Investigation to find the relationship between particle size and rate of reaction

Authors Avatar

                                                                                                                  

                                           Chemistry Coursework-                

                                        Investigation to find the

relationship between                                         particle size

and rate of reaction                                                                

                                                                                                

        Aim-                                                                                 

                To see when experimenting with hydrochloric acid and

calcium carbonate, how the surface area of CaCO3 affect the rate of

reaction.                                                                                        

                                                                Scientific

Knowledge-                                                                

        Reaction rates are explained by the collision theory. It simply

depends on how often and how hard the reacting particles collide

with each other. The more energy and the more often the particles

collide, the faster the reaction rate. When particles are colliding

original bonds are broken so those new bonds in the product

molecules can be formed. The energy needed to break a mole of bonds

is known as bond energy. In this experiment, the more surface area,

that is when the solid reactant is broken down into smaller pieces,

the rate of reaction increases. The speed increase happens because

smaller particles of the same mass of solid have a greater surface

area compared to larger pieces of solid. Therefore there is more

chance that a reactant particle will hit the solid surface and react.

The diagram below illustrate acid/marble chip reaction...                        

                                                

                                                             

        A) Here, acid molecules are not colliding often or hard enough.        

                                                                                                

                                                             

                                       B) Here, acid molecules have more area to

work on, so there's more                 useful collisions, resulting in

increase of reaction rate.                                                                

                                                                        Other factors

which affects rate of chemical reactions...                                

        -Temperature - when the temperature is increased the particles

all move           quicker and therefore collide more often. This speeds the

reaction rate.        -Concentration - if the solution is more

concentrated, it means the           particles of reactant are pressurized

and so are moving around between           the water molecules more.

This makes collisions between important           particles more likely.        

                                                                        -Catalyst - this

gives  the reacting particles a surface to stick to where           they could

bump into each other. This of course increases the number of          

collisions.                                                                                        

        The rate of a reaction is found by measuring the amount of

reactant used per unit of time or the amount of a product produced

per unit of time.                                                                                

                                        (Balanced) Equation...                                

                                                                                                

                                                        CaCO3 (s)  +   2HCl (aq)    

CaCl2 (aq)   +  H2O   + CO2                                Calcium

        hydrochloric        calcium          water         carbon                        

        carbonate        acid                        chloride                dioxide                

                                                                                                

Join now!

                        Prediction-                                                        

                                I predict that the powder size CaCO3 will have

the fastest rate of reaction,the small size chips will have the second

fastest reaction rate and the large size chips will have the slowest

reaction rate due to scientific knowledge.                                        

                                                                        Preliminary

work-                                                                        

        Results for powder...                                                                

                                                 

                        Ways to improve our method so that accurate and

reliable results can be         gained when doing main experiment...                

                                        - make sure apparatus are set out well        

                                                - when turning measuring cylinder  

upside down into the large bowl of            water, make sure there are

no bubbles as ...

This is a preview of the whole essay