Read All the Lab Steps Check the given tables *Then help with all...

Read All the Lab Steps

Check the given tables

*Then help with all questions

*Square the final answer

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Some questions must be answered using the below given notes 

 

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Question 10 In a second trial of this experiment, the student found the atmospheric pressure to be 757.4 mm Hg, the water vapor pressure to be 16.7 mm Hg and the liquid pressure to be 18.17 mm Hg. What would the pressure of the hydrogen gas be in this trial?

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Question 11 The student realized that they did not dissolve all of the magnesium in the reaction and had to redo the trial. The student then redid the calculations in Question #10 with the new data and found the pressure of hydrogen gas to be 731.7 mm Hg. If they generated 30.07 mL of hydrogen gas at 24.00C, what is the corresponding volume (in mL) at STP? Report your answer to FOUR sig figs.

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In trial 3, the student used 0.021 g of Mg. How many moles of H2 should be generated in this reaction? Ignore sig fig rules and report your answer to three significant figures in scientific notation. Please use the format 1.23x10"4 or 5.6?x10fl-3 [make sure you use this exact format including the spacing and x and negative sign if necessary}. If trial 3 gave a corrected volume of 22.33 mL H2 at STF'. and the student calculated that 9.56x10'4 moles of H2 should be generated in the reaction, what is the molar gas volume for this trial? This student was comparing data with a friend in another section. In one of the trials, his friend found the volume of hydrogen gas to be 3?.5 mL and the adjusted pressure of pure hydrogen to he T0165 mm Hg when 0.00144 mol of H2 were produced at 25.0050 What would the value of the ideal gas constant be for his friend in units of {L-athlmol-K]? Ignore sig flg rules for this problem and report your answer to FOUR decimal places.

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Introduction: Gases are very interesting compounds to study within the fields of chemistry and physics because they display many useful and unique proportionalities that other phases do not possess. The key properties of a gas include its pressure, volume, and temperature as well as the number of particles contained in a given sample of that gas. The relationships between these properties have been studied for centuries resulting in several key gas laws that affect how we consider these properties today. The main named gas laws to be aware of can be summarized as the following: I Boyle's Law: P1V1 = Png; the pressure and volume of a gas are inversely proportional when temperature and number of particles are held constant I Gay-Lussac's Law: P1 / T1 = P2 / T2; the pressure and temperature of a gas are directly proportional when volume and number of particles are held constant I Charles' Law: V1 / T1 : V2 / T2; the volume and temperature of a gas are directly proportional when pressure and number of particles are held constant I Avogadro's Law: V1 / m = V2 / 112; the volume and number of moles of a gas are directly proportional when pressure and temperature are held constant I Dalton's Law: Puma = P1 + P2 + ...; in a mixture of non-reacting gases, the total pressure of the system will equal the sum of the partial pressures of the individual gases When performing calculations using the previous equations, pressure and volume can be in any consistent units but temperature and number of particles must always be expressed in Kelvin and moles, respectively. By further examining how the different gas properties affect each other proportionally, two other very important gas laws can also be derived from the previous equations: I Combined Gas Law: (P1V1) 1' T1 = (P2V2) / T; I Ideal Gas Law: PV = nRT The combined gas law takes the proportionalities expressed in Boyle's, Gay-Lussac's, and Charles' Laws and, as the name would imply, combines them into a more widely applicable equation. Notice that if any one gas measurement is held constant in the combined gas law, then it can be simplified back down to one of the gas laws already listed. Unlike the other named laws and the combined gas law that pertain to a gas undergoing a change of conditions, the ideal gas law is a way to determine one of the fundamental gas measurements when information about the other three is readily available. Notice that the ideal gas law introduces the concept of "R", the ideal gas constant. R can have different values depending on the units used for the other measurements and therefore units must be carefiilly considered when performing ideal gas law calculations. Most frequently R is expressed as 0.08206 (L'atm) / (mol-K) meaning the units for volume, pressure, particles, and temperature must be liters, atmospheres, moles, and Kelvin, respectively. Another conn'nonly used value for R is 8.314 (L-kPa)/ (mol'K) where the unit of pressure is reported in kilopascals instead of atmospheres. The ideal gas law is extremely important in the study of gases, and although it is only an approximation, it provides a very useful insight into measurements that may be difficult to take directly. One such application was the discovery that one mole of any gas at standard temperature and pressure (abbreviated ST? and considered to correspond to 273 K and 1 atm) will occupy 22.414 L. This value is called molar gas volume and provides a useful and convenient way to relate stoichiometry and volume of a gas. In today's experiment, you will perform a reaction between magnesium metal and hydrochloric acid. This reaction produces hydrogen gas, in a "single-displacement" reaction, due to the fact that magnesium is more chemically active than hydrogen. The more active an element, the more inclined it is to react with other elements and to displace less active elements in chemical compounds. Magnesium is more active than hydrogen, thus, the more active magnesium metal displaces the hydrogen from hydrochloric acid, creating magnesium chloride and leaving the less active hydrogen on its own to form hydrogen gas, which bubbles out of the solution. Mg (s) + 2 HCl (aq) 9 MgClz(aq) + H2(g) Note: for every mole of Mg (5) that is reacted, one mole of H2(g) is produced. If we know the mass of Mg(s) we can convert to moles of Mg(s). Then, since we get 1 mole of Hg(g) for every mole of Mg(s), we can predict how many moles of H2(g) could be made (theoretical yield). We use an excess of HCl so that we would react all the Mg(s) before we used all of the HCl. We will collect the hydrogen gas in an inverted graduated tube called a eudiometer. As long as the magnesium reacts completely and none of the gas escapes, we expect a stoichiometric amount of hydrogen gas to be formed. Using this assumption that we will obtain 100% yield, it will be possible to experimentally determine a value for the ideal gas constant and molar volume.

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Procedure: 1. Initial Preparations and Data a. In a group of two, fill a large (~400 or 600 mL) beaker approximately halfway with tap water. d. Insert the handle of the copper wire containing the magnesium through the hole of a number 00 one-holed rubber stopper. Insert the magnesium into the open end of the eudiometer and seal it with the stopper. b. Obtain a strip of magnesium metal and use sandpaper to scrub off any oxide coating on both sides of the Push the stopper straight and tightly into the eudiometer. Add water if necessary to eliminate any bubbles strip. When sanding, be careful not to sand down the lab bench in addition to your Mg! After removing from the eudiometer - there should be no air space at all.) the oxide coating, accurately record the mass of the magnesium in your data table. It should be no heavier han 0.040 g. If it is heavier than this limit, consult your lab instructor; you may have to cut a small piece 3. Reaction of Mg and HCI; Collection of Hydrogen Gas off. To avoid depositing oils from your fingers onto the metal, use gloves to handle the magnesium after you have removed the oxide coating. a. Keeping your index finger tightly over the hole in the stopper, invert the eudiometer into the half-full beaker on your laboratory table. Once the stopper is under water level, remove your finger from the hole in the stopper and clamp the eudiometer to a buret clamp supported by a ring stand making sure that the stoppered end of the eudiometer remains submerged in the water in the beaker at all times. Rubber b. At this point you should be able to see the acid layer swirling down through the water layer toward the - Eudiometer stopper with hole magnesium metal, where the reaction will occur. The reaction is complete when no more bubbling is seen Clamp around the copper wire and all of the magnesium has reacted. At this point, lightly tap the eudiometer to Mg tied dislodge any bubbles that remain around the wire. in thread C. After the reaction is complete, measure the distance between the top of the liquid level in the beaker and H20 & HCI Soln. the top of the liquid level in the eudiometer using a ruler or meter stick as shown in the figure below. This will allow you to adjust for the difference in pressures inside and outside of the tube. In your data table, record this distance in millimeters. Also, record the volume reading on the eudiometer (being careful to Rubber stopper take an accurate reading due to the inversion of the tube). Using a thermometer, measure the temperature - Water of the water in the beaker and record it in your data table. Stand Thread - HC Magnesium coil 2. Assembly of Apparatus a. Roll the magnesium strip into a coil and tie it in a copper wire. Be sure the Mg is tightly secured in order to prevent it from coming loose during the reaction. Set this assembly aside for use later in the experiment. b. Obtain a clean, dry 50-mL gas collection tube (eudiometer). Using a 10-mL graduated cylinder or simply the markings on the eudiometer, carefully add 8-10 mL of 3 M hydrochloric acid into the eudiometer. You d. Dump the liquid from the eudiometer into the hazardous waste container then repeat the experiment two may add 1-2 drops of food coloring to the acid if desired to help visualize layer mixing. more times using different starting masses of Mg but never exceeding 0.040g. Try to ensure all three starting masses are different (i.e. 0.010 g, 0.025 g, 0.040 g). When doing trials 2 and 3 start with new c. Holding the eudiometer at a 45" angle, very carefully and slowly fill the eudiometer with water (either liquid in your eudiometer but leave all of the liquid in your beaker. distilled or tap water is fine) without mixing the acid and water. (This is contrary to the rule about adding acid to water, and we're intentionally creating two layers here, so that the acid will stay relatively e. Once finished with all three trials, pour the liquid in your beaker into the hazardous waste container. concentrated at the bottom of the eudiometer.) While adding the water, carefully rotate the eudiometer to make sure that any acid on the sides is washed to the bottom. The eudiometer should be filled to the point f. Before leaving lab, enter all of your data into the Excel spreadsheet as instructed. that the water is overflowing

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Data and Calculations The idea now is to determine your experimental values for two key values associated with gas laws, molar volume and the ideal gas constant, R. First, you will need to adjust the pressure of He present in your eudiometer. Once the experiment is complete, the total atmospheric pressure will equal the pressure inside the eudiometer. However, because the hydrogen gas was collected above water, and water has a significant vapor pressure, not all of the pressure can be attributed to hydrogen. Therefore, to get the pressure of pure (dry) hydrogen, we must subtract the vapor pressure of water by estimating its pressure at the temperature of the reaction (See Table 1). To read Table 1, find the singles digit of your temperature in the leftmost column and follow that row over to the tenth of a degree that matches your temperature. All pressures in Table 1 are given in units of mm Hg. For example, the water vapor pressure at 19.3'C would be 16.79 mm Hg. Table 1 - Vapor Pressure of Water at Various Temperatures 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 16 13.65 13.73 13.82 13.91 14.00 14.09 14.18 14.27 14.36 14.45 17 14.54 14.63 14.72 14.82 14.91 15.00 15.10 15.19 15.29 15.39 18 15.48 15.58 15.68 15.78 15.87 15.97 16.07 16.17 16.28 16.38 19 16.48 16.58 16.69 16.79 16.89 17.00 17.11 17.21 17.32 17.43 20 17.54 17.64 17.75 17.86 17.97 18.08 18.20 18.31 18.42 18.54 21 18.65 18.77 18.88 19.00 19.11 19.23 19.35 19.47 19.59 19.71 22 19.83 19.95 20.07 20.19 20.32 20.44 20.56 20.69 20.82 20.94 23 21.07 21.20 21.32 21.45 21.58 21.71 21.84 21.98 22.11 22.24 24 22.38 22.51 22.65 22.78 22.92 23.06 23.20 23.34 23.48 23.62 25 23.76 23.90 24.04 24.18 24.33 24.47 24.68 24.76 24.91 25.06 26 25.21 25.36 25.51 25.66 25.81 25.96 26.12 26.27 26.43 26.58 27 26.74 26.90 27.06 27.21 27.37 27.54 27.70 27.86 28.02 28.18 28 28.35 28.51 28.68 28.85 29.02 29.18 29.35 29.52 29.70 29.87

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