課題3-溶液的濃度

課題3溶液的濃度第九單元溶液學(xué)習(xí)目標(biāo)1.掌握溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)的概念2.會(huì)計(jì)算有關(guān)溶質(zhì)的質(zhì)量分?jǐn)?shù)對(duì)溶質(zhì)的質(zhì)量分?jǐn)?shù)概念的理解學(xué)習(xí)難點(diǎn)123燒杯編號(hào)溶液顏色比較溶劑質(zhì)量/g溶質(zhì)質(zhì)量/g溶液質(zhì)量/g123淺藍(lán)藍(lán)深藍(lán)2020200.120.520.120.522實(shí)驗(yàn)比較三支試管里硫酸銅溶液?哪種溶液最濃?哪種溶液最稀?飛機(jī)噴灑農(nóng)藥溶液濃度的表示方法----溶質(zhì)的質(zhì)量分?jǐn)?shù)溶質(zhì)的質(zhì)量分?jǐn)?shù)是溶質(zhì)質(zhì)量與溶液質(zhì)量之比表達(dá)式:定義:溶質(zhì)質(zhì)量溶液質(zhì)量100%推導(dǎo)式:溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)×溶質(zhì)的質(zhì)量分?jǐn)?shù)==溶質(zhì)質(zhì)量溶質(zhì)質(zhì)量+溶劑質(zhì)量×100%比較下列兩組溶液，補(bǔ)充完成下表溶質(zhì)質(zhì)量、溶劑質(zhì)量現(xiàn)象溶質(zhì)的質(zhì)量分?jǐn)?shù)1090全部溶解2080全部溶解10%20%有關(guān)溶質(zhì)質(zhì)量分?jǐn)?shù)的計(jì)算對(duì)于不飽和的溶液計(jì)算公式：注意：當(dāng)溶液為飽和溶液，并且溶質(zhì)有剩余時(shí)，未溶解的固體不能當(dāng)成溶質(zhì)來(lái)計(jì)算。溶質(zhì)的質(zhì)量分?jǐn)?shù)=實(shí)際溶解的溶質(zhì)質(zhì)量+溶劑質(zhì)量實(shí)際溶解的溶劑質(zhì)量練習(xí)1、20℃時(shí)，將50gNaCl放入100g水中，充分?jǐn)嚢韬笏肗aCl溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)是（20℃時(shí)NaCl的溶解度為36g）溶質(zhì)的質(zhì)量分?jǐn)?shù)=實(shí)際溶解的溶劑質(zhì)量實(shí)際溶解的溶質(zhì)質(zhì)量+溶劑質(zhì)量=3636+100討論：已知200C時(shí)，氯化鈉的溶解度是36g。有人說(shuō)：“200C時(shí)氯化鈉飽和溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為36%。”這種說(shuō)法對(duì)嗎？為什么？溶質(zhì)質(zhì)量/g溶劑質(zhì)量/g溶液質(zhì)量/g36

100

13636g136g100%×=26.5%推導(dǎo)：SS+100g×100%將31gNa2O溶于69g水中，所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)是多少？解析：由于酸性氧化物（或堿性氧化物）溶于水后，該物質(zhì)不是溶質(zhì)，而是與水發(fā)生反應(yīng)后，生成相應(yīng)的酸（或堿）才是溶質(zhì)，故解此類題時(shí)，應(yīng)先根據(jù)反應(yīng)的化學(xué)方程式計(jì)算出生成的溶質(zhì)量，再求溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)。解：設(shè)Na2O與水發(fā)生反應(yīng)生成NaOH的質(zhì)量為x628031gx解得：溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為溶液的稀釋稀釋前（濃）稀釋后（?。┤芤嘿|(zhì)量/gA溶質(zhì)的質(zhì)量分?jǐn)?shù)a%b%溶質(zhì)質(zhì)量/g加入水的質(zhì)量為xA+x(A+x)×b%A×a%？？？溶液稀釋前后，溶質(zhì)的質(zhì)量不變A×a%=(A+x)×b%影響溶液濃度的因素溶質(zhì)質(zhì)量溶劑質(zhì)量溶液質(zhì)量溶液濃度溶質(zhì)的質(zhì)量分?jǐn)?shù)取部分溶液增加溶質(zhì)增加溶劑(溶液稀釋)減少溶質(zhì)(降溫結(jié)晶)蒸發(fā)溶劑不變不變不變不變不變不變