Suppose a gas sample occupies 14.9 L at

STP. What is its volume at 400 K and 0.87 atm?

which equation would you use for this?

(P1V1/T1) = (P2V2/T2)

To solve this problem, we can use the combined gas law equation, which relates the initial and final conditions of a gas sample. The combined gas law is given by:

(P₁ * V₁) / (T₁) = (P₂ * V₂) / (T₂)

Where:
P₁ and P₂ are the initial and final pressures,
V₁ and V₂ are the initial and final volumes,
T₁ and T₂ are the initial and final temperatures.

In this case, the initial conditions are at STP (Standard Temperature and Pressure) which are defined as 0 degrees Celsius (273 K) and 1 atm. The final conditions are given as 400 K and 0.87 atm.

We are given V₁ = 14.9 L, T₁ = 273 K, P₁ = 1 atm, T₂ = 400 K, and P₂ = 0.87 atm.

Now we can substitute these values into the combined gas law equation and solve for V₂:

(1 atm * 14.9 L) / (273 K) = (0.87 atm * V₂) / (400 K)

To find V₂, we rearrange the equation:

V₂ = [(1 atm * 14.9 L * 400 K) / (0.87 atm * 273 K)]

Calculating this expression will give us the volume V₂ at the new conditions of 400 K and 0.87 atm.