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© Hachette Livre – H Prépa / Optique, 1 re année, MPSI-PCSI-PTSI –La photocopie non autorisée est un délit<br />

648<br />

Corrigés<br />

1) 2)<br />

(a) CH3COOH + C6H5NH2 = CH3COO – + C6H5NH + 3<br />

(b) NH + 4 + NO – 2<br />

= NH3 + HNO2 (c) NH + 4 + C6H5NH2 = NH3 + C6H5NH + 3<br />

3) K0 (a) = 0,56 ; K0 (b) = 1,3.10 –6 ;<br />

K0 (c) = 2,0 . 10 –5 9<br />

NH3<br />

CH3COO .<br />

–<br />

C6H5NH2 NO – pH<br />

9,2<br />

4,75<br />

CH3COOH 4,5<br />

C6H5NH 2 3,3<br />

HNO2 + NH<br />

3<br />

+ 4<br />

1) Acide dont le pKA 0.<br />

2) pH =–log c =2,4.<br />

3) a) c(S)=13,6 mol . L –1 .<br />

b) c(S’) = 0,54 mol . L –1 .<br />

c) Solution trop concentrée pour considérer que :<br />

a (H + (aq)) = [H + (aq)]/c0 10<br />

.<br />

1) Base telle qu’à 25°C pKA 14,0.<br />

2) pH =14,0 +log c =11,6.<br />

3) a) c(S)=0,44 mol . L –1 .<br />

b) c(S’) = 2,2.10 –3 mol . L –1 11<br />

et pH =2,7.<br />

c) pour une base forte pH =pKe+ log c et pKe dépend de<br />

T alors que pour un acide fort pH =–log c.<br />

1) HNO2 + H2O =NO – 2+ H3O +<br />

Pour toutes les solutions : [NO – 2] = [H3O + ] .<br />

Pour C1, [NO – 2]

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