Question

某環(huán)保小組監(jiān)測到一工廠向河中排放的酸性廢液中含有CuCl₂。為了測定廢液中CuCl₂的質(zhì)量分數(shù)。該小組取了100g廢液，逐滴滴入NaOH溶液至過量。測得生成Cu（OH）₂沉淀與所加NaOH溶液的質(zhì)量關(guān)系如下圖。

（1）計算廢液中CuCl₂的質(zhì)量分數(shù)

（2）說明圖上OA段未生成Cu（OH）₂沉淀的原因：_____________________________

Answer 1

（1）設(shè)廢液中CuCl₂的質(zhì)量為X。

CuCl₂  +  2NaOH ===== 2NaCl  +  Cu（OH）₂↓

135                                                                                                                    98

X                                   19.6g 

135 : 98 == X : 19.6g

X == 27 g                                                                                                                                                                                                    

廢液中CuCl₂的質(zhì)量分數(shù)為:                                        

（2）滴入的NaOH先與廢液中的酸產(chǎn)生反應