What is the physical change of fresh eggs?

Fresh eggs will have these physical changes during storage: Egg weight: The weight of fresh eggs will gradually decrease during storage, and the longer the storage time, the more weight will be lost, and the amount of change is related to the storage conditions.

The higher the storage temperature, the more weight loss the egg; The higher the storage humidity, the less weight loss the eggs; If the eggshell is thick, dense and less porous, the weightlessness of the egg will be less, and vice versa; Different preservation methods (such as coating method, grain C storage method, etc.) have different weight loss.

Air chamber: The air chamber is an important indicator of the freshness of the egg. During storage, the size of the gas chamber increases with the extension of storage time.

The enlargement of the air cell is caused by the evaporation of water and the drying out of the contents of the egg. Therefore, the increase of the air chamber and the decrease of egg weight are corresponding, and are also affected by storage temperature, humidity, eggshell condition and storage method.

Moisture: With the extension of storage time, the water in the egg white is continuously evaporated through the stomata and penetrates into the egg yolk through the yolk membrane, and its content continues to decrease, which can be reduced to less than 71%. The moisture in the yolk gradually increases.

pH: The pH of fresh egg yolk. 4. In the process of storage, it will gradually rise and approach or reach neutral.

When eggs are first formed, the pH of the egg white is 7. 5~7。 6;After the egg is produced, the pH of the egg white rises rapidly to 8.

7;After a period of storage (about 10 days), the pH of the protein continues to rise, reaching more than 9.

If you break it, it's a physical change.

Summary. If the egg white and yolk are mixed, and there is a rancid smell, it means that the egg is spoiled. Shake the egg, if the egg is heavy and there is no sound, it means that it is a fresh egg, if it is shaken with a sound similar to the sound of water, it means that the egg is not fresh, but it is not necessarily spoiled.

Manifestations of spoiled eggs.

Place the eggs in a basin of water, and if the eggs lie flat on the bottom of the water, the eggs are fresh.

If the raw egg is upright or inclined in the water, it means that the egg is not fresh. If a raw egg floats on the surface of the water, it means that the egg has gone bad.

If the egg white and yolk are mixed, and there is a rancid smell, it means that the egg is spoiled. Shake the egg, if the egg is heavy and there is no sound, it means that it is a fresh egg, if it is shaken with a sound similar to the sound of water, it means that the egg is not fresh, but it is not necessarily spoiled. Manifestations of egg spoilage Put the eggs in a basin with water, if the eggs lie flat on the bottom of the water, the eggs are fresh.

If the raw egg is upright or inclined in the water, it means that the egg is not fresh. If a raw egg floats on the surface of the water, it means that the egg has gone bad.

Egg boiling is a chemical change, the physical change is that there is no new substance generated, and the chemical change is the formation of new substance, egg white contains many proteins, and the energy when heated will stir the protein molecule to change its molecular structure, and the molecular structure changes to produce a new substance, forming an insoluble solid.

The only sign that distinguishes physical change from chemical change is whether new substances are formed, for example: water, whether it is liquid water, solid ice, or gaseous water vapor, they are still water, and no new substances are produced in the change, this change is called physical change. For example:

Rust of iron utensils produces rust, and food spoilage produces toxic substances, etc., and this change is called chemical change, and chemical change is generally accompanied by phenomena such as heating, luminescence, gas, and precipitation.

Chemical changes.

When heated, the egg is reversed from liquid to solid.

Proteins are composed of one or more polypeptide chains, which are formed by different amino acid molecules joined in sequence by peptide bonds, and adjacent amino acid molecules produce hydrogen bonds or other gravitational or repulsive forces with each other due to their different constituent elements and chemical properties, so that proteins fold into specific shapes; In general, the hydrophobic (or non-hydrophilic) part of a water-soluble protein structure is encapsulated inside, while the hydrophilic part is exposed on the outside and is therefore soluble in water.

However, the energy during heating will agitate the protein molecule, causing it to break free from the constraints of hydrogen bonds or other suction and repulsion forces, and the polypeptide chains that were originally folded into a specific shape will loosen and lose their original water-soluble structure, thus becoming an insoluble solid.

It is both a physical change and a chemical change.

When eggs are cooked, the main thing that happens is the denaturation of the protein by heat. The spatial structure of protein molecules changes, resulting in the formation of new substances, which is a chemical change. At the same time, its physical properties have changed (most notably the eggshell contents: liquid-solid), and there has also been a physical change.

The denaturation of protein is a very complex change, there are both physical changes and chemical changes, to determine whether the denaturation is a physical change or a chemical change, depending on the specific situation, if there is a break and formation of chemical bonds, it is a chemical change; If there is no chemical bond breakage and formation, it is a physical change.

Physical change, raw eggs are colloidal, and after cooking, they are heated to make the colloids settle into solids. The minimum particle size of colloids is 1nm-100nm

It's a physical change. It's just that the material structure of the egg changes at high temperatures.

It's a physical change, it's just that the protein solidifies, and the substance doesn't change much.

Chemical changes. When heated, the egg is reversed from a liquid to a solid.

Proteins are composed of one or more polypeptide chains, which are formed by different amino acid molecules joined together in sequence by peptide bonds, and adjacent amino acid molecules produce hydrogen bonds or other gravitational or repulsive forces to each other due to their different constituent elements and chemical properties, so that proteins fold into specific shapes; In general, the hydrophobic (or non-hydrophilic) part of a water-soluble protein structure is encapsulated inside, while the hydrophilic part is exposed on the outside and is therefore soluble in water.

However, the energy during heating will stir the protein molecule, causing it to break free from the constraints of hydrogen bonds or other suction and repulsion forces, and the polypeptide finger chains that were originally folded into a specific shape will loosen and lose their original water-soluble structure, thus becoming an insoluble solid.

Liquid.

Three basic states of matter.

Strictly speaking, the physical solid state should be referred to as the "crystalline state", that is, the state of various crystals. The most common crystal is table salt (chemical composition is sodium chloride, chemical symbol is NaCl). If you take a grain of table salt and look at it (preferably coarse salt), you can see that it is made up of many cubic crystals.

If you go to the Geological Museum, you can see many regular crystals of different colors and shapes, which are very beautiful. The salient feature of matter in the solid state is that it has a certain volume and geometry, and the physical properties can be different in different directions (called "anisotropic"); There is a certain melting point, that is, the temperature does not change when melting.

In solids, molecules or atoms are arranged in regular periodicities, just as we all do exercises at equal distances from each other. Each person moves in a certain position, just as each molecule or atom vibrates in its own fixed position. We refer to this structure of the crystal as a "spatial lattice" structure.

Liquid liquid has fluidity, and it has the shape of whatever shape it is placed in in the container. In addition, unlike solids, liquids also have the characteristic of "isotropic" (the same physical properties in different directions), because when an object changes from a solid to a liquid state, the molecules or atoms move violently due to the increase in temperature, and it is impossible to maintain the original fixed position, so the flow occurs. However, the attraction between molecules or atoms is still relatively large, so that they will not disperse away, so the liquid still has a certain volume.

In fact, there are still crystal-like structures in many small areas of the liquid – the "crystal-like zone". Fluidity is formed by the movement of "crystal-like regions" from one another to each other. Let's use an analogy, in the "traffic flow" of the asphalt road, the people in each car have a fixed position of a "crystal-like area", and the cars can move relative to each other, which causes the flow of the whole team.

Gaseous liquids become gaseous when heated. At this time, the movement of molecules or atoms is more violent, and the "crystalline region" does not exist. Due to the increased distance between molecules or atoms, the gravitational force between them is negligible, so the gaseous state is mainly manifested by the irregular motion of the molecules or atoms respectively, which leads to the gas properties as we know them:

It has fluidity, has no fixed shape and volume, and can automatically fill any container; Easy to compress; Physical properties are "isotropic".

Obviously, the liquid state is the form that is between the solid and gaseous states.

It should be in liquid form.

Compared with liquids and gases, solids have a relatively fixed volume and shape, and the texture is relatively hard.

The liquid state can flow, deform, and be microcompressible.

The liquid state is different from the gaseous state, which has a certain volume. The liquid state, unlike the solid state, is fluid and therefore does not have a fixed shape.

Liquid. Liquids are able to flow. Solids are immobile.

Liquid, if you air dry it, it will be solid, take it.

Fresh egg yolks should be in liquid form.

Liquid liquid has fluidity, and it has the shape of whatever shape it is placed in in the container.

1.The liquid state of the substance. A form of matter that can flow, deform, and be micro-compressed.

2.In liquid state, the main intermolecular force at work is the van der Waals force.

The van der Waals force is caused by the attraction of dipoles and opposite poles between molecules. So unlike chemical bonds, which have fixed angles, van der Waals forces only have an approximate direction. This is also the reason why liquids flow but solids cannot.

When the van der Waals force between the molecules of a liquid object is broken (heating, which increases the kinetic energy of a single molecule), the object changes from a liquid state to a gaseous state; When the intermolecular thermal motion of a liquid object decreases, so small that intermolecular chemical bonds can be formed, so that chemical bonds dominate between molecules, the liquid becomes solid.

Fresh egg yolk is colloidal and can undergo Tyndall effect or soluble in more water.

The yolk is the yellowing part of the inside of the egg. The protein of the egg is concentrated in the egg white and egg film, and the rest of the material is concentrated in the yolk. When the egg yolk is heated, the substance is denatured and forms a solid, which is a chemical change.

a. The temperature of the eggs taken out of the refrigerator is relatively low, and the water vapor in the air will liquefy when the eggs are cold, forming small water droplets attached to the eggs, so the eggs become wet; After a while, the egg dries out because the small water droplets on the egg vaporize (evaporate) and become water vapor and dissipate into the air.

b. Boiled eggs with tea leaves, the eggs change color from the shell to the inside, which is formed by the thermal movement of the molecules, this option is correct and does not conform to the topic;

c. After just fishing, there is water evaporation on the surface, evaporation and heat absorption, taking away the heat, so it is not too hot; However, after the water dries, there is no water to evaporate and absorb heat, and the temperature is high, so I feel that it is hot, and this option is correct and does not meet the topic;

d. After the water is boiled, although it is heated with a fierce fire, the temperature of the water is still kept at the boiling point and will not rise, and the eggs will not cook faster

Therefore, choose D