X lo9 dm3 mol-I s-'; 2Se03--Se (1V)+ Se (VI), k=(5.2 f 0.5) X lo8 dm3 mol-l sI; 2HSe042-- Se032-+ Se042-+ H20, k-5 X 10'dm3 mol-'sI; HSe04'-+ Se03-Se03'-+ Se042-+ H20, k-lo9 dm3 mol-'8; C032-+ Se03--C03-+ Se032-, k=(6 f 1) X lo6 dm3 in&'s-'; Se042-+ eai 2 HSe042- (SeOY+ OH-), k= 1.1 X lo9 dm3 mol-'sI; HSe04-+ H-(H2Se04-)-Se03-+ H20, k N lo6 dm3 mol- '8. The standard Gibbs energy of formation of Se03-and HSeO?-, i&CaO0 (SeO3-)=-201.6 ...