$($a$)$ How much heat flows from $1\mathrm{.}00$ kg of water at $37\mathrm{.}2$C when it is placed in contact with $1\mathrm{.}00$ kg of $22$C water in reaching equilibrium?

How is the heat lost by the hot water related to the heat gained by the cold water? J

$($b$)$ What is the change in entropy due to this heat transfer?

Consider the average temperature at which heat is transferred for the hot water and for the cold water. What decides if the change in entropy is positive or negative? What unit should you use for the temperature when calculating entropy change? J$/$K

$($c$)$ How much work is made unavailable, taking the lowest temperature to be $22$C$?$

Review the definition of unavailable work. J