When a chemical reaction takes place, the starting substances (substances that will undergo the change) are called _____.

Question 2 options:

products


mixtures


reactants


yeilders

Final answer:

An octet of electrons refers to an atom having eight valence electrons, providing stability similar to a noble gas. The octet rule primarily applies to main group nonmetals; however, exceptions like hydrogen that only needs two electrons and elements capable of expanded octets due to d orbitals exist.

Explanation:

The octet rule is a fundamental concept in chemistry that states atoms tend to bond in such a way that each atom has eight electrons in its valence shell, which provides stability and an electron configuration similar to that of noble gases. Elements strive to achieve an octet of electrons when forming chemical bonds, like in the case of carbon in carbon tetrachloride (CCl₄) where carbon forms four covalent bonds to obtain an octet.

Atoms from the main group elements, particularly nonmetals in the second period such as carbon (C), nitrogen (N), oxygen (O), and fluorine (F), typically follow this rule to form stable molecules. However, there are exceptions like hydrogen, which only requires two electrons to fill its valence shell. Moreover, expanded octet situations can occur with elements in the third period and beyond, where these atoms can hold more than eight valence electrons due to having available d orbitals, as in the case for phosphorus in phosphorous pentachloride (PCl₅).

Final answer:

Herodotus, in his work 'The Histories', explored the cultural differences between Greeks, Persians, and Egyptians, documenting complex societies and challenging the notion of cultural superiority.

Explanation:

Herodotus is known as the father of history, and in his work, The Histories, he delves into the cultural contrasts between Greeks, Persians, and Egyptians. He observed that, despite the Greek perspective that often labeled Persians as "barbarians," other societies such as Persia could rival Greece in complexity and military prowess. In Egypt, he noted differences in religious practices and governance, recognizing the peaceable hereditary transfer of power in contrast to the often tumultuous Greek city-state politics.

Herodotus was well-traveled and utilized his experiences to explore the encounter between different cultures. His inquiry aimed to ensure that "great and marvelous deeds" by both Greeks and non-Greeks would not be forgotten. This exploration led him to challenge the notion of one culture being superior to another and opened a dialogue about cultural relativism that remains relevant.

The answer is No, it is not possible that the reverse reaction will occur at ordinary conditions. This is because the entropy of the KCl and the O2 are much largely negative than that of the KClO3. The entropy component of the Gibbs free energy assures that the Gibbs free energy for the reverse reaction is positive (Positive Gibbs means nonspontaneous reaction). 

The formation of [tex]\( \text{KClO}_3 \)[/tex] from [tex]\( \text{KCl} \)[/tex] and [tex]\( \text{O}_2 \)[/tex] is not likely feasible under ordinary conditions due to its endothermic nature and decrease in entropy.

The decomposition of [tex]\( \text{KClO}_3 \)[/tex] into [tex]\( \text{KCl} \)[/tex] and [tex]\( \text{O}_2 \)[/tex] is exothermic and increases entropy, making it spontaneous under ordinary conditions. The reverse reaction, forming [tex]\( \text{KClO}_3 \)[/tex] from [tex]\( \text{KCl} \)[/tex] and [tex]\( \text{O}_2 \)[/tex], would be endothermic and decrease entropy, requiring energy input and typically not occurring spontaneously under normal conditions. Therefore, the formation of  [tex]\( \text{KClO}_3 \)[/tex] from [tex]\( \text{KCl} \)[/tex] and [tex]\( \text{O}_2 \)[/tex] is not likely to be feasible under ordinary conditions.

Answer:

79 protons, 79 electrons and 118 neutrons

Explanation:

Hi, the atomic number of an element is equal to the number of protons it has.

For gold (Au): [tex]Protons_{Au}=79[/tex]

If the atom is uncharged (and only if it is uncharged), the number of electrons it has is equal to the number of protons.

For gold (Au): [tex]Electrons_{Au}=79[/tex]

At last, the atomic mass represents the protons plus the neutrons an atom has in its core. So:

[tex]Neutrons_{Au} + Protons_{Au}=197[/tex]

[tex]Neutrons_{Au}=197 - 79[/tex]

[tex]Neutrons_{Au}=118[/tex]

" Two physical properties are melting point and boiling point. Two chemical properties are reactivity with other substances and flammability.

 Explanation:

 Physical properties are characteristics that can be observed without changing the identity or composition of the substance. They are used to describe matter and can be measured or perceived with the senses. Two examples of physical properties are:

  1. Melting point: This is the temperature at which a solid substance transitions to a liquid. It is a physical property because it does not involve a chemical change; the substance remains the same before and after melting.

 2. Boiling point: This is the temperature at which a liquid substance changes to a gas at a given pressure. Similar to melting point, boiling point is a physical property as it describes a physical change of state without altering the chemical composition of the substance.

  Chemical properties, on the other hand, describe the ability of a substance to undergo a chemical change or reaction. They are concerned with the chemical structure and composition of the substance. Two examples of chemical properties are:

  1. Reactivity with other substances: This refers to the tendency of a substance to react with other chemicals. For instance, some metals react with acids to produce hydrogen gas. This property is a chemical property because it involves a change in the chemical identity of the substances involved.

 2. Flammability: This is the ability of a substance to burn in the presence of oxygen. When a material burns, it undergoes a chemical reaction, often combining with oxygen to form new compounds such as carbon dioxide and water. Flammability is therefore a chemical property as it involves a chemical transformation."

We can calculate for the volume using the formula:

volume = mass / density

Therefore:

volume = 5.72 kg / (0.78 kg / L)

volume = 7.33333 L

We know that 1 mL = cm^3 and that 1 L = 1000 mL, therefore: 1  L = 1000 cm^3

volume = 7.33333 L * (1000 cm^3 / L)

volume = 7,333.33 L

Answer: [tex]N_2(g)+3H_2(g)\rightarrow 2NH_3(g)[/tex]

Explanation: According to the law of conservation of mass, mass can neither be created nor be destroyed. Mass remains conserved. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Haber's process used for manufacturing of ammonia in terms of balanced chemical equation is:

[tex]N_2(g)+3H_2(g)\rightarrow 2NH_3(g)[/tex]

The balanced chemical equation for the synthesis of ammonia using the Haber-Bosch process is N₂(g) + 3H₂(g) → 2NH₃(g), which is a crucial industrial reaction for producing fertilizers.

The balanced chemical equation for the Haber-Bosch process, where nitrogen and hydrogen combine to form ammonia, is as follows:

N₂(g) + 3H₂(g) → 2NH₃(g)

This represents the direct combination of nitrogen gas (N₂) and hydrogen gas (H₂) to yield ammonia (NH₃), which is widely utilized in the production of fertilizers. The Haber-Bosch process operates under high pressure and temperature to favor the formation of ammonia from its constituent elements. The coefficients in the balanced equation indicate the molar ratio at which the reactants combine to form the product.

The limiting reagent is the reactant that produces the least amount of product. Mass-mass calculations help determine this. The reactant that gives the lesser amount of product is the limiting reactant.

The limiting reagent is the reactant that produces the least amount of product. Mass-mass calculations can determine how much product is produced and how much of the other reactants remain. The key to recognizing which reactant is the limiting reagent is based on a mole-mass or mass-mass calculation: whichever reactant gives the lesser amount of product is the limiting reagent. For example, consider this reaction:

2A + 3B → C

If you have 4 moles of A and 5 moles of B, you can calculate the amount of product C formed from each reactant as follows:

4 moles A * (1 mole C / 2 moles A) = 2 moles C

5 moles B * (1 mole C / 3 moles B) = 1.67 moles C

From this calculation, you can see that A would be the limiting reagent since it produces the least amount of product C.

Assuming that the percent composition that is given is based on volume, therefore amount og agarose needed would simply be the product of the fractional composition and the total volume of the solution, that is:

required agarose = 0.01 * 40 mL

required agarose = 0.4 mL

To make a 40 ml 1% agarose gel, you will need 400 mg of agarose.

Agarose gel electrophoresis:

To calculate the amount of agarose needed to make a 40 ml 1% agarose gel, you can use the formula:

Amount of agarose (mg) = volume of gel (ml) x concentration (%) x 10

Substitute the values into the formula; for a 40 ml 1% agarose gel, you will need 400 mg of agarose.

The Aufbau Principle explains that electrons fill the lowest available energy levels in atomic orbitals before moving to higher levels. It helps determine the electron configuration of atoms, considering the periodic table, Hund's Rule, and the Pauli Exclusion Principle. This principle is essential for understanding atomic structure in chemistry.

The Aufbau Principle (German for “building up” principle) is a fundamental guideline in chemistry used to determine the electron configuration of an atom. It states that electrons fill atomic orbitals of the lowest available energy levels before occupying higher energy levels. In other words, the 1s subshell is filled before the 2s subshell, and the 2s subshell is filled before the 2p subshell, and so on.

This principle helps in constructing the electron configuration of an element by building it up step-by-step through the periodic table. For example, a carbon (atomic number 6) atom has an electron configuration of 1s2 2s2 2p2, which means it has filled the 1s subshell, then the 2s subshell, and finally partially filled the 2p subshell with two electrons.

Additionally, other rules like Hund's Rule and the Pauli Exclusion Principle work alongside the Aufbau Principle to determine the unique arrangement of electrons within orbitals. Hund's Rule states that electrons must occupy every orbital singly before any orbital is doubly occupied, and the Pauli Exclusion Principle asserts that no two electrons can have the same set of quantum numbers.

Utilizing these principles, students can accurately determine the ground-state electron configurations of atoms across the periodic table.

Final answer:

The balanced chemical equation for the standard heat of formation of CrO3(s) at 298 K is 2Cr(s) + 3/2O2(g) → Cr2O3(s). The standard heat of formation of CrO3(s) can be calculated using the standard heats of formation of the elements Cr(s) and O2(g) and the standard heat of formation of Cr2O3(s).

Explanation:

The balanced chemical equation for the standard heat of formation of CrO3(s) at 298 K is:

2Cr(s) + 3O2(g) + 3/2O2(g) → Cr2O3(s)

Now, we need to apply the equation to calculate the standard heat of reaction from the standard heats of formation. The standard heat of formation of a compound is the enthalpy change when one mole of the compound is formed from its constituent elements in their standard states. The standard heat of formation of CrO3(s) can be determined by subtracting the standard heat of formation of the reactants from the standard heat of formation of the product.

Therefore, the balanced chemical equation for the standard heat of formation of CrO3(s) at 298 K is 2Cr(s) + 3/2O2(g) → Cr2O3(s), and the standard heat of formation of CrO3(s) can be calculated using the standard heats of formation of the elements Cr(s) and O2(g) and the standard heat of formation of Cr2O3(s).

Among electromagnetic waves, UV rays are most dangerous because exposure to these radiation cause serious problems in living organism. Therefore,  it is not possible to take out electron from cesium using red light.

Electromagnetic wave is a wave which contain two component one is electric component and other is magnetic component. The electric and magnetic component are perpendicular to each other. There are so many wave that comes under electromagnetic wave like infrared wave , radio wave.

There is a relation between energy of wave. frequency of wave, and wavelength of wave

Mathematically,

E=hc/λ

where,

E = energy of electromagnetic wave

h is planks constant having value 6.67×10⁻³⁴js

c is speed of light that is 3×10⁸m/s

λ is the wavelength of electromagnetic wave =7×10⁻⁷m

frequency corresponding to this wavelength comes out to be 5.52 × 10¹⁴ Hz. The threshold energy for cesium to take out the outermost electron is  9.39 × 10¹⁴ Hz, which is more than 5.52 × 10¹⁴ Hz, which means it is not possible to take out electron from cesium using red light.

Therefore,  it is not possible to take out electron from cesium using red light.

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Answer:

it B the answer

Explanation:

hoped you enjoyed the joke :)

Mendeleev used atomic mass and periodical similarities in chemical properties to organize the elements into a periodic table. His predictions for undiscovered elements confirmed the accuracy of his method when they were later found with matching properties.

Dmitri Mendeleev, the Russian chemist, is known for his work on organizing the periodic table. He used atomic mass to arrange the elements, which was the crucial property in his table design. Although originally elements were ordered by increasing atomic mass, Mendeleev also took into account the repeatable patterns and similarities in chemical properties that occurred after certain intervals, a characteristic now known as periodicity. This approach enabled Mendeleev not only to organize known elements but also to predict the properties of elements that were yet to be discovered. In some instances, Mendeleev had to place elements out of the strict atomic mass sequence to maintain proper grouping based on properties, demonstrating a periodic nature in the elemental characteristics.

Published in 1869, Mendeleev's periodic table left gaps for undiscovered elements and made predictions about their properties. When these elements were eventually discovered and matched Mendeleev's predictions, his periodic table became widely accepted. Today's periodic table is largely based on his pioneering work, with the added advantage of organizing elements by atomic number rather than atomic mass.

In one mole of C12H22O11, there are 12 moles of Carbon, 22 moles of Hydrogen, and 11 moles of Oxygen. Hence, the conversion factors between moles of each of these elements and moles of the compound are 1:12, 1:22, and 1:11 respectively.

To establish the conversion factors between moles of each constituent element and moles of the compound for C12H22O11, we first need to determine the number of moles of each constituent element in one mole of C12H22O11. The molecule C12H22O11 has 12 Carbon (C), 22 Hydrogen (H), and 11 Oxygen (O) atoms. Therefore, one mole of C12H22O11 contains 12 moles of C, 22 moles of H, and 11 moles of O. These are the conversion factors between moles of each element and moles of the compound - there is a 1:12 factor between C and C12H22O11, a 1:22 factor between H and C12H22O11, and a 1:11 factor between O and C12H22O11.

These factors originate from the definition of mole as a unit of substance containing the same number of atoms, molecules, ions, and other entities as the number of atoms in exactly 12 grams of 12C. This means that the molar mass of any substance in grams is numerically equivalent to its atomic or formula weight in amu.

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The compound C₁₂H₂₂O₁₁ has conversion factors for each element: 1 mole C₁₂H₂₂O₁₁ is equivalent to 12 moles of C atoms, 22 moles of H atoms, and 11 moles of O atoms.

These factors assist in converting between moles of the elements and the compound.

For the compound C₁₂H₂₂O₁₁, we need to determine conversion factors between moles of each constituent element and moles of the compound.

Here's a step-by-step approach:

Identify the number of each type of atom in one mole of the compound: C₁₂H₂₂O₁₁ has 12 carbon (C) atoms, 22 hydrogen (H) atoms, and 11 oxygen (O) atoms per molecule.

Write the conversion factors:

These factors allow conversion between the moles of each element and the moles of the compound.

Correct question is: Write conversion factors between moles of each constituent element and moles of the compound for C₁₂H₂₂O₁₁ .

Explanation:

Density is defined as the degree of compactness or mass per unit volume.

Mathematically,         density = [tex]\frac{mass}{volume}[/tex]

It can be seen from the formula that mass is proportional to density. That is, more is the mass of an object more will be its density.

Therefore, it is given that iron nail sinks to the bottom this means that the iron nail has highest density as compared to the piece of wood and a styrofoam cup.

Thus, we can conclude that given experiment demonstrates the density of given objects.

Answer:

Corn

Explanation:

Being a plant and having chlorophyll in its structures, corn is able to capture sunlight and converting it into chemical energy, through photosynthesis.

Photosynthesis is a process carried out by plants to produce their own food. The plant draws carbon dioxide from the air and energy from the sun. Through this process, the plant produces its own food consisting essentially of glucose.

Briefly, we can say that photosynthesis uses carbon dioxide, water and sunlight (in the form of heat) to produce organic compounds (glucose) and oxygen.

A solar cell is the object that converts light to chemical energy.

The correct answer to the given question is option d.

The object that converts light to chemical energy is option d. solar cell.

A solar cell absorbs photons with energy greater than its energy gap and converts them into electrical energy using the photoelectric effect.

For example, a solar panel harnesses the power of sunlight and converts it into electricity.

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Answer:

[tex]2.0 g/cm^3 [/tex]is the density of the solid .

Explanation:

Mass of the solid = m = 3.60 g

Volume of the solid = V = [tex]1.8 cm^3[/tex]

Density of the solid ,d = ?

[tex]Density=\frac{Mass}{Volume}[/tex]

[tex]d=\frac{m}{V}=\frac{3.60 g}{1.8 cm^3}=2.0 g/cm^3 [/tex]

[tex]2.0 g/cm^3 [/tex]is the density of the solid .

Some  of the problems while using flame tests as a way to identify substances is that different elements can produce similar shades of flame color which can make identification of elements difficult.

It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.

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