An Investigation Into The Fact Essay Research

An Investigation Into The Fact Essay, Research Paper

An Investigation into the factors affecting the rate of reaction between magnesium and hydrochloric acid

Planning

* Hypothesis

I predict that as the temperature increases, the speed of the reaction will increase therefore the gas will be produced faster. I believe this because most chemical reactions happen faster when the temperature is higher. At higher temperatures molecules mover around faster, which makes it easier for them to react together. Usually, a rise of 10OC will double the rate of reaction.

Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As the temperature is increased the particles move faster since they have more energy. This means that they are colliding more often and more of the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster.

* Pilot Experiment

To decide on the best volume and concentration of hydrochloric acid and best mass of magnesium a number of calculations were done and a pilot experiment conducted.

The equation for the reaction is:

Magnesium(s) + Hydrochloric Acid(l) Magnesium Chloride(l) + Hydrogen(g)

Mg(s) + 2HCL(l) MgCl2(l) + H2(g)

We were advised to use 0.1g of magnesium ribbon (found to be 10.9 cm long). The Relative Molecular Mass (RMM) of magnesium is 24, therefore the moles of magnesium to be used was:

Moles= 0.1

24

Moles= 0.00416

In the reaction above, 1 mole of magnesium reacts with 2 moles of hydrochloric acid. The concentration of acid was 1mol/dm3. Therefore the volume of hydrochloric acid used was:

Volume = 0.00416 * 2

1

Volume = 0.0083dm3

Volume = 8.3cm3

It was decided to use an excess of hydrochloric acid to ensure all the magnesium reacted, therefore 10cm3 of acid was used in the pilot experiment. At room temperature 10cm3 of hydrochloric acid was added to 0.1g of magnesium and the gas was collected (see fig 1). The volume of gas produced was measured every 15 seconds. It was found that the reaction was too rapid to be effectively measured, therefore 10cm3 of water was added to halve the concentration of the acid.

* Investigation Experiment

I am going to investigate how temperature affects the rate of reaction between magnesium and hydrochloric acid. The procedure for the experiment is as follows;

* Using a measuring cylinder, measure 10cm3 of water and pour it into the side arm tube.

* Measure 10cm3 of hydrochloric acid (1 mol/ dm3) and add it to the water.

* Place the side arm tube in a water bath at 20OC, set up the apparatus below.

* Measure 10.9 cm of magnesium ribbon and check on the balance that it weighs 0.1g.

* Coil the ribbon around a pencil and then drop it into the side arm tube and quickly put a bung on the side arm tube (this must be done quickly to prevent gas escaping).

* Every 15 seconds measure the volume of gas produced until less than 1cm3 of gas is produced every 15 seconds.

* Repeat experiment two more times (for accuracy) and record all results in a table.

* Repeat the experiment for temperatures of 30 OC, 40 OC, 50 OC and 60 OC

It is important that only the temperature is changed since this is what is being investigated.

Method

* Apparatus

I have chosen to use a 10cm3 measuring cylinder to measure the volumes of substances used since it is more accurate than a pipette. I will use an electronic water bath for maintaining the mixture at a temperature since the temperature is more accurate than a water bath above a Bunsen burner.

A 100cm3 gas syringe should be appropriately accurate for measuring the gas produced since it is accurate to 1cm3 of gas. I will use a three figure balance to measure the mass of magnesium to be used since it is vital that as close to 0.1g of magnesium is used as possible.

* Variables

I have chosen to repeat the experiment 3 times because it therefore allows me to calculate an average rate of reaction. This will ensure that there are no abnormal results and it will increase accuracy. I have decided to start readings at 20OC and increase by 10OC each time until 60OC is reached, since it will allow me to see the increase in rate of reaction and 5 results should be enough to identify any trends.

* Rates of Reaction

Increasing the temperature increases the speed of the particles. The faster the particles move, the greater the number of collisions, and therefore the rate of the reaction increases. A 10OC rise in temperature almost doubles the rate of most reactions.

Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As the temperature is increased the particles move faster since they have more energy. This means that they are colliding more often and more of the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster.

Analysing Evidence

First three graphs were drawn (one for each time the whole experiment was carried out). So that the graphs did not become over crowded the curves were d

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