Chemistry Practical on Rate of Reaction
Aim:
The rate at which a reaction occurs, or takes place, is affected by various factors, such as the temperature at which the experiment is conducted in, the pressure which is given, the surface area which is exposed, use of catalysts, and the concentration. In this investigation, I would be investigating the affect of surface area, or particle size, in the rate at which a reaction occurs.
Background Information:
The more finely divided the solid is, the faster the reaction happens. A powdered solid will normally produce a faster reaction than if the same mass is present as a single lump. The powdered solid has a greater surface area than the single lump.
Note: Why normally? What exceptions can there be?
Imagine a case of a very fine powder reacting with a gas. If the powder was in one big heap, the gas may not be able to penetrate it. That means that its effective surface area is much the same as (or even less than) it would be if it were present in a single lump.
A small heap of fine magnesium powder tends to burn rather more slowly than a strip of magnesium ribbon, for example.
Imagine a reaction between magnesium metal and a dilute acid like hydrochloric acid. The reaction involves collision between magnesium atoms and hydrogen ions.
How does surface area affect a chemical reaction?
If one of the reactants is a solid, the surface area of the solid will affect how fast the reaction goes. This is because the two types of molecule can only bump into each other at the liquid solid interface, i.e. on the surface of the solid. So the larger the surface area of the solid, the faster the reaction will be.
Smaller particles have a bigger surface area than larger particle for the same mass of solid. There is a simple way to visualize this. Take a loaf of bread and cut it into slices. Each time you cut a new slice, you get an extra surface onto which you can spread butter and jam. The thinner you cut the slices, the more slices you get and so the more butter and jam
The rate at which a reaction occurs, or takes place, is affected by various factors, such as the temperature at which the experiment is conducted in, the pressure which is given, the surface area which is exposed, use of catalysts, and the concentration. In this investigation, I would be investigating the affect of surface area, or particle size, in the rate at which a reaction occurs.
Background Information:
The more finely divided the solid is, the faster the reaction happens. A powdered solid will normally produce a faster reaction than if the same mass is present as a single lump. The powdered solid has a greater surface area than the single lump.
Note: Why normally? What exceptions can there be?
Imagine a case of a very fine powder reacting with a gas. If the powder was in one big heap, the gas may not be able to penetrate it. That means that its effective surface area is much the same as (or even less than) it would be if it were present in a single lump.
A small heap of fine magnesium powder tends to burn rather more slowly than a strip of magnesium ribbon, for example.
Imagine a reaction between magnesium metal and a dilute acid like hydrochloric acid. The reaction involves collision between magnesium atoms and hydrogen ions.
How does surface area affect a chemical reaction?
If one of the reactants is a solid, the surface area of the solid will affect how fast the reaction goes. This is because the two types of molecule can only bump into each other at the liquid solid interface, i.e. on the surface of the solid. So the larger the surface area of the solid, the faster the reaction will be.
Smaller particles have a bigger surface area than larger particle for the same mass of solid. There is a simple way to visualize this. Take a loaf of bread and cut it into slices. Each time you cut a new slice, you get an extra surface onto which you can spread butter and jam. The thinner you cut the slices, the more slices you get and so the more butter and jam
Bibliography: 1. "The Effect of Surface Area on Rates of Reaction." Chemguide: Helping You to Understand Chemistry - Main Menu. N.p., n.d. Web. 06 Nov. 2010. http://www.chemguide.co.uk/physical/basicrates/surfacearea.html 2