Conceptual questions for the sophomore chemistry exam. A few questions in chemistry in the second ye

Electrons are lost, valency increases, is oxidized, and is a reducing agent;

Electrons are obtained, the valency is reduced, and it is an oxidizing agent.

In a nutshell:

Loss of high oxygen is also low.

1.In solution there are CH3COO-, Na+, H+, OH-, [CH3COO-]+OH-]=[Na+]+H+].Because pH=7, there is [oh-]=[h+].

Then [CH3COO-]=[NA+], so the ion concentration of the mixed solution of sodium acetate and acetic acid is ranked [CH3COO-]=[NA+]>H+]=[OH-].

2.Ammonium chloride and ammonia monohydrate are mixed, and they are alkaline at 1:1 (sodium acetate and acetic acid are mixed, 1:

1 is acidic, these two have no why, just remember), in the solution there is ci-, (NH4)+, OH-, H+, [Cl-]+OH-]=[(NH4)+]H+], because the solution is alkaline, then [OH-]>H+], that is, [(NH4)+]Cl-], then its concentration is arranged as [(NH4)+]Cl-]>OH-]>H+].

When it is neutral, the principle is the same as the first question, and the concentration arrangement is [(NH4)+]=[cl-]>oh-]=[h+].

The second question is written about the concentration arrangement of ions, if it refers to the concentration arrangement of particles, it should be [(NH4)+]Cl-]>OH-]>H+].oh-]=[h+].The reasons are all [.]

CH3COOH>[CH3COO-]=[NA+]>OH-]=H+ Because the solution is neutral, it is easy to conclude that OH- = H+ is equal to cation because the solution is not electrically sensitive.

So [ch3coo-]=[na+

Because acetic acid is a weak electrolyte, the degree of ionization is small, so the degree of ionization is small, so the acetic acid molecule should be greater than the concentration of acetic acid ions.

NH4+ >Cl- >OH >H+ is completely ionized because NH4CI is a strong electrolyte, whereas he hydrolyzes to a very small extent. The degree of ionization of ammonia is very large, and the hydrolysis is small. So ammonium is greater than Cl- and it is easy to get OH >H+

1. B silver nitrate - the yellow precipitate is potassium iodide, the light yellow is sodium bromide, the white is sodium chloride, and the turbidity is sodium sulfate;

2. B ether !! Heyhey, it's poisonous

3. b according to the general formula of organic matter combustion:

It is a "gaseous hydrocarbon" and can be set to cxhy

And "full combustion", then the carbon-containing gas generated is only Co by the change of pressure, which can be obtained: 2n(Co)=n(cxhy)+n(O), that is: Cxhy+(x+y 4)o =xco +y 2h o, 2x=1+(x+y 4).

Solution: x=3;y=8.

P4, from the figure, we can see that there are 6 P-P bonds, and their energy is 6*198kJ·mol-1; O2, 1 part O2 has 1 O-O bond, 3 parts O2 has 3 O-O bonds, and its energy is 3*498 kJ·mol-1; P4O6, we can count from the model that it has 12 P—O bonds, so its energy is 12* 360kJ·mol-1.

On the left side of the reaction formula, the bond energy is 6*198kJ·mol+3*498 kJ·mol-1, and the right bond energy of the reaction formula is 12*360kJ·mol-1, h=reactant enthalpy-product enthalpy=reactant bond energy-product bond energy=6*198+3*498-12*360=-1638 kj·mol-1

Heat of reaction = total bond energy of reactants - total bond energy of products.

Therefore, the heat of reaction = 6 * 198 + 3 * 498 - 12 * 360 = -1638 bond energy can be calculated as long as there are several sides of the geometric figure. Thank you.

h = reactant enthalpy - product enthalpy = reactant bond energy - product bond energy = 6 * 198 + 3 * 498-12 * 360 = -1638

On the left side of the reaction formula, the bond energy is 6*198kJ·mol+3*498 kJ·mol-1, and the right bond energy of the reaction formula is 12*360kJ·mol-1, h=reactant enthalpy-product enthalpy=reactant bond energy-product bond energy=6*198+3*498-12*360=-1638 kj·mol-1

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Solution: Let the organic matter be cxhy, then:

n(cxhy) = =

Then the amount of the substance that gives CO2:

The amount of H2O substance obtained:

Get: *18g mol = 18g

Get: y = 10

And because the organic substance only contains two elements, C and H, and does not contain any functional groups, and does not contain lipid rings, it is an alkane, that is: C4H10

The above explanation is very clear, but I think your title is wrong, anhydrous copper sulfate will also absorb some of the water when it turns blue, so the topic is not very logical, the above explanation is good, I won't repeat it.

cxhy

18gh2o=1mol h2o 2molh y=10

Because it is not said how much weight is gained by the clarified lime water, the molecular formula of carbon content cannot be obtained: C4H10 C5H10 C6H10 are all possible (alkanes, olefins, alkynes).