Which chemical experimental methods have been improving since ancient times

1.Control Variable Method (Studying the Effect of a Single Variable on an Event)2Hypothetical experimental method (guess big, argue carefully).

3.Analogical model methods (such as studying water molecules, which are easy to study as models) I will add when I think about it.

The main links of science**: raising questions, conjectures and hypotheses, making plans and designing experiments, conducting experiments and collecting evidence, analyzing and demonstrating, evaluating, communicating and cooperating

1.Control Variable Method (Studying the Effect of a Single Variable on an Event)2Hypothetical experimental method (guess big, argue carefully).

3.Analogical model method (such as the study of water molecules, it is convenient to make a model for research) distillation and extraction is a widely used separation and purification technology in actual production and life, and the problem of seawater desalination is an important way to solve the problem of increasing shortage of fresh water in the world, which has laid a certain knowledge foundation for the elective "Chemistry and Technology". Extraction is a new separation and purification technology for students, it is an application of the law of solubility, and its principle is also reflected in the study of halogen elements and organic substances in the future, and it is also applied in many aspects in life.

In the experiment to demonstrate the effect of catalyst on the chemical reaction rate, FeCl3 solution and CuSO4 solution were dropped into the H2O2 solution, respectively, and the catalytic effect was better

In the demonstration of the effect of FeCl3 on chemical equilibrium by increasing the concentration of reactants per mu, the dilute FeCl3 solution was mixed with the dilute KSCN solution, and the solution was light blood red. The light blood-red qi staring cavity was divided into two equal parts, and the same concentration of FeCl3 solution and dilute KSCN solution were added respectively, and the red color became darker with KSCN 1 point), and the chemical equilibrium constant was [Fe(sCN)N] [Fe3+]*SCN-]N

n" is the exponent, with the addition of fe3+

and scn-, scn- has a greater impact on the equilibrium.

The effect of high and high collapse mold on the rate of chemical code suspicion-catalytic group respecter.

(1) When pouring liquid, the label side of the reagent bottle should be facing the palm of the hand to prevent the reagent from flowing down and corroding the label;

2) The test tube clamp is an instrument specially used to clamp the test tube, and it should be noted when using it: it should be sleeved from the bottom of the test tube to the top and clamped in the middle and upper part of the test tube; When removing the tube clamp, it should also be removed from the bottom of the tube; Do not put your thumb on the short handle after clamping, so as not to open the test tube clamp and the test tube will fall off;

3) If the remaining drugs are put back into the original bottle, the drugs in the bottle will be contaminated; If discarded, it will cause waste and pollute the environment; It is dangerous to take out the laboratory; Therefore, the remaining drugs should be put into the designated container;

4) When the alcohol sprinkled on the table burns, a wet rag should be used to extinguish the fire by isolating oxygen;

5) The standard for cleaning glass instruments is: the water attached to the inner wall does not gather into droplets or flow down in strands

So the answer is: (1) towards the palm of the hand; (2) bottom; (3) Put it in a designated container; (4) Cover with a damp rag immediately; (5) The water attached to the inner wall does not gather into droplets or flow down in strands

This kind of problem is the conservation of atoms under investigation. To answer such a question, the process of reaction should be fully examined. The details are as follows:

Let the molecular formula of the organic matter be cxhyoz

The mixture is excavated by concentrated sulphuric acid, so that the water in the mixture is absorbed. The concentrated sulfuric acid increases the quality of the water.

m(h2o)=known).

n（h2o）=。

n（h）=。

n (organics) = known).

Then the number of hydrogen contained in the organic matter is y=.

The remaining gas components at this point are CO and CO2.

When such a gas mixture is passed into the hot CuO, CO+CuO==Cu+CO2 occurs. At this point, the CO will be all reflected.

Looking at the equation, we can see that the "copper oxide mass decreases" means that the oxygen atoms in the copper oxide are reduced.

Because: copper oxide carries an oxygen (Cuo) before the reaction, and loses this oxygen after the reaction. So the mass of oxygen is reduced by one of the hungry oaks.

Therefore, the mass of oxygen in copper oxide is.

n（o）=。

n(cuo)=n(o)limb model=.

So n(co)=.

In this case, we get n(CO2) = reflection from CO and CUO).

The mass added by soda lime is the mass of CO2.

So CO2 = due to the combustion of organic matter.

n（co2）=。

Therefore n(c) = n(co) + n(co2) =.

So x = now ask for the value of z.

n（h2o）=。==n（o）=

n（co）=。

n（co2）=。

So there is a total of n(o)=

And n(o)= has been given in the question.

So the excess n(o) = comes from the organic matter itself.

So organic matter contains n(o)=

Z=So the chemical formula of this organic matter is C2H6O2

Supplements: Organics happen to react with.

According to the functional groups in organic matter that can react with organic matter, the common ones are hydroxyl group and carboxyl group.

and because the organic matter is saturated.

So it cannot contain a carboxyl group.

So it can only be ch3-o-ch2oh. Such an organic substance containing a hydroxyl group.

Supplements: A hydroxyl group reacts with a sodium to form --- ONA. Get.

q（452490565）。

Supplement: Answer: c2h6o2

ch3-o-ch2oh。

Hopefully you'll find this kind of problem analysis in my process.

In fact, it is the conservation of atoms.

This kind of problem is the conservation of atoms under investigation. To answer such a question, it is necessary to make the bright score to examine the over-grasp of the reaction. The details are as follows:

Let the molecular formula of the organic matter be cxhyoz - the mixture passes through concentrated sulfuric acid, then the water in the mixture will be absorbed. The concentrated sulfuric acid increases the quality of the water. m(h2o)=known).

n（h2o）=。 n（h）=。n (organics) = known).

Then the number of hydrogen contained in the organic matter is y=. The remaining gas components at this point are CO and CO2. When such a gas mixture is passed into the hot CuO, CO+CuO==Cu+CO2 occurs.

At this point, the CO will be all reflected. Looking at the equation, we can see that the "copper oxide mass decreases" means that the oxygen atoms in the copper oxide are reduced. Because:

Copper oxide carries one oxygen (cuo) before the reaction, and loses this oxygen after the reaction. So the mass of oxygen is reduced by one. Therefore, the mass of oxygen in copper oxide is.

n（o）=。 n（cuo）=n（o）=。So n(co)=.

In this case, we get n(CO2) = reflection from CO and CUO). The mass added by soda lime is the mass of CO2. So CO2 = due to the combustion of organic matter.

n（co2）=。Therefore n(c) = n(co) + n(co2) =. So x = now ask for the value of z.

n（h2o）=。==n（o）= n（co）=。 n（co2）=。

So there is a total of n(o)= and n(o)= has been given in the question. So the excess n(o) = comes from the organic matter itself. So the organic matter contains n(o)= z= - so the chemical formula of this organic matter is C2H6O2 Supplement:

The organic matter happens to react with. According to the functional groups in the organic matter that can react with the organic matter, the common ones are hydroxyl segment, slippery and carboxyl group. and because the organic matter is saturated.

So it cannot contain a carboxyl group. So it can only be ch3-o-ch2oh. Such an organic substance containing a hydroxyl group.

Supplements: A hydroxyl group reacts with a sodium to form --- ONA. Get.

q（452490565）。Addendum: Answer:

c2h6o2. ch3-o-ch2oh。Hopefully you'll find this kind of problem analysis in my process.

In fact, it is the conservation of atoms.