ai giỏi làm giupse với ạ :)

`21)\ C_2H_2+5/2O_2` $\xrightarrow{t^o}$ `2CO_2+H_2O`

`22)\ C_4H_{10}+{13}/{2}O_2` $\xrightarrow{t^o}$ `4CO_2+5H_2O`

`23)\ C_2H_2+2Br_2->C_2H_2Br_4`

`24)\ C_6H_5OH+Na->C_6H_5ONa+1/2H_2`

`25)\ 2CH_3COOH+Na_2CO_3->2CH_3COONa+CO_2+H_2O`

`26)\ CH_3COOH+NaOH->CH_3COONa+H_2O`

`27)\ Ca(OH)_2+2HBr->CaBr_2+2H_2O`

`28)\ Ca(OH)_2+2HCl->CaCl_2+2H_2O`

`29)\ Ca(OH)_2+H_2SO_4->CaSO_4+2H_2O`

`30)\ Ca(OH)_2+Na_2CO_3->CaCO_3+2NaOH`

`31)\ Na_2S+H_2SO_4->Na_2SO_4+H_2S`