In an electrolysis cell similar to the one employed in this experiment, a studen

Question

In an electrolysis cell similar to the one employed in this experiment, a student observed that his unknown metal anode lost 0.208 g while a total volume of 96.30 mL of H. was being produced. The temperature in the laboratory was 25 degree C and the barometric pressure was 748 mm hg. At 25Degree C' the vapor pressure of water is 23.8 mm Hg. To find the equivalent mass of Ins metal, he filled in the blanks below. Fill in the blanks as he did. P_h_2 = p_bar - vp_h_2o = = mm Hg = atm V_h_2 = mL = l T = K n_h_2 = moles n_h_2 = pv/rt (where p = p_h_2) I mole H_2 requites passage of faradays No. of faradays passed = Loss of mass of metal anode = g No. grams of metal lost per faraday passed = no. grams lost/no. faradays passed = g = EM the student was told that his metal anode was made of iron. MM He = g. The charge n on the Fe ion is therefore. (See Eq. 3.) In ordinary units, the faraday is equal to 96.480 coulombs. A coulomb is the amount of electricity passed when a current of one ampere flows for one second. Given the charge on an electron. 1.6022 x 1o^-19coulombs, calculate a value for Avogadro's number.

Explanation / Answer

P(H2) = 748mmHg -23.8 mmHg =724 mmHg = 0.953 atm

Volume = 96.30 mL = 0.0963 L

T = 298 K

Moles of Hydrogen = 0.00375 moles

1 mole h2 required 2 faraday passed.

Number of faraday passed = 0.00375 * 2 = 0.00750

Loss of metal anode = 0.208 gm

No. of gms of metal lossed per faraday passed = 0.208gm/0.00750 faraday = 27.7

MM of Fe = 56gm/mol

Charge on metal = 56/ 27.7 = 2

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