CHEM LAB 12 - lab report PDF

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Gianina Favata ACHM 125 2/9/21

Pre-Lab 12

Title: The ideal Gas Law Objective: the objective for the first part of this lab is to experimentally determine the value of absolute zero, by using the ideal gal law with the equation PV=nRT. The objective for the second part of this lab is to determine the molar mass of the magnesium by using the ideal gas law to find out how many moles gas will be produced when the magnesium metal is reacted with the hydrochloric acid. Hypothesis 1: The temperature of total/ absolute zero ought to be -273.0℃. the two factors being diagramed here are the pressure, on the x-axis, and temperature on the y-axis. The graph will be utilized to decide absolute zero value by graphing a linear regression which will show that the y-intercept value is the experimental value of absolute zero. At, absolute zero, a gas will apply zero power onto its compartment and this empowers the experimenter to utilize the graph to discover absolute zero since the pressing factor at absolute zero can’t avoid being zero. That way you glance back at the graph where y is equivalent to zero to discover the estimation of the pressure. Hypothesis 2: the molar mass of magnesium is going to be determined to be about 24.3 grams. The reactants which can be utilized in the reaction is hydrochloric acid and magnesium metal. Which will lead to the assembly of hydrogen gas. The law which will be used to determine the pressure of the hydrogen gas is Dalton’s law of partial pressure and therefore the law for the determination of the moles of hydrogen is that the perfect gas law. The two variables which will be measured to work out the moles of hydrogen are the temperature of the room/atmospheric pressure and therefore the volume of the hydrogen gas. The stoichiometric relationship between the acid and the magnesium within the reaction is two HCl’s for each one of magnesium and therefore the relationship between the moles of hydrogen gas and magnesium metal is at least one. The variable that each one of this information will allow us to calculate the molar mass of magnesium.

Variables: Part 1

Independent Variable(s): Temperature (in Celsius)

Dependent Variable(s): Air pressure Part 2 Independent Variable(s): Mass of Magnesium Metal

Dependent Variable(s): Amount of Hydrogen Gas

Procedures:

Part 1

1. Gather all necessary materials and equipment 2. Fill up a 400mL beaker with about 250mL of water and place a stir bar into the beaker 3. Place the beaker onto the hot plate but do not turn it on until the rest of the apparatus is properly set up first. 4. For the next step, clamp a 125mL Erlenmeyer flask to the ring stand and have it placed above the beaker. Place the pressure sensor adapter assembly into the flask and then connect it to the microlab after placing the stopper into the flask. 5. Once the Erlenmeyer flask is stoppered, then submerge it into the beaker of water as far as possible (also the beaker should be as full as possible with water) 6. Place the thermistor into the microlab and place it into the beaker of water. Make sure to ensure that it is not touching any metal from the clamp or ring stand and the hot plate is still turned off. 7. Utilize the microlab section of the lab manual to set the microlab to record a new experiment. Change the “Read Sensors” rate to 10 seconds to 0.5 seconds. 8. Prior to turning on the hot plate, set the stirring to around 200 RPM. Plus, ensure that the Erlenmeyer flask is properly sealed and that there is no plastic or rubber tubing from the power cord or thermistor are touching the hot plate to prevent the tubing from melting and/or catching fire. 9. Now set the hot plate to 200°C until the water in the beaker reaches 60°C and then stop heating. 10. Check your graph after the first few minutes to make sure the experiment is working properly. Once you are done collecting the proper/ useable data, export the data into excel.

Part 2 :

1. Record the masses of the three separate pieces of magnesium ribbon and then tie a piece of string to each. 2. Prepare a 2000mL graduated cylinder with about 1800mL of tap water. 3. Add 10mL of colored, 3 M hydrochloric acid to three clean and labeled gas collection tubes. 4. Use a plastic pipet to layer the water on top of the acid, carefully, until each tube is completely full with no air bubbles. 5. Place the magnesium ribbon into the water and use the glass stirring rod to carefully puch it down to about 1-2 cm into the water. If any of the water comes out of the test tube use the beaker to fill the tube again. 6. Stopper the tubes with holed stoppers. Quickly invert the tubes and place them into the 2000mL graduated cylinder. 7. To avoid the water causing pressure in the tubes, level out the water in the tubes by lifting the collection of tubes up so the volume of the liquid in the tubes is at the same volume level as the graduated cylinder. 8. Repeat steps 1-7 for the three trials total. 9. Be sure to convert the volume in the gas collection tubes from mL to Liters to properly complete the ideal gas law calculations after recording the data for each of the trials.

Chemical hazards: Goggles and lab coats must be worn at all times. Hot plates can cause burns even with brief contact. Heating a closed container can be dangerous and should never be done with direct heat. Hydrochloric acid is corrosive and should be handled with caution. Goggles, gloves and lab coats must be worn when working with hydrochloric acid. Magnesium metal is reactive, and in combination with the acid will produce a flammable hydrogen gas and is slightly toxic magnesium chloride.

Key Math Equations: PV = nRT Absolute Zero -> T = 0 K

Conclusions:

Part 1: The results did support the hypothesis, the temperature of absolute zero was recorded to be -273.15°C. The equation for the line of best fit is y=0.3923x – 2730.15 the two variable that were graphed were pressure in torr and temperature in Celsius. The R2= 1, the information gained by the R2 value is that the experiment was accurate and precise. The accuracy of this experiment is indicated by the value of the Standard Deviation only being 0.004084086g/mol. The precision of this experiment is indicated by the percent error being less than 1% .

Part 2: The results did support the hypothesis for the mere fact that the average molar mass of magnesium was calculate to be 24.31 g/mol. The accuracy of this experiment was indicated by the fact that the ending molar mass of magnesium was 24.31g/mol. The precision of this experiment is indicated as stated in the previous conclusion is that the percent error is less than 1%....