Simple tangled chemistry questions, okay, chemistry questions

I'm also a sophomore in high school, and I'll ask you questions one by one, and give me a lot of advice. The first: energy is the energy of the substance itself, such as H2+O2=H2O, the energy of H2+O2 is greater than the energy of H2O, and the reaction is exothermic (the energy absorbed by bond breaking is less than the energy released by bonding), so the energy of the product H2O is reduced compared with the reactant and is more stable.

Second: reaction absorption or exothermic is related to the total energy of reactants and products, and bond energy is related to the properties of the substance itself, the tighter the atoms are combined, the greater the bond energy, and it is also related to the type of bond (single, double, three). The type of heat absorption and release of the reaction can also be judged by using the equation to calculate the heat change when the bond is broken into a bond, but there is no direct relationship between the energy of the substance and the bond energy.

Combustion is usually done with oxygen, but in some special cases, combustion can be carried out under oxygen-free conditions, such as hydrogen combustion in chlorine, magnesium combustion in carbon dioxide, etc. Definition General chemical definition of combustion: Combustion is a light, heat-rising, and violent chemical reaction.

Combustion is a violent, luminous and heat-generating chemical reaction between combustibles and combustibles (oxidants). Broad definition of combustion: Combustion refers to any violent reaction that emits light and heat, without necessarily having oxygen involved.

For example, sodium metal (Na) and chlorine (Cl2) react to form sodium chloride (NaCl), which does not involve oxygen, but is a violent chemical reaction that emits light and heat.

When we talk about energy, such as the energy of the reactant is greater than the energy of the product, in chemistry, it generally refers to the energy of the substance itself. (i.e., the energy required to form a bond, which can be understood as the energy stored in a chemical bond). Chemical bonds are formed, which are exothermic (released to the outside world).

Whereas, bond energy is the energy required to break a chemical bond, and bond breaking is endothermic (absorbed from the outside world).

There is generally no absolute relationship between the energy of the matter itself and the bond energy, but in the same reaction, the magnitude relationship between the energy (sum) of the reactant and the product is opposite to the magnitude relationship of the bond energy (sum).

Enthalpy change is a state value, not representing specific energy, enthalpy change is one of the important factors restricting whether a chemical reaction can occur, and the other is entropy change. (Simple understanding, enthalpy change, for internal energy, is all the energy of the reactant itself, spontaneous chemical reactions are always exothermic, otherwise they all need high temperature to spontaneously react.) ）

The correct statement for H2+O2 is that H2+O2 energy is high and bond energy is low.

Finally, why can't O2 burn, because combustion is a redox reaction (electron transfer), O2 can be burned, as long as the chemical reducibility (electron attraction ability) reacting with O2 is higher than that of oxygen.

The so-called energy level is actually a benchmark problem.

If we set the energy of the free atom to 0, then the energy of the bond with other atoms must be released, that is, the bond energy, and this bond energy is equal to the energy absorbed to dissociate the bond, the higher the bond energy, the lower the energy of the structure we think is formed.

As you mentioned the process of combining hydrogen and oxygen to form water, from the energy point of view, you can see that it undergoes a process of absorbing energy that decomposes into free hydrogen and oxygen atoms and an exergating process that combines to form water, so the energy absorbed by the former process is lower than the energy released by the latter process, so it is generally the energy released. Since the sum of the bond energies of two molecules of water is greater than the sum of the internal bond energies of two molecules of hydrogen plus one molecule of oxygen (they are of the same type and number of atoms), the energy required to crack the corresponding bonds is higher, and we consider the molecular energy of water to be lower.

The problem that you say that oxygen cannot be burned in hydrogen is actually a pseudo-problem. We are just used to calling the reducing agent in the combustion reaction a fuel, so we say fuel combustion. So we don't say that oxygen is combustible, but that oxygen fuels combustion.

The exothermic or endothermic mentioned in chemical reactions is the energy absorbed and released when their chemical bonds are broken or resynthesized, which is part of the energy of matter, in fact, matter is the carrier of energy, and it has no energy itself, it is a temporary storage place for energy! You can take a look at the books on philosophy. Add some knowledge of biology and you might get the idea!

Let o2 xmol and o3 ymol

2o3=3o2

Directly get the equation: ,, and push out y x=2 3

Mass fraction of oxygen: 32x (32x+48y), i.e. 1 (1+up and down divided by 32x) = 50%.

So the ozone mass fraction is also 50%.

In metal crystals, free electrons move through and are not exclusive to a metal ion but common to the entire metal crystal. These free electrons interact with all the metal ions to form some kind of bond, an action known as a metallic bond. Due to the free motion of electrons, the metallic bond does not have a fixed direction and is therefore a non-polar bond.

There is a problem with the first step of derivation, oxygen is 4 times that of nitrogen, so the ratio of mixed gas to nitrogen must be greater than 4, and the derivation result of the first step cannot be given by one condition alone, and the second step is no problem. It is mainly derived by using the ideal gas equation of state pv=nrt, which satisfies this formula in the ideal state of pure gas or mixed gas. Here's how to do this:

Under the same conditions, the ratio of the volume of the gas is equal to the ratio of the quantity of the substance, so let the quantity of nitrogen be x, then the amount of oxygen is 4x, and the amount of hydrogen is y.

After the mixture of hydrogen and oxygen is ignited, the piston is stationary at the midpoint of the cylinder, indicating that the volume on the left and right sides is equal; When the piston is stationary, the piston is evenly stressed, so the gas pressure on the left and right sides is equal; And they are all cooled to room temperature, so the temperature is equal on both sides.

According to the ideal gas equation of state pv=nrt, then the nitrogen equation on the left is pv=xrt, and the gas equation of state on the right is pv=n(remainder) rt, so the amount of matter of the remaining gas on the right can be obtained n(remainder)=x.

The remaining gas on the right may be hydrogen, or oxygen, and the reaction that takes place is: 2H2+O2=2H2O(L).

1) If the remaining gas is hydrogen, then n(h2)=n(remainder)+n(reaction)=n(remainder)+2n(o2)=x+2*4x=9x

Then the volume ratio of hydrogen to oxygen in the original gas mixture is 9x:3x=3:1

2) If the remaining gas is oxygen, then the oxygen of the reaction is 4x-x=3x, so the amount of H2 reacted with it is 2*3x=6x

Then the volume ratio of hydrogen and oxygen in the original gas mixture is 6x:4x=3:2

So it could be 3:1 or 3:2

The ratio of nitrogen to oxygen is 1:4. Finally, the piston is stationary, which means that the air pressure on both sides is the same after the reaction, and in the middle, the volume is equal, then there is PV=NRT, which means that the number of moles is the same.

Let nitrogen be n, oxygen is 4n, 2h2+o2=2h20No gas is produced in the reaction. Assuming that there is an excess of oxygen, the hydrogen is completely reflected, and there is 3n of oxygen to be reacted.

Then there is 6n of hydrogen. then hydrogen:oxygen = 3:

2.If there is an excess of hydrogen, then there is 4n of oxygen being reacted, and there is the presence of 2 4n + 1n = 9n of hydrogen, then hydrogen:oxygen = 9:4

1: Molecules are in constant motion.

2: The speed of motion of molecules increases when the temperature increases. ）

3: The spacing between hot molecules increases, and vice versa. (It's confusing to know that the volume of a molecule is constant!)

All matter is made up of molecules, and molecules are in constant motion. When the object is heated, the energy is gained, and the kinetic energy of the molecules increases, which makes the molecular motion faster and the distance between the molecules increases. In this way, the original volume cannot accommodate the activity of the molecules, so expansion occurs.

This is how objects expand when heated. The molecules of solid matter move slowly, have a large mutual gravitational force, and the expansion is not obvious after heating. The molecules of substances in the liquid state move faster, the molecules attract less to each other, and the expansion is more obvious after heating. The distance between gas molecules is larger than that of solids and liquids, and the mutual attraction between molecules is small, and the expansion is obvious after heating.

1.It embodies the volatility of the molecule.

2.It embodies the volatility of the molecule.

3.Thermal expansion and cold contraction. It reflects that the movement of molecules is affected by temperature.

1 molecule is in constant motion.

2. The higher the temperature, the faster the molecular thermal movement.

There are inter-molecule spacing, with gases being the largest, liquids second, and solids being the smallest.

1.The molecules are moving in a random way.

2.The higher the temperature, the faster the molecules move.

3.As the temperature increases, the intermolecular distance increases, and vice versa.

1 Because alcohol and gasoline are volatile.

2 Because clothes evaporate quickly in the sun.

3 For everything rises and shrinks.

Amount of protosulfate substance = *

The amount of sulfate substance after the reaction = *

So, the amount of sulfate species that are reduced to SO2 = - i.e., the amount of substances that produce SO2 is, and the volume is.

Cu+2H2SO4=CuSO4+SO2+2H2OSo, the amount of copper sulphate produced is .

100 ml of solution, the amount of CuSO4 substance concentration =

Cu + 2H2SO4 = CuSO4 + SO2 + 2H2O From the reaction formula, it can be seen that sulfuric acid ** is left in the solution to generate sulfur dioxide, so as long as you know the sulfate remaining in the solution, you can find the sulfur dioxide generated.

Solution: The amount of the substance of the original sulfate: The amount of the substance of the sulfate in the solution after the reaction: x mol Therefore, the amount of the substance that generates sulfur dioxide is: —= mol So the volume of sulfur dioxide under the standard condition is:

The amount of the substance of copper sulphate is mol

The concentration of the substance of copper sulphate in 100 ml of solution is: = mol l

The number of oxygen atoms contained in oxygen and sulfur dioxide per mole is the same, pay attention to the corner mark of oxygen atoms, so the first sentence is correct The second sentence is also correct Because the volume of gas with the same number of moles at the same temperature and pressure must be the same No matter how he mixes it As long as it is mixed together and does not react This piece of knowledge is relatively simple Do a few more questions and you will find the pattern High school chemistry knowledge points are relatively scattered So you must eat each piece thoroughly I wish you a happy study.

The number of moles of the gas under the same condition = the number of volumes.

The O contained in 1mol O2 and 1mol SO2 is 2Na, so the O contained in 1mol of gas obtained by mixing them in any ratio is also 2Na