Chemistry Dissolution Questions 23 00 ago

The answer is A, because it is saturated salt water, as long as there is no less water, then the quality of salt in it will not change.

Option B is due to the fact that after immersion, MgCl2 dissolves in water, resulting in a reduction.

Option C is due to the fact that after immersion, there is always a time when the magnesium chloride in the saturated salt water will be saturated, so that it cannot be used to remove magnesium chloride in the future.

Option d is that it is easier to dissolve magnesium chloride in saturated brine due to the small size of coarse salt, while it is more difficult when the particles are large.

Option A Since the solution is saturated, the solute mass of course does not change.

b In junior high chemistry, it can be considered that different solutes in the solution have no interaction with each other, so MgCl2 is dissolved in salt water.

c No, when MgCl2 is saturated, it does not play a role in removing MgCl2 from crude salt.

d The smaller the particles, the easier it is for MgCl2 to dissolve in solution and the faster it dissolves in solution. In other words, the finer the particles, the faster the MgCl2 dissolves in saturated salt water, and the smaller the MgCl2 content in immersion.

A right. B, MgCl2 will dissolve.

c, MgCl2 does not continue to dissolve after saturation.

D, the particles are too large, and MgCl2 is surrounded by NaCl and affects the amount of dissolution, which can only be used for the question of the third year of junior high school, and strictly speaking, A is also problematic.

A, saturated salt water, NaCl content unchanged.

b, the content of MgCl2 in water increased.

c, you cannot. Because the MgCl2 content will gradually increase and tend to be saturated.

d, the finer the particles, the easier it is to promote the dissolution of MgCl2.

A correct.

cacl2+na2co3=caco3+2nacl111 106 100 117

x 53g*20% y z

111/x=106/ =117/z

x= y=10g z=

The solute mass fraction in the solution resulting from the reaction (

The mass of Na2CO3 is grams, and the amount of the substance is Mo, then the amount of the substance of calcium chloride is also Mo, and the mass is grams.

The original sodium chloride is grams, the amount of substances that produce sodium chloride is mo, the mass is grams, and the mass of sodium chloride in the reaction solution is grams.

The amount of the substance that produces calcium carbonate precipitate in the reaction is 10 grams, and the mass of the solution obtained by the reaction is 25 + 173 + 53 10 241 grams, then the mass fraction of the solution obtained by the reaction is.

2. The mass of the solution obtained by the reaction is the total mass before the reaction minus the mass of the precipitate.

Solution: Let the mass of the original unreacted NaCl be Y1

The mass of the generated NaCl is Y2

The mass of the generated cac03 is y3

cacl2 + na2co3===cac03↓+ 2 nacl

25g--y1 53g x 20% y3 y2

Find y1==

y2==y3==10g

Then the solute mass fraction in the solution obtained by the reaction:

25g +173g +53g--10g) x100%==

The solute mass fraction of the solution obtained by the reaction = [

25+173+53-10 minus 10 is the mass of precipitated caCO3.

Exactly the complete reaction, and the last thing left is NaCl, find the sum of the mass of Cl and the mass of Na divided by the total mass minus the amount of calcium carbonate.

During the experiment, a student found that the sodium hydroxide solid was exposed to the air for a period of time, and then deliquescent, and he also found that the biscuits would become soft when exposed to moisture at home. These phenomena indicate that the air contains [water vapor], please combine your life experience or scientific knowledge to give two other examples to explain that the air contains this substance:

Scientific knowledge: Put white colorless copper sulfate in the air, and after a period of time, it will turn blue from white (anhydrous copper sulfate meets water to form blue copper sulfate pentahydrate) indicates that there is water vapor in CuSO4+5H2O=

Life experience: In winter, due to the temperature difference between indoor and outdoor, the water vapor in the air condensed on the glass window will be small water droplets, which is obvious.

A B is already unsaturated because the temperature rises and the solubility decreases.

The quality of B to C remains unchanged.

d The mass does not increase because it cannot be dissolved anymore and the added vigilance does not enter the solution.

Melamine molecular formula C3H6N6, the mass of nitrogen in raw milk is 1000, and the nitrogen content of 2 grams of melamine.

14 6 divided by 126, multiplied by 2g =, 1000g of milk powder after adding 2g of total mass is 1002g

After adding 2g of melamine to 1000g of protein, the total mass of N element = the mass of nitrogen in the raw milk + the amount of nitrogen contained in 2 grams of melamine = so after adding melamine, N % (The purpose of adding melamine: when the nitrogen content is small, add a mixture with more nitrogen content, and the nitrogen content can be increased.

1 law. The original nitrogen content is 1000, and the nitrogen content of melamine is 14 6 divided by 126, and then multiplied by 2g, which is equal to. And then (, got to pass.) Melamine has a high nitrogen content, and it is cheap to make nitrogen, and it cannot be detected by general inspection methods.

2 Law. 2 grams of melamine were added to 1000g of milk, the total mass was 1002g, and the nitrogen element in the raw milk was 1000

Therefore, after the addition of melamine, n% (

Question g: Because B does not precipitate, as can be seen from the figure, the content of B is less than 20 grams, that is, 40% (the solution of the solution question is all dissolved by default).

Question 2: 1) W% >A W) x 100% (because W< A+B, only the content of A should be greater than Ag).

2) w% >w - b) w x 100% (because w> a+b, only the content of b is considered to not exceed b grams).

1.It doesn't matter if it's all dissolved, as long as B is all dissolved. The mass of b in the mixture cannot be higher than 50g*20g100g=not mass fraction)

2.It's not a point.