Quiz — 65b517377ae99_énoncé_serie26 chimie (ph d'une solution aqueuse (2) ).pdf

Question 1 sur 5 10:00

[{"id":1774,"question":"Quel est le pH d'une solution dont la concentration en ions H₃O⁺ est de 10⁻⁴ mol\/L ?","option_a":"pH = 4","option_b":"pH = 10","option_c":"pH = -4","option_d":"pH = 0","option_e":"","option_f":"","bonne_reponse":"a","explication":"Le pH se calcule avec la formule pH = -log[H₃O⁺]. Ici, pH = -log(10⁻⁴) = 4. Un pH de 4 indique une solution acide.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"pH = 4\", \"b\": \"pH = 10\", \"c\": \"pH = -4\", \"d\": \"pH = 0\"}}","_debug_options_count":4},{"id":1775,"question":"Parmi ces indicateurs, lequel est le plus adapté pour un titrage acido-basique avec un saut de pH autour de pH = 7 ?","option_a":"Phénolphtaléine (zone de virage : 8,2–10)","option_b":"Bleu de bromothymol (zone de virage : 6–7,6)","option_c":"Hélianthine (zone de virage : 3,1–4,4)","option_d":"Rouge de méthyle (zone de virage : 4,2–6,3)","option_e":"","option_f":"","bonne_reponse":"b","explication":"Le bleu de bromothymol a une zone de virage qui inclut pH = 7, ce qui le rend adapté pour les titrages où l'équivalence se situe autour de la neutralité.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"Phénolphtaléine (zone de virage : 8,2–10)\", \"b\": \"Bleu de bro","_debug_options_count":4},{"id":1776,"question":"Pour une solution d'acide chlorhydrique (HCl) de concentration 0,01 mol\/L, quel est le pH initial de la solution ?","option_a":"pH = 2","option_b":"pH = 1","option_c":"pH = 0,01","option_d":"pH = -2","option_e":"","option_f":"","bonne_reponse":"a","explication":"HCl est un acide fort qui se dissocie totalement : [H₃O⁺] = 0,01 mol\/L. Donc pH = -log(0,01) = 2.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"pH = 2\", \"b\": \"pH = 1\", \"c\": \"pH = 0,01\", \"d\": \"pH = -2\"}}","_debug_options_count":4},{"id":1777,"question":"Lors d'un titrage acido-basique, si le volume équivalent est de 20 mL et que la concentration de la solution titrante est de 0,1 mol\/L, quelle est la quantité de matière titrée ?","option_a":"2 mmol","option_b":"0,1 mol","option_c":"2 mol","option_d":"0,02 mol","option_e":"","option_f":"","bonne_reponse":"a","explication":"La quantité de matière titrée = C × V = 0,1 mol\/L × 0,02 L = 0,002 mol = 2 mmol.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"2 mmol\", \"b\": \"0,1 mol\", \"c\": \"2 mol\", \"d\": \"0,02 mol\"}}","_debug_options_count":4},{"id":1778,"question":"Quelle est la constante d'acidité (Ka) d'un acide faible dont le pH d'une solution à 0,1 mol\/L est de 3 ?","option_a":"Ka = 10⁻⁵","option_b":"Ka = 10⁻³","option_c":"Ka = 10⁻⁶","option_d":"Ka = 10⁻⁴","option_e":"","option_f":"","bonne_reponse":"a","explication":"Pour un acide faible, [H₃O⁺] = √(Ka × C). Ici, [H₃O⁺] = 10⁻³ mol\/L. Donc Ka = ([H₃O⁺]²) \/ C = (10⁻⁶) \/ 0,1 = 10⁻⁵.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"Ka = 10⁻⁵\", \"b\": \"Ka = 10⁻³\", \"c\": \"Ka = 10⁻⁶\", \"d\": \"","_debug_options_count":4}]