`3)`

`C_2H_4+H_2O` $\xrightarrow{t^o,H^+}$ `C_2H_5OH`

`C_2H_5OH+O_2` $\xrightarrow{men\ giam}$ `CH_3COOH+H_2O`

`CH_3COOH+C_2H_5OH` $\buildrel{{t^o,H^+}}\over\rightleftharpoons$ `CH_3COOC_2H_5+H_2O`

`CH_3COOC_2H_5+NaOH` $\xrightarrow{t^o}$ `CH_3COONa+C_2H_5OH`

`4)`

`n_{CH_3COOH\ l t}={30}/{60}=0,5(mol)`

`n_{C_2H_5OH\ l t}={41,4}/{46}=0,9(mol)`

`CH_3COOH+C_2H_5OH` $\buildrel{{t^o,H^+}}\over\rightleftharpoons$ `CH_3COOC_2H_5+H_2O`

`0,5<0,9->H` theo `CH_3COOH`

`->n_{CH_3COOC_2H_5\ l t}=n_{CH_3COOH\ l t}=0,5(mol)`

`->m_{CH_3COOC_2H_5\ t t}=0,5.88.60\%=26,4(g)`