Question

在化學(xué)反應(yīng)2A+B═C+D中，已知25gA與15gB剛好完全反應(yīng)，生成10gD，并且C的相對(duì)分子質(zhì)量為60，那么A的相對(duì)分子質(zhì)量為　　．                                                

Answer 1

【考點(diǎn)】根據(jù)化學(xué)反應(yīng)方程式的計(jì)算．                             

【專題】有關(guān)化學(xué)方程式的計(jì)算．                                 

【分析】根據(jù)質(zhì)量守恒定律，C物質(zhì)的質(zhì)量應(yīng)為A和B物質(zhì)的質(zhì)量之和減去D物質(zhì)的質(zhì)量，即（25g+15g）﹣10g=30g，根據(jù)反應(yīng)物和生成物中各物質(zhì)之間的質(zhì)量比，等于它們相對(duì)分子質(zhì)量總和之比進(jìn)行計(jì)算．         

【解答】解：根據(jù)質(zhì)量守恒定律可知，參加化學(xué)反應(yīng)的各物質(zhì)的質(zhì)量總和等于反應(yīng)后生成的各物質(zhì)的質(zhì)量總和，即C的質(zhì)量為（25g+15g）﹣10g=30g                                         

設(shè)A的相對(duì)分子質(zhì)量為x                                          

 2A+B═C+D                                                  

 2x   60                                                    

 25g  30g                                                   

=                                                   

x=25                                                        

故答案為：25．                                              

【點(diǎn)評(píng)】本題綜合考查了質(zhì)量守恒定律的應(yīng)用和化學(xué)方程式表示的含義．反應(yīng)物和生成物中各物質(zhì)的相對(duì)分子質(zhì)量總和之比，等于它們之間的質(zhì)量比．