问题 填空题

(4分)(1)t℃时,测得纯水中c(OH)=2×107mol·L1, 则t    25℃(填“>”、“<”或“=”),该温度下,水的离子积常数为                 ;

(2)25℃时,某K2SO­4溶液中c(SO42)=1×104mol·L1,取该溶液1mL加水稀释至100mL,则稀释后的溶液中c(K+): c(H+)=                   ;

(3)已知H2(g)+Cl2(g)=2HCl(g)   △H=-184.6 kJ/mol;则反应1/2H2(g)+1/2Cl2(g)=HCl(g) 的△H                      

答案

(4分)(1)>; 4×1014  (2) 20 : 1 (3)-92.3 kJ/mol

(1)电离是吸热的,所以如果测得纯水中c(OH)=2×107mol·L1, 则t>25℃。该温度下,水的离子积常数为=2×107×2×107=4×1014

(2)硫酸钾溶液显中性,所以吸收后氢离子浓度还是1×107mol·L1c(SO42)=1×104mol·L1,则c(K+)=2×104mol·L1,所以稀释后c(K+)=2×106mol·L1,因此稀释后的溶液中c(K+)︰c(H+)="20" : 1。

(3)反应热和化学计量数成正比,所以△H=-184.6 kJ/mol÷2=-92.3 kJ/mol。

阅读理解

A teddy bear from Cumbria is launching into space to raise cash for charity(慈善).

Terence, an experienced traveller who has been to Iraq, will be the guest of honour on aviation(航行) legend Burt Rutan’s Spaceship One when it flies above Earth. The mission takes off from California on September 29, and on his return the cuddly toy will be auctioned off(拍卖) in aid of the North Air Ambulance Appeal(北部空中救护服务中心).

Spaceship One is the world’s first private spacecraft, and is competing for a prestigious space travel prize. Chief executive of the Great North Air Ambulance Service (GNAAS), Graham Pickering, said “flying officer” Terence had been handed over to the RAF six months ago and staff had been receiving postcards from him ever since.

He said, “Terence was a fundraising idea that really took off. We have received pictures of him in a U2 craft, trying parachuting and even looking drunk and disorderly. When the RAF finally discharge him he will be a very rare bear indeed—we just hope he does not burn up on re-entry to Earth.”

GNAAS, which needs charitable donations of more than £2m a year, has three air ambulances(空中救护机).

Peter Bond, spokesman for the Royal Astronomical Society, said Terence’s safety was not guaranteed. He said, “This is a new and experimental craft and this will only be the second time it has flown. During its first voyage it developed technical problems but hopefully they have now been resolved.”

Since May, Terence has spent time with members of 100 Squadron(空军中队) based at RAF Leeming in Basra, Iraq, and at air shows with performing fighter planes.

Spaceship One will fly 100km (62 miles) above the Earth’s surface, just breaking through the planet’s atmosphere.

If it repeats the feat(技艺) inside two weeks, it will claim the $10m Ansari X-Prize set up to encourage the private space flight business.

小题1:Terence is ________.

A.a real bear living in England

B.an experienced astronaut

C.an air force officer

D.a toy bear小题2:We can infer that________.

A.after this space flight, Spaceship One will get the $10m Ansari X-Prize

B.it is dangerous for a spaceship to re-enter the earth atmosphere

C.Terence will be very safe on the flight

D.Spaceship One is just an ordinary plane小题3:Which of the following is true of Spaceship One?

A.Spaceship One is the world’s first spacecraft.

B.The purpose of its flight is to collect money for the charity.

C.The purpose of its flight is to compete for a prestigious space travel prize.

D.Spaceship One has never flown.小题4:Which of the following is the best title?

A.Teddy bear astronaut to lift off

B.Spaceship One to lift off

C.Space flight

D.The toy bear will be auctioned off

单项选择题