①設(shè)混合物中NaHCO3的質(zhì)量為X
2NaHCO3=△=Na2CO3+ H2O + CO2↑ △m
168 106 168-106
X 2.74g-2.12g
168:(168-106)=X:(2.74g-2.12g)
X=1.68g
混合物中NaHCO3的質(zhì)量分?jǐn)?shù)=1.68g/2.74g*100%=61.3%
2.74克混合物中含碳酸鈉的質(zhì)量=2.74g-1.68g=1.06g
設(shè)1.68克碳酸氫鈉、1.06克碳酸鈉分別與鹽酸反應(yīng)生成二氧化碳的質(zhì)量為Y、Z
NaHCO3 + HCl =NaCl + H2O + CO2↑
84 44
1.68g Y
Y=0.88g
Na2CO3 + 2HCl = 2NaCl + H2O + CO2↑
106 44
1.06g Z
Z=0.44g
0.88g+0.44g=1.32g=再取樣品生成二氧化碳,說(shuō)明再樣品的質(zhì)量與第一樣品的質(zhì)量相同.
②設(shè)1.68克碳酸氫鈉反應(yīng)所需鹽酸中含氯化氫的質(zhì)量為X1,1.06克碳酸鈉反應(yīng)所需鹽酸含氯化氫的質(zhì)量為Y1,
NaHCO3 + HCl =NaCl + H2O + CO2↑
84 36.5
1.68g X1
X1=0.73g
Na2CO3 + 2HCl = 2NaCl + H2O + CO2↑
106 73
1.06g Y1
Y1=0.73g
鹽酸的質(zhì)量分?jǐn)?shù)=(0.73g+0.73g)/100g*100%=1.46%
答:①混合物中NaHCO3的質(zhì)量分?jǐn)?shù)61.3%；
②鹽酸的質(zhì)量分?jǐn)?shù)1.46%.