從100g5%的食鹽溶液中取出20g溶液后,再向剩余溶液中加入20g水,則其溶質(zhì)質(zhì)量分數(shù)變?yōu)椋ā 。?/div>
分析:溶液具有均一性,從100g5%的食鹽溶液中取出20g溶液后,剩余溶液的溶質(zhì)質(zhì)量分數(shù)仍為5%,再向剩余溶液中加入20g水,根據(jù)溶質(zhì)質(zhì)量分數(shù)=
×100%,進行分析解答.
解答:解:溶液具有均一性,從100g5%的食鹽溶液中取出20g溶液后,剩余溶液的溶質(zhì)質(zhì)量分數(shù)仍為5%,再向剩余溶液中加入20g水,則其溶質(zhì)質(zhì)量分數(shù)變?yōu)?span id="gsiawoq" class="MathJye" mathtag="math" style="whiteSpace:nowrap;wordSpacing:normal;wordWrap:normal">
(100g-20g)×5% |
100g-20g+20g |
×100%=4%.
故選:B.
點評:本題難度不大,掌握溶質(zhì)質(zhì)量分數(shù)的有關(guān)計算并能靈活運用是正確解答本題的關(guān)鍵.