Question

Determine which law is appropriate for solving the following problem. What temperature will 215 mL of a gas at 20°C and 1 atm pressure attain when it is subject to 1.5 atm of pressure? what Law is used: Combined gas law, Charles Law, or boyles law?

Answer 1

Answer : The temperature will be 439.5 K and combined gas law is used.

Solution : Given,

Volume = 215 ml

Initial conditions,

$T_1=20^oC=273+20=293K$   $(0^oC=273K)$

$P_1=1atm$

$P_2=1.5atm$

Using combined gas law,

$\frac{PV}{T}=constant$

where,

P = pressure of gas

V = volume of gas

T = temperature of gas

As per the problem, at constant volume the combined gas law is expressed as,

$\frac{P_1}{T_1}=\frac{P_2}{T_2}$

Now put all the given values in this formula, we get

$\frac{1atm}{293K}=\frac{1.5atm}{T_2}$

By rearranging the term, we get the value of $T_2$.

$T_2=439.5K$

Therefore, the temperature will be 439.5 K and combined gas law is used.

Answer 2

Answer:

The Combined Gas Law

Explanation:

Let’s compare the two conditions.

p₁ = 1     atm; V₁ = 215 mL; T₁ = 20 °C

p₂ = 1.5 atm; V₂ = 215 mL; T₂= ?

The only variables are pressure and temperature.

The most appropriate law would be Gay-Lussac’s Law (p₁/T₁ = p₂/T₂), but that’s not an option.

The only other option involving p and T is the Combined Gas Law:

p₁V₁/T₁ = p₂V₂/T₂

Since V₂ = V₁, we can write

p₁V₁/T₁ = p₂V₁/T₂     Divide both sides by V₁

    p₁/T₁= p₂/T₂         Multiply both sides by T₂

p₁T₂/T₁ = p₂               Multiply both sides by T₁

    p₁T₂= p₂T₁            Divide both sides by p₁

      T₂ = T₁ × p₂/p₁

Now, convert your temperature to kelvins, insert the values into the formula, and calculate the new temperature.