what must occur for a change to be a chemical reaction?
​

Answer:

C. 4%

Explanation:

The answer is 4%

When the moving car brakes to the stop the kinetic energy of car will be converted to the heat energy.

The mechanical brake will be applies to the friction force and it convert the kinetic energy of the car into the thermal energy that which then dissipates on atmosphere. The process of the braking will follow the principle of the conservation of the energy.

The conservation of the energy is the principle, that is expressed in its the most general form, and it is the first law of the thermodynamics. The first law of thermodynamics explains that "the energy of the universe remains the same."

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This question is incomplete, the complete question is :

A car in motion has kinetic energy. A moving car is suddenly stopped. Why does the car stop? Where did the energy go?

Answer:

27 mg/L

Explanation:

From the given information:

To determine the 5-day BOD using the formula:

\(BOD_5 = \dfrac{DO_i -DO_f}{P} \ \ ---(1)\)

where;

BOD = biochemical oxygen demand

\(DO_i\) = initial dissolved oxygen

\(DO_f\) = final dissolved oxygen

P = dilution factor

The dilution factor \(P = \dfrac{V_w}{V_m}\)

where;

\(V_w = \text{volume of waste water} \\ \\ V_m = \text{volume of mixture}\)

\(P = \dfrac{50}{300} \\ \\ P = 0.167\)

replacing the value of P into equation  (1);

\(BOD_5 = \dfrac{(9.0 - 4.5)mg/L}{0.167}\)

\(BOD_5 = \dfrac{(4.5)mg/L}{0.167}\)

\(\mathtt{BOD_5 = 26.946 \ mg/L}\)

\(\mathtt{BOD_5 \simeq 27 \ mg/L}\)

Answer:

Correct option is

A

Explanation:

The number of molecules of CO involves in the slowest step will be 0 because CO is not involve in the slowest step i.e. rate determing step.

Answer:

a and b

Explanation:

Opals are formed when water in oceans dribble through the Earth, picking up silica from sandstone along the way. And really, that only happens when the ocean water touches the land.

Answer: -40

Explanation: Percent error is calculated by subtracting the value you actually recieved from the literature value (175 in your case)  SO your answer should be 135-175=-40.

The equation of the dissociation of the compound is \(AgNO_{3} (s)---- > Ag^{+} (aq) + NO_{3^{-} (aq)\)

The term dissociation has to do with the process by which a substance is broken up into its constituents. Now we know that the electrolytes are composed of ions. These ions are the charge carriers that are responsible for the fact that the solution is able to be a conductor of the electric current as we know the electrolytes to be as usual.

We can now write the equation of the dissociation from the equation; \(AgNO_{3} (s)---- > Ag^{+} (aq) + NO_{3^{-} (aq)\). The water has been omitted as was instructed in the question.

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The equation for the dissociation of the electrolyte AgNO₃(aq) is:

\(\rm AgNO_3\rightarrow Ag ^+ + NO_3 ^-\)

Dissociation is defined as a broad process in which molecules (or ionic compounds like salts, or complexes) split or separate into different elements like atoms, ions, or radicals, typically in a reversible way.

We now know that ions make up the electrolytes. These ions are the charge carriers that make it possible for the solution to serve as a conductor of the electric current in the manner that we have come to expect from electrolytes.

Thus, the equation for the dissociation of the electrolyte AgNO₃(aq) is:

\(\rm AgNO_3\rightarrow Ag ^+ + NO_3 ^-\)

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Explanation:

Hund's first and second rules describe how electrons are arranged in an atom's orbitals. Hund's first rule states that when electrons occupy orbitals of equal energy (such as the three p orbitals in a given shell), they will each first occupy separate orbitals before any orbital receives a second electron. This means that electrons will always try to maximize their spin, with one electron in each orbital having the same spin before any pairing occurs.

Hund's second rule states that if two or more orbitals of the same energy level are available, electrons will occupy empty orbitals before they pair up in an orbital that already has an electron.

Now, let's look at the orbital notation for sulfur. The atomic number of sulfur is 16, which means it has 16 electrons.

The orbital notation for sulfur would be:

1s² 2s² 2p⁶ 3s² 3p⁴

This indicates that sulfur has two electrons in the 1s orbital, two electrons in the 2s orbital, and six electrons in the 2p orbital, fully occupying all three 2p orbitals with two electrons in each and spinning in the same direction. Sulfur also has two electrons in the 3s orbital and four electrons in the 3p orbital, with a single electron in each of the three 3p orbitals and the fourth 3p orbital being half-filled. The half-filled 3p orbital is a consequence of Hund's rule, which predicts that electrons will fill each of the three 3p orbitals with one electron before any two orbitals receive a second electron.

Explanation:

hybridization refers to the process of mixing atomic orbitals in a way that creates new hybrid orbitals. This is commonly observed in organic chemistry, where hybridization is used to explain the shapes and bonding properties of molecules.

The hybridization of atomic orbitals occurs when atoms bond to form molecules. In the hybridization process, the valence electrons of an atom are rearranged and redistributed in order to form new orbitals with different shapes and energies. This can result in stronger and more stable bonding between atoms.

The most common types of hybridization are sp, sp2, and sp3, which involve the mixing of s and p orbitals. For example, in the sp3 hybridization of carbon, the 2s orbital and three 2p orbitals are combined to form four sp3 hybrid orbitals, which are arranged in a tetrahedral shape.

The effects of hybridization in chemistry include changes in the bond angles, bond lengths, and overall shape of molecules. This can affect the reactivity and chemical properties of the molecule, such as its acidity or basicity.

Explanation:

The correct formula for calcium fluoride is CaF2 (with two fluoride ions per calcium ion). Therefore, 2.25 moles of CaF2 contains:

- 2.25 moles of Ca2+ ions (since there is one calcium ion for every molecule of CaF2)

- 2 x 2.25 = 4.50 moles of F- ions (since there are two fluoride ions for every molecule of CaF2)

So, in total, 2.25 moles of CaF2 contains 2.25 moles of Ca2+ ions and 4.50 moles of F- ions.

Answer:

Explanation:

The calculated formula masses to 133.5 amu, we find that the substance with a formula mass closest to 133.5 amu is (d) AlCl3. Therefore, the answer is option D.

To identify the substance with a formula mass of 133.5 amu, we need to calculate the formula mass of each given substance and compare it to 133.5 amu.

(a) MgCl2:

The formula mass of MgCl2 can be calculated by adding the atomic masses of magnesium (Mg) and chlorine (Cl).

Mg: atomic mass = 24.31 amu

Cl: atomic mass = 35.45 amu

Formula mass of MgCl2 = (24.31 amu) + 2(35.45 amu) = 95.21 amu

(b) SCl:

The formula mass of SCl can be calculated by adding the atomic masses of sulfur (S) and chlorine (Cl).

S: atomic mass = 32.07 amu

Cl: atomic mass = 35.45 amu

Formula mass of SCl = 32.07 amu + 35.45 amu = 67.52 amu

(c) BCl:

The formula mass of BCl can be calculated by adding the atomic mass of boron (B) and chlorine (Cl).

B: atomic mass = 10.81 amu

Cl: atomic mass = 35.45 amu

Formula mass of BCl = 10.81 amu + 35.45 amu = 46.26 amu

(d) AlCl3:

The formula mass of AlCl3 can be calculated by adding the atomic mass of aluminum (Al) and 3 times the atomic mass of chlorine (Cl).

Al: atomic mass = 26.98 amu

Cl: atomic mass = 35.45 amu

Formula mass of AlCl3 = 26.98 amu + 3(35.45 amu) = 133.78 amu. Option D

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Answer:

(A) Climate Change (B) Climate Change and Plant Communities (C) Effect on Sea Levels (D) Reduction of Biodiversity (E) Effect on Agriculture (F) Effect on Arctic Ecosystems (G) Overall Effect.

Explanation:The increase in temperature will be greatest at high latitudes and over large continents. Climatic changes as a result of global warming will naturally affect the biotic communities on this earth. Rising temperatures will cause glaciers to melt and the polar ice caps to shrink. As mentioned above increased temperatures, inundation of some coastal biological communities and changes in the pattern of distribution of many species over a long period of time are likely to cause reduction in biodiversity in aquatic and terrestrial ecosystems. The global climate change may have important effects on agriculture. Global climate change will have profound effects on arctic ecosystems. The overall effect of global warming on world climate has many dimensions, some of which are discussed above. The natural greenhouse maintains the earth’s temperatures within the limits for physiological functions. But studies suggest that even a moderate increase in the average global temperature could result in significant changes in biotic communities including reduction in biodiversity both in terrestrial and aquatic ecosystems.

Answer:

The human population has increased by the billions, and we have been creating better and more complex technology over the years. So, overall there is a difference between now and 50 years ago.

In this equation, two molecules of aluminum hydroxide react with three molecules of sulfuric acid to produce one molecule of aluminum sulfate and six molecules of water.

What is Molecules?

A molecule is a group of two or more atoms that are chemically bonded together. Atoms can combine to form molecules by sharing electrons between them, forming a covalent bond. Molecules can also be formed by the attraction between oppositely charged ions, known as ionic bonding.

Molecules can be made up of atoms of the same element or atoms of different elements. For example, oxygen gas (O2) is a molecule made up of two oxygen atoms, while water (H2O) is a molecule made up of two hydrogen atoms and one oxygen atom.

The balanced chemical equation for the reaction between aluminum hydroxide and sulfuric acid is:

2Al(OH)3 + 3H2SO4 → Al2(SO4)3 + 6H2O

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The enthalpy change for the reaction \(C2H4(g) + H2(g) → C2H6(g)\) is -137.15 kJ/mol.

Given:C2H4(g) + H2(g) → C2H6(g)The enthalpy of formation of C2H6(g) is -84.68 kJ mol-1The enthalpy of formation of C2H4(g) is 52.47 kJ mol-1The enthalpy of formation of H2(g) is 0 kJ mol-1Hence, using Hess's Law, the enthalpy change for the reaction \(C2H4(g) + H2(g) → C2H6(g)\) can be calculated by considering the formation of reactants and products from their respective elements. It can be given as:

\($$C_2H_4 + H_2 → C_2H_6$$$$\Delta H = H_f(C_2H_6) - [H_f(C_2H_4) + H_f(H_2)]$$$$\Delta H = -84.68 - [52.47 + 0]$$$$\Delta H = -84.68 - 52.47$$$$\Delta H = -137.15 kJ/mol$$.\)

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Answer: K is bigger in atomic size. The metallic character increases as the size increases.

Explanation:

Reactivity of a metal is defined as the tendency of an element to lose electrons. The metallic character increases as we move down a group and it decreases as we move across a period.

When the size of an element increases, the valence electrons gets away from the nucleus and the tendency of an element to loose electrons increases.

In a group, the size of an element increases because there is an addition of new shell and electron is added in that shell.

Thus for alkali metals, the metallic character increases from Lithium to sodium to potassium and so on.

A) The answer to whether an average-size, single-family home be built with one day’s output from the saw mill is; No, it can't be built from one days output

B) The number of days will it take for the saw mill to produce enough lumber to build a neighborhood of 100 average-size homes is; 1100 days

A) From research, the average size capacity saw mill usually produces around 1500 board feet of boards per day.

Now, converting board ft to cubic meter gives;

1 board feet = 1/424 m³

Thus; 1500 board feet = 1500 * 1/424 ≈ 3.54 m³

Now, we are told that it takes 38 m³ of boards and plywood to build an average size single family home.

Since one days output = 3.54 m³

It is less than the volume required for the average sized house and so the daily output will not be sufficient.

B) Number of days to produce enough boards and plywood for the average sized family home = 38/3.54 ≈ 11 days

Thus, for 100  homes;

Number of days = 100 * 11 = 1100 days

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Nuclear Fission

Nuclear fission, subdivision of a heavy atomic nucleus, such as that of uranium or plutonium, into two fragments of roughly equal mass. The process is accompanied by the release of a large amount of energy. In nuclear fission the nucleus of an atom breaks up into two lighter nuclei.

Nuclear fission is a process where the nucleus of an atom is split into two or more smaller nuclei, known as fission products. The fission of heavy elements is an exothermic reaction, and huge amounts of energy are released in the process.

The hydroxide ion concentration of the given solution is 7.94 x 10⁻⁶ M.

The hydroxide ion concentration, [OH⁻], can be calculated from the pH of a solution using the equation:

pH + pOH = 14.

Since we have the pH of the solution as 8.81, we can first calculate the pOH as follows:

pOH = 14 - pH

pOH = 14 - 8.81

pOH = 5.19

Now, we can use the definition of pOH to calculate the hydroxide ion concentration:

pOH = -log[OH⁻]

5.19 = -log[OH⁻]

[OH⁻] = 7.94 x 10⁻⁶ M

The pH of a solution is a measure of its acidity or basicity, which is determined by the concentration of hydrogen ions, [H⁺], in the solution. A pH value of 8.81 indicates that the solution is slightly basic, meaning that it has a lower concentration of hydrogen ions and a higher concentration of hydroxide ions.

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Answer:

blood circulation The circulation of blood refers to its continual flow from the heart, through branching arteries, to reach and traverse the microscopic vessels in all parts of the body, reconverging in the veins and returning to the heart, to flow thence through the lungs and back to the heart to start the circuit.

That is the answer. Your welcome

The temperature increase from 20 °C to 46 °C indicates that the reaction between zinc and copper sulfate solution is exothermic, with heat being released into the surroundings.

In the given reaction between zinc and copper sulfate solution, the temperature change can provide insights into the type of heat change occurring during the reaction. Based on the provided information, the initial temperature of the copper sulfate solution was 20 °C, and the final temperature of the mixture after the reaction was 46 °C.

The temperature increase observed in this reaction indicates an exothermic heat change. An exothermic reaction releases heat energy into the surroundings, resulting in a temperature rise. In this case, the reaction between zinc and copper sulfate solution is exothermic because the final temperature is higher than the initial temperature.

During the reaction, zinc displaces copper from copper sulfate to form zinc sulfate and copper metal. This displacement reaction is known as a single displacement or redox reaction. Zinc is more reactive than copper and therefore replaces copper in the compound.

The formation of new chemical bonds during the reaction releases energy in the form of heat. This energy is transferred to the surroundings, leading to an increase in temperature. The heat released is greater than the heat absorbed, resulting in a net increase in temperature.

The exothermic nature of this reaction can be explained by the difference in bond energies between the reactants and products. The breaking of bonds in the reactants requires energy input, while the formation of new bonds in the products releases energy.

In this case, the energy released during the formation of zinc sulfate and copper metal is greater than the energy required to break the bonds in copper sulfate and zinc.

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Answer:

Explanation:

Therefore, the pH of the HCl solution is 5.

Answer:

Sp3

Explanation:

According to the question, atom 1 is an N atom bonded to 2 C atoms and 1 H atom through single bonds.

Whenever nitrogen is bonded to three atoms via single bonds (in this case two carbon atoms and one hydrogen atom) the nitrogen atom is sp3 hybridized and in tetrahedral geometry. The lone pair on nitrogen atom occupies one of the hybrid sp3 orbitals.

Cyanazine is used as an herbicide to control the growth of weeds and annual grasses. The herbicide has been phased out due to increased toxicity to the environment and humans.

The hybridization of the molecule is sp³.

The given information in the question suggests that Nitrogen (atom 1) to two Carbon atoms and single bonded to 1 hydrogen atom.

The nitrogen is bonded with three single bonds, two with carbon and one with a hydrogen bond.

Based on the given data, the hybridization of the molecule will be sp³ and will have tetrahedral geometry. The lone pair present on the nitrogen atom will occupy one of the hybrid sp³ orbitals.

Therefore, the sp3 hybridization of the cyanazine molecule will exist.

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Answer

The sun releases approximately 384.6 septillion watts (3.846×1026 W) of energy, this is almost equal to 9.192×10^10 megatons per second.

If you have 2.60 x 10²³ molecules of (NH₄)₃PO₄, you have 64.7 grams of it.

The number of particles contained in a sample is measured in terms of the mole. One mole of a compound is the quantity of that substance that has a mass in grams equal to its relative atomic or molecular mass (atomic weight).To find the number of moles of (NH₄)₃PO₄, we'll need to use the Avogadro constant, which is 6.02 x 10²³. We can use the formula:moles = particles ÷ Avogadro constantThe number of particles is given as 2.60 x 10²³. Substituting the values:moles = 2.60 x 10²³ ÷ 6.02 x 10²³moles = 0.432Molar massNow that we have the number of moles of (NH₄)₃PO₄, we can compute its mass. The molecular mass of (NH₄)₃PO₄ is 149.0 g/mol. We can use the formula:mass = moles x molecular mass Substituting the values:mass = 0.432 x 149.0mass = 64.7 grams

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Answer:

How do amoeba respire.

Define Diffusion.

The mass of  iron (III) hydroxide, Fe(OH)₃, produced is 3.44 g

The percent yield for the experiment is 83.97%.

The balanced chemical equation for the reaction between sodium hydroxide (NaOH) and iron (III) chloride (FeCl₃):

3 NaOH + FeCl₃ → 3 NaCl + Fe(OH)₃

The mole ratio between NaOH and Fe(OH)₃ is 3:1.

The number of moles of NaOH and FeCl₃ are calculated based on the given masses:

The molar mass of NaOH = 40.00 g/mol

Number of moles of NaOH = 3.45 g / 40.00 g/mol

Number of moles of NaOH ≈ 0.08625 mol

The molar mass of FeCl = 162.20 g/mol

Number of moles of FeCl₃ = 5.23 g / 162.20 g/mol

Number of moles of FeCl₃ ≈ 0.03223 mol

Therefore. the number of moles of Fe(OH)₃ produced = 0.03223 mol

The mass of Fe(OH)₃ produced:

Molar mass of Fe(OH)₃ = 106.88 g/mol

Mass of Fe(OH)₃ produced = 0.03223 mol × 106.88 g/mol

Mass of Fe(OH)₃ produced ≈ 3.44 g

To calculate the percent yield:

Percent yield = (2.89 g / 3.44 g) × 100

Percent yield ≈ 83.97%

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Complete question:

A reaction occurs between sodium hydroxide and iron (III) chloride to produce sodium chloride and iron (III) hydroxide.

If 3.45 g of sodium hydroxide is being reacted with 5.23 g of iron (III) chloride, how many grams of iron (III) hydroxide would be produced?

After separating out the solid, you discover that you have produced 2.89 g of iron (III) hydroxide. What is the percent yield for your experiment?