Question

Phosphine, PH3(g), decomposes according to the equation 4PH3(g) --> P4(g) + 6H2(g) The kinetics of the decomposition of phosphine at 950 K was followed by measuring the total pressure in the system as a function of time. The data to the right were obtained in a run where the reaction chamber contained only pure phosphine at the start of the reaction.

Answer 1

good luck with that. I thought I had it, but it was not right.

Answer 2

Choose the rate law that describes this reaction: Rate = k (PH3)

Explanation:

The kinetics of the decomposition of phosphine at 950 K was followed by measuring the total pressure in the system as a function of time. The data to the right were obtained in a run where the reaction chamber contained only pure phosphine at the start of the reaction. Choose the rate law that describes this reaction

Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. PH3 have the density, 1.379 g/l, gas (25 °C)

The chemical equation of PH3 is:

4PH3(g)  →   P4(g) + 6H2(g)

At t=0, there was only PH3, therefore:

$P_{total} = P_{PH3} = 100 torr$  

At t=40 min, we need to use the ICF chart (attached below) to determine the pressure of PH3.

At t=40 min, total system pressure is 151 torr

$100-4x+x+6x = 151\\3x = 151\\x = 17$

The pressure of PH3 at t=40 is

$P_{PH3} =100 torr-4*17 torr$

$P_{PH3} = 32 torr$

At t=80 min, total system pressure is 168 torr,

$100-4x+x+6x = 168\\3x = 68\\x = 22.7$

Therefore, pressure of PH3 at t=80 is:

$P_{PH3} =100 torr-4x* torr$

$P_{PH3} = 100 torr-4*22.7 torr = 9.2 torr$

At t=100 min, total system pressure is 171 torr

$100-4x+x+6x = 171\\3x = 71\\x = 23.7$

Then the pressure of PH3 at t=100 is:

$P_{PH3} =100 torr-4x torr$

$P_{PH3} = 100 torr-4*23.7 torr = 5.2 torr$

Then we can  plot the pressure against time in a line graph (attached below)

Therefore we found that the first order shows the most linear relationship between pressure and time and then the dissociation of Phosphine is in the first order (attached below)

Therefore the rate law is:  $Rate = k (PH3)$

Learn more about the rate law https://brainly.com/question/13301088

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