问题 问答题

甲醇是一种可再生能源,具有广泛的开发和应用前景,因此甲醇被称为21世纪的新型燃料.工业上用CO生产燃料甲醇,一定条件下发生反应:CO(g)+2H2(g)⇌CH3OH(g).图l表示反应中能量的变化;图2表示一定温度下,在体积为2L的密闭容器中加入4molH2和一定量的CO后,CO和CH3OH(g)的浓度随时间变化图.

请回答下列问题:

(1)在“图1”中,曲线______(填“a”或“b”)表示使用了催化剂;该反应属于______(填“吸热”或“放热”)反应.

(2)根据“图2”判断,下列说法正确的是______

a.起始充入的CO为1mol

b.增加CO浓度,可使H2的转化率增大

c.容器中压强恒定时,反应已达平衡状态

d.保持温度和密闭容器容积不变,再充入1molCO和2molH2,再次达到平衡时n(CH3OH)/n(CO)会增大

(3)从反应开始到建立平衡,v(H2)=______;该温度下CO(g)+2H2(g)⇌CH3OH(g)的化学平衡常数为______.若保持其它条件不变,将反应体系升温,则该反应的化学平衡常数将______(填“增大”、“减小”或“不变”).

(4)请在“图3”中画出平衡时甲醇蒸气百分含量(纵坐标)随温度(横坐标)变化的曲线,要求画压强不同的2条曲线(在曲线上标出P1、P2,且P1>P2).

答案

(1)加入催化剂,可降低反应的活化能,由图象可知b活化能较低,应加入催化剂,反应物的总能量大于生成物的总能量,则反应为放热反应,

故答案为:b;放热;

(2)A.CO的起始浓度为1moL/L,体积为2L,则起始充入的CO为2mol,故a错误;

B.增加CO浓度,平衡向正方向移动,H2的转化率增大,故b正确;

C.由于反应前后气体的体积不等,则容器中压强恒定时,反应已达到平衡状态,故c正确;

D.保持温度和密闭容器容积不变,再充入1mol CO和2mol H2,相当于在原来的基础上缩小体积,压强增大,平衡向正反应方向移动,则平衡时

n(CH3OH)
n(CO)
会增大,故d正确.

故答案为:bcd;

(3)从反应开始到建立平衡,v(CO)=

1mol/L-0.25mol/L
10min
=0.075moL/(L•min),

则v(H2)=2v(CO)=0.15moL/(L•min),

平衡时:c(CO)=0.25mol/L,c(CH3OH)=0.75mol/L,

则消耗n(CO)=0.75mol/L×2L=1.5mol,消耗的n(H2)=3mol,

平衡时c(H2)=

4mol-3mol
2L
=0.5mol/L,

k=

0.75
0.25×0.52
=12,

故答案为:0.15moL/(L•min);12;

(4)增大压强,平衡向正反应方向移动,则甲醇的百分含量增大,温度升高,平衡向逆反应方向移动,甲醇的百分含量降低,则图象可为

故答案为:

单项选择题

As one works with color in a practical, or experimental way, one is impressed by two apparently unrelated facts. Color as seen is a mobile, changeable thing (1) to a large extent on the relationship of the color (2) other colors (3) simultaneously. It is not (4) in its relation to the direct stimulus which (5) it. On the other hand, the properties of surfaces that give (6) to color do not seem to change greatly under a wide variety of illumination color, usually (but not always) looking much the same in artificial light as in daylight. Both of these effects seem to be (7) in large part to the mechanism of color (8) .

When the eye is (9) to a colored area, there is an immediate readjustment of the (10) of the eye to color in and around the area (11) . This readjustment does not promptly affect the color seen but usually does affect the next area to which the (12) is shifted. The longer the time of viewing, the higher the (13) , and the larger the area, the greater the effect will be (14) its persistence in the (15) viewing situation. As indicated by the work of Wright and Schouten, it appears that, at (16) for a first approximation, full adaptation takes place over (17) time if the adapting source is moderately bright and the eye has been in (18) darkness just previously. Also, (19) of the persistence of the effect if the eye is shifted around from one object to another, all of which are at similar brightness or have similar colors, the adaptation will tend to become (20) over the whole eye.

15()

A.transparent

B.succeeding

C.simultaneous

D.proceeding

单项选择题