问题 实验题

今用铝、稀硫酸和氢氧化钠溶液为原料,在实验室制备一定量的氢氧化铝。可分别采用如下化学方程式所表示的两种方法:

①2Al+3H2SO4=Al2(SO4)3 +3H2

Al2(SO4)3+6NaOH=2Al(OH)3↓+3Na2SO4

②2Al+2NaOH +2H2O=2NaAlO2 +3H2

2NaAlO2+ H2SO4+ 2H2O=2Al(OH)3↓+Na2SO4

(1)上述哪一种方法比较节约试剂[提示:试从每生产2 mol Al(OH)3所耗费的试剂用量予以说明]

(2)原料相同,请设计一种更为节约试剂的方法(说明其可以节约试剂的根据)。

答案

(1)后一种方法比较节约试剂。

(2)用2 mol Al中的0.5 mol Al与H2SO4反应(消耗mol H2SO4)生成0.5 mol Al3+

用2 mol Al中的1.5 mol Al与NaOH 反应(消耗1.5 mol NaOH)生成1.5 mol AlO2-

二者混合生成 2 mol Al(OH)3

阅读理解

MONEY – SAVING TIPS FOR DISNEY WORLD

Every time you visit Disney World, there’s something new to see. What began in 1971 as the Magic Kingdom now includes the high – tech, movie-mad Disney and Animal Kingdom . Each time the park expands(扩大), so do your chances to spend money. How can you save ? As a family guide to Disney World, I've been to the park more than 25 times with my kids , and I've developed a few money-saving tips for you.

●Buy the Five-Day All-in-One Hopper Pass. Even if you're visiting for fewer days , it's a deal (The pass costs $ 229 for visitors aged 10 and up , $ 183 for kids aged three to nine and is free for kids under age three). Without the pass , you'll have to pay separately for Pleasure Island and the water parks . A single trip to Blizzard Beach , for example , would cost a family of four $100.

  ● Dine out at Lunchtime. The prices at some of the nicer restaurants , especially those in Epcot's World Showcase , are much lower at noontime than at any other time. It's wise to make reservations(预定)before you leave home . Call 407-W-DISNEY .

 ● Become a Gold Card Member.  For $ 65 , you can get a Magic Kingdom Club Gold Card (call 1-800-56-DISNEY). Cardholders get up to 20% off Disney hotel rooms , plus prices on character breakfast , theme park tickets and goods from Disney stores .

 ● Don't Pay Extra to See a Character.  Character-theme dinner shows are expensive , costing a family of four about $ 140 , and even a character breakfast , where Mickey or Donald Duck joins you for cakes , can set you back $ 50. If your budget (预算) is tight, try to meet the characters inside the theme parks and at free in-park shows . You can watch the Diamond Horseshoe show , for example , in the Magic Kingdom for no additional cost , while the similarly themed Hoop-Dee-Doo Musical Revue needs expensive tickets .

 ● Wait Until the End of Your Trip to Buy Souvenirs.  By then , the kids will really know what they want , and you won't waste money on expensive things .

67.If you are short of money, the writer suggests you should not        .

A.buy things for the kids from Disney stores.

B.buy souvenirs at the beginning of the trip

C.make a trip to Blizzard Beach

D.have your meals out at noontime

68.Which of the following can be used in place of “set you back”

A.offer you  B.save you   C.return you D.cost you

69.You should pay more money if you         .

A.have a five – day All – One Hopper Pass while you’re visiting for four days.

B.do not make a reservation for hotel rooms in advance..

C.are not a Magic Kingdom Club Gold Card holder.

D.have lunch at a restaurant in Epcot’s World Showcase

70.In the writer’s opinion, the better way of meeting the Disney cartoon character is        .

A.to have a character breakfast

B.to watch the Diamond Horseshoe show

C.to pay separately for Pleasure Island and the water parks

D.to attend the Hoop – Dee – Doo Musical Revue

单项选择题