The decomposition of hi has a rate constant of 1.80 × 10-3 m-1s-1. how much hi remains after 8.50 min if the initial concentration of hi is 4.78 m?

Answer:

MgO

Explanation:

Mass of Mg = 60.3 g  

Molar mass of Mg = 24.305 g/mol

Moles of Mg = 60.3 g/ 24.305 g/mol = 2.48 mol

Mass of O = 39.7g  

Molar mass of O = 16 g/mol

Moles of O = 39.7g/ 16 g/mol = 2.48 mol

So the molar ration of Mg:O is 1:1  

Therefore the empirical formula is MgO

Answer:

First: A. One molecule of oxygen is split into two atoms.

Second: C. One atom of oxygen collides with one molecule of oxygen.

Explanation:

Ozone (O3) is a molecule composed of three chemically bonded oxygen atoms, unlike oxygen, which contains 2 atoms. It may seem that, as they are composed of the same atoms, oxygen and ozone are alike, but the truth is that they are very different.

The O2 has no smell or color, The O3 instead has a blue color, a very intense smell and is even harmful to health. Unless it is in the stratosphere, it is essential for life on Earth. In addition to this, the O3 is much scarcer.

O3 is produced by a photochemical reaction

First:

02 + hv --> O + O (λ = 242.4 nm)

where hv is a photon of absorbed energy light

Second:

02 + 0 + M --> 03 + M

The statement which is true about ionic compounds is: B. Ionic compounds have varying solubilities in water.

An ionic compound can be defined as a crystalline solid (chemical compound) that contains neatly packed and oppositely charged ions, which are typically bonded through electrostatic forces.

In Chemistry, some examples of ionic compounds are:

Solubility refers to a measure of how readily a substance or chemical compound dissolves in a solvent to produce (form) a solution.

Hence, a substance or chemical compound is generally considered to be soluble if it is able it dissolve completely in a solvent.

Basically, the solubilities of ionic compounds in water tends to vary because of the difference existing between its hydration energy and its lattice energy.

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Answer:

To prepare a supersaturated solution, the added amount must be higher than the solubility for the given volume of solvent

Explanation:

Hello,

This could be answered by knowing that all the solutes have a property called solubility which accounts for the maximum amount of it that can be thoroughly dissolved into a specific solvent. Thus, to prepare a supersaturated solution, the added amount must be higher than the solubility for the given volume of solvent at a specific temperature. For example, at 20°C, 45.8g of aluminium chloride are completely dissolved into 100 mL of water, so at that amount, the solution will be saturated, thus, if one adds more than 45.8g the solution will start being supersaturated.

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According to trends in the periodic table, the atomic radius decreases from left to right across a period. Therefore, potassium, being furthest to the left, would have the largest atomic radius followed by calcium and then scandium.

The subject of this question is the atomic radius of elements on the periodic table, specifically potassium, calcium, and scandium. The atomic radius generally decreases as you go from left to right across a period in the periodic table due to the increasing positive charge of the nucleus (i.e., the increasing atomic number), which draws the electrons closer to the nucleus, thereby decreasing the atomic radius.

In the case of potassium (atomic number 19), calcium (atomic number 20), and scandium (atomic number 21)

, potassium should have the largest atomic radius, followed by calcium, and then scandium with the smallest atomic radius.

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Answer: 0.03 moles

Explanation:

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\textMolar mass}}[/tex]    ....(1)

For ethyl amine [tex]CH_3CH_2NH_2[/tex]

Mass of ethyl amine [tex]CH_3CH_2NH_2[/tex]= 1.50 g

Molar mass of ethyl amine [tex]CH_3CH_2NH_2[/tex]= 45 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of ethyl amine}=\frac{1.50g}{45g/mol}=0.03moles[/tex]

Final answer:

The mass of oxygen gas that reacted with the iron nail to form rust was 43 grams, which is the difference between the original mass of the iron nail (100g) and the mass after rusting (143g).

Explanation:

The mass of oxygen gas that most likely reacted with the iron nail to produce rust can be calculated by finding the difference in mass before and after the rusting process. Initially, the mass of the iron nail was 100g, and after rust formation, the mass increased to 143g. The increase in mass is due to the oxygen from the air reacting with the iron to form rust, which consists of hydrated iron(III) oxide.

Therefore, the mass of the oxygen that reacted with the iron nail can be calculated as follows:

Mass of rusted nail - Original mass of iron nail = Mass of oxygen

143g - 100g = 43g

Thus, 43 grams of oxygen reacted with the iron nail to form rust.

Americium-241 is used in smoke detectors because of its alpha decay, which helps detect smoke by ionizing air between electrode plates. The decay can be understood as a tunneling process, with a very low probability for Americium-241, indicating stable and long-lasting functionality for smoke detectors. Furthermore, the activity of Americium-241 can be calculated based on its known decay rate.

Americium-241 is a man-made radioactive isotope used in smoke detectors. It emits alpha particles (extomega particles) that ionize the air between two electrode plates in the detector's ionization chamber. This ionization process is critical because it generates a small electric current which can be disrupted by smoke, triggering the alarm. With a half-life of 432 to 458 years, Americium-241 decays slowly, ensuring the detector remains functional over long periods without requiring a replacement of the radioactive source. The concept of alpha decay can also be linked to a tunneling process, which relates to the probability of a particle escaping from the nucleus, despite an energy barrier. For Americium-241, this tunneling probability is extremely low, at about 1×10−29, making its decay by alpha particle emission feasible over large time scales. When considering other types of decay, such as emitting a helium-3 nucleus, theoretical calculations might suggest a higher probability, but this type of decay is rarely observed because helium-3 is less stable than helium-4, reducing the energy available for such decay processes. Additionally, the question also inquires about the activity of a certain amount of Americium-241 in a smoke detector. The activity refers to the rate at which the atoms of the radioactive substance decay, often measured in becquerels (Bq).

To determine which concentration(s) will have increased when the mixture reaches equilibrium, we can compare the reaction quotient (Qc) to the equilibrium constant (Kc):

N2(g)   +  3  H2(g) =  2NH3(g)

Qc =  (NH3^2)   / { (N2)(H)^3)}

Qc=  0.48^2  /{ ( 0.60) (0.760^3) }=  0.875

Qc < Kc  therefore  the  equilibrium  will   shift     to  the  right.  This  implies  that  Nh3  concentration  will    increase    

Calculate Qc using the initial concentrations and the balanced chemical equation.

Compare Qc to Kc:

If Qc < Kc, the reaction will proceed to the right (towards products) to reach equilibrium.

If Qc > Kc, the reaction will proceed to the left (towards reactants) to reach equilibrium.

In this case, if Qc is less than Kc, it indicates that the concentrations of products ([NH₃]) will increase, and the concentrations of reactants ([N₂] and [H₂]) will decrease when the mixture reaches equilibrium.

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DNA is made of repeating units known as nucleotides, including a pentose sugar, a nitrogenous base, and phosphoric acid, forming a double helix structure.

DNA, or deoxyribonucleic acid, is composed of repeating units called nucleotides. Each nucleotide consists of a pentose sugar (a sugar with five carbon atoms), a nitrogenous base (a base containing nitrogen atoms), and phosphoric acid (H3PO4). The typical DNA of a mammalian cell contains about 3 × 10⁹ nucleotides. Nucleotides work together to form nucleic acids that are essential for directing cellular activities such as cell division and protein synthesis. The DNA structure is like a double helix, where two polymers of nucleotides are coiled around each other. The sugar-phosphate combination forms the backbone of the structure, with nitrogenous bases in the interior, held together by hydrogen bonds.

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The reducing agent in the reaction between zinc metal and hydrochloric acid is zinc metal.

The reducing agent in the reaction between zinc metal and hydrochloric acid is zinc metal.

In this reaction, zinc is oxidized and loses electrons to form zinc ions (Zn²+). The hydrogen ions (H+) in the hydrochloric acid are reduced and gain electrons to form hydrogen gas (H₂). Therefore, the zinc metal is the reducing agent because it causes the reduction of the hydrogen ions.

By using the formula of free fall equation:

[tex]s = \frac{1}{2}gt^{2}[/tex]

where,

[tex]s[/tex] is height

[tex]g[/tex] is acceleration due to gravity = [tex]9.8 ms_2[/tex]

[tex]t[/tex] is time

[tex]s = 9.2 m[/tex] (given)

Substituting the values in the above equation:

[tex]9.2 m = \frac{1}{2}9.8 ms^{2} \times t^{2}[/tex]

[tex]t^2 = 1.877[/tex]

[tex]t = \sqrt{1.877 s^{2}}[/tex]

[tex]t = 1.37 s[/tex]

Hence, trapeze will take [tex]t = 1.37 s[/tex] to fall.

Final answer:

At 0 °C, a solution with a pH of 7.25 is considered basic since the neutrality point at this temperature is approximately pH 6.31.

Explanation:

The pH of a solution at 0 °C that reads 7.25 would actually be basic. This is because the neutrality point of pH at 0 °C is not exactly 7 but approximately 6.31. At this temperature, a solution is considered neutral at pH 6.31, acidic if the pH is less than 6.31, and basic if the pH is greater than 6.31. Given that a pH of 7.25 is more than 6.31, the solution at 0 °C would be classified as basic.

To calculate the volume of 10.0 M HCl needed to exhaust the remaining capacity of the buffer, determine the moles of TrisHCl remaining after adding hydrogen ions and use stoichiometry to calculate the required volume.

To calculate the additional volume of 10.0 M HCl needed to exhaust the remaining capacity of the buffer, we need to determine the number of moles of TrisHCl that remain after adding 0.0200 mol of hydrogen ions to half of the buffer. This will give us the amount of TrisHCl that needs to be neutralized. From there, we can calculate the volume of 10.0 M HCl needed to neutralize the remaining TrisHCl.

The calculated volume will be the additional volume of 10.0 M HCl needed to exhaust the remaining capacity of the buffer.

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An additional 18 mL of 10.0 M HCl is required to exhaust the remaining capacity of the buffer. This is determined by calculating the amount of Tris that remains unreacted and can further neutralize HCl.

What additional volume of 10.0 M HCl would be needed to exhaust the remaining capacity of the buffer after the reaction described in Part B?

First, we need to understand the capacity of the buffer system. From Part A, we have 31.52 g of TrisHCl.

Step 1: Calculate the moles of TrisHCl.

Step 2: Calculate the initial moles of Tris (conjugate base) and TrisH+ (conjugate acid).

Step 3: Determine the remaining capacity to neutralize more HCl.

Step 4: Calculate the volume of 10.0 M HCl needed to exhaust the buffer.

Therefore, an additional 18 mL of 10.0 M HCl is required to exhaust the remaining capacity of the buffer.

The structure of B is

         H

         |

   H3C - C ≡ N

         |

         H

The reaction of (R)-2-butanol with phosphorus tribromide (PBr3) undergoes substitution reaction, replacing the hydroxyl group with a bromine atom, resulting in compound A, which is 2-bromobutane (C4H9Br).

Compound A is then treated with sodium cyanide (NaCN) in dimethylformamide (DMF), undergoing a nucleophilic substitution reaction. The cyanide ion replaces the bromine atom, forming compound B, which is 2-butyne nitrile (C5H9N).

Compound B is optically active due to the presence of the chirality at the carbon atom adjacent to the nitrile group. The carbon atom bonded to the nitrogen and the two methyl groups creates a chiral center, resulting in optical activity.

The specific rotation of B would depend on the configuration of the chiral carbon.

Complete Question:

(R)-2-butanol reacts with phosphorus tribromide to give A (C_4H_9Br). Treatment of A with sodium cyanide in DMF gives B (C_5H_9) N. B is optically active. Draw the structure of B.

The formula for the conjugate base of the strong acid HClO₄ (perchloric acid) is ClO4⁻.

The conjugate base of an acid is formed when the acid donates a proton (H+) to a base. In the case of perchloric acid (HClO₄), the conjugate base is derived by removing the acidic hydrogen ion (H+) from the acid.

The formula for the conjugate base of HClO₄, known as perchlorate ion, is ClO₄-. The perchlorate ion has a negative charge (-1) due to the loss of the hydrogen ion from the acid.

The perchlorate ion is the conjugate base of perchloric acid. Its chemical formula is ClO4-. The perchlorate ion consists of one chlorine atom (Cl) bonded to four oxygen atoms (O) in a tetrahedral arrangement.

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The snow or snowflakes are formed when water vapor, which is present in a cloud transforms directly into the crystals of ice. The formation of sleet takes place when rain droplets fall via a layer of air below the zero degree Celsius, resulting in the droplets to freeze into solid ice as they fall. Freezing rain refers to just the usual droplets of rain, which falls as a liquid but freeze once they land on a cold surface.

Answer:

The temperature increases.

Explanation:

Hello,

In this case, a change in the temperature is being observed as long as initially, it is stated that the snow is present as itself but for some reason it becomes sleet and finally freezing rain. Such stepwise change is caused by the slight increase of the temperature which induces the change from the solid frozen water (snow) to freezing liquid water (freezing rain). Thus, since the water molecules receive energy, due to the aforesaid increase in the temperature, they are allowed slightly change from solid to liquid.

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