题干

某化学兴趣小组为探究“氢氧化钠溶液与盐酸发生中和反应时溶液温度的变化情况”,进行了如下实验:

实验一:配置质量分数为10%的氢氧化钠溶液50g.

(1)计算,需称取氢氧化钠的质量为____ g.

(2)配置该溶液所需要的仪器有:烧杯、量筒、胶头滴管和____ (写仪器名称).

实验二:在一定体积的10%的氢氧化钠溶液中滴加10%的盐酸(室温下),反应中溶液温度的变化如下:

(1)该反应的化学方程式为____ .

(2)表中△t1的值为____ .

(3)试绘出溶液温度变化与加入盐酸体积之间的关系图____ .

(4)根据所绘曲线分析,加入盐酸的体积在0~10mL时,溶液温度变化的趋势及其原因是____ .

(5)其他条件不变,若改用20%的盐酸进行滴加,结合对上述曲线的分析,大胆猜想新曲线最高点的位置(不考虑溶液密度和比热容的变化及热量散失等影响因素).

①横坐标及猜想理由:____ ;

②纵坐标及猜想理由:____  .

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5,\u73bb\u7483\u68d2,NaOH+HCl=NaCl+H2O,0,,\u968f\u7740\u4e2d\u548c\u53cd\u5e94\u7684\u8fdb\u884c\uff0c\u7531\u4e8e\u53cd\u5e94\u653e\u70ed\uff0c\u6eb6\u6db2\u6e29\u5ea6\u4e0a\u5347,5\uff0c\u5f53\u6070\u597d\u5b8c\u5168\u53cd\u5e9

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    Well, parents, surprise! Lots of us are using Twitter and Facebook to thumb rides, and not just to school. It's awkward to be refused when you call a friend and ask for a ride. But with Twitter, you just look for other people heading the same way.

    It may sound risky, so many teens stay within their own social circles to find rides, and don't branch out beyond friends when asking on Twitter just like me, but to some young people, especially those taking longer trips, stranger danger is less of a concern.

    “I think the digital connection of young people is really important, because younger generations grew up sharing things on line, sharing files, photos, music, etc, so they've been very used to sharing,” said Juliet Schor, a sociology professor at Boston College.

    The sharing economy got big during the recession (经济衰退), allowing people to access more goods, services using technology and even to share costs. And that technology, for me, is what the car was for my mom, a gateway to more freedom, like what my friend Earl says, “The symbol of freedom isn't the car any more because there's technology out there connecting you to a car.”

    According to the researchers at the University of Michigan, 30 years ago, eight in ten American 18-year-olds had a driver's license compared to six in ten today. So it's not that surprising that on my 16th birthday I wasn't rushing to get a license but an iPhone.

“Driving, for young people, does mean they have to disconnect from their technology, and that's a negative. So if they could sit in the passage side and still be connected, that's going to be a plus.” Schor continued.

    To me, another plus is that ridesharing represents something, something much bigger than trying to save money. I see it as evidence that people still depend on each other. My generation shares their cars and apartments the way neighbors used to share cups of sugar. For the system to work, some of us still need our own cars. But until I get my own version of the silver Super Beetle, you can find me on Twitter.