用标准的NaOH滴定未知浓度的盐酸，选用酚酞为指示剂，造成测定结果偏高的原因可能是
A．滴定终点读数时，俯视滴定管的刻度，其它操作均正确
B．盛装未知液的锥形瓶用蒸馏水洗过，未用待测液润洗
C．滴定到终点读数时发现滴定管尖嘴处悬挂一滴溶液
D．未用标准液润洗碱式滴定管
CD
考查中和滴定误差分析
A：滴定终点读数时，俯视滴定管的刻度，导致读数偏小，标准溶液体积偏小，测定结果偏低
B：操作正确，测定结果正确
C：导致标准溶液体积偏大，测定结果偏高
D：导致标准溶液浓度偏小，标准溶液体积偏大，测定结果偏高
答案为CD
Why is setting goals important? Because goals can help you do, be, and experience everything you want in life. Instead of just letting life happen to you, goals allow you to make your life happen. Successful people how their life should be and set lots of goals. By setting goals you are taking control of your life. It’s like having a to show you where you want to go. Think of it this way. There are drivers. One has a destination（目的地）in mind (her goal) which can be found on a map. She can drive straight there without any wasted time or wrong turns. The other driver has no goals or destination or map. She starts off at the same time from the same place as the first driver, she drives aimlessly around, never getting anywhere, just using up gas (汽油). Which driver do you want to be? Winners in life set goals and follow through on them. They decide what they want in life and then get there by making and setting goals. people just let life happen by accident. Goals aren’t difficult to set—and they aren’t difficult to reach. It’s up to you to find out what your goals really are. You are the one who must what to achieve and in what direction to aim your life. Research tells us that when we write a goal down, we are more to achieve it. Written goals can be regularly, and have more power. Like a contract（契约） with yourself, they are harder to forget. Also you write your goals in a particular way, you are able to make yourself continuously aware of situations that will bring you nearer to your goal.
|