Endothermic reactions are reactions that proceed by the absorption of heat (energy) while exothermic reactions involve a release of energy.
a) Formation of frost on a car window in winter is an exothermic process as heat is liberated when liquid water freezes to form crystals
b) Formation of water condensate on a glass of ice water is an endothermic reaction since heat is absorbed by the cold water from the glass container thereby cooling it.
c) A decrease in the temperature as ammonium nitrate is added to water is an endothermic reaction
a) and b) are exothermic processes because they release heat to the surroundings. c) is an endothermic process because it absorbs heat from the surroundings.
Let's analyze each option:
a) Frost forms on a car window in winter: Exothermic
Frost forming is an exothermic process because it releases heat as water vapor in the air condenses and freezes on the cold car window, giving off energy in the form of heat to the surroundings.
b) Water condenses on a glass of ice water on a humid summer afternoon: Exothermic
Similar to the first scenario, water condensation is exothermic. As water vapor from the humid air comes into contact with the cold glass of ice water, it condenses into liquid water, releasing heat to the surroundings.
c) Adding ammonium nitrate to water causes the temperature of the solution to decrease: Endothermic
This process is endothermic because dissolving ammonium nitrate in water absorbs heat from the surroundings, causing the temperature of the solution to decrease.
Learn more about exothermic and endothermic processes:
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b. attractions between its atoms.
c. the number of valence electrons in atoms of the element.
d. the ratio of protons to neutrons in atoms of the element
The tendency of an element to react is closely related to the number of valence electrons in atoms of the element (answer C).
Explanation
Valence electrons are outer shell electrons of an atom.They govern the bonding behavior of an element.
when element react to form compound, valence electron are involved.
Valence electrons are involved in a reaction either by sharing among atoms or may be transferred from one atom to another.
For example in formation of NaCl bond there is transfer of valence electron between Na and Cl. Na donate 1 valence electron while Cl accept 1 electron to form NaCl
b. the pancreas and stomach
c. the liver and gallbladder
d. the small intestine and large intestine
The correct answer is C. The liver and gallbladder.
Explanation
The liver, is an organ of the digestive system, is the most voluminous in the human body, and performs three vital functions essential for the organism: Detoxification in which it acts as a filter that collects and eliminates numerous toxins; the liver metabolizes carbohydrates, fats, lipids and proteins, secreting bile, an essential element for our digestion. Also, it prevents bleeding through a coagulation process; finally, works as a container for vitamins and glycogen, carbohydrates, and energy is stored in the form of sugar. On the other hand, the gallbladder is an organ of the digestive system, whose function is to store and concentrate the bile secreted by the liver required by the digestion process. The gallbladder stores bile until a stimulus caused by food intake, especially meat or fat. According to the above, if the functions of these two organs are impaired, the most likely is that the person will have trouble digesting fats. So, the correct answer is C. The liver and gallbladder.
C
came from edginuity
The atoms that would sterically interact with methyl group located axially are highlighted in pink color in the attached image.
Further Explanation:
The stereoisomer of a molecule that has same chemical formula and connectivity of bond but differs in the arrangement of the atoms in space is known as conformer. The rotation about the carbon-carbon single bond can lead to the formation of conformer of a molecule.
There are four conformers of cyclohexane molecule as follows:
Chair conformation is considered as the best conformation of cyclohexane. The hydrogen in blue denote the axial positions and the hydrogen in pink denote equatorial positions. (Refer to the attached image)
The stable conformation is that in which the bulky groups such as hydroxyl, methyl, and nitro group occupy the equatorial positions while the relatively small groups such as hydrogen atoms occupy axial positions. The reason is that the axially placed substituents suffer more steric repulsion and that generates strain in the molecule. The strain leads to high energy and thus less stability.
While writing the chair conformation the bulkier groups are preferentially placed at equatorial positions. The conformation that has bulky group at equatorial position is more favorable than the conformation that has bulky group at axial position. The reason for the stability of the conformation is diaxial interactions.
1,3-diaxial interaction: The 1,3-diaxial interactions occur among the axial substituent present at 1 and 3 positions.
The conformation in the problem has axial substituent hydrogen and bromine at the two positions 3 and 3’ which lead to 1,3-diaxial strain in the molecule and makes it unstable. (Refer to the attached image)
Learn more:
1. Balanced chemical equation brainly.com/question/1405182
2. Oxidation and reduction reaction: brainly.com/question/2973661
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Conformation of cyclohexane
Keywords: Cyclohexane, planar, chair conformation, axial positions, equatorial positions, steric repulsion, high energy, 1, 3-diaxial interaction, 1, 3-diaxial strain.
In a substituted cyclohexane, 1,3-diaxial interactions happen between groups on the same side of the ring but are two carbons apart. In this scenario, the hydrogen atoms on carbons 3 and 5 would interact with the methyl group, causing steric strain.
In a substituted cyclohexane compound, 1,3-diaxial interactions occur between groups that are on the same side of the ring but are two carbons apart. In this case, the question focuses on the steric interactions with the methyl group. Assuming that the methyl group is on carbon-1 of the ring, the hydrogen atoms on carbons 3 and 5 (both axial positions) on the same face of the ring would sterically interact with the methyl group in a 1,3-diaxial fashion. This steric interaction leads to steric strain, which destabilizes the compound and promotes a conformational flip to relieve this strain.
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b. gas tail
c. dust tail
d. Giant Red Spo
The correct answer is A. cloud of gases that forms around the nucleus of a comet is called a coma. The coma is a dusty, fuzzy cloud around the nucleus of a comet. Other parts of a comet are the nucleus and the tail.
Answer:
giant red spo
Explanation:
Answer:
Explanation:
Substances with giant covalent structures are solids with high melting and boiling points due to the nature of the covalent bonds and the three-dimensional network they form within the crystal lattice. This structure is also often referred to as a network covalent structure. Let's break down the key reasons why these substances have such properties:
1. **Strong Covalent Bonds**: In giant covalent structures, each atom forms strong covalent bonds with neighboring atoms. Covalent bonds involve the sharing of electrons between atoms. This sharing results in the formation of very strong and directional bonds, which require a significant amount of energy to break.
2. **Three-Dimensional Network**: In these substances, the covalent bonds extend in a three-dimensional network throughout the entire structure. This means that every atom is bonded to several neighboring atoms in all three spatial dimensions. This extensive network of covalent bonds creates a robust and interconnected structure.
3. **Lack of Weak Intermolecular Forces**: Unlike some other types of solids (e.g., molecular solids or ionic solids), giant covalent structures lack weak intermolecular forces, such as Van der Waals forces. In molecular solids, weak intermolecular forces are responsible for their relatively low melting and boiling points. In giant covalent structures, the primary forces holding the atoms together are the covalent bonds themselves, which are much stronger.
4. **High Bond Energy**: The covalent bonds in giant covalent structures have high bond energies, meaning that a substantial amount of energy is required to break these bonds. When a solid is heated, the energy provided must be sufficient to overcome the covalent bonds' strength, leading to the high melting and boiling points.
5. **Rigidity and Structural Integrity**: The three-dimensional covalent network imparts rigidity and structural integrity to the substance. This network resists deformation and allows the substance to maintain its solid form at high temperatures, as the covalent bonds continuously hold the structure together.
Examples of substances with giant covalent structures include diamond (composed of carbon atoms), graphite (also composed of carbon atoms but arranged differently), and various forms of silica (e.g., quartz and silicon dioxide). Diamond, in particular, is known for its exceptional hardness, high melting point, and remarkable optical properties, all of which are attributed to its giant covalent structure.
In summary, giant covalent structures have high melting and boiling points because of the strong covalent bonds, the three-dimensional network of bonds, and the absence of weak intermolecular forces. These factors combine to create a solid with exceptional stability and resistance to temperature-induced phase changes.
Substances with simple molecular structures are usually gases, liquids, or solids with low melting points due to the intermolecular forces between their molecules. The chemical identities of the molecules determine the types and strengths of these attractions, influencing the physical state of the substance.
Substances with simple molecular structures tend to be gases, liquids, or solids with low melting and boiling points because of the nature of intermolecular forces at play. Intermolecular forces are the attractions between molecules, which determine many of the physical properties of a substance. For instance, small, symmetrical molecules, such as H2, N2, O2, and F2, have weak intermolecular attractive forces and form molecular solids with very low melting points (below -200 °C).
In a liquid, intermolecular attractive forces hold the molecules together, though they still have sufficient kinetic energy to move relative to each other. In gases, the molecules have large separations compared to their sizes due to which the forces between them can be ignored, except during collisions.
Therefore, the chemical identities of the molecules in a substance determine the types and strengths of intermolecular attractions possible; this subsequently influences whether the substance is a gas, liquid, or solid, and its melting and boiling points.
Learn more about Intermolecular Forces here:
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