NATRI THIOSULFAT

Natrii thiosulfas

Natri hyposulfit

Na2S2O3. 5H2O P.t.l: 248,2

Natri thiosulfat phai cha t 99,0 en 101,0% Na2S2O3. 5H2O.

Tnh chat

Tinh the trong, khong mau, len hoa trong khong kh kho.

Rat tan trong nc, thc te khong tan trong ethanol 96%, tan trong nc ket tinh cua no khoang 49 oC.

nh tnh

A. Lay 1 ml dung dch S, them vai giot dung dch iod 0,1 N (TT), dung dch mat mau.

B. Lay 2 ml dung dch S, them 1 ml acid hydrocloric (TT), se xuat hien tua lu huynh va co mui cua kh lu huynh dioxyd, kh nay se lam xanh giay tam ho tinh bot co iodat (TT)

C. Lay 1 ml dung dch S, them 2 ml dung dch bac nitrat 0,1 N (TT), co tua trang chuyen nhanh sang vang roi dan dan sang en.

D. Dung dch S phai cho phan ng (A) cua ion natri (Phu luc 8.1).

o trong va mau sac cua dung dch

Dung dch S: Hoa tan 10,0 g che pham trong nc khong co carbon dioxyd (TT) va pha loang thanh 100 ml vi cung dung moi.

Dung dch S phai trong (Phu luc 9.2) va khong mau (Phu luc 9.3, phng phap 2).

pH

Dung dch S phai co pH t 6,0 en 8,4 (Phu luc 6.2).

Clorid

Khong c qua 0,02% (Phu luc 9.4.5).

Lay 5 ml dung dch S, them 15 ml dung dch acid nitric 2 M (TT), un soi nhe trong 3 - 4 phut. e nguoi, loc, pha loang dch loc thanh 25 ml bang nc. Lay 12,5 ml dung dch thu c, pha loang thanh 15 ml bang nc va tien hanh th.

Sulfat    va sulfit

Khong c qua 0,2%.

Lay 2,5 ml dung dch S, pha loang vi nc thanh 10 ml. Hut 3 ml dung dch thu c, them 2 ml dung dch iod 0,1 N (TT), them tiep tng giot dung dch iod 0,1 N (TT) cho en khi co mau vang rat nhat ben vng, roi pha loang vi nc thanh 15 ml, tien hanh th gii han sulfat (Phu luc 9.4.14).

Sulfid  

Lay 10 ml dung dch S, them 0,5 ml dung dch natri nitroprusiat 0,5% (TT) mi pha, dung dch khong c co mau tm.

Kim loai nang  

Khong c qua 10 phan trieu (Phu luc 9.4.8).

Lay 10,0 ml dung dch S, them 0,05 ml dung dch natri sulfid (TT), e yen 2 phut. Dung dch nay khong c co mau am hn mau cua dung dch oi chieu gom 10 ml dung dch ch mau 1 phan trieu (TT) va 0,05 ml dung dch natri sulfid (TT).

nh lng  

Hoa tan 0,500 g che pham trong 20 ml nc va chuan o bang dung dch iod 0,1 N (C). Vao luc cuoi chuan o, them 1 ml dung dch ho tinh bot (TT).

1 ml dung dch iod 0,1 N (C) tng ng vi 24,82 mg Na2S2O3. 5H2O.

Bao quan  

ng trong lo kn.