pH standart bufer eritmasi nima? Uning xususiyatlari qanday?
1. pH standart bufer eritmasi nima? Uning xususiyatlari qanday?
PH bufer eritmasi barqaror pH qiymatini saqlab turadigan eritmadir. Agar bu eritmaga oz miqdorda kislota yoki asos qo‘shilsa yoki eritmadagi kimyoviy reaksiya natijasida oz miqdorda kislota yoki asos hosil bo‘lsa va eritma mos ravishda suyultirilsa, eritmaning pH qiymati asosan barqaror va o‘zgarmagan bo‘ladi. Kichik miqdordagi kislota yoki asos yoki katta yoki kichik suyultirishga qarshilik ko'rsatadigan va pH qiymatini o'zgarmagan holda saqlay oladigan bu eritma bufer eritma deb ataladi.
Standart pH buferi quyidagi xususiyatlarga ega:
(1) Standart eritmaning pH qiymati ma'lum va belgilangan aniqlikka etadi;
(2) Standart eritmaning pH qiymati yaxshi takrorlanuvchanlik va barqarorlikka, katta bufer sig'imiga, kichikroq suyultirish qiymatiga va kichikroq harorat koeffitsientiga ega;
(3) Eritmani tayyorlash usuli oddiy;
pH standarti bufer eritmasini qanday tayyorlash mumkin?
Umumiy pH o'lchash uchun pH tarkibidagi reagentlarning to'liq to'plamidan (250 ml tayyorlashga qodir) foydalanish mumkin. Eritmani tayyorlashda erigan karbonat angidridni olib tashlash uchun deionizatsiyalangan suvdan foydalanish va 15-30 daqiqa davomida oldindan qaynatish kerak. Plastik qopni kesib oling, reagentni stakanga quying, uni kerakli miqdorda deionizatsiyalangan suv bilan eritib oling, qadoqlangan qopni yuving, uni 250 ml hajmli o'lchov kolbasiga quying, shkalagacha suyultiring va yaxshilab silkiting.
3. PH bufer eritmalarini qanday to'g'ri saqlash va ishlatish kerak?
After preparing the buffer solution, it should be packed in a glass or polyethylene bottle (alkaline pH buffer solution, such as pH=9.18, pH=10.01, pH=12.46, etc., should be packed in a polyethylene bottle) with a tight lid. It should be stored in a refrigerator at low temperature (5-10 ℃) and can generally be used for about six months. If there is turbidity, mold, or precipitation in the existing mixer, it cannot be used again. When using, several 50mL polyethylene small bottles should be prepared, and the component solution from the large bottle should be poured into the small bottles. The bottles should be left at ambient temperature for 1-2 hours, and the temperature should be balanced before use. After use, it is not allowed to pour it into a large bottle to avoid contamination. The buffer solution in the bottle can be used for 2-3 days under environmental conditions>10 daraja. Odatda, pH=7.00, pH=6.86 va pH=14.00 uzoqroq vaqt davomida ishlatilishi mumkin. pH=9.18 va pH=10.01 eritmalari havodagi karbonat angidridni oʻzlashtiradi va ularning pH qiymatini oʻzgartirish nisbatan oson.
4. pH bufer eritmasidan maqsad nima?
(1) pH o'lchashdan oldin pH o'lchagichni sozlang.
(2) U pH o'lchagichning aniqligini tekshirish uchun ishlatiladi, masalan, pH=6.86 va pH=14.00. PH o'lchagichni kalibrlashdan so'ng, pH elektrodini pH=9.18 eritmasiga soling va asbobning ko'rsatilgan qiymati Standart eritmaning pH qiymatiga mos kelishini tekshiring.
(3) Umumiy aniqlik o'lchash vaqtida pH o'lchagichni qayta kalibrlash zarurligini tekshiring. PH o'lchagichni kalibrlash va ishlatishdan keyin siljish yoki o'zgarishlar bo'lishi mumkin. Shuning uchun, sinovdan oldin, elektrodni o'lchangan eritmaga yaqin bo'lgan standart tampon eritmasiga soling va xatolik kattaligiga qarab qayta kalibrlash zarurligini aniqlang.
(4) pH elektrodining ishlashini tekshiring.
