need help answering 1 through 8 and the pre-lab questions. Experiment 8 Eudiomet

Question

need help answering 1 through 8 and the pre-lab questions.

Experiment 8 Eudiometer (Gas Measuring Tube) Hydrogen Gas and Water Vapor Water Magnesum rubber stopper Figure 1 Table 1. Vapor Pressure of Water at Different Temperatures Temperature, "C Pvo mm Hg 13.6 14.5 15.5 Temperature, C mm Rg 16 °C 17°C 18°C 19 °C 20 °C 21°C 22 °C 23 °C 24°C 25 °C 26 C 27 °C 19.8 21.1 22.4 23.8 25.2 26.7 17.5 18.7 Experiment Overview The purpose of this experiment is to determine the volume of one mole of hydrogen gas at standard temperature and pressure (STP). Hydrogen will be generated by the reaction of a known mass of magnesium with excess hydrochloric acid in an inverted gas measuring tube filled with water. The volume of hydrogen collected by water displacement will be measured and corrected for differences in temperature and pressure in order to calculate the molar volume of hydrogen at STP Pre-Lab Questions (Use a separate sheet of paper to answer the following questions) A reaction of 0.028 g of magnesium with excess hydrochloric acid generated 31.0 mL of gas. The gas was collected by water displacement in a 22 °C water bath. The barometric pressure in the lab that day was 746 mm Hg. 1. Use Dalton's law and the vapor pressure of water at 22 °C (Table 1) to calculate the partial pressure of 2. Use the combined gas law to calculate the "corrected" volume of hydrogen at STP. Hint: Watch your units 3. What is the theoretical number of moles of hydrogen that can be produced from 0.028 g of Mg? Hint: Refer 4. Divide the corrected volume of hydrogen by the theoretical number of moles of hydrogen to calculate the hydrogen gas in the gas collecting tube for temperature and pressure to Equation 1 for the balanced equation for the reaction molar volume (in L/mol) of hydrogen at STP Laboratory Experiments for AP Chemistry

Explanation / Answer

Part 1

Dalton's Law says that when a gas is collected over a liquid such as water, the gas is mixed with vapor from the liquid (e.g. water) and so is a mixture of the gas + water vapor. Then the total pressure = partial pressure of the gas + partial pressure of water vapor.

from table 1- vapor pressure of water at 22 degree Celsius= 19.8 mm Hg

Ptotal = Pwater vapor + P gas

746 = 19.8 + P gas

P gas = 726.2 mm Hg (0.955 atm)

Part 2

Combined gas law- PV/T = K (constant)

P1V1/T1 = P2V2/T2

0.955 atm x 31 ml / 295.15 K = 1 atm x V2 / 273.15 K

V2 = 27.398 ml ( Hydrogen volume at STP)

Part 3  

Magnesium reacts with HCl to produce Hydrogen according to the reaction-

Mg(s) + 2 HCl(aq) --> MgCl 2(aq) + H2(g)

1 mole of Mg will produce one mole of hydrogen,

0.028 gm of Mg contains 0.00115 moles of Mg

Hence, this amount of Mg will produce 0.00115 moles of Hydrogen.

Part 4

Molar volume of hydrogen = Corrected volume of Hydrogen/ theoretical number of moles of Hydrogen

= 27.398 x 10-3 (L)/ 0.00115 (Moles)

= 23.82 Liter per Moles

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