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What is the amount of hydrogen released in the following case:Silicon steel is an alloy...

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thisisalongword | Student, Grade 11 | Salutatorian

Posted January 8, 2012 at 7:58 PM via web

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What is the amount of hydrogen released in the following case:

Silicon steel is an alloy of the elements iron, carbon and silicon. An alloy sample was reacted with excess hydrochloric acid and the following reaction occurred:

Fe (s) + 2HCl (aq) ---> FeCl2 (aq) + H2 (g)

The carbon and silicon in the alloy did not react with the acid. If an alloy sample with a mass of 0.160 g produced 62.0 mL of hydrogen gas, measured at SLC, calculate the amount of hydrogen evolved in the reaction.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted January 8, 2012 at 9:07 PM (Answer #1)

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When a sample of silicon steel that is made up of iron, carbon and silicon is reacted with excess hydrochloric acid the following reaction occurs:

Fe (s) + 2HCl (aq) ---> FeCl2 (aq) + H2 (g)

The mass of the sample used is 0.16 g and the volume of hydrogen produced when measured at standard laboratory conditions with a temperature of 25 C and a pressure of 1 atm. is 62 mL

The amount of hydrogen released can be calculated using the ideal gas law, PV = n*RT, where P is the pressure, V is the volume, n is the amount of the gas in moles, T is the temperature and R is a constant.

1*62 = n*82.05746*298

=> n = 2.53*10^-3 moles.

The amount of hydrogen produced is 2.53*10^-2 moles.

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xinchaoyo | Student , Grade 11 | Honors

Posted January 9, 2012 at 5:49 PM (Answer #2)

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Can you please explain to me how R = 82.05746?

 

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