Question 20 on Chemical Equations

1.The chemical equation for the reaction of dilute sulfuric acid with copper oxide cuo+h2so4=cuso4+h2o phenomenon: the black copper oxide powder gradually disappears, and the solution gradually turns blue.

2.Chemical equation for the reaction of rust (Fe2O3) with dilute hydrochloric acid Fe2O3+6HCl=2FeCl3+3H2O Phenomenon: The red rust gradually disappears, and the solution gradually turns yellow.

The black copper oxide powder gradually disappears, and the solution gradually turns blue (the color of copper ions).

The reddish-brown rust gradually disappears, and the solution gradually turns yellow (the color of ferric ions).

1.Equation: H2SO4 + Cuo = CuSO4 + H2O Phenomenon: The black copper oxide powder gradually disappears, and the solution gradually turns blue.

2.Equation: Fe2O3 + 6HCl = 2FeCl3 + 3H2O

Phenomenon: The brownish-red rust gradually disappears, and the solution gradually turns yellow.

1, H2SO4+CUO=CUSO4 +H2Oblack copper oxide--- blue CuSO4,

2, Fe2O3 + 6HCl = 2FeCl3 + 3H2O red --- black brown.

1. Add hydrogen bromide solution to liquid bromine and divide the liquid. 2hbr+cl2=2hcl+br2

2. Add NaOH solution and filter again. al2o3+2naoh=2naalo2+h2o

3. The mixed gas is passed into the saturated NaHCO3 solution. so2+nahco3=nahso3+co2

4. Personally, I think it can be heated directly. NH4Cl is decomposed first and then combined.

5. It is also direct heating. 2Na2O+O2 heats 2Na2O2

6. When FeCl2 solution is mixed with FeCl3, add iron powder and then filter. 2fecl3+fe=3fecl2

When FeCl2 is mixed with FeCl3 solution, excess Cl2 is introduced. 2fecl2+cl2=2fecl3

7. The mixed gas is passed into the saturated NaHSO4 solution.

8. Direct heating. 2NaHCO3 heats NaCO3+H2O+CO2

9. Cl2 is mixed with HCL and directly penetrates saturated saline. HCl is mixed with SO2 and is introduced into a saturated NaHSO4 solution.

10. Bleach powder dew fails when placed in the air. ca(clo)2+co2+h2o=caco3+2hcl+o2

Na2SiO3 fails when left in the air. na2sio3+h2o+co2=naco3+h2sio3

11. Na2SO3 deterioration. 2na2so3+o2=2na2so4

12. The H2SO3 solution becomes more acidic when exposed in air. H2SO3 is a weak acid, partially ionized H+ ions, and SO3(2-) ions are oxidized by air [2SO3(2-)+O2=2SO4(2-)] to become SO4(2-). H2SO4 is a strong acid and is completely ionized, so the concentration of H+ ions in the solution becomes larger and more acidic.