What are the experiments on iodine, the experimental phenomena in the extraction of iodine

Iodine clock experiment, kelp iodine extraction experiment, salt iodine detection test, fingerprint iodine detection experiment, iodine extraction experiment, nitrogen iodide experiment, iodine and starch discoloration experiment.

The same amount of iodine is less soluble in water than in organic solvents (in this case, carbon tetrachloride).

In the extraction process, the iodine elements in iodine water are all added to carbon tetrachloride. Carbon tetrachloride contains more iodine, and the color naturally darkens. Whereas, iodine water will become lighter in color.

It is also necessary to correct that the iodine element is purple-red, and the iodine water is brownish-yellow.

1. Take 10ml of iodine saturated aqueous solution with a graduated cylinder, pour it into the separating funnel, and then inject 4ml of carbon tetrachloride and cover the glass stopper.

2. Press the mouth of the separating funnel with the right hand, hold the piston part with the left hand, turn the separating funnel upside down and oscillate, so that the two liquids are fully in contact, open the piston after oscillation, and the gas in the funnel is released.

3. Place the separating funnel on the iron frame and let it stand.

4. After the liquid is stratified, open the glass plug on the neck of the separating funnel, or align the groove (or small hole) on the plug with the small hole on the funnel, and then unscrew the piston under the separating funnel to make the lower liquid flow down the beaker wall slowly.

Phenomenon: After standing, the solution is stratified, and the upper layer is an aqueous solution, colorless; The lower layer is an iodine solution of carbon tetrachloride, which is purplish-red.

Principle: Compared with water and carbon tetrachloride, iodine is more soluble in carbon tetrachloride.

1) Observe the cell structure.

, add iodine solution dropwise to stain, easy to observe the cell structure Starch turns blue when exposed to iodine, which can be used to test starch 2) Decolorization: Put the leaves into a small beaker with alcohol.

medium, heat the water to make the chlorophyll in the leaves.

Dissolved into alcohol, the leaves turn yellowish-white.

3) The data of the students are different, and the possible reasons are: there is no insulation device, the heating area of the test tube is small, etc., which leads to the loss of more heat when the peanut is burned; inaccurate measurements; There is an error in the calculation, etc

Therefore, the answer is: (1) stain the cells to test the starch;

2) water and alcohol; Heating over water; (3) Non-standard operation, inaccurate measurement, calculation error, etc

Summary. In scientific experiments, it is usually necessary to accurately weigh or measure the amount of various reagents for the following reasons:1

Accuracy of experimental results: small differences in the dosage of different reagents may lead to obvious changes in experimental results, so it is necessary to accurately weigh or measure the dosage of various reagents to ensure the accuracy of experimental results. 2.

Integrity of the reaction: Some tests require a specific proportion of reagents to achieve optimal reaction results, and if used in insufficient or excessive amounts, the reaction may be incomplete or invalid. 3.

Economy: Accurately weighing or measuring reagents can not only ensure the accuracy of experimental results, but also reduce the waste of reagents and improve the economy of experiments. 4.

Safety: In scientific experiments, some reagents are toxic or flammable, and if the dosage is inaccurate, it may affect the health of the experimenter, so it is necessary to accurately weigh or measure the dosage of various reagents to ensure the safety of the experiment. Therefore, the amount of iodine used in this experiment needs to be weighed accurately.

Need. Excuse me, but please go into more detail?

In scientific experiments, it is usually necessary to accurately weigh or measure the amount of various reagents for the following reasons:1Accuracy of experimental results:

Small differences in the dosage of different reagents may lead to significant changes in the experimental results, so it is necessary to accurately weigh or measure the dosage of various reagents to ensure the accuracy of the experimental results. 2.Integrity of the reaction:

Some tests require a specific ratio of reagents to achieve optimal results, and if used in insufficient or excessive amounts, the reaction may be incomplete or ineffective. 3.Economic Simplicity:

Accurate weighing or measuring of reagents can not only ensure the accuracy of experimental results, but also reduce the waste of reagents and improve the economy of experimental blindness. 4.Security:

In scientific experiments, some reagents are toxic or flammable, and if the dosage is inaccurate, it may affect the health of the experimenter, so it is necessary to accurately weigh or measure the dosage of various reagents to ensure the safety of the experiment. Therefore, the amount of iodine used in this experiment needs to be weighed accurately.

Summary. In experiments, iodine is a commonly used reagent and is often used to detect substances such as starch. When using iodine reagents, the right amount of iodine needs to be weighed accurately to ensure the accuracy and reproducibility of experimental results.

If the dosage is insufficient, it may not be able to respond completely, resulting in low experimental results; If the amount is used in too much, it may affect the rate of reaction or have other adverse effects. Therefore, when using iodine reagents in experiments, it is necessary to weigh the right amount of iodine accurately and follow the correct operating procedures and safety specifications. In this way, the reliability and accuracy of the experimental results can be ensured.

In experiments, iodine is a commonly used reagent and is often used to detect substances such as starch. When using iodine reagents, the right amount of iodine needs to be weighed accurately to ensure the accuracy and reproducibility of experimental sterling silver results. If the dosage is insufficient, it may not be able to respond completely, resulting in low experimental results; If the amount is used in too much, it may affect the rate of reaction or have other adverse effects.

Therefore, when using iodine reagents in experiments, it is necessary to accurately weigh the appropriate amount of iodine and follow the correct operating procedures and safety specifications. In this way, the reliability of the experimental results and the accuracy of the experiment can be ensured.

Can you tell us more about that?

Accuracy and reproducibility of the experiment. If the dosage is too much or too little, the delay can lead to errors in the experimental results and affect the reliability of the experiment. In addition, iodine is a toxic substance, so you need to pay attention to safety when using it.

Accurately weighing the right amount of iodine can avoid excessive waste and unnecessary risk of stupidity. Therefore, it is very important to weigh the amount of iodine accurately in the experiment, and the experimental procedure should be followed to ensure the accuracy and safety of the experimental results.

Steps: Seal the glass tube of Weiyuxun, put solid iodine at one end, and the side with iodine is cocked, and heated with an alcohol blowtorch.

Phenomenon: Iodine will sublimate and condense in the upper part, but will not melt and flow downward.

Explanation: Because the sublimation point and melting point of iodine are relatively close, the vapor pressure of iodine increases dramatically as the temperature increases. The melting point of iodine is , and the triple point of iodine is , and the vapor pressure is kpa

At the three-phase point O, solid, liquid, and gaseous iodine coexist. Obviously, the higher the vapor pressure at the three-phase point, the easier it is for the solid substance to sublimate. Usually the solid of iodine is heated in an open container, and because the vapor of the iodine is constantly escaping, it cannot reach the air pressure of kPa, and the solid iodine is directly sublimated without melting.

To obtain liquid iodine, conditions are created where the vapor pressure exceeds kPa. Liquid iodine can be obtained by heating a sufficient amount of iodine in a fine-fingered distillation flask. In our general iodine sublimation experiments, if the heating is relatively fast, the iodine vapor is relatively concentrated, and it is not condensed in time, so it is directly promoted and dismantled without going through the liquid state.