1. All knowledge points that must be tested in the comprehensive high school entrance examination of junior high school chemistry Slightly soluble substances in the solution may also become precipitates.

Such as calcium hydroxide, calcium sulfate, etc.

When a metal reacts with a salt solution, the salt must be soluble, with the exception of potassium, calcium and sodium.

Acid-base indicators and pH test paper can only detect the acidity or alkalinity of a solution.

At a certain temperature, the concentration of a saturated solution of the same substance remains unchanged.

When adding water to dilute a solution, the mass fraction of the solution is reduced by half, then the mass of the added water is equal to the mass of the original solution.

Under one standard atmospheric pressure, the temperature of a solution (the solute is water) can only be raised to a maximum of 100°C.

Maybe the solute in this solution still cannot be completely dissolved at 100 degrees Celsius, so be aware of the trap.

Both carbon monoxide and carbon dioxide can kill people, but carbon monoxide poisons people, while carbon dioxide suffocates people.

In chemical equations, the ratio of coefficients before a gas is the volume ratio of that gas.

In acid-base salts, hydrogen ions are responsible for acidity, and hydroxide ions are responsible for alkalinity.

Solubility must be measured in units of "g".

Relative atomic (molecule) mass must not have units.

Recyclable materials include: metal, waste paper, glass, cloth, and plastic.