"84" disinfectant is a kind of high-efficiency disinfectant bleaching agent, mainly sodium hypochlorite, which is widely used in hospitals, hotels and families.

(1)① the expression of hydrolysis equilibrium constant K=c(HClO)? C (oh? )c(ClO？ ); As the temperature rises, the PH value rises, the concentration of hydroxyl ion rises, the concentration of hypochlorous acid rises, and the concentration of hypochlorous acid decreases, so K rises.

So the answer is: c(HClO)? C (oh? )c(ClO？ ); Increase;

② "84" disinfectant has bleachability, which can make colored substances fade.

A "84" disinfectant has bleachability, which can make the dried pH test paper fade, so A is wrong;

B "84" disinfectant has bleachability, and pH test paper wetted with distilled water can fade, so B is wrong;

C. "84" disinfectant does not change the acidity meter (or acidity meter), so C is correct;

So, the answer is: c;

(2)① Hypochloric acid is weaker than carbonic acid. Sodium hypochlorite reacts with carbon dioxide and water to produce hypochlorous acid and sodium carbonate 2ClO-+CO2+H2O=2HClO+CO32-, which increases the concentration of hypochlorous acid and the disinfection effect.

So the answer is: 2ClO-+CO2+H2O=2HClO+CO32- and so on;

(2) Hypochloric acid is unstable and can be decomposed into hydrogen chloride and oxygen 2HClO under illumination. Light? . ? 2HCl+O2↑ reduces the concentration of hypochlorous acid, so the disinfection effect is reduced.

So the answer is: 2HClO? Catalyst? . ? 2 HCl+O2↑；

(3) Sodium hypochlorite has strong oxidation, hydrochloric acid has reducibility, and sodium hypochlorite can react with hydrochloric acid to generate chlorine gas, which is toxic. Therefore, mixing "84" disinfectant with cleaning agents (including hydrochloric acid) will lead to poisoning accidents.

So the answer is: NaClO reacts with HCl to generate Cl2 or ClO-+Cl-+2h+= Cl2 =+H2O;

(4)① According to Figure 2, the device and reagent can produce a small amount of "84" disinfectant. If the X electrode produces chlorine gas, the chlorine gas will be led out from the catheter mouth, so no disinfectant can be obtained, so only the Y electrode produces chlorine gas, that is, the Y electrode is the anode and the X electrode is the cathode, so A is the negative electrode and B is the positive electrode, so the answer is: negative electrode;

②y is the anode, and the electrons on the anode lose the oxidation reaction. The discharge capacity of chloride ions in the solution is greater than that of hydroxide ions, so chloride ions discharge on the anode to produce chlorine gas. The electrode reaction formula is 2cl-2e-= Cl2 ↑.

So the answer is: 2cl-2e-= Cl2 ↑;

(5) For 2A(g)+B(g)? For 2C(g)+D(s) reaction, when the reaction reaches equilibrium, the amount of gaseous substances decreases. For example, at the same temperature, the pressure should decrease, but the pressure should increase, indicating that the positive and negative reactions should be exothermic when the temperature increases. When the temperature increases, the equilibrium constant decreases.

So the answer is: k decreases with the increase of temperature.