问题 填空题

分别取40mL的0.50mol/L盐酸与40mL 0.55mol/L氢氧化钠溶液进行中和反应。通过测定反应过程中所放出的热量可计算中和热。请回答下列问题。

(1)理论上稀强酸、稀强碱反应生成1mol水时放出57.3kJ的热量,写出表示稀硫酸和稀氢氧化钠溶液反应的中和热的热化学方程式                           

(2)如右图所示,仪器A的名称是_______________;在实验过程中,如果不把温度计上的酸用水冲洗干净直接测量NaOH溶液的温度,则测得的△H       (填“偏大”、“偏小”或“无影响”);

(3)假设盐酸和NaOH溶液的密度都是1g/cm3,又知中和后生成溶液的比热容c=4.18×10-3  kJ/(g·℃)。为了计算中和热,某学生实验记录数据如下:

 

依据该学生的实验数据计算,该实验测得的中和热△H=___________;(结果保留一位小数)

(4)若用0.50mol/L醋酸代替盐酸和氢氧化钠溶液反应则测得中和热会       (填“偏大”、“偏小”或“无影响”)。

答案

(1)1/2H2SO4(aq)+ NaOH (aq)="=" 1/2Na2SO4(aq)+H2O(1);△H=-57.3kJ·mol1(2分)

(2)环形玻璃搅拌棒(1分)偏大(1分)

(3)-51.8 kJ/mol(2分)

(4)偏小(1分)

问答题
单项选择题

Looking back on my childhood, I am convinced (1) naturalists are born and not made. Although we were all brought (2) in the same way, my brothers and sisters soon gave up their pressed flowers and insects. (3) them, I had no ear (4) music and languages, I was not an early reader and I could not do mental arithmetic.Before World War I we (5) our summer holidays in Hungary. I have only the memory of the house we lived (6) , of my room and my toys. I can hardly (7) clearly the large family of grandparents, aunts, uncles and cousins who gathered (8) door. But I do have a clear memory of the dogs, the farm (9) , the local birds and, (10) all, the insects.I am a (11) , not a scientist. I have a p (12) of the natural world, and my enthusiasm has led me into varied investigation. I love discussing my favorite topics and enjoy (13)  the midnight oil  (14)  reading about other people’s observations and discoveries. Then  (15)  happens that brings these observations together  (16)  my conscious mind. Suddenly you fancy (想象), you see the answer  (17)  the riddle, and books, of which some might honor with the title of scientific research.But curiosity, a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist; one of the outstanding and essential  (18)  required is self-discipline, a quality I lack. A scientist requires not only  (19)  but also hard training, determination and a goal. A scientist, up to a point, can be made. A naturalist is  (20) . If you can combine the two, you get the best of both worlds.

 

第(16)空应选择()

A.of

B.on

C.to

D.over