Quiz — 65e03d873c4f3_corrigé_série chimie n°13 acides base.pdf

Question 1 sur 10 20:00

[{"id":33220,"question":"Parmi ces espèces, laquelle est un acide selon Brønsted-Lowry ?","option_a":"NH₃","option_b":"HCO₃⁻","option_c":"CH₃COOH","option_d":"OH⁻","option_e":"","option_f":"","bonne_reponse":"c","explication":"CH₃COOH (acide acétique) est un acide car il peut céder un proton H⁺. Les autres espèces sont des bases ou des ampholytes.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"NH₃\", \"b\": \"HCO₃⁻\", \"c\": \"CH₃COOH\", \"d\": \"OH⁻\"}}","_debug_options_count":4},{"id":33221,"question":"Le pH d'une solution d'acide chlorhydrique de concentration 10⁻² mol\/L est :","option_a":"2","option_b":"7","option_c":"12","option_d":"14","option_e":"","option_f":"","bonne_reponse":"a","explication":"Pour un acide fort, pH = -log[H₃O⁺] = -log(10⁻²) = 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\": \"2\", \"b\": \"7\", \"c\": \"12\", \"d\": \"14\"}}","_debug_options_count":4},{"id":33222,"question":"Un couple acide\/base est caractérisé par :","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"a","explication":"Vrai : un couple acide\/base est défini par un acide et sa base conjuguée qui diffèrent par un proton H⁺.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":33223,"question":"Quelle est la constante d'acidité Ka d'un acide faible ?","option_a":"Ka \u003E 1","option_b":"Ka = 1","option_c":"Ka \u003C 1","option_d":"Ka = 0","option_e":"","option_f":"","bonne_reponse":"c","explication":"Pour un acide faible, Ka \u003C 1 car la dissociation est partielle.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"Ka \u003E 1\", \"b\": \"Ka = 1\", \"c\": \"Ka \u003C 1\", \"d\": \"Ka = 0\"}}","_debug_options_count":4},{"id":33224,"question":"Lors d'un dosage acido-basique, le point équivalent correspond à :","option_a":"La fin de la réaction","option_b":"L'équivalence des quantités de matière","option_c":"Le changement de couleur de l'indicateur","option_d":"La neutralisation totale des réactifs","option_e":"","option_f":"","bonne_reponse":"b","explication":"Le point équivalent est atteint lorsque les quantités de matière d'acide et de base sont stœchiométriquement égales.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"b\", \"options\": {\"a\": \"La fin de la réaction\", \"b\": \"L'équivalence des quantités de m","_debug_options_count":4},{"id":33225,"question":"Le pH d'une solution de soude (NaOH) de concentration 10⁻³ mol\/L est :","option_a":"3","option_b":"7","option_c":"11","option_d":"14","option_e":"","option_f":"","bonne_reponse":"c","explication":"Pour une base forte, pH = 14 + log[OH⁻] = 14 + log(10⁻³) = 11.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"3\", \"b\": \"7\", \"c\": \"11\", \"d\": \"14\"}}","_debug_options_count":4},{"id":33226,"question":"Un indicateur coloré doit avoir un pKa proche du pH du point équivalent.","option_a":"Vrai","option_b":"Faux","option_c":"","option_d":"","option_e":"","option_f":"","bonne_reponse":"a","explication":"Vrai : cela garantit un changement de couleur net au point équivalent.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"Vrai\", \"b\": \"Faux\", \"c\": \"\", \"d\": \"\"}}","_debug_options_count":4},{"id":33227,"question":"Quelle est l'expression de la constante d'acidité Ka pour le couple CH₃COOH\/CH₃COO⁻ ?","option_a":"Ka = [CH₃COO⁻][H₃O⁺]\/[CH₃COOH]","option_b":"Ka = [CH₃COOH]\/[CH₃COO⁻][H₃O⁺]","option_c":"Ka = [H₃O⁺]\/[CH₃COOH]","option_d":"Ka = [CH₃COO⁻]\/[CH₃COOH]","option_e":"","option_f":"","bonne_reponse":"a","explication":"Ka = [produits]\/[réactifs] = [CH₃COO⁻][H₃O⁺]\/[CH₃COOH].","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 = [CH₃COO⁻][H₃O⁺]\/[CH₃COOH]\", \"b\": \"Ka = [CH₃COOH]","_debug_options_count":4},{"id":33228,"question":"Lors d'un titrage, si la courbe de titrage présente un saut de pH brutal, cela signifie :","option_a":"L'acide ou la base titré(e) est fort(e)","option_b":"Le titrage est mal réalisé","option_c":"L'indicateur est mal choisi","option_d":"La réaction est lente","option_e":"","option_f":"","bonne_reponse":"a","explication":"Un saut de pH brutal indique que l'acide ou la base titré(e) est fort(e), ce qui est souhaité pour un titrage précis.","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"a\", \"options\": {\"a\": \"L'acide ou la base titré(e) est fort(e)\", \"b\": \"Le titrage est m","_debug_options_count":4},{"id":33229,"question":"Le pH d'une solution de chlorure d'ammonium (NH₄Cl) est :","option_a":"7","option_b":"Supérieur à 7","option_c":"Inférieur à 7","option_d":"Impossible à déterminer","option_e":"","option_f":"","bonne_reponse":"c","explication":"NH₄⁺ est l'acide conjugué de NH₃ (base faible), donc la solution est acide (pH \u003C 7).","points":1,"type":"qcm","actif":1,"section_id":null,"ordre":0,"_debug_answer_data_type":"string","_debug_answer_data_preview":"{\"correct\": \"c\", \"options\": {\"a\": \"7\", \"b\": \"Supérieur à 7\", \"c\": \"Inférieur à 7\", \"d\": \"Impossi","_debug_options_count":4}]