observing the time taken for the effervescence (bubbling) to stop, indicating that all the calcium carbonate has reacted.

The rate of reaction can be calculated by dividing the quantity of reactant used or product formed by the time taken. In this case, you could measure the volume of carbon dioxide gas produced over time. The faster the reaction (i.e., the shorter the time taken), the higher the reaction rate.

The results should show that the powdered marble reacts faster than the small chunks, which in turn react faster than the large piece. This is because the powdered marble has a larger surface area exposed to the acid, allowing more particles to collide and react at the same time. This demonstrates that increasing the surface area of a reactant increases the rate of reaction.

Remember, safety is paramount when conducting these experiments. Always wear safety goggles and lab coats, and handle acids with care.