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Equivalent Weight of Magnesium

Equivalent Weight of Magnesium. Experiment # 16. What we are doing today:. We are going to verify the atomic mass of Magnesium. We are going to determine the # of moles of hydrogen displaced during a reaction. This will be accomplished using the Ideal Gas Law.

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Equivalent Weight of Magnesium

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  1. Equivalent Weight of Magnesium Experiment # 16

  2. What we are doing today: • We are going to verify the atomic mass of Magnesium. • We are going to determine the # of moles of • hydrogen displaced during a reaction. • This will be accomplished using the Ideal Gas Law. • Once we calculate the # of moles of Hydrogen produced • we can calculate the # of moles of Mg that reacted. • We will verify the atomic mass of magnesium by • comparing the grams of Mg used to the number of moles • of hydrogen displaced.

  3. Idea Gas Law PV=NRT In order to use the Ideal gas law the following information must be true:

  4. Mg + HCl → H2 + MgCl2 Procedure: • Obtain and scrape with steel wool a 5 cm piece of Mg. • do not touch the Mg until it has been weighed. • Using a mg balance accurately determine the mass of the Mg. • Coil the Mg around a pencil • Add 10 of 6M HCl to your eudiometer tube. • Slowly fill the tube with water. • Do NOT MIX THE WATER AND THE ACID.

  5. Procedures Continued • Obtain a 1000 mL. beaker and fill it with water. • Carefully lower the coil into the tube holding the • string. • Use your thumb to close the tube and then invert it. • Place your tube in your 1000 mL. beaker and • clamp it in place. • Once your eudiometer tube is secured measure the • amount of gas produced. • Also measure the water column measurement in mm. • Record the barometric pressure

  6. # 1 Mg mass = 0.040g # 2 Volume of H 2 collected = 47.0 mL from eudiometer tube # 4 Barometric pressure: 759 mm of Hg. Water temp: 20 OC K = 273 + OC = 293 K # 5 Height of water = top of water to the gas line: 34.8 cm = 348 mm # 6 Use my data as trial # 1 and you do two trials

  7. Pressure of water column: must be in mm of Hg so we must convert from mm of H2O to mm of Hg 348 mm of H20 is the height of my water column #6 #7 Water vapor pressure (P H2O)see chart on pg 172 of lab book. My water temp was 20OC and my pressure is 17.5 mm of Hg #8

  8. Pressure Dry H2 =PAtm - Pwater Vapor – P water column = 759 mm of Hg – 17.5mm of Hg - 25.58 mm of Hg = 715.92 mm of Hg To use the ideal gas law pressure must be in atms. .942 atms is the pressure of the dry H2 #9

  9. Now that we have pressure we can solve for moles of H2 produced :

  10. # 13 on chart 21.85 g/mole was the mass of Mg that I determined. The actual mass of Mg is 24.3 g/mole SHOW ALL WORK FOR FULL CREDIT

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