Chemistry masters to answer, ask chemistry masters to answer?Or experienced.

C Because CO reduces CuO, HCl and NaHCO3 form H2O, and the volume of water reacts with NaOH to become smaller, and it is possible that CO2 or N2 is generated when CO restores CuO.

The addition of zinc chloride is one way to go.

In the concentrated solution of zinc chloride, it has significant acidity due to the formation of compound acid --- hydroxydichlorozinc acid, which can dissolve metal oxides

zncl2+h2o===h[zncl2（oh）] feo+2h[zncl2(oh)]===fe[zncl2(oh)]2+h2o

The removal of oxides from the metal surface with a concentrated solution of zinc chloride when welding metals is based on this property. The 'wrought water' used in welding metals is a concentrated solution of zinc chloride. It does not damage the metal surface during welding, and after the heat of water evaporates, the molten salt covers the metal surface, so that it no longer oxidizes.

The addition of sulfuric acid increases the concentration of hydrogen ions.

Let's take advantage of the principle of the galvanic battery.

Add a little copper sulphate.

Construct a Fe-HCL-Cu galvanic cell.

It should be ok.

As shown in the round calendar, let the orange bureau rotten tomb.

dBecause iron displaces copper.

Iron also reduces trivalent iron to bivalent iron.

Set: the disturbance quality of CaCO3 in limestone is slow, and the conghui fraction is Zheng Ku xcaCO3+2HCl=CaCl2+H2O+CO2100 44 10x

Carbon dioxide mass: 50+ Substituting carbon dioxide into the equation to obtain a calcium carbonate mass of 8 grams, so the carbon defeat beats the calcium carbonate mass fraction.

(1) The steps of solution preparation: calculation, weighing, measuring and dissolving;So you need an instrument glass rod, beaker, graduated cylinder, rubber tip dropper;Therefore, fill in: glass rods, beakers;

2) When the pH of the solution is equal to 7, the mass of the sodium hydroxide solution consumed by the complete reaction is 8g, and the solute mass fraction of the dilute hydrochloric acid is X, NaOH + HCl = NaCl + H2O

408g×1% x×20g

40 8g×1% = x×20g

x=A: The solute mass fraction of this dilute hydrochloric acid is;

3) When the pH of the solution reaches 2, it means that the solution is acidic, and there is a surplus of hydrochloric acid, so the solute in the solution has NaCl and HCl

The first overdose.

Because when sodium carbonate reacts with hydrochloric acid, the first step is that the carbonate ion CO32- reacts with H+ to form the bicarbonate ion HCO3-;Next, if there is an excess of H+, HCO3- will continue to react with H+ to form H2CO3.

The excess sodium carbonate reacts with 1 mole of hydrochloric acid to form sodium bicarbonate, and then reacts with the remaining 1 mole to produce sodium chloride, carbon dioxide, and water.

The first excess, the difference is that the first one has gas coming out.