A small beaker containing hydrochloric acid of the same volume and concentration of the same substance is placed in each of the two plates of the tray balance. After adjusting the balance, add Fe powder and Zn powder of the same quality to the two beakers respectively. The following phenomena are impossible () A. At the beginning, the zinc adding end of the balance rises B. Finally, the zinc added end of the balance rises C. The final balance is still balanced D. At last, the iron adding end of the balance rises

A small beaker containing hydrochloric acid of the same volume and concentration of the same substance is placed in each of the two plates of the tray balance. After adjusting the balance, add Fe powder and Zn powder of the same quality to the two beakers respectively. The following phenomena are impossible () A. At the beginning, the zinc adding end of the balance rises B. Finally, the zinc added end of the balance rises C. The final balance is still balanced D. At last, the iron adding end of the balance rises

When Fe and Zn react with hydrochloric acid, the valence is + 2. When equal mass Fe and Zn react with sufficient hydrochloric acid, the final mass of hydrogen is determined by the relative atomic mass of the metal. The greater the relative atomic mass, the less the final mass of hydrogen, and vice versa. The relative atomic mass of Zn is 65, while the relative atomic mass of iron is 56, Therefore, with the progress of the reaction, the mass of hydrogen produced in the end is more at the end of adding iron, so the end of adding iron is light. Therefore, the balance pointer finally deviates to the end of adding zinc, the end of adding zinc drops and the end of adding iron rises
Therefore: B

There are 3 moles of 100 ml of hydrochloric acid and 100 ml of sulfuric acid per liter. Iron powder of equal quality is added respectively. The mass ratio of hydrogen produced after the reaction is 3:4. What is the mass of iron powder added to hydrochloric acid?

V = 0.1L, then the hydrogen ion in hydrochloric acid is 0.3mol, and the hydrogen ion in sulfuric acid is 0.6mol
If Fe is excessive, the ratio of hydrogen generated is hydrochloric acid: sulfuric acid = 1:2 = 2:4
If hydrochloric acid is excessive, the ratio of hydrogen generated is hydrochloric acid: sulfuric acid = 1:1 = 4:4
It is concluded that hydrochloric acid reacts completely and sulfuric acid remains
It can be deduced according to the amount of hydrochloric acid, and the hydrogen generated by the reaction of hydrochloric acid is 0.15mol
The hydrogen generated by the reaction of Fe with sulfuric acid is 0.2mol. The reaction of Fe in sulfuric acid is complete, and the amount of Fe is calculated according to this
0.2mol
0.2mol × 56g/mol=11.2g

Add 200ml 3mol / L hydrochloric acid to Fe2O3 solid powder, and the solid powder is just completely dissolved. Add a certain amount of iron powder to the resulting solution. At this time, drop KSCN solution to the solution, and there is no obvious phenomenon. Trial calculation: (1) What is the amount of Fe2O3? (2) What is the minimum mass of iron powder?

1. Fe2O3 + 6hcl = FeCl3 + 3h2o1 6x 200 * 3 / 1000, x = n (Fe2O3) = 0.1mol2. Add KSCN solution, there is no obvious phenomenon, indicating that there is no Fe3 + and it has been completely transformed into Fe2 + 2fe3 + Fe = 3fe2 + 2 10.1 * 2 x, x = n (FE) = 0.1mol, then add iron powder at least

1、 Immerse 10g iron sheet in 200ml 0.2mol/l copper sulfate solution, take out the iron sheet after reaction, wash and dry it, and the mass is 10.16g. Calculate the concentration of copper sulfate in the solution after reaction 2、 In order to determine the chemical formula of sodium sulfate crystal, 32.2g of sample is prepared into 100ml solution, and then 5mol / L barium chloride solution is dropped. When 20ml is dropped, precipitation happens not to occur. Try to write the chemical formula of sodium carbonate crystal through calculation 3、 0.44g of the mixture composed of sulfur and iron is burned in oxygen to convert all the sulfur into sulfur dioxide, then all the sulfur dioxide is oxidized into sulfur trioxide and converted into sulfuric acid, which is exactly neutralized with 20ml of 0.5mol/l sodium hydroxide. What is the mass fraction of sulfur in the original compound?

1. M difference = 64-56 = 8 0.16, i.e. 0.02mol CuSO4 is consumed, the original 0.2x0.2 = 0.04mol CuSO4, so the reflected concentration = 0.02mol/0.2l = 0.1mol/l2. BaCl2 = 5x0.02 = 0.1mol, so the consumption of sodium carbonate is also 0.1mol m (Na2SO4) = 142, so the mass of sodium carbonate is 14.2g, and the rest is water 32

The optional reaction names are as follows: oxidation, reduction, addition, substitution, esterification and hydrolysis 1 ethylene to ethanol 2 ethanol to acetaldehyde 3 acetaldehyde to acetic acid 4 ethanol and acetic acid into ethyl acetate

1. Addition double bond fracture
2. Oxidation hydroxyl to aldehyde group
3. Oxidation of aldehyde group to carboxyl group
4. Esterification is a kind of substitution

The volume of SO2 obtained by reacting Cu with concentrated hydrochloric acid is 4.48l (standard condition). Please calculate, 1: the amount of reduced sulfuric acid. 2: dilute the obtained solution to 500ml to calculate the amount and concentration of CuSO4 in the solution

First of all, Cu does not react with hydrochloric acid. If you get SO2, it should be that Cu reacts with concentrated sulfuric acid
According to the equation: Cu + 2 H2SO4 = = = CuSO4 + 2 H2O + SO2
4.48l divided by 22.4l/mol, the amount of substance generating SO2 is 0.2mol
The sulfuric acid in the reaction is 2 * 0.2mol = 0.4mol, of which 0.2mol is reduced to SO2, and the other 0.2mol of sulfate is not reduced, but CuSO4 (AQ) is generated. Therefore, the first question is 0.2mol
If the amount of CuSO4 generated is 0.2mol and the dilution is 500ml, i.e. 0.5L, then the amount concentration of CuSO4 in the solution is 0.2mol divided by 0.5L, i.e. 0.4mol/l, which is the second answer