Find a junior chemistry 30, find a junior chemistry

Ordinary iron blocks do not generate heat and cannot be used for heating. The rusting of iron is a redox reaction that is accompanied by the release of energy.

The iron in the hand warmer is not ordinary iron, it is specially treated, generally reduced iron powder, the particles are very fine, the chemical reaction activity is much higher than that of ordinary iron, and the hand warmer will generally add some catalysts to speed up the reaction. Therefore, the speed at which the hand warmer can release heat can reach the level of warmth. The main function of c is to be used as a water-retaining agent and to provide galvanic motor to accelerate the reaction.

There are many ways to prove the formation of ferric oxide, such as it can be dissolved with dilute hydrochloric acid, and then added to KSCN solution, if it is blood-red, it means that it contains Fe3+. Or use the gravimetric method to weigh the fixed mass of the product, and weigh it again after complete reduction, and the reduced mass is the mass of oxygen in the product, so that the mass ratio of each element in the reaction product can be obtained, and then the chemical formula of the product can be obtained.

C60 (footballene) is a cage-like molecule containing 60 C atoms. As for the reason, this is a fixed representation. To put it simply, the number of protons and neutrons in the nucleus of an atom does not vary much.

Moreover, the representation of C13 is not exact, if you want to represent such atoms, it is generally so.

6, I can't hit the big c, you can see the two broken lines as c, the proton number is in the lower left part, and the mass number is in the upper left side.

The principle of warming the baby is made of iron, charcoal and salt water, and the galvanic cell reacts relatively slowly. It is self-evident why a piece of iron does not burn when placed on the ground. C is used to form galvanic cells with iron, and the reason why C is chosen is because it has the right amount of reducibility, does not react too fast or too slowly, and it is very cheap.

To prove that the product has ferric oxide, take the used warm baby apart, mix the contents with water, and then filter. Take the filter residue and suck it with a magnet, and there is no reaction, indicating that there is no iron and no ferric tetroxide. The filter residue is then dissolved with hydrochloric acid and the clear is filtered.

Then add KSCN, which is blood-red. The basic judgment product contains ferric oxide. However, it cannot be strictly proven, for example, that the product is not iron hydroxide.

It can only be said that from the physical properties, theoretical and conventional analysis, it is likely to be ferric oxide.

The molecule of soccer olene is made up of 60 C atoms. As for the carbon atom with 54 neutrons, on the one hand, it does not exist, and on the other hand, it is written differently than soccer alkene. The 60 of the football dilute is written in the lower right corner of c, and the 60 of this carbon atom should be written in the upper left corner, or written as Chinese carbon-60.

Fe and C form the galvanic cell, which accelerates the reaction rate, and C is the positive electrode of the galvanic cell.

It's not more heat than usual, but faster than usual.

Inspect Fe2O3

Add a sufficient amount of hydrochloric acid, and then add KSCN solution.

Appears blood-red.

Carbon-60 is a carbon molecule composed of 60 carbon atoms.

The names are similar, but they don't have much to do with it, isotopes are called that, and C60 is a special case.

1.This is explained in high school chemistry, where the galvanic cell reaction takes place, where reactive metals such as iron are oxidized as the negative electrode and C as the positive electrode. The galvanic cell accelerates the reaction rate, which accelerates the oxidation of iron, and the heat release is naturally more violent

2.It is a molecule composed of 60 C atoms, making C a kind of elemental substance, similar to a football.

Attached: As a positive electrode, it constitutes a galvanic cell.

2.Because the number of neutrons is calculated by the difference between the number of masses and the number of protons. The number of protons is equal to the number of nuclear charges and the number of atomic numbers, and the mass number is the number of 13 of the so-called c13, which is usually given in the title.

It is nano-scale iron powder, which is highly reactive, and there is sodium chloride as a positive catalyst in the bag, which reacts faster than usual, and the exothermic will not become more.

It's iron powder inside! A carbon molecule composed of 60 carbon atoms.

Remove a small amount of the residue after the reaction in the test tube, put it into another test tube, drop in dilute sulfuric acid, and fully react. The solution turns blue, indicating that the patina contains the element (copper). Note: Because copper ions are blue in solution.

The chemical reaction equation for the decomposition of patina:

Cu2(OH)2CO3 = Heating = 2CuO + CO2 + H2O

(1)30%x=600g*5%

x=100g

2) Is it still 600 grams? If still.

h2o2: 100g/( cm3

H2O: (600g-100g) (1g cm3)=500 cm3 Ratio: 1000 11 500=2:11

Apply the formula. Mass of concentrated solution * mass fraction = mass of dilute solution * mass fraction (because solute mass is the same in both solutions).

I didn't want to do much, but let's talk about it. The problem itself is not difficult, the key is that you are too lazy, just write down the equation and do a simple multiplication. Don't blame me for being troublesome, it's for your own good.

This kind of question can be asked, what's wrong with today's children, they have been poisoned by the Internet to such an extent, sad

The ratio of the three compounds is unknown, so the mass ratio of oxygen to sulfur is uncertain, but all three compounds have 2 sodium and 1 sulfur, and this ratio is fixed!

This type of multiple-choice calculation problem generally has some tips.

For example, in this problem, the oxygen removal part of the three substances is Na2S, so it can be seen as the mass fraction of Na2S in Na2S, which is 78 * (46 78) = 46%.

The chemical formula of sodium sulfate above is written incorrectly, it should be Na2SO4According to the ratio of the number of Na atoms to S atoms of 2:1, the mass ratio of Na to S can be calculated as 46:32, and the mass fraction of O in the mixture is 22%.

So the sum of the mass fractions of Na and S is 78%, so the mass fraction of Na is 46%.

I can see that you are quite careless, the question was copied in a few wrong places, naso4 should be na2so4;

The element oxygen should be the element sulfur;

The percentage content is 22%, which should be 32%.

Otherwise, the solution to the problem is not 46%.

Now, according to my imagination, let's talk about the problem-solving process:

The ratio of the number of Na atoms to S atoms in Na2S, Na2SO3 and Na2SO4 is 2:1, and the mass ratio of Na to S can be calculated.

Because the mass fraction of sulfur in the mixture is 32%.

Assuming that the total mass of the mixture is x grams, the sulfur element mass is 32%x, and the sodium element content * x : 32%x = 46 : 32 sodium element content = 46 * 32% 32 = 46%.

a ：na2co3 b：h2o c：nacl d:co2 e：c f：h2 g：o2 h：co i：hcl

The condition of reaction 2 is that it is energized.

The equation for reaction one: Na2CO3+2HCl=2NaCl+H2O+CO2 The equation for reaction three CO2+C=(high temperature)2CO

Dear, you don't understand this, or you can change the way, such as a+b==c, etc., we can also understand it, you don't know what it is at all.

D is CO2 because the amount of N2 in the air is about 71% and oxygen is about 20% more, and there is very little less CO2 than 1%, so it should be CO2.

A is hydrochloric acid, b is water, c, calcium chloride, d, carbon dioxide e carbon, f hydrogen, g oxygen, h carbon monoxide, i is calcium carbonate.

The condition of the reaction is: energizing.

2HCI+CAC3=H2O+CAC2+CO2 High temperature C+CO2====2CO

1. A is HCI, B is water, C is calcium chloride, D is carbon dioxide, E is carbon, F is hydrogen, G is oxygen, and H is carbon monoxide.

2. The condition is high temperature.

3. Ca2CO3+2HCl=2CaCl2+H2O+CO2 4, CO2+C=(high temperature)2CO

Conditional electrolysis (as the name suggests, is energized at high temperatures).

a：caco3 b：h2o c：cacl2 d：co2 e：c f：h2 g：o2 h：co i：hcl

Tell you all the substances, and this question will be done!

The products are 13 g of C and 5 g of D, and the reactants are A and B

According to the conservation of mass, the mass of the product adds up to 18g, then the reactant should also have 18g, and the title says that A is completely reacted, indicating that A10g is fully reacted, and the other 8g is provided by B. Then the mass ratio of the two substances A and B of the reaction is 10:8 or 5:4.

According to the law of conservation of mass, the total mass in the reaction is constant, and the mass of b participating in the reaction is x

Increment of mass = 13 + 5-10-x = 8 - x = 0

So x=8, so the answer is 5:4

The answer is 5:4 According to the law of conservation of mass, the mass of the product is 13 g + 5 g = 18 g A is a complete reaction of the substance, then the other 8 g of the substance is provided by the B substance, so a:b = 5:4

c The amount of change (21-10) 44 = 1 4 A The amount of the changed substance (25-10) 30 = 1 2 b The amount of the changed substance 5 20 = 1 The mass of 4 d is: According to the conservation of the quantity of the substance, a decreases by 15 g b increases by 15 g c decreases 11 g so d generates d mass is 9 g so the mol of d is 9 18 = 1 2

The proportion of ABCD moles changed was 2,1,1,2

The least common multiple is 2, so 2a+b=c+2d

The knowledge of the third year to solve can be done in the following way: (Pending coefficient method).

Suppose the equation is.

AA+BB=CC+DD (where ABCD is the coefficient to be determined before the equation, and the relative molecular mass of A is 30B; The relative molecular mass is 20; c The relative molecular mass is 44; d The relative molecular mass is 18).

Then: Equation: AA + BB = CC + DD

The product of the relative molecular mass and the coefficient of the equation: 30a 20b 44c 18d

Reaction change mass: 25-10 5-0 21-10 25+5+10-10-21

according to the theorem of conservation of mass).

Column ratio: 30a 15 = 20b 5....1）

30a/15=44c/11...2）

30a/15=18d/9...3）

It is obtained: A=2b is obtained from equation (1).

From equation (2) gives a=2c

From equation (3) a=d

Bring back the original equation to obtain: aa+1 2ab=1 2ac+ad

Multiply the two sides of the equation by 2 a to get :

2a+b=c+2d

A2) Or: according to the mass ratio equal to the ratio of the relative molecular mass to its coefficient score.

25-10）/(5-0)=30a/20b...a=2b, the same way, a=2c, a=d

Bring back the original equation to obtain: aa+1 2ab=1 2ac+ad

Multiply the two sides of the equation by 2 a to get :

2a+b=c+2d

However, this question does not state whether oxygen is involved in the reaction, and the equation obtained is only a relational of the reaction.