更多

关闭

当前位置:语言中心 > 英语 > SAT > SAT学习 > SAT化学 > SAT化学练习:Equilibrium

成绩查询考试日历

SAT化学练习:Equilibrium

http://yingyu.yinghuaedu.com  来源:英华教育(青岛)语言中心  发布时间:2012-09-11 13:49:55

英华教育(青岛)语言中心--SAT化学练习:Equilibrium-英华外语整理SAT化学练习:Equilibrium,供学员学习。班制灵活,随报随学,英华教育咨询热线:400-0532-757

 Chemical equilibrium has been reached in a reaction when the rate of the forward reaction is equal to the rate of the reverse reaction. When a chemical reaction has reached equilibrium, collisions are still occurring: the reaction is now happening in each direction at the same rate. This means that reactants are being formed at the same rate as products are being formed, and this is indicated by double arrows, . At equilibrium, the reaction can lie far to the right, meaning that there are more products in existence at equilibrium, or far to the left, meaning that at equilibrium there are more reactants. The concentration of the reactants and products in a reaction at equilibrium can be expressed by an equilibrium constant, symbolized K or Keq:For the general reaction

  aA + bB cC + dD

  In the above expression, the brackets, as always, symbolize the concentration of the reactants and products in molarity. However, while in the above expression we used the plain symbol K to symbolize the equilibrium constant, there are several types of equilibrium constants. For example, Kc symbolizes the equilibrium constant in an aqueous solution, Kp symbolizes the partial pressures of gases in equilibrium, and Ksp symbolizes the solubility product of solids classified as insoluble. K values have no units, and a K > 1 means that the reaction favors the products at equilibrium, while a K < 1 means that the reaction favors the reactants at equilibrium.Here are a couple of rules to follow when using equilibrium constant expressions on the exam: Pure solids do not appear in the equilibrium expression. Pure liquids do not appear in the equilibrium expression. Water, either as a liquid or solid, does not appear in the equilibrium expression. When a reactant or product is preceded by a coefficient, its concentration is raised to the power of that coefficient in the Keq expression. When the Keq of a reaction has been multiplied by a number, the K is raised to the power of the multiplication factor (Kn), so if it has been multiplied by 2, K is squared, if it has been multiplied by 3, K is cubed, and so on. The Keq of a reaction occurring in the reverse direction is simply the inverse of the Keq of the reaction occurring in the forward direction (1/Keq). The Keq of a net reaction that has two or more steps is found by the product of the Keq s for each of the steps: Ks = (K1K2K3 . . .).  Let’s work through an example now of an equilibrium question.   ExampleWrite the equilibrium expression for the following equation:

  H2(g) + I2(g) 2HI(g)

  If K is calculated to have a value of 2.5 for the reaction above, what is the value of the equilibrium constant for the following reaction?

  4HI(g) 2H2(g) + 2I2(g)

  ExplanationThe equilibrium constant expression for the reaction is

  The reaction has been doubled and reversed, so the new K is the reciprocal of the old K squared (since the reaction coefficients are doubled):

(责任编辑:)

转载时请注明本文地址:http://yingyu.yinghuaedu.com/sat/satstudy/sahuaxue/view_677.html

相关关键字: SAT 化学 练习 英华 青岛 教育 考试

上一篇:SAT化学练习:Energy Diagrams

下一篇:SAT化学:Half-Lives

扫描二维码加微信好友
扫描二维码查看手机名片
青岛英华英语-岛城权威英语培训机构
青岛学外语选青岛英华外语学校

问吧

更多>>
咨询关于贵校俄语教师招...
你好,招聘事宜可以发送个人简历至人事部邮箱,相...[详细]
您好,打算寒假学德语,...
同学你好,学校2013年寒假开设各级别德语课程,具...[详细]
你好,请问现在有葡萄牙语...
同学你好,学校现有葡萄牙语白天,晚班和周末班班...[详细]
我要提问
#

英华外语承诺

全国免费咨询电话:0532-85925679

学费更优惠!
青岛英华教育语言中心,作为全国AAA级语言中心,秉承“平等教育、惠及大众”的原则,以公平合理的收费,超一流教学质量,赢得了广大学员认可与赞誉!
教学更权威!
语言中心采用“质量生存法则”,打造了一支由外国持证专家+海归硕士组成的精英教学团队,是岛城教学研究,教材研发的权威机构,岛城外语教学领航者。
服务更超值!
“想同学之所想,急家长之所急”是英华教育服务的理念。学校采用四位一体的服务模式,即:教务主管+课程顾问+班主任+任课教师的综合服务模式,属岛城首创!
报名更放心!
“选择英华,收获未来!”是所有英华人的承诺。中心课程包教包会,学不会免费重学。开课前无条件转班、调课。中心采用学员否决制,由学员对教学团队进行严格考核!