Chemistry Subject, College Chemistry, Help

Oh my God, you're amazing! I usually do a good job in big questions, so I deduct a few points sporadically, and I often get about 10 points wrong if I don't pay attention to multiple-choice questions. If you don't do well in the big questions, I don't think your ability to answer the questions is enough, or the comprehensive strength of chemistry is not too high.

I believe your progress will be great!

Experiments to master common devices, preferably with special training. Calculation is a common method to master. Such as conservation method, difference method, relational method, etc.

Plus explanation. It's too slow to know.

The main question is basically that, the inorganic aspect of the identification of several atoms, there will basically be a few substances for you to identify, this requires memorizing their reactions and the phenomena of the reaction, and having a certain understanding of the periodic table. There is also the calculation of trim and reaction products, raw materials, rates, and constants, and it is impossible to calculate without trim, which requires understanding the three major conservats and doing more calculation problems. Organic is basically to write down the reaction formula and its principle (a principle can solve a number of similar reactions), and then balance, usually to use the reverse deduction method to solve the organic problem, doing the problem is like the separation and regrouping of various groups, you can assemble or split the next step of the basic general direction of the substance, it is right, the rest is how to synthesize the reaction of the latter from the former.

(1) Find qv (i.e., rum).

The molar mass of octane C8H18 is 114g mol, and the thermal effect is:

qv = * 114 = (kj mol)(2) to find rhm

Reaction by complete combustion: C8H18(L) +25 2)O2(G) = 8CO2(G) +9H2O (L).

And: RHM = rum +NRT where n= 8 - 25 2 =

Get: rhm = rum +nrt= -

5459216 （j/mol)

The molar mass of 1 mol of octane is 114 g mol, multiply the thermal effect by 114.

The mass of potassium chloride in the mixture is:

Gram. The mass of manganese dioxide is: Gram.

1.Write a chemical reaction program (available in a textbook);

2.Calculate the mass ratio of potassium chlorate to oxygen in the reaction formula (check the relative molecular weight);

3.From the title, the reduced mass is the mass of oxygen released, according to which the mass of potassium chlorate participating in the reaction m can be calculated; Therefore, the mass of potassium chlorate in the original mixture is 2m, and the mass of manganese dioxide is 12g-2m.

Alcl3 is a covalent compound, because the melting point of AlCl3 in the solid state is low, all AlCl3 in the molten state exists in the form of AlCl3 molecules, and if the molten wild AlCl3 is heated continuously, it will vaporize to form gaseous aluminium hexachloride Al2Cl6 molecule, that is, the dimer of AlCl3. From the above properties, it can be judged that Alcl3 is a covalent compound. This is also the reason why the industry does not use AlCl3 electrolysis to produce Al aluminum, but uses a mixture of molten Al2O3 and cryolite to produce metal elemental aluminum.

The color reaction of potassium K is purple (or lavender), which can only be seen through blue cobalt glass.

The color of bromine water is orange-yellow, and bromine is generally orange-red in non-polar solvents (Ccl4 and benzene) and orange-yellow in polar solvents (alcohol and water);

The color of iodine water is brownish-yellow, iodine is generally purple-red in non-nuclear polar solvents (CCL4 and benzene), and generally brownish-yellow or tan in polar solvents (alcohol and water), such as iodine wine is tan.

NO2, also known as nitric peroxide, is a typical molecule with a large bond structure. The major bond contains three electrons, two of which enter the bonding orbital and one into the antibonding orbital. Because the N atom does not reach the 8-electron stable structure, NO2 is unstable and is easy to form dimer N2O4, which is relatively stable and has lower energy than NO2.

NO2 is an odd-electron molecule with a V-shaped spatial configuration, and the nitrogen atom is bonded with the oxygen atom in a sp2 hybrid orbital, in addition to forming a three-center, three-electron bond. The N-O bond is 120 PM long and has a bond angle of 134 degrees.

It took a lot of effort! Hope! Thank you!

no2：..

o n o (Note scattering Huai: the horizontal o n o vertical three points are all two points This is problematic to play out Khan. ）

Voltaic lead polar covalent bonds

Bromine water color: orange (liquid bromine is dark reddish-brown).

The color of iodine water: yellow to brown (depending on the concentration).

K's flame reaction color: Lack of digging good lavender.

1.High school does not require the electronic formula of no2 to be written, and high school knowledge cannot solve this problem in no2 n is bonded by sp2 hybrid orbital, there are 2 bonds, and a 3 (3 is superscript) and 3 (3 is a subscript) key.

2.Mixed matrix of bromine elemental and water. Bromine is soluble in water, and more than 80% of the bromine will react with water to form hydrobromic acid and Yanzhou only bromidic acid, but there will still be a small amount of bromine elemental dissolved in water, so the bromine water is orange-yellow, reddish-brown.

3.Brown, brown.

The flame color reacts to purple.

2.The color of bromine water is orange-yellow.

3.The color of iodine water is brownish-yellow.

The flame color reaction color can be seen through the blue cobalt glass, and the ascending omen can be seen as a purple bureau.

5.Bromine elemental soluble in organic solvents is orange-red Tongxiaostool, and iodine elemental soluble in organic solvents is purple-red.

Color reaction: Regret orange rent sodium yellow potassium purple calcium brick Wu Yuan red F is light yellow chlorine is yellow-green br is dark reddish brown dissolved in water is orange i is purple black.

AGCL is white, AGBR is pale yellow, and AGI is yellow.