楼主:放心互动 时间:2017年10月24日 08:20:14 点击:0 回复:0
So let#39;s start with the basics我们从基础开始考虑What is an acid and a base? 酸和碱是什么One definition is that一种定义是acids are compounds that donate a hydrogen ion酸是一种化合物,它能贡献一个氢离子or H plus 或者说H+to another compound给另一种化合物and the compound that accepts that hydrogen ion is a base 而接受这个氢离子的化合物就是碱了So acids are hydrogen ion donors酸是贡献氢离子的物质and bases are hydrogen ion acceptors而碱则是接受氢离子的物质Here are some examples 我举一些例子Sodium hydroxide is a base氢氧化钠是碱It#39;s used to make soap 能用于制造肥皂And acetic acid which looks like this而醋酸是酸,它是这样的it makes vinegar sour 它让醋具有酸味Alright, let#39;s look back at our cylinders here好,我们再来回头看这些柱形容器This first set of cylinders contains the indicator bromothymol blue第一组柱形容器中装的指示剂是溴百里酚蓝Let#39;s take a look at the spectrum 我们来看看光谱Alright, so let#39;s take a look at bromothymol blue好,我们来看看溴百里酚蓝the indicator in the first set of cylinders 这是第一组柱形容器中的指示剂As you can see here, there#39;s a scale of numbers. This is the pH scale这里可以看到一些数字刻度,这些是pH值刻度The higher the number, the more basic the solution pH值越高,表示溶液碱性越强the lower the number, the more acidicpH值越低,表示酸性越强So our solution started off basic 我们的溶液最开始是碱性的It was blue and had sodium hydroxide in it它是蓝色的,其中有氢氧化钠And this is what the chemical structure of the molecule looks like when it#39;s blue 这是指示剂分子呈蓝色时的化学结构The chemical bonds in the molecule are absorbing分子中的化学键能够吸收colors of the visible spectrum that are not blue蓝色以外的可见光谱so blue is reflected back to our eyes 所以蓝色反射回我们的眼睛Now if a compound picks up a hydrogen ion 但如果该化合物结合一个氢离子which it would if you add an acid to it加入酸时它确实会这样the molecule changes color 此时分子会变色Now it absorbs blue and reflects yellow它开始吸收蓝光,并反射黄光Since the colors depend on the structure of the molecule由于颜色依赖于分子结构a chemist could reprogram the molecule to switch its color at化学家可以重新构造分子other pHs, other numbers on this scale 让颜色变化发生在其它pH值上That#39;s useful depending on the kind of reactions she may want to study这对于所要研究的化学反应很有用Now nature experiments with color all the time 自然界也在不断使用着颜色Animals use color to avoid predators, attracts mates动物使用颜色来避开捕食者,吸引配偶scare off enemies, etc 吓退敌人,等等Alright, so now let#39;s take a look at 好,我们再来看看what#39;s happening in the second set of cylinders that started off pink 第二组最开始是粉色的柱形容器中发生了什么The indicator in there is phenolphthalein 这里的指示剂是酚酞The same thing is happening as with our bromothymol blue 情况和溴百里酚蓝很类似but this time when the solution is basic, it#39;s pink 但这次,溶液呈碱性时,它是粉色and when it#39;s acidic, it#39;s colorless 呈酸性时,则是无色But why does adding dry ice那么为什么加入干冰change the solution from basic to acidic?会让溶液从碱性变为酸性呢Well, dry ice is solid carbon dioxide 因为干冰是固态二氧化碳When you add it to water, it bubbles 加到水中时,它会冒泡and part of every bubble of carbon dioxide dissolves每个泡泡中都会有二氧化碳溶解when it does, it forms carbonic acid. Let#39;s look at that equation这时就会生成碳酸,我们来看看方程式So there#39;s more and more carbonic acid in the water水中的碳酸越来越多and this acid reacts with the sodium hydroxide until there#39;s none left这种酸会同氢氧化钠反应,一直将其耗尽为止So the solution becomes acidic 于是溶液变成酸性So we saw our bromothymol blue 所以我们看到溴百里酚蓝turning from blue to yellow as a solution became more acidic 随着溶液酸性越来越强,从蓝变黄And we saw our phenolphthalein 而酚酞turn from pink to colorless as it became more acidic 随着溶液酸性越来越强,从粉色变为无色Now let#39;s watch again what happens in the final set of cylinders 下面再来看看最后一组柱形容器中的实验Alright, so now, I ask you to focus your attention on this cylinder好,现在我要求你们注意这个柱形容器Actually, you can focus your attention on anything you want to 实际上,你们也可以关注别的You can even not pay attention if you want to 甚至不关注任何东西都行We live in a free country我们生活在一个自由的国度But if you want to follow the experiment with me 但如果你想跟随我的实验步伐I want you to focus your attention on this one我希望你能关注这个and tell me, count them out how many different color changes you see数一下我加入干冰后有多少种颜色变化as I dropped the dry ice in there 数一下我加入干冰后有多少种颜色变化I#39;m listening to you on the radio 我是在收音机前听你们讲One, wow, I heard wow, what kind of account is that?一,哇,我听到有人说哇,这数的是什么Three so far目前我听到三了Three different color changes 三种不同颜色变化but you know I#39;m listening to you on the radio 但我是在收音机前听你们讲You want me to appreciate what you#39;re seeing 你们要让我理解你们看到了什么So what were the color changes that you saw?你们具体看到了什么颜色变化Why couldn#39;t you say those? 告诉我具体的You see how we have to help our brain make the right observations 你们应该知道如何帮助大脑作出正确观测and make the right reporting 并正确报告OK so, in the final set of cylinders 在最后一组柱形容器中Dr. Shakhashiri has a mixture of indicatorsShakhashiri士使用了指示剂的混合物This created the color changes that occurred as the solution became more and more acidic这样一来,随着溶液酸性变强,颜色会多次变化There were three changes that we saw 这里我们看到了三次变化It went from purple to blue 首先是从紫色变为蓝色to green 再变为绿色to yellow再变为黄色Alright, that#39;s it for me today好,今天就到这里I will see you next time我们下次再见 Article/201501/353337

It#39;s going to be cold for a while, but you can still look hot. Consider the ways you can brighten your face and distract yourself from the doldrums of a long winter.寒冷的天气将会持续一段时间,但是你仍然可以看上去热情似火。考虑下面的方法,可以让面部熠熠生辉,转移漫漫寒冬的暗淡无光。You Will Need你需要Oil-based moisturizer油性保湿霜Foundation primer美白隔离底霜Foundation粉底Eye shadow眼影Concealer遮瑕膏Lip gloss唇Sunscreen (optional)防晒霜(可选)Steps步骤Step 1 Put on moisturizer1.涂抹保湿霜Use an oil-based moisturizer, rather than mineral-based, before applying your makeup. Minerals can dry skin and offer little protection against cold and low humidity. Look for moisturizer that provides essential vitamins that can rejuvenate the skin.化妆之前先涂抹油性保湿霜,而不是矿物质成份的保湿霜。矿物质会导致皮肤干燥,而且在寒冷干燥的空气中不能保护皮肤。寻找能够恢复皮肤活力,可以提供必需维他命的保湿霜。Put on sunscreen to further protect yourself if you are going to be out in the sun a lot. The sun can still burn when it reflects off snow.如果曝露在阳光下的时间比较长,涂抹一层防晒霜,进一步保护皮肤。在雪的反射下,阳光仍然会灼伤皮肤。Step 2 Build the foundation2.打粉底Smooth on a foundation primer before your foundation, which will make it last longer without fading. Light foundation in winter works well with all skin types. Then apply a moisturizing foundation to further combat the effects of dry winter weather.涂抹粉底之前先涂一层美白隔离底霜,可以让妆容保持更长时间。冬季,轻薄的粉底适合所有皮肤类型。然后涂抹一层保湿效果的粉底,进一步抵抗寒冷干燥的天气。Step 3 Counteract winter effects3.抵消冬季影响Counteract winter#39;s effects on under-eye circles by working in concealer a shade or two lighter than your skin tone under each eye.眼袋部位涂抹比皮肤颜色稍浅一点的眼影,抵消冬季的影响。Lip gloss tends to stay on longer than plain lip balm.唇的持续时间比普通润唇膏的持续时间更长。Step 4 Go for neutral shades4.选择中性眼影In general, opt for neutral shades of winter makeup. Choose light browns, grays, and pinks, and matte eye shadows in gray and brown.总体来说,冬季妆容选择比较中性的眼影。选择淡棕色,灰色,粉红色,灰色和棕色的无光泽眼影。American women, influenced by Hollywood, began using suntanning powders after 1920.受好莱坞电影影响,美国女性从1920年以后开始使用晒黑粉。 Article/201411/339614

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