Question

20．某同學(xué)要配制50g溶質(zhì)質(zhì)量分?jǐn)?shù)為16%的食鹽溶液，其步驟為計(jì)算、稱量、溶解；需要食鹽的質(zhì)量為8g，水的質(zhì)量為42g．

Answer 1

分析 根據(jù)配制溶質(zhì)質(zhì)量分?jǐn)?shù)一定的溶液的基本步驟，溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)，溶劑質(zhì)量=溶液質(zhì)量-溶質(zhì)質(zhì)量，進(jìn)行分析解答．

解答 解：某同學(xué)要配制50g溶質(zhì)質(zhì)量分?jǐn)?shù)為16%的食鹽溶液，首先計(jì)算配制溶液所需食鹽和水的質(zhì)量，再稱量所需的食鹽和量取水，最后進(jìn)行溶解．
溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)，配制50g溶質(zhì)質(zhì)量分?jǐn)?shù)為16%的食鹽溶液，需食鹽的質(zhì)量=50g×16%=8g；溶劑質(zhì)量=溶液質(zhì)量-溶質(zhì)質(zhì)量，則所需水的質(zhì)量=50g-8g=42g．
故答案為：計(jì)算、稱量、溶解；8g；42g．

點(diǎn)評(píng) 本題難度不大，掌握配制溶質(zhì)質(zhì)量分?jǐn)?shù)一定的溶液的基本步驟、注意事項(xiàng)等是正確解答本題的關(guān)鍵．