Ideal Gas Law: Stoichiometry Objectives: 1. To measure the mass of gas produced

Question

Ideal Gas Law: Stoichiometry Objectives: 1. To measure the mass of gas produced using temperature, pressure, and volume. 2. To calculate the theoretical yield of gas from starting quantities 3. To determine the percent yield of gas. 4. To understand partial pressures and mole fractions of gases Safety: Wear safety goggles Hydrochloric acid is corrosive. Avoid contact, and wash thoroughly with water after any contact Procedure: 1. Weigh a short strip of magnesium ribbon on an analytical balance. If the mass of the ribbon is greater than 0.045g 2, Use a thistle tube to add 15mL(± 1 mL) of 3 M hydrochloric acid to a eudiometer tube. 3. While holding the eudiometer tube at an angle to minimize the mixing of the acid at the bottom, add deionized water 4. Bend the weighed magnesium strip and push it into the open end of the eudiometer tube (like a small spring) so that it 5. Finish filling the eudiometer tube completely with water so no air bubble will be trapped when the tube is inverted. 6. Using your index finger to fully cover the eudiometer opening, invert the tube into the beaker. Remove your finger 7. Hold the eudiometer tube upright (either by hand or with a ring stand) until the magnesium ribbon completely reacts. shorten the ribbon to reduce its mass to 0.045 g or less. Record the mass. slowly to fill it within a centimeter of the end. will not fall out when the tube is inverted Also add at approximately 350 mL of tap water to a 400 mL beaker when the tube opening is under water. the ribbon falls out of the tube, seek assistance from the instructor If the magnesium stays at the bottom of the tube, the reaction will run faster if the tube is tilted at about 30 degrees from vertical. If the magnesium ribbon floats inside the tube, it is probably better to hold the tube straight up. When the reaction is complete, cap the eudiometer tube with your index finger and transfer the tube to the tall cylinder of room-temperature water. same inside and outside the tube. 8. Read and record the volume of gas in the eudiometer tube when the water levels are the Notice the scale increases going down the eudiometer tube. 9. Repeat steps 1-8 for the second trial. 0. Obtain the barometric pressure in the room and record it 11. Measure the temperature of the water in the tall cylinder and look of the vapor pressure of water for that temperature. Assume this is the temperature of the gas at the volume and pressure measured 46 ", Data: Trial 1 Trial 2 0444 Mass of magnesium ribbon Volume of gas collected Temperature of the gas Barometric pressure Vapor pressure of water Partial pressure of hydrogen gas . 0 372 21.b C 30.19 11.35 30. 20 1.35

Explanation / Answer

You have multiple questions in the same post. Try to post your questions per separate so you can get better and faster answers. In this case, I will answer A and B. For part D post that in another question thread, and if possible, no more than 3 or 4 questions in a post.

The reaction is as follow for both parts:
Mg + 2HCl = MgCl2 + H2

Part A.

1. According to this reaction, Mg is the limiting reactant, so, calculate the moles of Mg:
moles Mg = 0.0372 / 24 = 1.55x10-3 moles

These moles are the same moles produced of hydrogen by stechiometry.

mH2 = 1.55x10-3 * 2 = 3.1x10-3 g

2. Doing the same thing as above question:
moles Mg = 0.0444 / 24 = 1.85x10-3 moles
mH2 = 1.85x10-3 * 2 = 3.7x10-3 g

Part B.

1. In this part, use the following equation: PV = nRT
We have pressure, temperature and volume, so we can calculate moles:
n = PV/RT
PRessure is in mmHg (I assume) so converting that to atm:
P = 30.19/760 = 0.0397 atm
n = 0.0397 * 0.046 / (0.0821) * (273+21.6) = 7.55x10-5 moles
m = 7.55x10-5 * 2 = 1.51x10-4 g

2. Doing the same thing as above:
P = 30.2/760 = 0.0397 atm
n = 0.0397*0.048 / 0.0821*294 = 7.89x10-5 moles
m = 7.89x10-5 * 2 = 1.58x10-4 g

Finally for part C.

%1 = 1.51x10-4/3.1x10-3 * 100 = 4.87%
%2 = 1.58x10-4/3.7x10-3 * 100 = 4.27%

Hope this helps

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.