Demonstrate that the work done against the atmosphere when $1.00\,\text{kg}$ of liquid water changes into water vapour is $1.71 \times 10^5\,\text{J}$.
The first law of thermodynamics can be written as $\Delta U = +q + w$, where $\Delta U$ is the rise in internal energy of the system. Explain the meaning of $+q$.
Explain the meaning of $+w$ in the expression $\Delta U = +q + w$.
The specific latent heat of vaporisation of water at $100\,^{\circ}\text{C}$ is $2.26 \times 10^6\,\text{J kg}^{-1}$. A mass of $1.00\,\text{kg}$ of liquid water becomes water vapour at $100\,^{\circ}\text{C}$. Determine, using your answer in (a), the increase in internal energy of this mass of water during vaporisation.
The first law of thermodynamics can be written as $\Delta U = + q + w$, where $\Delta U$ is the rise in internal energy of the system. Explain the meaning of (1) $+q$, (2) $+w$.