Consequently, this would have led to a decrease in the mass of the magnesium, one that would have been unknown at the time. Solid metal was placed in a metal ion solution to determine if a reaction would occur. Another discrepancy that may have occurred during the experiment was that the magnesium strip may have reacted with the oxygen in the air before it was poured into the calorimeter. Introduction Reactions may or may not occur between two elements based on the activity series. This weight was recorded to three significant figures. The experiment will be carried out at room temperature 25 0C The study variables are summarized in the table below: Variables Operationalization of variables The dependent variables The duration of reaction, time taken for Magnesium to dissolve in hydrochloric acid completely measured using a stopwatch in seconds. The reaction is straightforward, the mechanism is slightly more complicated, but it is necessary to determine if the reaction will take place.
Consequently, the heat value, or Q, would have been lower which also would have lead to a lower enthalpy value, like the one that was found. The magnesium ribbon should be clean and free from obvious corrosion or oxidation. These holes could have let heat escape as the reaction was taking place which would have lowered the final temperature value. This will reduce reaction errors related to impurities. Provide students with data for the length and mass of the polished ribbon. This was a key observation for calcium to be placed at the top of the activity series, because it was able to react with magnesium, zinc, iron, tin, and copper ions.
For the reaction to take place the reduction potential on the reactant side must be greater than the reduction potential on the product side. The experiment incorporates the use of technology, graphing, and spreadsheet data analysis and is appropriate for either a general or introductory chemistry laboratory. Although this does not completely stop heat from escaping it certainly decreases the amount that can escape. So if you soak a penny, with cuts in it for the hcl to reach the zinc, will leave behind a copper shell. Aims and objectives of the experiment The aim of this experiment is to verify the effects of surface area of solid reactants and concentration of aqueous reactants on the rates of acid-base chemical reactions. At higher acid concentration, the rates of bubble forming were rapid than those in lower acid concentrations were. Aluminum will react with oxygen gas.
The experiment itself takes only a few minutes. Wear gloves when polishing the magnesium metal ribbon. When the Mg dissolves, it forms magnesium ions with a +2 charge Mg2+ , and when the hydrogen atoms form H2 gas, they leave behind chloride ions, Cl-. Suspected errors Error Significance Possible Improvements For the 10 cm magnesium metal used, there was slight variation in weight. From the first trial, 135 mm 1. My results are very good.
Students should not have access to any source of ignition. The constants controlled variables The quantity of Magnesium metal used will be held constant by way of using equal lengths of Magnesium ribbons and equivalent weights in grams of powdered Magnesium metal. I felt that when performing the experiment, I could have gotten some error from my temperature readings. However, the very small quantities and low dilutions used in or produced by this demo present little hazard. Reactants with high surface area provide a greater binding surface for other reacting molecules, and therefore increase the number of successful collisions at any moment. Although we had predicted and hypothesized that the duration of the reaction would be reduced by a half, the data partially supported the hypothesis since the data was 89.
The experiment will be carried at a room temperature 25 0C. Polishing removes impurities from the metal ribbon surface. It showed that temperature and rate of reaction increase proportionally due to a greater number of collisions. Given that, the experiment was carried out under the same conditions, the data obtained are reliable and generalizable. Though low hazard, eye protection is necessary as you may get a spray as tiny bubbles burst. To find the molar mass of magnesium, I took the mass of the magnesium used divided by the number of moles used. Include the heat of reaction calculated above.
The volume of hydrogen gas produced is measured over a few minutes, and the results are used to plot a graph. Introduction Based on the Kinetic Molecular Theory, the central idea of the collision model is that molecules must collide to react. Procedure a Measure 50 cm 3 of 1M hydrochloric acid using one of the measuring cylinders. Aluminum could also be tucked in the space between the lid and the calorimeter to once again lock the heat in. With concentrated and strong hydrochloric acid solutions, the results are too high. To measure, the effect of each of above factors, one has to hold some factors constant during rate reaction experimentation.
This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. However the acid is in excess, so it is mainly the loss of magnesium surface area becomes smaller that causes the change in the rate. To prevent even the slightest anomalies, in future any holes on the calorimeter can be covered by tape or another item that could block the passage. In the equation for the reaction, there are an equal number of moles of hydrogen and magnesium used. Finally, to find the average percent error, I added the two percents and divided by two: 0. The final error that may have occurred during the experiment was the loss of heat during the pouring stage.
Data Processing: Discussion: This investigation was conducted in order to determine the enthalpy of formation for magnesium oxide by manipulation of the three equations given. Practical Chemistry activities accompany and. One error that may have caused a lower enthalpy of change value than expected could have been that heat escaped from the calorimeter used during the experiment. Surface Area and Rate of Reaction. Cut a 1-meter length of magnesium ribbon. This can be seen on the graph, as the slope becomes less steep and then levels out when the reaction has stopped when no more gas is produced.
To find percent error, I took the absolute value of the true value minus my calculated value divided by the true value and multiplied by 100%. A small length of ribbon is cut and its length measured. Therefore due to increase in average kinetic energy of the particles, the collision rate increases proportionally resulting in a higher rate of reaction. Two nested cups hold the fluid. Surface area of Magnesium ribbon: This will be changed by using Magnesium ribbons and powdered Magnesium metal in separate experiments. There were two holes on the lid of the calorimeter and one was being used for the thermometer, however the second, although very small, was left open. Both of these conditions would have lead to a lower final temperature value.