A junior high school chemistry problem chemical equation calculation problem .

The first case: the amount of dilute hydrochloric acid is small, the magnesium and zinc are not reacted completely or the zinc is just completely reacted, and the balance is balanced.

The second case: dilute hydrochloric acid is sufficient, magnesium and zinc are not excess, and the balance is biased to the zinc side.

The third case: dilute hydrochloric acid is appropriate, magnesium has not been reacted, zinc has been reacted, and the balance is biased to the magnesium side.

1. If the hydrochloric acid is a small amount, the quality of hydrogen generated is determined by the quality of hydrochloric acid, so the amount of hydrogen generated is the same, so the balance is still balanced.

2.If the metal is small, the mass of hydrogen produced is determined by the amount of metal substance, because magnesium produces more hydrogen with the same mass of magnesium and zinc, so the balance is tilted towards one end of zinc.

It depends.

If you put a sufficient amount of hydrochloric acid, then the side where you put magnesium is upturned!!

With the same mass of magnesium and zinc, magnesium reacts with more hydrochloric acid and releases more hydrogen.

If the amount of hydrochloric acid is insufficient, the hydrochloric acid is not enough at all, and the magnesium and zinc are both magnesium reactions, then the balance is still the same as when the magnesium was placed.

It is unlikely that the magnesium reaction is complete and the zinc is not. This question should be in high school.,How did I learn it in junior high school.,Now junior high school really learns fast!

The beaker weight of zinc should be put because the less the amount reacts with hydrochloric acid, the less hydrogen is released and the less weight is lost. 24:2=10:x， x=;

65:2=10:x, x=;

It can be seen that more hydrogen is released from the magnesium reaction.

The main component of plant ash is known to be a potassium-containing compound. Take a small amount of plant ash and put it into the test tube, and then add dilute hydrochloric acid to the test tube, there are bubbles, and the gas produced is passed into the clarified lime water, and the clarified lime water becomes turbid, and the main components of plant ash are inferred from the above phenomenon. and complete the corresponding chemical equations.

Analysis] This question is actually the test of carbonate ions, and all substances containing carbonate can react with dilute hydrochloric acid to release gas. The colorless and odorless gas produced by the root can make the clarified lime water turbid, proving that the gas is CO2, thus proving that the plant ash contains carbonate ions.

Answer] The main component of plant ash is K2CO3. The chemical equation is: K2CO3+2HCl 2KCl+H2O+CO2, Ca(OH)2 + CO2 = CaCO3 +H2O;

na2co3+2hci=2nacl+h2o+co2↑ △x

So x = i.e. Na2CO3 is added to the beaker on the right.

Put in the left beaker, i.e. the mass increases. In order for the balance to finally be balanced, the right side should also be added.

Let the mass of Na2CO3 be added to the beaker on the right as XNa2CO3+2HCI=2NaCl+H2O+CO2 as the mass of the solution increases.

x106/x=62/

So x = i.e. Na2CO3 is added to the beaker on the right

The calculation teacher in junior high school chemistry has never taught calculations from the perspective of ions: bacl2+na2so4 baso4+2nacly= x= g z=

10% Na2SO4 solution by mass

The mass m of NaCl in a solid mixture of NaCl and BaCl2 is:

The mass fraction of the solute (actually NaCl) in the solution obtained when the reaction is exactly complete is: (m+z) (You count!)

Note 1: The solution of BaCl2 and Na2SO4 happens to react completely!! Note 2: According to the law of conservation of mass, the total mass of the NaCl solution after the complete reaction is: the mass of the precipitated solution cannot be used as the mass of the solution, so it should be subtracted).

Exactly when the reaction is complete, the mass of NaCl in solution =

The mass of the resulting NaCl solution at exactly the complete reaction = =

Mass fraction of solute = ( ) 100% =

The chemical equation was used to find the mass of Na2SO4 and the mass of sodium ions in it. Then according to the mass of barium chloride, the mass of sodium chloride in the original mixture and the mass of sodium ions in it are obtained, and the mass of the two sodium ions is the mass of sodium ions in the solution after the reaction, according to the mass of the elements before and after the reaction, the other steps are the same.

However, I think it is more troublesome to solve this problem from the point of view of ions, and I hope you will receive a simpler algorithm.

First of all, know that the mass of barium sulfate is , then the mass of sodium sulfate can be found then the total weight is a certain value, which is the mass of the solution after the reaction. The quality of barium chloride, so it is clear at a glance. The method of using sodium ions is done by conserving mass.