Investigating the Effect of Different Concentration Of Acid Rain On The Rate Of Reaction Between Acid Rain And Magnesium.

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Investigating the Effect of Different Concentration Of Acid Rain On The Rate Of Reaction Between Acid Rain And Magnesium

Planning Experimental Procedures

Background Scientific Information:

Acid Rain is a form of air pollution in which airborne acids produced by electric utility plants and other sources fall to Earth in distant regions. The corrosive nature of acid rain causes widespread damage to the environment.

The process that leads to acid rain begins with the burning of fossil fuels. Burning, or combustion, is a chemical reaction in which oxygen from the air combines with carbon, nitrogen, sulphur, and other elements in the substance being burned. The new compounds formed are gases called oxides. When sulphur and nitrogen are present in the fuel, their reaction with oxygen yields sulphur dioxide and various nitrogen oxide compounds. In the United States, 70 percent of sulphur dioxide pollution comes from power plants, especially those that burn coal. In Canada, industrial activities, including oil refining and metal smelting, account for 61 percent of sulphur dioxide pollution. Nitrogen oxides enter the atmosphere from many sources, with motor vehicles emitting the largest share—43 percent in the United States and 60 percent in Canada. These acid pollutants reach high into the atmosphere, travel with the wind for hundreds of miles, and eventually return to the ground by way of rain, snow, or fog, and as invisible “dry” forms

Damage from acid rain has been widespread in eastern North America and throughout Europe, and in Japan, China, and Southeast Asia. Acid rain leaches nutrients from soils, slows the growth of trees, and makes lakes uninhabitable for fish and other wildlife. In cities, acid pollutants corrode almost everything they touch, accelerating natural wear and tear on structures such as buildings and statues. Acids combine with other chemicals to form urban smog, which attacks the lungs, causing illness and premature deaths. Acid rain and the dry deposition of acidic particles damage buildings, statues, automobiles, and other structures made of stone, metal, or any other material exposed to weather for long periods. The corrosive damage can be expensive and, in cities with very historic buildings, tragic. Both the Parthenon in Athens, Greece, and the Taj Mahal in Agra, India, are deteriorating due to acid pollution.

Rates of reaction can alter not only by catalysts but also by changes in temperature, surface area of reactants and by changes in concentration of the reactants.

Raising the temperature increases the rate of reaction by increasing the kinetic energy of the molecules of the reactants, thereby increasing the likelihood of transition states being achieved. Increasing the concentration increases the reaction rate by increasing the rate of molecular collisions and how hard the collision is.

Why Magnesium

Magnesium will be used as it reacts well. It is fast enough to give me an accurate result. However magnesium is not used in structural situations, but the reason why I am stilling magnesium, is the simple reason that the surface area is easy to measure and the rates provided by magnesium are sufficient.  

Sulphuric will be used as it is the main cause of acid rain.

Aim:        

The aim of this investigation is to investigate the effect of different concentrations of Sulphuric acid (H2SO4) on the rate of reaction between Sulphuric acid (H2SO4 ) Magnesium.

Hypothesis:

I predict that if I double the concentration of the Sulphuric acid (H2SO4) being used in the experiment I will double the rate of reaction (the volume of Hydrogen being given off in any given time), i.e. the rate of reaction is directly proportional to the concentration of the Sulphuric acid. For example, if the concentration of Sulphuric acid is 10% and the rate of reaction is 3cm3/s and the concentration is doubled to 20% then the rate of reaction should increase to 6cm3/s. I can make a formula for my prediction:

xY means the rate of reaction will be xS

This would be when ‘x’ is the number of the original concentration ‘Y’ is multiplied by and ‘S’ is rate of reaction which is unknown and trying to be obtained.

I predict that the higher concentrations will give off H2 faster for the reasons in the justification of hypothesis section. These higher concentrations are shown as the steepest lines in the graph below which shows my prediction for the volume of H2 given off against time.

The graph below illustrates my prediction for the graph which will be rate against concentration. Due to the fact that I predicted rate of reaction and concentration to be directly proportional the graph shows direct proportionality.

However I predict that there will be a limit to an increase of concentration of H2SO4 increasing the rate of reaction, eventually as the concentration of Sulphuric acid (H2SO4) is continually increased well passed a point of excess Sulphuric acid, the reaction will begin to benefit less from an increase of Sulphuric acid. This will be because reaction will finish so fast due to the high number of Sulphuric acid particles that any extra particles will either not get an opportunity to collide with the Magnesium particles or they will begin to bounce off each other causing the rate not to increase. However this would be in such an extreme case that it should not effect my investigation as the Sulphuric acid from which the different concentrations of Hydrochloric acid is being made is only 2 moles per dm3, this is why this has not been illustrated on the graph above.

Justification of Hypothesis:

        I can justify my hypothesis with some simple theory. If I double the concentration of Sulphuric acid I am doubling the number of Sulphuric acid particles in a given volume. Therefore there is now double the chance that there will be a successful collision between a Mg molecule and a H2SO4 molecule, hence the rate of reaction will be doubled, assuming all other variables are controlled. For example if in an area there are 50 Mg molecules and 100 H2SO4 molecules and then the number of H2SO4 molecules are tripled so that there are now 300 H2SO4 molecules and 50 Mg molecules obviously the probability of a collision (successful or not) is three times higher. If the probability of a collision is three times higher then chance of a successful collision is also three times higher and the rate of reaction is three times higher, this is why I predict that in my first graph the steepest lines (showing the highest rates of reaction) will be from the higher concentrations of H2SO4

The diagram above illustrates what I said earlier. As the beaker on the right has twice as many H2SO4 molecules as the beaker on the left the chance of a collision and therefore a successful collision is twice as high and therefore the rate of reaction is twice as fast.

I can also justify my prediction of there being a limit to where an increase of Sulphuric acid concentration increases the rate of reaction proportionally. This will be because reaction once the number of Sulphuric acid particles are well past an excess amount the reaction will finish so fast due to the high number of Sulphuric acid particles that any extra particles will either not get an opportunity to collide with the Magnesium particles or they will begin to bounce off each other causing the rate not to increase.

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Moles calculations

   

                        Mg + H2SO4                   MgSO4 + H2

Mole ratio                    1       :          1            :                      1       :      1

Info                             100cm3 of H2

         Moles   =              100   = 0.00417

                        24000

We use mole ratio   1:1; therefore we need 0.00416 moles of Mg

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