3.1 Common feature Spontaneous change Some things happen spontaneously, some things don t Common feature --irreversible A gas expands to fill the available volume it does not spontaneously contract into something smaller a hot body cools to the temperature of its surroundings, it does not spontaneously get hotter at their expense 4上一内容下一内容令回主目录 返回 2021/221上一内容 下一内容 回主目录 返回 2021/2/21 3.1 Common feature Spontaneous change :Some things happen spontaneously, some things don`t. Common feature —irreversible A gas expands to fill the available volume; it does not spontaneously contract into something smaller. A hot body cools to the temperature of its surroundings;it does not spontaneously get hotter at their expense