Hydrogen sulfide gas is bubbled through excess
potassium hydroxide solution.
h2s + 2oh– → s2– + 2h2o

write the balanced chemical equation excluding spectator ions. how do you get there from
h2s + koh -> k2s + h2o ?

 separate the atoms from the molecules and give them charges
H2S = 2 H+ + S^-2
 double replacement reaction. AB + CD = AD + CB
Hydrogen sulfide gas is bubbled through excess potassium hydroxide solution, but you only put H2S + 2OH– → S2– + 2H2O
H2S + KOH -> K2S + H2O to here... H2S + 2OH– → S2– + 2H2O


AB + CD = AD + CB H2=A;S=B;K=C;(OH)=D [AD]=H2+(OH)=H2O [CB]=K+S=KS

They can measure  the amount of energy gained or lost