Question

hòa tan hoàn toàn Mg vào 50ml dd CH3COOH. cô cạn dd thu được 1,42g muối khan

a. viết PTHH

b. tính C_M của dd CH3COOH

c. cần bao nhiêu dd NaOH 0,5M để trung hòa hết 100ml dd CH3COOH?

Answer 1

Mg + 2CH3COOH => (CH3COO)2Mg + H2

n muối = m/M = 1.42/142 = 0.01 (mol)

Theo phương trình ==> nCH3COOH = 0.02 (mol). 50ml = 0.05 (l)

C_{M dd CH3COOH} = n/V = 0.02/0.05 = 0.4 M

CH3COOH + NaOH => CH3COONa + H2O

50ml---> 0.02 mol; 100ml => 0.04 mol

==> nNaOH = 0.04 (mol)

V dd NaOH = n/Cm = 0.04/0.5 = 0.08 l = 80ml

Answer 2

n(CH3COO)2Mg= 0.01 (mol)

2CH3COOH + Mg --> (CH3COO)2Mg + H2

nCH3COOH= 0.02mol

CM CH3COOH= 0.02/0.05=0.4M

c) n CH3COOH= 0.4*0.1=0.04 mol

CH3COOH + NaOH --> CH3COONa + H2O

=> nNaOH= 0.04 (mol)

VNaOH= 0.04/0.5=0.08 l