Electrolysis and Current A student designs an ammeter (a device that measures el

Question

Electrolysis and Current A student designs an ammeter (a device that measures electrical current) that is based on the electrolysis of water into hydrogen and oxygen gases. When electrical current of unknown magnitude is run through the device for 2.00 min, 13.2 mL of water-saturated H2 (g) is collected. The temperature and pressure of the system are 25 ° C and 715 torr The vapor pressure of water changes with tem as shown here T(C) P (torr) Part A 21 18.7 19.8 21.1 22.4 23.8 25.2 26.7 28.4 30.0 31.8 How many moles of hydrogen gas are produced? Express your answer to three significant figures and include the appropriate units. 23 24 25 26 27 28 29 30 Value Units Submit Hints My Answers Give Up Review Part Part B

Explanation / Answer

We will use ideal gas equation here

PV = nRT

So number of moles of hydrogen = Pressure of dry hydrogen X volume / gas constant X temperature

Pressure of hydrogen = given pressure - Pressure of vapour (at 250C, given in table)

Pressure = 715 - 23.8 = 691.2 torr

Temperature = 298 K

Volume = 13.2 mL = 0.0132 L

R = 62.36 LTorrK1 mol1

so number of moles = 691.2 X 0.0132 / 298 X 62.36 = 4.909 X 10^-4 moles

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