A piece of magnesium reacts with an aqueous solution of HCI to produce H2 gas. T

Question

A piece of magnesium reacts with an aqueous solution of HCI to produce H2 gas. The hydragen gas is collected over the HCi solution at a temperature of 22.0°C. fthe total pressure of the system is 0.953 atm, and the volume of gas collected is 720. mL, what are the partial pressure and the mass of Hz produced? (You may assume that the dissolved HCI has no effect on the vapor pressure of water, which is 19.8 torr at 22.0°C.) partial pressure 927 mass Did you remember how collecting a gas over water affects the total pressure? Did you do all necessary unit canversions? atm Periodic Table Constants and Factors Addtional Materials L Section 93 Calcium carbonate, Cacog(s), decomposes upon heating to give Cao(s) and Co (o) A sample of Caco, is decamposed, and the carbon dioxide 250 mL flask. After the decomposition is compiete, the gas has a pressure of 1.6 atm at a temperature of 33 C. equation: PV- RT) s collected in a sealed How many moles of co, gas were generated? (Tisnal gae mo Materiels Periodic Tabie supplem ntal Data

Explanation / Answer

Mg + 2HCl = H2 + MgCl2

T = 22°C = 295 K

Ptotal = 0.953 atm

V = 720 mL = 0.72 L

find P gas

Ptotal = Pgas + Pwater

Pgas = PTotal - Pwater = 0.953 - 19.8/760 = 0.9269 atm

PV = nRT

n = PV/(RT) = (0.9269)(0.72)/(0.082*(22+273))

n = 0.02758 moles

mass = mol*MW =0.02758*2 = 0.05516 g of H2

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