A few questions in the third year of chemistry, give the next step, thank you

Question 1: Let the molecular weight of m be x, because it is 3 valence, so the oxide is m2o3, so you can list the equation: 2x (2x+48)=70%, and then calculate x 56

Question 2: Physical change (a change without new matter is a physical change) Question 3: When an object is heated, the kinetic energy of molecules and atoms increases, and the average degree of freedom increases due to an increase in volume (there are also special substances that are not like this).

1.Because it is 3 valence, so, 3 m trioxide, 16 * 3 = 48, 48 * 7 3 = 112, 112 2 = 56

2.It is the liquid water molecule that becomes a gaseous water molecule and vaporizes.

3.When an object is heated, the intramolecular energy becomes larger and the range of motion is greater.

1 Iron oxide (ferric oxide Fe2O3) 56x2 56x2+16x3= so m is Fe 56

2 Atoms and molecules do not change, only physical changes (vaporization, water becomes gas, endothermy).

3 is that the molecules are constantly doing irregular motion, and the thermal molecules are exacerbated by the thermal motion, and the gap between the molecules is changed.

c Let the chemical formula of the compound be M2O3

w(m)=ar(m)*2/mr(m2o3)*100％w(m)=70％

2m/2m+16*3=70％

m = 56 physical change.

As the temperature increases, the spaces between the atoms become larger and the volume becomes larger (except for water).

1) Combustion: C+O2=CO2

2CO+O2=2CO2CH4+2O2=CO2+2H2O (Description: There are many of these types, all hydrocarbons (called hydrocarbons) are burned to form CO2+H2O) C2H5OH+3O2=2CO2+3H2O (Description: There are also many in this category, and all compounds formed by hydrocarbon, hydroxide and oxygen elements are burned to generate CO2+H2O).

2) Thermal decomposition source: CaCO3== CaO+CO2 (Note: All carbonates that are insoluble in water can be decomposed into metal oxides and CO2 at high temperatures) NH4HCO3== NH3 +CO2 +H2O2NaHCO3== Na2CO3+CO2 +H2O (Say: Zheng Ming:

All bicarbonates can be thermally decomposed to form carbonates, CO2 and H2O)Cu(OH)2(CO3)2== CuO+2CO2 +H2O

3) Carbonate and acid antibisanson: CaCO3 + 2HCl = = = CaCl2 + CO2 +H2O (Note: All carbonates can react with strong acids to form new salts, CO2 and H2O) NaHCO3 + HCl = ==NaCl + CO2 +H2O (Description:

All bicarbonates can react with strong acids to form new salts, CO2 and H2O).

4) Redox reactions (except combustion):

C + 2H2SO4 (concentrated) ==CO2 +2SO2 +2H2OC+4HNO3 (concentrated) ==CO2 +4NO2 +2H2O

8. The State Environmental Protection Administration stipulates that all kinds of laboratories will be included in the scope of environmental protection supervision from January 1, 2005. Students in class A and B of the ninth grade of a middle school respectively did experiments on the reaction of common acids and bases with indicators, as shown in the figure on the right (**Description: The phenolphthalein test solution was dropped into three test tubes filled with lime water, hydrochloric acid and sodium hydroxide solution).

After the experiment, the waste liquid was concentrated in a waste tank for each class.

The research team tested the waste liquid from the two classes, and the results are shown in the table below.

1) Please help them analyze the composition of the waste liquid by filling in the blanks in the table below.

Detection method and results: Observe that the waste liquid is colorless.

Inference of the composition of the waste liquid (chemical formula of the filling substance, phenolphthalein and water are not filled): The waste liquid contains (hydrochloric acid.

Class B: Detection method and results: Observe that the waste liquid is red.

Inference of the composition of the waste liquid (chemical formula of the filler, phenolphthalein and water are not filled): there is no (hydrochloric acid) in the waste liquid, it contains (

lime water, sodium hydroxide solution)

2) It is reported that at present, all kinds of waste liquid discharged from chemical laboratories of many universities, middle schools and scientific research units in Nanjing have entered the sewer without strict treatment. What is the hazard caused by the waste liquid of Class A if it is discharged directly into the cast iron pipe sewer? （

corroded cast iron pipe sewers). What do you recommend for what to do with this waste? (Neutralized by acid and alkali and discharged).

naoh+hcl=nacl+h2o

xx=20*

hcl=