Use standard reduction potentials to find the equilibrium constant for the following reaction at 25°C: 2Ce4+(aq) + 2Cl−(aq) ⇌ 2Ce3+(aq) + Cl2(g) Enter your answer in scientific notation to one significant digit.

May someone me with these science questions

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?