A 20.8 g sample of nickel(s) is placed in excess HCl(aq) and the gas produced is

Question

A 20.8 g sample of nickel(s) is placed in excess HCl(aq) and the gas produced is collected over water in 2.5 L container. The vapor pressure of water is 21.1 mmhg at 23deg C. After the reactant is finished, a total pressure of 3.23 atm is measured.

a) How many moles of limiting reactant are avaliable before the reaction begins?

b) What is the presuure of H^(2) gas produced?

c)What is the percent yield of H2 gas?

d) The other product formed in the reaction is nickel(ll) chloride. If the volume of reaction is constant(650ml). What is the molarity of NCl2 after the reaction is completed?

e)After the experiment has ended, the water vapor and hydrogen gas are separated. Assuming the temperature is the same , the two gases will have different average kinetic energies. True or false

f) Which of the gases would you expect to effuse faster?

Explanation / Answer

Balanced equation:
Ni + 2 HCl ===> NiCl2 + H2
Reaction type: single replacement

Question a

20.8 g sample of nickel = 20.8 / 58.69 = 0.35438 Moles

Question b

Pressure of H2 gas produced = 2454.8 - 21. 1 = 2433.7 mm hg or 3.2022 atm

Question c

Let us calculate the moles of H2

PV= nRT

P = Pressure in atm                       V= Volume in Liter

n = no of moles               R = 0.0821 L atm K-1 Mol-1

T = Temperature in Kelvin

n = PV / RT = 3.2022 x 2.5 / 0.08206 x 296 K = 0.3295 Moles

Thoretical yield of H2 =  0.35438 Moles

Percentage yield = 0.3295 x 100 / 0.35438 = 93 %

Question d

Molarity of NiCl2 =  0.3543 x 1000 /650 = 0.545 M

Question e

To figure the total kinetic energy, you multiply the average kinetic energy by the number of molecules you have. Hence the statement is true.

Question f

SInce number of H2 molecules are excess iH2 gas will effuse faster

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