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13 votes
13 votes
A flexible plastic bag at standard pressure and temperature is heated to 350. K. If the final volume is 2.75 L, calculate

the initial volume

User Hinton
by
2.7k points

1 Answer

16 votes
16 votes

Answer:

2.15 L

Step-by-step explanation:

We can use the combined gas law to answer this:

P1V1/T1 = P2V2/T2

where P, V, and T are the Pressure, Volume, and Temperature (in Kelvin) for the initial (1) and final (2) states. We may assume the pressure remains the same between both states (1 atmosphere. or standard pressure). Ci=onvert the Celcius temperatures into Kelvin by add 273.15 to the C value.

We want the original volume, V1. Rearrange the equation to solve for V1:

V1 = V2(P2/P1)(T1/T2)

Note how the pressure and temperature variables are formatted: as ratios. This allows us to more easily visualize how the changes in both will impact the value of V1. A rise in temperature between T1 and T2 would mean that the ratio (T1/T2) would be less than 1, so the initial volume, V1, would be smaller than the final volume, V2. The raio of the pressures P2/P1 simply reduces to 1, since they are the same. So even before we get our a calculator, we can predict that V1 will be smaller than V2.

Enter the data: V1 = (2.75L)*(1)*(273.15K/350K)

The pressure and temperature units cancel, leaving only voulume (Liters).

V1 = 2.15L

This is less than 2.75L, which is what we already expected. The initial volume is 2.15 L.

User Mario Fusco
by
3.0k points