Explain why all the elements of period 3 is placed on the periodic table in period 3

The enthalpy of vaporization for Benzene is 30.8 kJ/mol. 39.42 kJ is the energy change when 100g of Benzene boils at 80.1 degrees Celsius.

The amount of enthalpy or energy that must be added to a liquid substance into gas substance is called Enthalpy of Vaporization. It is also known as Latent heat of vaporization.

To calculate the energy use this expression:

[tex]Q = n \Delta H_{\text{vapo.}[/tex]

where,

Q = Energy change

n = number of moles

[tex]\Delta H_{\text{Vapo.}}[/tex] = Molar enthalpy of vaporization

Now find the number of moles

Number of moles (n) = [tex]\frac{\text{Given Mass}}{\text{Molar mass}}[/tex]

                                   = [tex]\frac{100\ g }{78\ g/mol}[/tex]

                                   = 1.28 mol

Now put the values in above formula we get

[tex]Q = n \Delta H_{\text{vapo.}[/tex]

   = 1.28 mol × 30.8 kJ/mol

   = 39.42 kJ

Thus from the above conclusion we can say that The enthalpy of vaporization for Benzene is 30.8 kJ/mol. 39.42 kJ is the energy change when 100g of Benzene boils at 80.1 degrees Celsius.

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Question: The enthalpy of vaporization for Benzene is 30.8 kJ/mol. What is the energy change when 100g of Benzene boils at 80.1 degrees Celsius?

The energy profile representing the reaction of the formation of NO2  is energy profile B; option D.

An energy profile diagram is a diagram which illustrates in the form of a graph the energy changes that occur as reactant molecules react to form products.

An energy profile has energy of the molecules plotted on the y-axis and the reaction pathway or the reaction progress on the x-axis.

The shape of an energy profile depends on whether the reaction is an endothermic or exothermic reaction.

An exothermic reaction will have the energy of reactants higher than that of products, whereas an endothermic reaction will have the energy of products higher than the reactants.

The formation of NO2 is an endothermic reaction which requires 33.1kJ/mol of energy to complete.

Therefore, the energy profile representing the reaction is energy profile B.

In conclusion, an energy profile diagram shows energy changes that occur in a reaction graphically.

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Answer:

E) 9.0

Explanation:

pH = -log [1×10^-9] = 9

The statement that describes the oxidizing agent in a chemical reaction is the substance that is reduced because it gains electrons (option D).

A redox reaction is a chemical reaction in which some of the atoms have their oxidation number changed.

In a redox reaction, there are oxidizing and reducing agents. The oxidizing agent is the substance that receives electrons from another substance, hence, becoming reduced.

Therefore, the statement that describes the oxidizing agent in a chemical reaction is the substance that is reduced because it gains electrons.

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Answer:D

Explanation:

took test

Answer:

68.46 gms

Explanation:

2 molal solution means there is 2 moles of sucrose per kg of solvent (generally 1000 cc)

2 moles / 1000 ml * 100 ml = .2 moles

mole weight of sucrose = 342.3 gm/mole

342.3 gm/mole * .2 mole = 68.46 gms

Hydrocarbons (typically petroleum products), which separate in water and have a Specific Gravity of less than one, represent a significant hazard to firefighters. Why?

Any member of the class of organic chemical compounds known as hydrocarbons only includes the atoms carbon (C) and hydrogen (H). The hydrogen atoms bond to the carbon atoms in a variety of ways to create the compound's structural framework.

Although there could be thousands of different hydrocarbon molecules in a given crude oil, these descriptions only focus on the type of hydrocarbon that predominates in the combination. Typically, each sort of molecule can be found in all naturally occurring crude oils.

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Reaction at anode

2 Br-​ (aq) -----> Br2 (g) + 2e-

The product formed at the anode is Br2 (g).

In chemistry and production, electrolysis is a technique that makes use of direct electric present-day (DC) to power an otherwise non-spontaneous chemical response.

Electrolysis is commercially crucial as a degree inside the separation of factors from clearly going on sources including ores the usage of an electrolytic cell.

The voltage that is wanted for electrolysis to occur is called the decomposition capacity. The word "lysis" way to split or break, so in phrases, electrolysis would imply "breakdown via power".

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Because of the very short period in which nucleosynthesis occurred before it was stopped by expansion and cooling (about 20 minutes), no elements heavier than beryllium (or possibly boron) could be formed.

Big Bang nucleosynthesis occurred inside the first three minutes of the start of the universe and is chargeable for an awful lot of the abundance of H (protium), H (D, deuterium), He (helium-three), and He (helium-4).

Although He remains produced by stellar fusion and alpha decays and hint quantities of H remain produced by way of spallation and certain sorts of radioactive decay, most of the mass of the isotopes inside the universe is thought to be produced in the Big Bang.

The nuclei of these elements, together with a few Li and Be are taken into consideration to have been fashioned between 100 and 300 seconds after the Big Bang whilst the primordial quark-gluon plasma froze out to form protons and neutrons.

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Answer:

10.2 °C

Explanation:

If all other variables are held constant, you can find the new temperature using the Charles' Law equation. The equation looks like this:

V₁ / T₁ = V₂ / T₂

In this equation, "V₁" and "T₁" represent the initial volume and temperature. "V₂" and "T₂" represent the final volume and temperature. You can find the new temperature by plugging the given values into the equation and simplifying.

V₁ = 122 mL                     V₂ = 50 mL

T₁ = 25 °C                        T₂ = ? °C

V₁ / T₁ = V₂ / T₂                                         <----- Charles' Law equation

122 mL / 25 °C = 50 mL / T₂                    <----- Insert values

4.88 = 50 mL / T₂                                     <----- Divide 25 from 122

4.88 x T₂ = 50 mL                                    <----- Multiply both sides by T₂

T₂ = 10.2 °C                                             <----- Divide both sides by 4.88

A photon has an energy of 2.88 × 10⁻¹⁸ J. The energy into eV is 17.97 eV.

The energy which is carried by a single photon is called Photon energy.

It is expressed as:

E = hf

where,

E = Photon energy

h = Planck's energy

f = Wave frequency

To convert J into eV

E(eV) = E(J) × 6.241509 × 10¹⁸

         = 2.88 × 10⁻¹⁸ × 6.241509 × 10¹⁸

         = 17.97 eV

Thus from the above conclusion we can say that A photon has an energy of 2.88 × 10⁻¹⁸ J. The energy into eV is 17.97 eV.

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Answer:

1.15 moles H₂

Explanation:

To find the moles of H₂ gas, you need to use the Ideal Gas Law equation. The equation looks like this:

PV = nRT

In this equation,

-----> P = pressure (atm)

-----> V = volume (L)

-----> n = moles

-----> R = Ideal Gas Constant (0.08206 L*atm/mol*K)

-----> T = temperature (K)

Before you can plug the given values into the equation and simplify, you need to convert Celsius to Kelvin.

P = 0.923 atm                     R = 0.08206 L*atm/mol*K

V = 29.6 L                           T = 17.0 °C + 273.15 = 290.15 K

n = ? moles

PV = nRT

(0.923 atm)(29.6 L) = n(0.08206 L*atm/mol*K)(290.15 K)

27.3208 = n(23.809709)

1.15 = n

Metal which produces hydrogen gas:

Aluminum metal produces hydrogen gas with dilute hydrochloric acid as well as sodium hydroxide.

What are amphoteric oxides?

Amphoteric oxides are the metal oxides which reacts with both acids and bases.

Some metals are also amphoteric, ie. on reaction with acid or base, the product will be salt and Hydrogen gas.

Amphoteric metal + acid/base →  salt + hydrogen gas

Few metals of the periodic table are amphoteric in nature. Like Aluminum, Zinc etc.

Reactions:

Reaction with dilute NaOH:

2Al + 2NaOH + 2[tex]H_{2}[/tex]O → 2NaAl[tex]O_{2}[/tex] + [tex]H_{2}[/tex]

Reaction with dilute HCl:

2Al + 6HCl(aq) → 2Al[tex]Cl_{3}[/tex] + 3[tex]H_{2}[/tex]

Dilute and Aqueous (aq) means mixed with water ([tex]H_2O[/tex])

These reaction are balanced in order to follow the Law of conservation of mass.

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In the endpoint when the indicator changes color it gives the information that the acid is neutralized by the base.

Titration is also known as titrimetry is a technique where a solution of known concentration is used to calculate the concentration of the unknown solution. Titration is a laboratory technique.

The point at which the indicator changes the color is known as Endpoint.

Thus from the above conclusion we can say that In the endpoint when the indicator changes color it gives the information that the acid is neutralized by the base.

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Answer:

terminal

Explanation:

When a hydrogen atom is part of a molecular structure, it is always a terminal atom.

3 NADH + [tex]1FADH_{2}[/tex] + 1GTP (=ATP)  is used during Krebs Cycle in every  acetyl CoA

The pyruvate is important chemical compound in the biochemistry.The pyruvate is primary used as transporter of carbon atoms into the mitochondria and do complete oxidation of this  carbon atoms into carbon dioxide.

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Answer:

The coefficient for Al(s) is 2.

Explanation:

__ Al(s) __ O2(g) --> __ Al2O3(s)

__ Al(s) __ O2(g) --> 1 Al2O3(s)

1 Al(s) __ O2(g) --> 1 Al2O3(s)

1 Al(s) + 1.5 O2(g) --> 1 Al2O3(s)             [Use a fraction to make it balance]

2 Al(s) + 3 O2(g) --> 2 Al2O3(s)             [Convert the 1.5 fraction to a whole number by multiplying all coefficients by 2]

Halogens are rarely found in native state because halogens are highly reactive.  

The group 17 elements are known as Halogen group. These elements include Fluorine, Chlorine, Bromine, Iodine and Astatine. Halogens react with metals to form salts. Halogens are non metals. Halogens are highly reactive and halogens are never found in pure form. Halogens not occur in free state.

Halogens have seven valence electrons in the outermost shell. The electronic configuration of Halogen is ns² np⁵.

Thus from the above conclusion we can say that Halogens are rarely found in native state because halogens are highly reactive.

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Answer:

Pb(NO3)2 + 2NaCl = 2NaNO3 + PbCl2

The free energy is always negative and the dissolution is feasible when enthalpy is negative and entropy is positive. Option A

Water is known as the universal solvent. Water is a polar substance hence it is often used to dissolve polar substances. It has a dipole and being that there is a high degree of electronegativity difference between the oxygen and the hydrogen atoms in water, it is feasible that the degree of hydrogen bonding between the two is high.

We know that dissolution is favored when there will be an increase in entropy as a result of that, that is; if more particles will appear. Now we know that ΔG = ΔH - TΔS.

Given the equation above, it then follows that the free energy is always negative and the dissolution is feasible when enthalpy is negative and entropy is positive. Option A

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The mass of the solution will be 4,394 mg

The mass percent of a component in a solution can be derived as follows:

Mass percent = mass of component/total mass of solution x 100%

In this case, the mass percent of KCN in the solution is 0.208 and the mass of KCN is 914 mg.

The mass of the 0.208% KCN solution will be:

                           914/0.208 = 4,394 mg

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The equilibrium would shift in the direction of the products

Equilibrium in chemistry is the state that exists when a chemical reaction and its opposite reaction happen at the same rates. This word's Latin origins may be traced to the prefix aequi-, which means equal, and lbra, which means scale or balance.

[tex]{\displaystyle {\begin{aligned}{\text{forward reaction rate}}&=k_{+}{\ce {A}}^{\alpha }{\ce {B}}^{\beta }\\{\text{backward reaction rate}}&=k_{-}{\ce {S}}^{\sigma }{\ce {T}}^{\tau }\end{aligned}}}[/tex]

where A, B, S and T are active masses and k+ and k− are rate constants. Since at equilibrium forward and backward rates are equal:

[tex]{\displaystyle k_{+}\left\{{\ce {A}}\right\}^{\alpha }\left\{{\ce {B}}\right\}^{\beta }=k_{-}\left\{{\ce {S}}\right\}^{\sigma }\left\{{\ce {T}}\right\}^{\tau }}{\displaystyle k_{+}\left\{{\ce {A}}\right\}^{\alpha }\left\{{\ce {B}}\right\}^{\beta }=k_{-}\left\{{\ce {S}}\right\}^{\sigma }\left\{{\ce {T}}\right\}^{\tau }}[/tex]

and the ratio of the rate constants is also a constant, now known as an equilibrium constant.

[tex]{\displaystyle K_{c}={\frac {k_{+}}{k_{-}}}={\frac {\{{\ce {S}}\}^{\sigma }\{{\ce {T}}\}^{\tau }}{\{{\ce {A}}\}^{\alpha }\{{\ce {B}}\}^{\beta }}}}{\displaystyle K_{c}={\frac {k_{+}}{k_{-}}}={\frac {\{{\ce {S}}\}^{\sigma }\{{\ce {T}}\}^{\tau }}{\{{\ce {A}}\}^{\alpha }\{{\ce {B}}\}^{\beta }}}}\\[/tex]

H₂ + I₂→ 2HI

Rate constants - The proportionality constant in the equation that defines the link between the rate of a chemical reaction and the concentrations of the reacting chemicals is known as the rate constant, also known as the specific rate constant.

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V₂O₅ (s) + 2H₂ (g) → V₂O₃ (s) + 2H₂O(l) is the balanced chemical equation for the reaction of solid vanadium(V) oxide with hydrogen gas to form solid vanadium(III) oxide and liquid water.

The balanced chemical equation is the equation in which the number of atoms on the reactant side is equal to the number of atoms on the product side in an equation.

The word based equation is

Vanadium(V) oxide + Hydrogen gas → Vanadium (III) oxide + Water

Now write the chemical equation

V₂O₅ (s) + 2H₂ (g) → V₂O₃ (s) + 2H₂O(l)

Reactant side                Product side

V = 2                                V = 2

O = 5                                O = 5

H = 4                                 H = 4

We can see that the number of atoms on reactant side is equal to the number of atoms on product side. So the given equation is balanced.

Thus from the above conclusion we can say that V₂O₅ (s) + 2H₂ (g) → V₂O₃ (s) + 2H₂O(l) is the balanced chemical equation for the reaction of solid vanadium(V) oxide with hydrogen gas to form solid vanadium(III) oxide and liquid water.

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A symbol of magnesium, Mg, with two dots representing two free electrons. The correct option is D.

Magnesium is represented by Mg.

Magnesium has an atomic number of 12. Thus the electron configuration will be 2,8,2.

This means that there are two valence electrons in every Mg atom.

Therefore, the electron do diagram would be the symbol of the element with two dots representing the two valence electrons.

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Answer:

Two dotted M

Explanation:

The amount, in grams, of carbon tetrachloride that would be present, will be 22.99 grams.

For every one mole of any substance, there are 6.022 x [tex]10^{23}[/tex] atoms of particles. This is according to Avogadro.

Now, there are 9 x [tex]10^{22[/tex] particles in this particular carbon tetrachloride.

If 1 mole = 6.022 x [tex]10^{23}[/tex] particles

Then,

9 x [tex]10^{22[/tex] particles =  9 x [tex]10^{22[/tex] x 1/6.022 x [tex]10^{23}[/tex] particles

                       = 0.1495 moles

Carbon tetrachloride has the chemical formula CCl4 and has a molar mass of 153.82 g/mol.

Recall that: mole = mass/molar mass

Hence, mass = mole x molar mass.

Mass of 0.1495 moles CCl4 = 0.1495 x 153.82 = 22.99 grams

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Filling out the table below following the outlined order:

An element can be defined as a substance that can not be broken down into simpler substances.

An element serves as a building blocks for compounds and mixtures.

In conclusion, each element and its property as requested in the table are given above.

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Answer:

Mn₁O₂

Explanation:

To find the empirical formula, you need to (1) determine how many grams of each element are within the compound, then (2) convert grams to moles (via the atomic masses of each element), and then (3) determine the mole-to-mole ratio of each element.

(Step 1)

Because the percents add to equal 100%, we can say that each percent is the mass of each element.

63% Mn ----> 63 grams Mn

37% O ----> 37 grams O

(Step 2)

We need to convert each mass to moles using the atomic masses. The atomic masses are a ratio comparing the mass of each element per every 1 mole.

Atomic Mass (Mn): 54.983 g/mol

Atomic Mass (O): 15.998 g/mol

63 grams Mn                 1 mole
----------------------  x  -------------------------  =  1.15 moles Mn
                                 54.983 grams

37 grams O                1 mole
--------------------  x  ------------------------  =  2.31 moles O
                               15.998 grams

(Step 3)

You can find the mole-to-mole ratio of each element in the compound by dividing the calculated mole values by the smallest mole value. In this case, since 1.15 moles was the smallest value calculated, it should be the divisor. The resulting amounts are the subscripts within the empirical formula.

1.15 moles Mn / 1.15 moles  =  1 moles Mn

2.31 moles O / 1.15 moles  =  2 moles O

Ratio of MnO = 1:2

This make the empirical formula: Mn₁O₂

Sodium represents by the (Na).

Green, because it has less volume and less amount of matter.

Density is the mass of a material substance per unit volume. d = M/V, where d is density, M is mass, and V is volume, is the formula for density. Grams per cubic centimeter are a typical unit of measurement for density.

Because it enables us to predict which compounds will float and which will sink in a liquid, density is a crucial notion. If an object's density is lower than the liquid's, it will often float.

The dimensions of two colored cubes.

Red: 4 12

Green: 3 10

density = mass/volume

so compare

[tex]12/4^{3}[/tex] and [tex]10/3^{3}[/tex]

None of the choices is the real reason. But is the closest. It is green because 10/27 > 12/64

But red would have been denser for a side of 3.9, and green would still have had less volume and less matter.

Green, because it has less volume and less amount of matter.

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