Question

小明將14.4g含雜質的純堿樣品（碳酸鈉與氯化鈉的混合物）與90g稀鹽酸相混合，恰好完全反應，測得反應生成氣體的質量（m）與反應時間（t）的數(shù)據如下表所示：

反應時間t/s	t0	t1	t2	t3	t4	t5	t6	t 7
氣體質量m/g	0	0.88	1.76	2.64	3.52	4.4	X	4.4

(26)                                                                                                                                                                                                                                                                表中X的值為        ；

(27)                                                                                                                                                                                                                                                                計算樣品中NaCl的質量；

(28)                                                                                                                                                                                                                                                                計算完全反應后所得溶液中溶質的質量分數(shù)。

Answer 1

(1) 4.4（1分）

(2) Na₂CO₃ + 2HCl = 2NaCl + H₂O + CO₂↑

106            117         44

y              z          4.4g

    g   （1分）      

樣品中m_(NaCl) = 14.4g – 10.6g = 3.8g（1分）

(3)         （1分）

    11.7g + 3.8g = 15.5g（1分）

    （2分）