Rates of Reaction

Experiment: Investigation into the factors that effect the rate of reaction

I am going to investigate how different factors affect the rate of a reaction.

Introduction

What is a reaction? A reaction is when two particles (reactants) join to form a new product or products.

What is rate? Rate is a measure of how fast or how slow something is. Rate is a measurement of the change that happens in a single unit of time, any suitable measurement can be used such as seconds, minutes, hours or even days.

What is the rate of a chemical reaction? The rate of a chemical reaction is how fast the reactants react.

How to find the rate of a reaction? In general to find the rate of a reaction, you should measure either the amount of reactant used up per unit of time or the amount of product produced per unit of time.

The rate during the reaction does not stay constant, it changes throughout the reaction, its greatest at the start but gets slower as the reaction proceeds. I think this is mainly to do with the fact the longer the reaction has taken place the more of the reactants react leaving fewer reactants with less chance of reacting.

Successful collision. For the reactants to be able to react they have to successfully collide with each other. The chance of a successful collision can be increased or decreased by using many different factors.

Temperature - Temperature alters the rate of a reaction by supplying the reactant particles with more energy, the more energy the reactants have the faster they move around increasing they're are chance of bumping into one another and having a successful collision. Also the more energy they get from the heat the more particles have enough energy to react, this is known as activation energy. Generally the greater the temperature the faster the rate of a reaction, the rate doubles every 10oc.

Surface Area - The greater the surface area of the reactants the more particles are available for a successful collision.

A Catalyst - A catalyst is a substance that changes the rate of a chemical reaction but remains chemically unchanged itself.

Concentration - Concentration effects the rate of a reaction because the higher the concentration of particles the greater the chance of a successful collision. The general trend for the concentration is the rate doubles as the concentration doubles (they're directly proportionate).

What is Activation energy? Activation energy is the amount of energy required for the reactants to successfully react. The reactants need a certain amount of energy, any extra energy increases they're chance of a successful collision.

Experiment

To investigate the rate of reaction I have decided to use the concentration as a variable. I am going to use marble chip (Calcium Carbonate) and Hydrochloric acid. I will alter the concentration of the hydrochloric acid each time, and I will measure the amount of Carbon Dioxide product given off.

I have chosen to use these because during the reaction Carbon Dioxide is given off, this is a gas and highly insoluble in water. The method I have planned will accommodate this.

Though some carbon dioxide is soluble in water the amount is negligible,

At room temp (20oc) in 1l of water 1.69 Ò' 10 will dissolve.

Equation

Prediction Hypothesis

I think that the higher the concentration of hydrochloric acid the faster the carbon dioxide will be given off. I think this because the higher the concentration of acid molecules the more particles available to react. Also the higher the concentration of acid particles the more chance of a particle having enough activation energy. The more particles available at any one time with enough activation energy means that in a given time more of the product is produced, or it takes a less amount of time to produce a certain amount of product, in this case Carbon Dioxide. The activation energy is the amount of energy needed to make the two particles react, without it the particles would not successfully react.

Apparatus

Conical flask

Delivery tube

Measuring Cylinder Ò'2

Beaker

Bowl of water

Weighing scales

Stopwatch

Hydrochloric Acid Solutions and Marble chips

Diagram

Method

After collecting the apparatus and arranging as followed, fill the bowl full of water and measure out 30ml of 0.5 mol acid and pour into conical flask.

Weigh out the marble chip/s, try and decide on a suitable weight because each time you will need to use the same weight. Place the chip/s into the conical flask and insert the bung.

As the reaction takes place bubbles should start to come out of the delivery tube into the upturned measuring cylinder. From the first bubble measure how long it takes for 20 ml of gas to be given off.

Record the result and refill the upturned measuring cylinder with water, wash out the conical flask and weigh out the next lot of marble chips.

Repeat the experiment but each time using a different concentration of acid 0.5 mols more each time until you get to 2 mols, you may want to repeat the experiment about three times to get a more accurate average for each concentration.

Safety

You will be using concentrated acid, so at all times you must be very careful and you MUST wear goggles. If any spills onto your hands it should be washed