Choose all that correctly complete the statement. Chemical reactions can...

A. create products more complex than the reactants.
B. break down reactants into simpler products.
C. give off energy as heat..
D. change one element into another element.

Answer:

Narcotics

Explanation:

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23.7 g of Ca₃(PO₄)₎₂ contains 9.20 x 10^22 ions of PO₄³⁻  

23.7 g of Ca₃(PO₄)₎₂ contains 0.1528 moles of PO₄³⁻ which is equivalent to 9.20 x 10^22 ions of PO₄³⁻

Therefore;

Ca₃(PO₄)₎₂ ionizes to give out 3 Ca²⁺ ions and 2 PO₄³⁻ ions

Ca₃(PO₄)₎₂ → 3Ca²⁺ + 2PO₄³⁻

Required to determine the number of ions of PO₄³⁻ ions

Number of moles = Mass /Molar mass

Molar mass of Ca₃(PO₄)₎₂ = 310.1767 g/mol

Thus;

Moles = 23.7 g/310.1767 g/mol

          = 0.0764 moles

1 mole of  Ca₃(PO₄)₎₂ ionizes to give 2 moles PO₄³⁻ ions

Therefore;

0.0764 moles will produce;

 = 0.0764 moles x 2

 = 0.0152 moles PO₄³⁻ ions

1 mole of PO₄³⁻ ions contains 6.022 x 10^23 ions

Therefore;

0.01528 moles PO₄³⁻ ions contains;

= 0.01528 x 6.022 x 10^23 ions

= 9.20 x 10^22 ions

Keywords: Atoms, ions, Moles, molar mass

Level: High school

Subject: Chemistry

Topic: Moles

Sub-topic: Avogadro's constant

Explanation:

An element that gains one electron will tend to acquire a negative charge whereas an element that tend to lose an electron will acquire a positive charge.

Similarly, an element losing two electrons will acquire a 2+ charge.

For example, calcium is a group II element and has 2 valence electrons. Therefore, to attain stability it loses two electrons and thus changes into [tex]Ca^{2+}[/tex] ion.

Hence, we can conclude that an element of Group II loses two electrons in the process of a chemical combination then its ionic charge will be +2.

Answer:

The mass we will get from AgCl is 0.839g

Explanation:

Hello!

Let's solve this!

The reaction is:

2AgC2H3O2 + MgCl2 ---> 2AgCl + Mg (C2H3O2) 2

The data we have are:

V1 = 75mL * (1L / 1000L) = 0.075L

M1 = 0.078M

V2 = 55mL * (1L / 1000mL) = 0.055L

M2 = 0.109M

The molarity formula is

M = mol / V

We calculate the moles of each compound:

molAgC2H3O2 = 0.075L * 0.078mol / L = 0.00585mol

molMgCl = 0.055L * 0.109M = 0.005995

We calculate the compound that is in excess, and then use the limiting reagent to calculate the amount of product we will obtain.

Since there are two Cl in MgCl2, this means that we have 0.01199 mol to produce the product, but we will only use 0.00585 mol which is the amount we have of AgC2H3O2. So MgCl is the excess reagent.

Then:

AgCl mass = 0.00585mol * (2mol AgCl / 2molAgC2H3O2) * (143.34g AgCl / 1mo AgCl) = 0.839gAgCl

The mass we will get from AgCl is 0.839g

0.839 g of AgCl is formed.

Given a reaction between:

Question:

What mass, in g, of AgCl is formed?

The Process:

Step-1:

Let us find the mole numbers of both reagents:

[tex]\boxed{ \ Concentration \ (M) = \frac{moles \ (n)}{volume \ (V)} \ } \rightarrow \boxed{ \ n = MV \ }[/tex]

AgC₂H₃O₂ → 0.078 x 0.075 = 5.85 mmol

MgCl₂ → 0.109 x 0.055 = 5.995 mmol

Step-2:

The equation for the reaction is

[tex]\boxed{ \ 2 AgC_2H_3O_2_{(aq)} + MgCl_2_{(aq)} \rightarrow 2 AgCl_{(s)} + Mg(C_2H_3O_2)_2_{(aq)} \ }[/tex]

According to the equation, 2 mol of AgC₂H₃O₂ react with 1 mol of AgCl.

Let us check which substances will be a limiting reagent.

AgC₂H₃O₂ → [tex]\boxed{ \ \frac{5.85}{2} = 2.925 \ }[/tex]

MgCl₂ → [tex]\boxed{ \ \frac{5.995}{1} = 5.995 \ }[/tex]

AgC₂H₃O₂ is the limiting reagent because the test results are the smallest.

Step-3:

As AgC₂H₃O₂ is the limiting reagent, the amount of AgCl produced will be determined by the amount of AgC₂H₃O₂. Since the proportion between the mole numbers of AgC₂H₃O₂ and AgCl is one to one, their mole numbers will be equal:

[tex]\boxed{ \ The \ mole \ of AgCl = \frac{1}{1} \times the \ mole \ of \ AgC_2H_3O_2 \ }[/tex]

So the amount of AgCl is 5.85 moles.

Step-4:

Prepare the molar mass of AgCl.

Mr = 108 + 35.5 = 143.5 g/mol

Let us find out how many mass, in g, of AgCl is formed.

[tex]\boxed{ \ mol \ (n) = \frac{mass \ (g)}{molar \ mass \ (Mr)} \ } \rightarrow \boxed{ \ g = n \times Mr \ }[/tex]

Mass = 5.85 mmol x 143.5 g/mol

Mass = 839.475 mg ≈ 0.839 g.

Thus the amount of AgCl is formed is 0.839 g.

Answer: The energy of the photon having the given wavelength is [tex]2.96\times 10^{-19}J[/tex]

Explanation:

We are given:

Wavelength of microwave = [tex]670.8nm=670.8\times 10^{-9}m[/tex]    (Conversion factor:  [tex]1m=10^9nm[/tex]  )

To calculate the energy of one photon, we use Planck's equation, which is:

[tex]E=\frac{hc}{\lambda}[/tex]

where,

h = Planck's constant = [tex]6.625\times 10^{-34}J.s[/tex]

c = speed of light = [tex]3\times 10^8m/s[/tex]

[tex]\lambda[/tex] = wavelength = [tex]670.8\times 10^{-9}m[/tex]

Putting values in above equation, we get:

[tex]E=\frac{6.625\times 10^{-34}J.s\times 3\times 10^8m/s}{670.8\times 10^{-9}m}\\\\E=2.96\times 10^{-19}J[/tex]

Hence, the energy of the photon having the given wavelength is [tex]2.96\times 10^{-19}J[/tex]

Answer:

Principal energy level, sublevel, orbital, electron.  A table relating these classifications is attached.

The given for the problem:

100 cm^3 butane

Get first the molecular formula of butane and it is C4H10

To solution for the problem is:

2 C4H10 + 13 O2 = 8 CO2 + 10 H2O
n = V/22.4

n (C4H10) = 0.1/22.4 = 0.0047 mol

n (CO2) = 4 · n (C4H10) = 4 · 0.0047 = 0.018 mol

Burning 100 cm³ of butane in excess oxygen at STP produces 0.4 liters of carbon dioxide, as calculated through the stoichiometry of the balanced combustion reaction of butane.

When butane (C₄H₁₀) is burned in excess oxygen, the combustion reaction can be represented by the balanced equation:

2 C₄H₁₀(g) + 13 O₂(g) → 8 CO₂(g) + 10 H₂O(g)

The balanced equation shows that 2 moles of butane produce 8 moles of carbon dioxide (CO₂). At standard temperature and pressure (STP), 1 mole of any gas occupies 22.4 L. Therefore, for every 2 moles (2 × 22.4 L) of butane, 8 moles (8 × 22.4 L) of CO₂ are produced. If we burn 100 cm³ (which is equivalent to 0.1 L) of butane, we need to determine how many moles this quantity represents and then calculate the corresponding volume of CO₂ produced.

First, we calculate the moles of butane:

0.1 L butane × (1 mole butane / 22.4 L) = 0.00446 moles butane

Using the stoichiometry of the reaction, the moles of CO₂ produced are 4 times the moles of butane:

0.00446 moles butane × (4 moles CO₂ / 1 mole butane) = 0.01784 moles CO₂

Now, we convert the moles of CO₂ to volume at STP:

0.01784 moles CO₂ × (22.4 L / 1 mole CO₂) = 0.4 L CO₂

Therefore, 100 cm³ of butane will produce 0.4 liters of carbon dioxide at STP when burned in excess oxygen.

Elemental sulfur actually has 16 electrons with a neutral charge. 
The most common sulfur ion that is formed is the sulfide ion which has a negative 2 charge.

The substance that can be decomposed by chemical means is [tex]\boxed{{\text{c}}{\text{. methane}}}[/tex].

Further Explanation:

The pure form of matter is called substance whereas the combination of atoms and molecules is known as mixture.

Substance is further divided into two types:

1. Element

It is a type of pure substance and is the simplest form that cannot be broken down by any chemical means. Copper, iron, and cobalt are some of the examples of elements.

2. Compound

It is composed of two or more different elements that are held together by chemical bonds. These can be broken down into their respective constituents. Their properties are quite different from those of their constituent elements. NaCl, [tex]{\text{C}}{{\text{O}}_{\text{2}}}[/tex] and [tex]{{\text{H}}_{\text{2}}}{\text{O}}[/tex] are examples of compounds.

a. Cobalt is an element so it is the simplest form in which it can exist. Therefore it cannot be broken down or decomposed by chemical methods.

b. Krypton is an element so it is the simplest form in which it can exist. Therefore it cannot be broken down or decomposed by chemical methods.

c. Methane is formed from one carbon and four hydrogen atoms so it is a compound. Since compounds can be decomposed chemically, methane is also decomposed by chemical means.

d. Zirconium is an element so it is the simplest form in which it can exist. Therefore it cannot be broken down or decomposed by chemical methods.

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Answer details:

Grade: High School

Subject: Chemistry

Chapter: Elements, compounds, and mixtures

Keywords: substance, methane, cobalt, zirconium, krypton, element, compound, chemical means, decomposed, broken down, simplest form.

LiBr does not represent a molecular compound; it is an ionic compound because it is made up of lithium (metal) and bromine (nonmetal).

The student is inquiring about which of the provided options does not represent a molecular compound. Molecular compounds, also known as covalent compounds, are formed when nonmetal atoms share electrons to form discrete molecules with covalent bonds. Examples include water (H₂O) and carbon dioxide (CO₂). On the other hand, ionic compounds like sodium chloride (NaCl) are formed from the electrostatic attraction between cations and anions, which result from the transfer of electrons from metal to nonmetal atoms. Here, the substance that does not represent a molecular compound is LiBr, as it is an ionic compound composed of lithium (a metal) and bromine (a nonmetal). The formulas for molecular compounds generally display the number of each type of atom in a molecule, whereas the formula for an ionic compound represents the relative number of ions rather than discrete molecules.

Answer:

it is equivalent to the erosion of the rocks.

Explanation:

It can be said that the process of dissolving a rock is equivalent to the erosion process because erosion is the wear and tear on the rocks that is produced by the action of wind and water in their different forms. This wear is produced by the dragging of the particles from the rocks, produced by the impact of the particles that are moved in the medium against the rocks. When dissolving a rock in an acid, for example lemon or acetic acid, these acids react with the stone dissolving it, allowing the stone to break.

First let us consider the CO₂ formed in the reaction where the variables are:

>Pressure, P = (731.8/760) atm

>Volume, V = 37.6 mL = 0.0376 L

>Gas constant, R = 0.0821 atm L / (mol K)

>Temperature, T = (273.2 + 21.3) K = 294.5 K

From the ideal gas law : PV = nRT

Then, n = PV/(RT)

number of moles CO₂ formed, n = (731.8/760) × 0.0376 / (0.0821 × 294.5) mol = 0.001497 mol

The complete balanced chemical equation for the reaction is:

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

We see that the mole ratio is Na₂CO₃ : CO₂ = 1 : 1

Hence, the number of moles of Na₂CO₃ which reacted

 => n = 0.001497 mol

Calculating for molar mass of Na₂CO₃

 => (23.0×2 + 12.0 + 16.0×2) g/mol = 106.0 g/mol

Therefore, mass of Na₂CO₃ reacted

=> (0.001497 mol) × (106.0 g/mol) = 0.159 g

So the percent purity of Na₂CO₃ in the sample is

=> (0.159/0.169) × 100% = 94.1%

Summary of answers:

a. 731.8 mm Hg; 0.963 atm

b. 0.001497 mol

c. 0.001497 mol

d. 0.159 g

e. 94.1%

The CO₂ gas's partial pressure is found using atmospheric pressure, with conversion to atm. Moles of CO₂ and Na₂CO₃ are calculated using the ideal gas law and stoichiometry. The percent purity of Na₂CO₃ is determined by comparing pure Na₂CO₃ mass to the original sample mass.

To determine the partial pressure of CO₂ gas produced, we use the ideal gas law, corrected for non-standard conditions and vapor pressure of water (which is negligible here). Given the atmospheric pressure, we take that as the total pressure, assuming CO₂ is the only gas collected. The conversion to atm from mm Hg is done using the conversion factor: 1 atm = 760 mm Hg.

To find the number of moles of CO₂, we will use the ideal gas equation (PV=nRT) with the provided volume, temperature, and pressure. For the temperature, we'll convert from Celsius to Kelvin by adding 273.15.

To determine the moles of Na₂CO₃, we use the stoichiometry of the reaction between sodium carbonate and sulfuric acid, knowing that it produces sodium sulfate, water, and CO₂. The molar mass of Na₂CO₃ is needed to find the mass of the pure sodium carbonate in the sample.

Finally, the percent purity of Na₂CO₃ in the original sample is calculated using the mass of pure Na₂CO₃ obtained and the original mass of the sample.

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Final answer:

Solid zinc sulfate dissolves in water by dissociating into zinc ions (Zn²⁺) and sulfate ions (SO₄²⁻), making it a strong electrolyte. This shows the nature of ionic compounds dissociating in solutions.

Explanation:

The question asks about the reaction when solid zinc sulfate is dissolved in water, incorrectly referencing reactions of zinc with hydrochloric acid and copper(II) sulfate. However, for zinc sulfate in water, the correct dissociation reaction is:

ZnSO₄(s) → Zn²⁺(aq) + SO₄²⁻(aq)

This equation shows that solid zinc sulfate dissociates into zinc ions (Zn²⁺) and sulfate ions (SO₄²⁻) when it is put into water, making it a strong electrolyte. It highlights the process by which ionic compounds like zinc sulfate split into their respective ions in a solution, thereby enhancing the solution's ability to conduct electricity.

Answer:

C

Explanation:

C) All elements, including those in our body, that are heavier than hydrogen are produced by fusion at the center of stars. Explosions of these stars then lead to the creation of planets and organisms.

Fission occurs at the star's core to create all elements heavier than hydrogen, including those found in human body. The subsequent explosions of these stars and it dust result in the formation of planets and life.

Stars are massive objects in the universe with shining light and are grouped to any galaxy by the force of gravitation. Sun is a star who provide energy for us.

There are many more elements in each star which are formed through fusion such as hydrogen and helium in sun. Stars are thus the source of nuclear fusion.

Each stars have a definite life time and after that it will die by explosion and this result in a huge dust particles which are then contributing to the formation of other planets and gaseous atmosphere.

By fission takes place in the starts other elements are generated to form a stable atmosphere and that's why the musical group says that everything including them are from stardust and the statement is true.

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Answer:

D) 4

Explanation:

By applying Hess's law, we can calculate the unknown standard enthalpy of formation for AgI(s) using the given standard enthalpy of reaction, and the standard enthalpies of formation for the other reactants and products.

In order to determine the value of ΔHf° for AgI(s), we need to use Hess's law which states that the total enthalpy change in a chemical reaction is independent of the pathway over which the reaction takes place. The formula is as follows: ΔHrxn = Σ ΔHf°(products) - Σ ΔHf°(reactants).

Given: ΔHrxn = -54.0 kJ, ΔHf° for AgBr(s) = -100.4 kJ/mol, and ΔHf° for Br2(g) = +30.9 kJ/mol. Making AgI(s) the subject of the formula, we find ΔHf° for AgI(s) =  Σ ΔHf°(products) - ΔHrxn, which upon substituting the values gives us the answer.

This method which employs Hess's law, enthalpy of formation, and the known quantities to provide the unknown standard enthalpy of formation for AgI(s) is representative of typical approaches in thermochemistry.

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The enthalpy of formation for AgI(s) is calculated using Hess's Law with the known enthalpies of formation for AgBr(s) and Br₂(g). Applying the enthalpy change for the reaction, the ΔH°f for AgI(s) is found to be -15.5 kJ/mol.

To determine the enthalpy of formation (ΔH°f") of AgI(s) for the reaction AgI(s) + Br₂(g) → AgBr(s) + I₂(s) using Hess's Law:

Enzymes speed up chemical reactions by decreasing the energy needed for the reaction to occur and by providing a specific location (the active site) where the reaction can take place more easily.

Enzymes are proteins that act as biological catalysts, meaning they speed up chemical reactions that take place within the cells of organisms. They do this by reducing the energy of activation (Ea) necessary for the reaction to take place. The energy of activation is the minimum amount of energy that reactants must have to undergo a chemical reaction. By reducing the Ea, an enzyme essentially 'lowers the bar' for the reaction to happen, allowing it to proceed faster.

The reactants in the reaction that an enzyme catalyzes, also known as the substrate, bind to a specific part of the enzyme called the active site. The enzyme and substrate fit together in a manner often compared to a 'lock and key'. Once the substrate is bound to the active site, the enzyme can facilitate the reaction, converting substrate to product and then releasing the product.

To summarize, enzymes increase the rate of chemical reactions by reducing the energy of activation and by providing a suitable environment for the reaction to occur at the enzyme's active site.

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Answer:

Nickel

Explanation:

The element which have the electronic configuration of [Ar]4s²3d⁸ is Nickel

This is the arrangement of electrons in the various energy levels of an atom.

The number of electrons to be filled in the energy levels is equal to the atomic number of the element

Atomic number of element = Ar + 2 + 8

Atomic number of element = 18 + 2 + 8

Atomic number of element = 28

From the periodic table, only Nickel has atomic number of 28.

Thus, we can conclude that the element having the electronic configuration of [Ar]4s²3d⁸ is Nickel

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