Question

在農(nóng)業(yè)生產(chǎn)上，有時(shí)用質(zhì)量分?jǐn)?shù)為10%-20%的食鹽溶液來選種．現(xiàn)有NaC1質(zhì)量分?jǐn)?shù)為30%的食鹽水60g，與NaC1質(zhì)量分?jǐn)?shù)為10%的溶液混合來配制溶液中NaC1質(zhì)量分?jǐn)?shù)為15%的選種液，則配制這樣的選種液需NaC1質(zhì)量分?jǐn)?shù)為10%的食鹽溶液多少克？

Answer 1

解：設(shè)需10%的食鹽溶液質(zhì)量為x．
60g×30%+x×10%=（60g+x）×15%
解得x=180g
答：需要10%的食鹽溶液180g．
分析：需要濃溶液中溶質(zhì)質(zhì)量與稀溶液中溶質(zhì)質(zhì)量之和與配制成的溶液中溶質(zhì)質(zhì)量相等，據(jù)此可得本題答案．
點(diǎn)評(píng)：本題考查同溶質(zhì)的濃、稀溶液混合的溶質(zhì)質(zhì)量分?jǐn)?shù)的相關(guān)計(jì)算，難度稍大．