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An ideal gas undergoes a reversible isochoric process. The initial pressure is 2 \mathrm{~atm}, and the initial temperature is 300 \mathrm{~K}. During the process,800 \mathrm{~J} of heat is added to the gas. Calculate the final temperature of the gas. Given the heat capacity at constant volume \mathrm{\left(C_v\right) \: is\: 20 \mathrm{~J} / \mathrm{K}.}
 

Option: 1

200 \mathrm{~K}


 


Option: 2

300 \mathrm{~K}
 


Option: 3

240 \mathrm{~K}
 


Option: 4

340 \mathrm{~K}


Answers (1)

best_answer

Given data:

Initial pressure \mathrm{\left(P_i\right)=2 atm}

Initial temperature \mathrm{\left(T_i\right)=300 \mathrm{~K}}

Heat added \mathrm{(Q)=800 \quad \mathrm{~J}}

Heat capacity at constant volume \mathrm{\left(C_v\right)=20 \mathrm{~J} / \mathrm{K}}

The change in internal energy \mathrm{(\Delta U)}     during an isochoric process is given by:

\mathrm{ \Delta U=Q=n C_v \Delta T }

Solving for the change in temperature \mathrm{ (\Delta T): }

\mathrm{ \Delta T=\frac{Q}{n C_v} }

Substitute the values and calculate \mathrm{ \Delta T : }

\mathrm{ \Delta T=\frac{800 \mathrm{~J}}{n \cdot 20 \mathrm{~J} / \mathrm{K}}=\frac{800 \mathrm{~J}}{1 \mathrm{~mol} \cdot 20 \mathrm{~J} / \mathrm{K}}=40 \mathrm{~K} }

The final temperature \mathrm{ \left(T_f\right) } can be calculated by adding \mathrm{ \Delta T } to the initial temperature \mathrm{ \left(T_i\right) : }
\mathrm{ T_f=T_i+\Delta T=300 \mathrm{~K}+40 \mathrm{~K}=340 \mathrm{~K} }

Therefore, the final temperature of the gas is \mathrm{ 340 \mathrm{~K}. }

So correct option is 4.

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