题目

已知：2Zn（s）+O2（g）=2ZnO（s）        △H=-701.0kJ·mol-1         2Hg（l）+O2（g）=2HgO（s）        △H=-181.6kJ·mol-1 则反应Zn（s）+ HgO（s）=ZnO（s）+ Hg（l）的△H为 A. +519.4kJ·mol-1                 B. +259.7 kJ·mol-1  C. -259.7 kJ·mol-1                D. -519.4kJ·mol-1  答案：【答案】C 【解析】反应的焓值由盖斯定律直接求出。即(△H1-△H2)/2=-259.7 kJ·mol-1。误区警示：本题中两负数相减易出错，此外系数除以2时，焓值也要除2。读短文，选择正确答案。It is half past four. Jane and Tom are in the supermarket now. Jane has got eight yuan. Tom has got ten yuan. The supermarket is very big. They can see clothes, food, fruit and flowers in it. Jane likes chocolate. A large packet of chocolate is twelve yuan. A small packet of chocolate is seven yuan. Tom is thirsty. A large bottle of orange juice is eleven yuan. A large bottle of apple juice is ten yuan. Jane has got the chocolate and Tom has got the juice. They are happy.【1】Jane and Tom are in the _____ now. ( )A.supermarketB.toy shopC.food shop【2】Which chocolate can Jane buy? ( )A.The large one.B.The small one.C.Both.【3】Which juice can Tom buy? ( )A.The orange juice.B.The apple juice.C.Both.