Investigating a factor that affects the rate of an acid / metal reaction

Plan

1. Full the beaker with 450 ml of water
2. Put 5 ml of H2So4  high in the test tube
3. Place the test tube and a thermometer  in the beaker  
4. Put a  Bunsen burner under the beaker
5. Light the Bunsen burner , start heating the water in the beaker
6. Take the oxide layer off the magnesium with  sand paper

7. a, When the water  reaches 20C , 30C , 40C ,50C put the 0,01 gram magnesium in the            

         test tube

            b, The same time that the magnesium is put in the test tube start the watch to                                      

                   measure the time it took for the Mg to dissolve and record this value.

     8, When the reaction is over empty the test tube and fill it again with Sulfuric Acid

     9, Do the same steps from 2 till you have done all four of the set temperatures.

Results

 1. try

2.try

Analysis of results

      Our 1. try  does not show a pattern .This  is because we did not use exactly the same amount of Sulfuric acid and even a few drops can make a tremendous amount of change if we are working with so small numbers.

     Secondly, we did not remove the oxide layer.

     Thirdly we did not   measure Magnesium.

      Then we improved these factors. We can clearly recognize the pattern in the 2.try. As we increased the temperature the reaction went faster. We also observed factors which  indicated this. We can see that when the temperature was 20 C we observed that the test tube got warm. When we increased the temperature we also observed bubbles. These show that the reaction got more rapid.

Conclusion & Explanation of Conclusion

    In Conclusion I would say that our Hyphothesis was right. As we increased the temperature the reaction went faster. I think this is because the determining factor of the speed of a chemical reaction are the collisions between molecules. By increasing the temperature we increase  the number of collisions  between the molecules and  also  the energy of the collisions. So its more likely that the molecules will react.

      In this experiment we also have to bare in mind the properities of Magnesium which takes the fourth   place in the reactivity series. When a metal is put together with a solution, a reaction occurs if the metal is more reactive than the one in the solution. The less reactive one is given out while another solution is formed. Hydrogen is less reactive then Magnesium so Hydrogen is given out from the H2So4 solution and Mg takes it’s place. Hydrogen is given out to the air as bubbles. In our experiment we observed bubbles , this proves that our experiment  was correct.

Metal + Acid   → Hydrogen Gas + Salt

Magnesium + Sulfuric Acid  →   Hydrogen Gas + Magnesium Sulfate

( Equation in first experiment when we did not remove the oxide layer )

Mg0 + H2S04 → MgSO4 + H2O

(Equation in second experiment when we removed the oxide layer)

Mg + H2SO4 → MgS04 + H2

Evaluation

 There are several things that we could improve on.

      We already did some of them. We did the whole experiment two times because first we got unexpected results so we found out that the oxide layer of magnesium might effect our results so we decided to take the oxide layer off the magnesium and measure it exactly.

      We also decided we mark the test tube so we will use exactly same amount of Sulfuric acid each reaction

       We figured out that it is better if we dry the test tubes because a few drops of water can change the amount and concentration of Sulfuric Acid. With these improvements our results showed the pattern we expected.

 

         We might have made some mistakes using the chronometer  since it was difficult to observe the magnesium through the beaker and record the exact second when it disappeared.

        We could have gotten even better results if we would worked with bigger amounts of Magnesium and Sulfuric Acid. Then the reaction would have went slower and it would have been easier to observe the exact time when the Mg dissolves.

        We could have used a less concentration of acid so that the reaction would take longer and it would be easier to observe.

      We used sand paper to remove the oxide layer from the magnesium. We tried to remove all of the oxide layer but it is impossible with sand paper. It would be better if there would be a more effective way with which we could remove the oxide layer.