Question

                                        

新新用大理石與稀鹽酸反應(yīng)制取二氧化碳氣體，反應(yīng)產(chǎn)生的二氧化碳氣體的質(zhì)量與加入的稀鹽酸的質(zhì)量關(guān)系如圖所示．稀鹽酸中溶質(zhì)的質(zhì)量分數(shù)；                                         

（2）恰好完全反應(yīng)時所得溶液的質(zhì)量．                            

                                        

Answer 1

【考點】根據(jù)化學(xué)反應(yīng)方程式的計算；有關(guān)溶質(zhì)質(zhì)量分數(shù)的簡單計算．         

【專題】溶質(zhì)質(zhì)量分數(shù)與化學(xué)方程式相結(jié)合的計算；綜合計算（圖像型、表格型、情景型計算題）．           

【分析】（1）根據(jù)二氧化碳的質(zhì)量可求出鹽酸的質(zhì)量，再求所用稀鹽酸的溶質(zhì)質(zhì)量分數(shù)；        

（2）據(jù)圖可看出石灰石樣品恰好完全反應(yīng)時所加稀鹽酸的質(zhì)量為36.5g，所得溶液的質(zhì)量=所加入的所有物質(zhì)的質(zhì)量總和﹣生成氣體的質(zhì)量﹣沉淀的質(zhì)量．                                   

【解答】解：（1）由圖可知生成二氧化碳2.2g．                        

設(shè)碳酸鈣的質(zhì)量為x，參加反應(yīng)的HCl的質(zhì)量為y，                      

    CaCO₃+2HCl═CaCl₂+H₂O+CO₂↑                                  

     100   73              44                                  

      x    y               2.2g                                

，                                                

x=5.0g                                                      

                                                   

y=3.65g                                                     

參加反應(yīng)的鹽酸的質(zhì)量分數(shù)為=×100%=10%                        

（2）恰好完全反應(yīng)時加入的鹽酸的質(zhì)量為36.5g；                       

反應(yīng)后得到溶液的質(zhì)量為：36.5g+5.0g﹣2.2g=39.3g                     

答：（1）稀鹽酸中溶質(zhì)的質(zhì)量分數(shù)10%；                           

（2）恰好反應(yīng)后所得溶液的質(zhì)量為39.3g．                         

【點評】求反應(yīng)后所得溶液的質(zhì)量的計算是初中化學(xué)計算的一個重點內(nèi)容，其方法一般是：所加入的所有物質(zhì)的質(zhì)量總和﹣生成氣體的質(zhì)量﹣生成沉淀的質(zhì)量．