26- lab.mashg’uloti. 13 guruh elementlari. Bor birikmalariva xossalari. Laboratoriya ishining maqsadi: Talabalarni 13 guruh elementlar, bor guruhchasi elementlari va ularning birikmalari bilan tanishtirish.
Bor guruhchasi elementlari va ularning birikmalari bo’yicha tajribalar: Zarur asboblar: ko‘k va qizil lakmus. Chinni kosachalar, tigellar, fenolftalein.
Reaktivlar: kons. H2SO4 (ρ=1,84 g/sm3), H3BO3 (kr), etil spirti, Na2B4O7 (kr), kons. HCl ( =1,19 g/sm3). HNO3 ( =1,4 g/sm3) . Al bo‘lakchalari. NH4Cl (kr).
Eritmalar:Na2B4O7-to‘yingan issiq: AgNO3 (0.05 n). 2 nCuSO4 ; 2 n HCl; 2 n H2SO4 ; 2n HNO3; 2 n NaOH; 0.5 n Al2(SO4)3; 2 n CH3COONa; 2 n Na2CO3.
1-tajriba. Borat kislotaning olinishi Bura ( Na2B4O7) ning konsentrlangan issiq eritmasidan 5-6 tomchisini alohida probirkaga solib, unga konsentrlangan sulfat kislotadan 2-3 tomchi qo‘shing. Hosil bo‘lgan H3BO3ning eruvchanligini kamaytirish uchun probirkadagi aralashmani tezroq soviting. Mayda oq kristallar hosil bo‘lishini kuzatib, reaksiya tenglamasini molekulyar va ionli shaklda yozing.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Xulosa._______________________________________________________________________________________________________________________________________________________________________________________________________________2-tajriba. Ortoborat kislotaning xossalari Probirkaga 2 ml distillangan suv quyib, unga ortoborat kislota ( H3BO3) ning bir necha kristallaridan tushiring. Aralashmani kuchsiz qizdiring. H3BO3 ning sovuq va issiq
suvdagi eruvchanligini kuzating. Eritmani ikkiga bo‘lib, bir qismida lakmus eritmasi yoki
ko‘k lakmus qog‘ozi yordamida muhitni aniqlang. H3BO3 kuchli kislotami yoki kuchsizmi? Eritmaning ikkinchi qismiga ozroq magniy qirindisidan qo‘shing. Gaz ajralib chiqishini kuzating. Ortoborat kislotaning bosqichli dissotsiatsiyasini yozing. Har bir bosqichning dissotsiatsiya konstantasini jadvaldan toping. Ortoborat kislota bilan magniyning o‘zaro ta’sir reaksiyasi tenglamasini yozing.
___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Xulosa._______________________________________________________________________________________________________________________________________________________________________________________________________________3-tajriba. Etilborat efirining olinishi va uning yonishi Kichikroq chinni kosachaga yoki tigelga ozroq ortoborat kislota kristallaridan solib, ustiga 1-2 tomchi konsentrlangan H 2SO 4 tomizing. Aralashmaga yana 5-6 tomchi etil spirtidan qo‘shib, shisha tayoqcha bilan aralashtiring. Reaksiya natijasida ajralib chiqayotgan etilborat B(OC2H5)3 efirini yoqing. Alanganing o‘ziga xos rangiga e’tibor berib, etilborat efirning hosl bo‘lishi va yonishi reaksiya tenglamalarini yozing.
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Xulosa._______________________________________________________________________________________________________________________________________________________________________________________________________________4-tajriba. Buraning gidrolizi Probirkaga 1 ml distillangan suv quyib, unga 2-3 dona bura kristallaridan tashlang, eriting. Ko‘k va qizil lakmus qog‘ozlari yoki bir tomchi fenolftalein bilan ta’sir etib, eritmaning muhitini aniqlang. Buraning bosqichli gidrolizlanishini hisobga olgan holda (birinchi bosqichda H3BO3 va NaBO2 , ikkinchi bosqichda yana H3BO3 va NaOH) gidroliz tenglamasini molekulyar va ionli shaklda yozing.
___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Xulosa._______________________________________________________________________________________________________________________________________________________________________________________________________________5-tajriba. Qiyin eriydigan boratlar hosil qilish.
Ikkita probirka olib, har biriga 5-6 tomchidan buraning to‘yingan eritmasidan quying. Birinchi probirkaga cho‘kma hosil bo‘lgunicha bir tomchi AgNO3 , ikkinchisiga esa
CuSO4 eritmasidan tomizing. Probirkalarning birinchisida kumush metaborat, ikkinchisida misgidroksometaborat hosil bo‘lishini hisobga olgan holda (cho‘kmalarning rangiga e’tibor berib) , reaksiya tenglamalarini molekulyar va ionli shaklda
yozing.
___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Xulosa._______________________________________________________________________________________________________________________________________________________________________________________________________________
