Magnesium ribbon

The magnesium methyl iodide is first prepared and is formed by the action of methyl iodide on the metal. T hc magnesium ribbon or powder is placed in a diy, round flaslc... 

Titanium, which was in commercial production in 1950, is thermodynamically a very reactive metal (machining swarf can be ignited in a similar fashion to that of magnesium ribbon) but this is offset by its strong tendency to passivate i.e. to form a highly stable protective oxide film. 

Enthalpy of formation. Magnesium ribbon reacts with oxygen to give MgO, a white solid, and 601.7 kJ of heat per mole of MgO formed. Hence AW MgO(s) = -601.7 kJ/mol. 

Apart from the three broad categories of student conceptions discussed above, students displayed several inappropriate conceptions relating to the stractural properties of substances. For example, 14% of students suggested that Mg + ions were present in magnesium ribbon. A second example involved the chemical reaction between copper(II) oxide powder and dilute sulphuric acid. In this instance, 25% of students suggested that Cu + ions were present only in aqueous solution but not in the solid and liquid states. This view was rather unexpected because students had earlier been introdnced to ionic and covalent compounds. It is likely that students had merely rote-learned the general rale without sufficient understanding that ionic solids are formed between metallic and non-metallic elements. 

Obtain two pieces of magnesium ribbon that are 3-5 cm long. 

Place the second piece of magnesium ribbon into the test tube and record your observations. 

Clean a 30-cm strip of magnesium ribbon with sandpaper. Cut the ribbon into 3.0-cm pieces. 

Wait 3 min, then place a piece of magnesium ribbon into the acid. Use the stirring rod to keep the magnesium completely submerged throughout the reaction. 

Place a strip of magnesium ribbon in the test tube. 

An intimately powdered mixture, usually ignited by magnesium ribbon as a high-temperature fuse, reacts with an intense exotherm to produce molten iron and was used formerly (before the advent of gas or arc welding) in the commercial thermite welding process. Incendive particles have been produced by this reaction on impact between aluminium and rusty iron. (The term thermite reaction has now been extended to include many combinations of reducing metals and metal oxides) [1], Some accidents in demonstrating the thermite reaction are described [2],... 

Figure 5.5.1 Formation of a white magnesium oxide coating as magnesium ribbon reacts with oxygen. From Masterton and Hurley, Chemistry Principles and Reactions, 4th edition. Orlando Harcourt, 2001. Photo courtesy of Charles D. Winters. 

Magnesium ribbon reacts with sulphuric acid to cause a vigorous reaction, as demonstrated by the large volume of hydrogen gas evolved, according to... 

Materials test tube, test-tube rack, 10-mL graduated cylinder, hydrochloric acid, magnesium ribbon, sandpaper, cardboard, wood splint, safety matches... 

Use sandpaper to clean the surface of a 3-cm length of magnesium ribbon. 

Compare the appearance of the magnesium ribbon before and after you used the sandpaper. What did the sandpaper remove ... 

Roll 25 cm of magnesium ribbon into a loose ball. Place it in the crucible. Measure the mass of the magnesium and crucible and record this mass in the data table. 

Analyzing Data Use the masses in the table to calculate the mass of the magnesium ribbon and the mass of the magnesium product. Record these masses in the table. 

Why is it important to clean the magnesium ribbon How might not polishing a piece of metal affect the reaction involving that metal ... 

Repeat the procedure in step 5 using 10 cm of magnesium ribbon. Place a piece of the Mg ribbon in each row B well that contains solution. 

Use emery paper or sandpaper to polish the magnesium ribbon until it is shiny. Use scissors to cut the magnesium into four 1-cm pieces. 

Using the tongs, place a 1-cm length of magnesium ribbon into test tube 1. Record the time in seconds that it takes for the bubbling to stop. 

Repeat step 7 using the remaining three test tubes of HC1 and the three remaining pieces of magnesium ribbon. Record in the data table the time (in seconds) it takes for the bubbling to stop. 

Materials iron nails (4) magnesium ribbon (2 pieces, each about 5 cm long) copper metal (2 pieces, each about 5 cm long) 150-mL beakers (4) distilled water saltwater solution sandpaper... 

Use the sandpaper to buff the surfaces of each nail. Wrap two nails with the magnesium ribbon and two nails with the copper. Wrap the metals tightly enough so that the nails do not slip out. 

Magnesium ribbon burns in air in a highly exothermic combustion reaction. (See equation (1).) A very bright flame accompanies the production of magnesium oxide, as shown in the photograph below. It is impractical and dangerous to use a coffee-cup calorimeter to determine the enthalpy change for this reaction. 

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