How can I tell if there is salt NACL and starch in my water? 20

Haha, the way to identify whether there is salt (sodium chloride) in the water is actually very simple. Just put the salt water (i.e. sodium chloride solution) in a beaker. Note:

You don't have to put too much, just a few milliliters. Then put an alcohol lamp at the bottom of the beaker, stir while burning, and wait until the water evaporates, there will be salt crystals (note, salt crystals will jump, be careful), then you can remove the alcohol lamp. Of course, if there are no crystals, then it proves that there is no sodium chloride in the water.

It's as simple as that, hehe.

If you can, get some silver nitrate from the laboratory, drop a few drops into it, there will be NaCl if there is a white precipitate, and then get some iodine into it, and it will turn blue to indicate that there is starch.

Go get a little iodine wine (it's easy to find for disinfection) and drop one drop into each of the two types of water, the one that turns blue is the starch, and the one that doesn't change is the salt water, this method is the most simple and straightforward

The easiest way to do this is to pick it up and taste it

You can use the purple potion at home as iodine to detect starch, and it's really hard to get salt.

The homework must be to test whether you know iodine or not. So just iodize it directly. Turning blue is the addition of starch, and household iodine wine contains iodine.

Iodine wine was used to identify starch components, and combustion method was used to identify salt content.

Isn't starch discolored when it reacts with anything? I don't remember it for a long time.

When iodized water is added to the water, the water does not turn blue to prove that there is no starch. Hydrochloric acid acidified silver nitrate is then added to the water, and there is a white precipitate to prove the presence of table salt.

It's such a coincidence, our school also has this experiment, are you Guangya? I used iodine wine to see if there was any starch, and found that there was none, and then evaporated to see if there was any salt precipitation

The water level of starch does not change, and the water level of salt changes greatly.

Go get a little iodine wine (it's easy to find for disinfection) and then drop one drop into two kinds of water, the one that turns blue is the starch The one that doesn't change is the salt water This method is the most simple and clear If you can, get some silver nitrate from the laboratory, drop a few drops into it, there will be NaCl if there is a white precipitate, and then get some iodine into it, and it will turn blue to indicate that there is starch.

From a chemical point of view:

In fact, the appearance of starch is very different from monosodium glutamate and salt. Edition.

However, if you do not distinguish from the appearance, you can take a small amount of the above three substances and put them in a test tube or beaker.

Then, add a little water to it.

At this time, you will find that MSG and salt are silently dissolved, and there is no special situation.

The starch turns into a white paste.

If you still can't tell the difference, then the easiest and most straightforward way to do it:

To the above three solutions, iodine water is added. The starch solution turns blue rapidly. The other two solutions did not change significantly.

The main component of monosodium glutamate is sodium glutamate, while the table salt component is sodium chloride.

Therefore, when an excessive amount of AGNO3 (silver nitrate) solution is added to it, a large amount of white precipitate appears.

A small amount of white precipitate or no precipitate is monosodium glutamate. (Because MSG may also contain a small amount of NaCl).

Thus it is distinguished ... I don't know if it's the way you want?

Add iodine water, and the starch that turns blue is the starch;

AgNO3 is added, and a large amount of white precipitate is NaCl;

The rest is monosodium glutamate;

If you have any questions, please follow! ~

Taste the taste, if you can't taste the taste, you can make these three things into a solution, add potassium permanganate solution dropwise to it, turn blue is starch, and then add silver nitrate solution dropwise, there is a white precipitate to produce table salt, and the rest is monosodium glutamate.

The salt in starch can only be diluted with water.

Add more water and stir the starch to precipitate, then change the water and stir again.

Repeat this several times to remove the salt.

The presence of table salt in the water will reduce the freezing point of the water, and your question may not be accurate, since it is distilled water, it should not contain table salt, and the water containing table salt should be water containing impurities.

The freezing temperature of salt water will be below 0 degrees Celsius!

Raise it, because last time I put water, flour and salt together, they solidified.

It is lower. Then distillation will know whether there is salt or not.

Put some silver nitrate, as long as there is precipitation, it means that there is.

Take a part of the water in the large beaker and put it in two clean test tubes, add nitric acid and silver nitrate in one of them to observe whether there is a white precipitate, and add iodium to the other test tube to see if the solution turns blue, the conclusion is that the test tube with silver nitrate produces precipitation, and the iodized test tube solution does not change color, indicating that the sodium chloride solution can penetrate the semi-permeable membrane, while the starch colloid cannot, indicating that the dialysis of the colloid can separate the mixture.

How to check: Add agno3 and i2

The aim is to verify the size of the colloid.

The conclusion is that there is table salt and no starch.

Indicates that the colloid cannot pass through the semi-permeable membrane.

Change it with the 1st floor, because it is a home experiment, so you have to consider its rationality and economy, agno3 is very expensive.

The purpose should be to investigate the permeability of semi-permeable membranes.

Test: Taste the taste of water (table salt) with a salty taste indicates that there are Na+Cl- ions through, and no means no. The iodized wine tested for starch, and no blue color appeared, proving that there was no starch.

Conclusion: Sodium chloride ions can penetrate semi-permeable membranes, but starch molecules cannot permeate semi-permeable membranes.

Explanation: Ions can pass through a semi-permeable membrane freely, and the degree of ion passage is only related to the corresponding ion concentration on both sides of the membrane. The starch molecule is too large to pass through the pores of the semi-permeable membrane.

Interpretation; First of all, the chloride ions in the brine (NaCl) can be tested with silver nitrate to test for white precipitate! Starch is tested with iodine solution (iodine turns blue when starch is encountered)!

Semi-permeable membranes allow only small molecules to pass through! Starch is a carbohydrate macromolecular substance! Can't pass. Ions belong to small molecules that can pass through! That's it!

The purpose of this experiment is to investigate what molecules are allowed to pass through the semi-permeable membrane, and what particles of salt and starch are used!

The conclusion is; There is only table salt in the water.

Salt water has no oxidation, BC is oxidized by iodine ions to produce iodine element, and the solution will turn blue, and D is added to iodine, so the solution turns blue.

The reason why the powder turns blue in solution is because the starch reacts with iodine to form a blue complex. Starch and potassium iodide do not work and are colorless solutions. If potassium iodide is added to the starch potassium iodide solution to oxidize the substance, iodine can be formed (and the solution turns blue), it must be an oxidant (potassium iodide is a reducing agent).

2] Chosen answer:

a (is the answer to this question); a。Salt water (the main ingredient is sodium chloride), in which there is no oxidizing agent that can oxidize potassium iodide, therefore, it "cannot make the solution blue".

b (not the answer to this question): Bromine water is an oxidizing agent (the standard electrode potential is v) that can oxidize potassium iodide (the standard electrode potential is to produce iodine, which makes the solution blue;

c (not the answer to this question): chlorine water is an oxidizing agent (the standard electrode potential is v) that can oxidize potassium iodide (the standard electrode potential is to produce iodine, which makes the solution blue;

D (not the answer to this question): After iodine water is added, iodine reacts with starch to make the solution blue.

A: Sodium chloride in salt water is not oxidizing, and it does not contain iodine, so it cannot make the starch potassium iodide solution blue.

The reduction of chlorochlorobromide iodine is weakened, so bromine water and chlorine water can replace the iodine in potassium iodide, and the iodine water itself contains iodine element, and the salt is sodium chloride, and the chlorine is in negative one valence, which is the lowest valence, so it cannot react with potassium iodide to replace the iodine element, therefore, the salt water cannot make the potassium iodide starch solution blue.