In an electrolysis experiment such as the one you are going to perform, 47.4 mL

Question

In an electrolysis experiment such as the one you are going to perform, 47.4 mL of hydrogen gas were collected. The temperature was 23 degrees Celsius and the barometric pressure was 643 mm Hg. The vapor pressure of water at 23 degrees Celsius is 21 mm Hg. The number of moles of hydrogen gas formed in the experiment was

1.60 x 10^-3

3.19 x 10^-3

1.35 x 10^0

1.21 x 10^0

1.70 x 10^-3

3.08 x 10^-3

1.65 x 10^-3

2)In an electrolysis experiment such as the one you will perform, 1.76 x 10^-3 moles of hydrogen gas were collected, and the metal electrode lost 0.1983 g. The equivalent mass of the metal is approximately what?

62.3

36.9

28.1

87.2

98.7

56.3

112.4

76.8

In an electrolysis experiment such as the one you will perform, the equivalent mass of a metal is found to be 17.33. The metal is known to form a 3+ ion. The atomic mass of the metal is approximately what?

5.78

52.0

24.3

27.0

17.3

34.7

69.7

Explanation / Answer

The first question:
n = PV/RT
n = (643+21/760) * 0.0447 / 0.0821 * 296
n = 1.7x10-3 moles

The second question:*
MW = 0.1983 / 1.76x10-3 = 112.67 g/mol

Now to get the equivalent mass we need to know the charge of the metal ion (1+, 2+ or 3+) so we can divide the MW by this ion charge.

The third question:
17.33 * 3 = 51.99 g/mol

Hope this helps

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