Gas Heating F76Ff5
1. **Problem statement:**
A gas sample initially has volume $V_1=0.26$ m³, pressure $P=140000$ Pa, and temperature $T_1=24^\circ C$. It is heated at constant pressure to $T_2=75^\circ C$. The gas mass is $m=0.45$ kg and gas constant $R=287$ J/kg·K. We need to find:
i. Initial specific volume $v_1$.
ii. Final volume $V_2$ after heating.
iii. Work done by the gas during heating.
2. **Convert temperatures to Kelvin:**
$$T_1=24+273.15=297.15\,K$$
$$T_2=75+273.15=348.15\,K$$
3. **Calculate initial specific volume $v_1$:**
Specific volume is volume per unit mass:
$$v_1=\frac{V_1}{m}=\frac{0.26}{0.45}=0.5778\,m^3/kg$$
4. **Calculate final volume $V_2$ using Charles's Law:**
At constant pressure and mass, volume is proportional to temperature:
$$\frac{V_1}{T_1}=\frac{V_2}{T_2} \implies V_2=V_1 \times \frac{T_2}{T_1}$$
Substitute values:
$$V_2=0.26 \times \frac{348.15}{297.15}=0.26 \times 1.1719=0.3047\,m^3$$
5. **Calculate work done by the gas during heating:**
Work done at constant pressure is:
$$W=P\Delta V=P(V_2 - V_1)$$
Substitute values:
$$W=140000 \times (0.3047 - 0.26)=140000 \times 0.0447=6258\,J$$
**Final answers:**
- Initial specific volume $v_1=0.5778$ m³/kg
- Final volume $V_2=0.3047$ m³
- Work done $W=6258$ J