At 700 K acetaldehyde decomposes in the gas phase to methane and carbon monoxide. The reaction is:

CH3CHO (g) →CH4 (g) + CO (g)

A sample of CH3CHO is heated to 700 K and the pressure is measured as 0.15 atm before any reaction takes place. The kinetics of the reaction are then followed by measurements of total pressure and these data are obtained:

t (s) 0 1000 3000 7000

PTotal (atm) 0.15 0.16 0.18 0.20

Find total pressure after 1.95*10^4s.

Express your answer to two significant figures and include the appropriate units

After 1.95x10⁴ s, total pressure is 0.34 atm

Explanation:

t (s) 0 1000 3000 7000

PTotal (atm) 0.15 0.16 0.18 0.20

These are the data of the experiment, so let's make a linear regression

X | Y

0 | 0.15

1x10³ | 0.16

3x10³ | 0.18

7x10³ | 0.20

You can do this by the calculator, but let's do it manually.

Y = mx + b

m = (Y₂ - Y₁) / (X₂ - X₁)

m = 0.18 - 0.16 / 3x10³ - 1x10³

m = 0.02 / 2x10³ = 1x10⁻⁵

b = 0.15 (y-intercept, where x is 09

Y = 1x10⁻⁵ X + 0.15

Notice that in the statement, after 7000 s, pressure is 0.22 atm

1x10⁻⁵. 1.95x10⁴ + 0.15 = 0.34atm