2.10 保护质量
章节大纲
-
If you build a campfire like this one, you start with a big pile of logs. As the fire burns, the pile of logs slowly shrinks. By the end of the evening, all that’s left is a small pile of ashes. What happened to the matter that you started with? Was it destroyed by the fire?
::如果你建造了像这样的营火,你就会从一大堆木头开始。当火烧的时候,成堆的木头慢慢收缩。到晚上结束时,剩下的只有一小堆灰烬。你开始的事情发生了什么?它被火烧掉了吗?Where’s the Matter?
::物质在哪里?It may seem as though burning destroys matter, but the same amount, or mass, of matter still exists after a campfire as before. Look at the sketch in Figure . It shows that when wood burns, it combines with oxygen and changes not only to ashes but also to carbon dioxide and water vapor. The float off into the air, leaving behind just the ashes. Suppose you had measured the mass of the wood before it burned and the mass of the ashes after it burned. Also suppose you had been able to measure the oxygen used by the fire and the gases produced by the fire. What would you find? The total mass of matter after the fire would be the same as the total mass of matter before the fire.
::燃烧似乎摧毁了物质, 但物质的数量, 或质量, 和以前一样。 看看图中的草图。 它显示当木柴燃烧时, 它会与氧气结合, 并且不仅改变为灰烬, 而且还会改变为二氧化碳和水蒸气。 浮到空中, 只留下灰烬。 假设你测量了木柴燃烧前的重量和烧火后的灰灰质量。 也假设你能够测量到火中使用的氧气和火产生的气体。 你会发现什么? 火后的物质总量将与火前的物质总量相同 。Q: What can you infer from this example?
::问题:你能从这个例子中推断出什么?A: You can infer that burning does not destroy matter. It just changes matter into different substances.
::A:你可以推断燃烧不会摧毁物质。它只是将物质改变为不同的物质。Law of Conservation of Mass
::保护质量法This burning campfire example illustrates a very important law in science : the law of conservation of mass . This law states that matter cannot be created or destroyed. Even when matter goes through a physical or , the total mass of matter always remains the same.
::焚烧营火的例子表明了科学中一项非常重要的法律:保护质量法。 该法规定,不能创造或摧毁物质。 即使物质经过身体或身体,物质的总质量始终保持不变。Q: How could you show that the mass of matter remains the same when matter changes state?
::问题:当物质改变状态时,你如何证明物质质量保持不变?A: You could find the mass of a quantity of water. Then you could freeze the water and find the mass of the ice. The mass before and after would be the same, showing that mass is conserved when matter changes state.
::A:你可以找到水的质量。然后你可以冻结水,找到冰的质量。前后的质量是一样的,这表明当物质改变状态时质量会得到保存。Summary
::摘要-
Burning and other changes in matter do not destroy matter. The mass of matter is always the same before and after the changes occur.
::燃烧和其他物质变化不会摧毁物质,物质质量在变化发生之前和之后总是一样。 -
The law of conservation of mass states that matter cannot be created or destroyed.
::保护大众法规定,不可制造或摧毁物质。
Review
::回顾-
What is the law of conservation of mass?
::保护质量的法律是什么? -
Describe an example of the law of conservation of mass.
::说明保护质量法的例子。
Resources
::资源 -
Burning and other changes in matter do not destroy matter. The mass of matter is always the same before and after the changes occur.
