cho dd hỗn hợp X gồm HCL 1M và ALCL3 1,5M tính thể tích dd hỗn hợp NAOH 1M và KOH 2M nhiều nhất cần dùng để khi cho vào 100ml dd X thì thu đc 7,8 gam kết tủa

2 câu trả lời

\(n_{HCl}=0,1mol, n_{AlCl_3}=0,15 mol,n_{Al(OH)_3}=0,1mol\)

gọi thể tích cần dùng là V

OH- + H+ ------> H2O

0,1 \(\leftarrow\) 0,1

\(Al^{3+} + 3OH^- ----->Al(OH)_3 \)

0,15 \(\to\) 0,45

do n kết tủa < \( n_{Al^{3+}} \) nên kết tủa bị hòa tan

\( Al(OH)_3 + OH^- -----> {AlO_2}^- +2H_2O\)

0,15-0,1 0,05

\( n_{OH^-}= 0,6mol\)

gọi mol NaOH và KOH là x, y ta có x+ y= 0,6, x/1=y/2 => x=0,2

=> V = 0,2/1=200 ml

Đáp án:

Giải thích các bước giải: nAl(OH)3 =0,1

Đạt nNaOH=x , nKOH=2x

nOH- max=4nAl3+ - n kết tủa + nH+

3x = 4.0,15 -0,1 +0,1

x = 0,2

⇒ V = 0,2(l)

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