What contribution did John Dalton make to atomic theory? a. He discovered that every atom was positively charged. b. He discovered that atoms had nuclei. c. He discovered that every element consisted of one type of atom. d. He discovered that atoms could be divided into smaller parts.

The molality of the ethanol solution is 0.859 moles per kilogram of water.

To calculate the molality, divide the mass of the solute (ethanol) by the mass of the solvent (water) and multiply by the appropriate conversion factor to express the result in moles per kilogram. To calculate the molality, we first need to determine the mass of ethanol in the solution. We know that the solution is 16.9% ethanol by mass, so we can calculate the mass of ethanol in the solution as follows:

0.169 x total mass of solution = mass of ethanol.

To convert this mass of ethanol to moles, we divide by the molar mass of ethanol (46.07 g/mol), and then divide the number of moles by the mass of the solvent (water) to get the molality. Finally, we must convert the answer to the correct units (moles per kilogram) to express the molality of the solution.

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Answer: there could be two lunar eclipses per year

The molecular weight of a propane molecule, (C₃H₈) is equals to the 44.0 g/mol.

We have a Propane molecule, C₃H₈. The organic molecule C₃H₈ is also known as propane. This gas molecule is used in gas grills and propane heaters and appliances. It consists three atom of carbon, eight atoms of hydrogen. The molar mass is defined as the mass of one mole of substance. It is also called molecular weight of substance which is expressed in terms of g/mol. Molecular weight of a molecule is calculated by the addition of the masses of the individual atoms within the their quantities present in a molecule. So, the molecular mass of C₃H₈, is sum of individual masses of carbon, and hydrogen atoms with number of their atoms. The atomic mass of carbon atom, C =12 g/mol

The atomic mass of hydrogen atom, H =1 g/mol

Now, Molar mass of C₃H₈ = 3 × atomic mass of carbon + 8× atomic mass of hydrogen atom

= 3×C + 8×H

= 3× 12 g/mol + 8×1g/mol

= 36 g/mol + 8 g/mol

= 44 g/mol

Hence, the molecular mass of C₃H₈ is 44.0 g/mol.

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To convert from molecules/atoms to moles, divide by Avogadro's Number:

[tex]6.02*10^{23}[/tex]

We're given:

Divide by Avogadro's Number:

[tex]\dfrac{3.2*10^{24}}{6.02*10^{23}}[/tex]

[tex]= 5.3[/tex]

B. 5.3 moles

When an electron moves from a higher energy level to a lower energy level in an atom, it releases energy in the form of a photon of electromagnetic radiation. This process is known as emission.

What is Atomic Level?

The atomic level refers to the scale at which individual atoms and their properties are studied. At this level, matter is composed of discrete particles, known as atoms, which are the fundamental building blocks of all chemical elements.

As the energy levels in an atom are quantized, only certain energy transitions are allowed, which correspond to the emission of specific wavelengths of light.

The energy released by the emission can be in the form of visible light, ultraviolet light, or other forms of electromagnetic radiation, depending on the energy levels involved. For example, if an electron moves from the second energy level to the first energy level in a hydrogen atom, it will emit a photon of ultraviolet light.

Emission is one of the ways in which atoms can lose energy and return to a lower energy state. The opposite process, absorption, occurs when an electron is excited from a lower energy level to a higher energy level by absorbing a photon of electromagnetic radiation with an energy equal to the difference between the energy levels.

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Answer:

The balanced chemical equation for the reaction between BaCl2 and Na2SO4 is:

BaCl2 + Na2SO4 → 2 NaCl + BaSO4

This equation shows that one mole of BaCl2 reacts with one mole of Na2SO4 to produce two moles of NaCl and one mole of BaSO4. Therefore, to determine how many moles of NaCl can be produced from 2.5 moles of BaCl2, we need to use the stoichiometry of the reaction.

Steps:

Step 1: Write down the balanced chemical equation for the reaction between BaCl2 and Na2SO4.

BaCl2 + Na2SO4 → 2 NaCl + BaSO4

Step 2: Identify the stoichiometric ratio of BaCl2 to NaCl from the balanced chemical equation.

From the balanced chemical equation, we see that 1 mole of BaCl2 produces 2 moles of NaCl.

Step 3: Calculate the number of moles of NaCl produced from 2.5 moles of BaCl2.

Using the stoichiometric ratio, we can calculate the number of moles of NaCl produced from 2.5 moles of BaCl2 as follows:

2.5 moles BaCl2 x (2 moles NaCl / 1 mole BaCl2) = 5 moles NaCl

Therefore, 2.5 moles of BaCl2 can produce 5 moles of NaCl.

Blue is the color absorbed by a solution that should appear as the given color orange. If the material absorbs blue you will glimpse the color orange.

When sunlight shines through an orange solution, the violet, blue and green wavelengths are immersed. The different colors enact through. The transmitted light is the light we see, and it glances orange. Colored liquids or solutions glance colored because they absorb some of the light shined on them. Colored objects look the way they do because of reflected light. When sunlight is shined on a green leaf, the violet, red and orange wavelengths are absorbed. The various wavelengths within the visible part are reliable for the different colors we see.

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The synthetic organic chemist who successfully synthesized physostigmine was Robert Burns Woodward.

He was an American organic chemist who is considered by many to be the preeminent organic chemist of the twentieth century. Woodward's synthesis of physostigmine, an alkaloid found in the Calabar bean, was an important milestone in modern organic chemistry. Physostigmine works by obstructing acetylcholine metabolism. The enzyme that breaks down acetylcholine in the synaptic cleft of the neuromuscular junction, acetylcholinesterase, is inhibited in a reversible manner by this substance.Woodward's method of synthesizing physostigmine was the first successful total synthesis of a complex natural product, and it established the precedent for modern organic synthesis.

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A compound which has molar mass 123.22g/mol will have a molecular formula as ZrO₂. so the correct option is D..

To determine the molecular formula of a substance with a given molar mass, we need to know the empirical formula of the compound and the number of empirical formula units in the molecular formula.

Let's calculate the empirical formula weight for each of the options:

A) Co₂H₄:

Co: 2 x 58.93 = 117.86

H: 4 x 1.01 = 4.04

Total: 121.9 g/mol

B) PSF:

P: 1 x 30.97 = 30.97

S: 1 x 32.06 = 32.06

F: 1 x 18.99 = 18.99

Total: 82.02 g/mol

C) SrS₃:

Sr: 1 x 87.62 = 87.62

S: 3 x 32.06 = 96.18

Total: 183.8 g/mol

D) ZrO₂:

Zr: 1 x 91.22 = 91.22

O: 2 x 16.00 = 32.00

Total: 123.22 g/mol

Now we can divide the given molar mass by the empirical formula weight to find the number of empirical formula units in the molecular formula:

A) Co₂H₄: 123.22 / 121.9 = 1.01, so the molecular formula is approximately the same as the empirical formula, Co₂H₄.

B) PSF: 123.22 / 82.02 = 1.50, so the molecular formula is 1.5 times the empirical formula, which we can round to PS₃F₃.

C) SrS₃: 123.22 / 183.8 = 0.67, so the molecular formula is 0.67 times the empirical formula, which we can round to SrS₂.

D) ZrO₂: The molar mass is already equal to the empirical formula weight, so the molecular formula is the same as the empirical formula, ZrO₂.

Therefore, the molecular formula for the compound with a molar mass of 123.22 g/mol is D) ZrO₂.

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The equilibrium concentrations are approximately:

[H2] = 0 M

[Br2] = 0 M

[HBr] = 0.668 M.

At equilibrium, the equilibrium constant, K, indicates the connection between the reactants and products of a reaction. When the rates of forwarding and backward reactions are equal, a reaction has reached equilibrium.

The equilibrium constant expression for the reaction is:

Kc = [HBr]^2 / ([H2] * [Br2])

We are given that Kc = 2.180 × 10^6 at 730°C. We can use this information to set up an ICE (initial, change, equilibrium) table and solve for the equilibrium concentrations of the three species.

Initial concentrations:

[HBr] = 5.20 mol / 18.7 L = 0.278 M (since 2HBr are formed from 1 mol Br2 and 1 mol H2, initial [Br2] and [H2] are both 0)

Change in concentrations:

Let x be the change in concentration of HBr. Then, the change in concentration of H2 and Br2 will be -2x and -x, respectively.

Equilibrium concentrations:

[H2] = 0 - 2x

[Br2] = 0 - x

[HBr] = 0.278 + x

Substituting these concentrations into the equilibrium constant expression and solving for x gives:

Kc = [HBr]^2 / ([H2] * [Br2])

2.180 × 10^6 = (0.278 + x)^2 / (2x * x)

Solving for x using this equation gives:

x = 0.390 M

Therefore, the equilibrium concentrations are:

[H2] = 0 - 2x = -0.780 M (Note: negative concentration is unphysical, but indicates that all H2 reacted)

[Br2] = 0 - x = -0.390 M (Note: negative concentration is unphysical, but indicates that all Br2 reacted)

[HBr] = 0.278 + x = 0.668 M

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The kinetic-molecular theory is a model that describes the behavior of matter at a microscopic level.

In solids, this theory suggests that the particles (atoms or molecules) that make up the solid are in constant motion and are held together by strong intermolecular forces. The particles vibrate about their fixed positions and the amplitude of the vibration increases as the temperature increases. This theory also explains properties such as thermal expansion, specific heat, and thermal conductivity of solids.

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The proper Lewis structure of HCOOH consists of four atoms and has an oxygen atom in the center with two single bonds to the hydrogen atoms and two double bonds to the carbon atom.

The oxygen atom forms a double bond with the carbon atom by sharing two electron pairs with it and two lone pairs with itself. A single bond is formed between the oxygen atom and two hydrogen atoms, each of which possesses one electron pair.

Four electron pairs are present on the carbon atom: two from the oxygen atom and two lone pairs. One bond is created when the oxygen atom donates one electron pair to each of the two hydrogen atoms.

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There are three prevailing exceptions to the octet rule: Molecules, such as NO, with an odd number of electrons; Molecules in which one or more atoms possess additionally than eight electrons, such as SF6.

Molecules such as BCl3, in which one or additional atoms possess less than eight electrons. General exceptions to the octet rule incorporate molecules that have an odd number of electrons and molecules in which one or more atoms possess more or fewer than eight electrons. Molecules with an odd number of electrons are somewhat rare in the s and p blocks but instead familiar among the d- and f- block elements. Compounds with more than an octet of electrons around an atom are named expanded-valence molecules.

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Answer: C. Kr

Explanation:

Ru is the symbol for rubidium.

Rubidium is a transitional metal. To use the noble gas core, look at the noble gas one row above where rubidium is. Rubidium is in row 5 on the periodic table, so we move up to row 4. Krypton is the noble gas core in the electron configuration for Ru.

The vapor pressure of the NaCl solution is approximately 21.87 torr.

To calculate the vapor pressure of the NaCl solution, we can use Raoult's law which states that the vapor pressure of the solvent above the solution is proportional to the mole fraction of the solvent in the solution.

The mole fraction of water in the solution can be calculated as:

X_water = moles of water / total moles

The moles of water can be calculated from the mass of water and its molar mass, and the moles of NaCl can be calculated from its mass and molar mass:

moles of water = mass of water / molar mass of water = 200.0 g / 18.015 g/mol = 11.098 mol

moles of NaCl = mass of NaCl / molar mass of NaCl = 50.0 g / 58.44 g/mol = 0.855 mol

The total moles of solute and solvent in the solution is the sum of the moles of NaCl and water:

total moles = moles of NaCl + moles of water = 0.855 mol + 11.098 mol = 11.953 mol

The mole fraction of water is then:

X_water = moles of water / total moles = 11.098 mol / 11.953 mol = 0.9292

The vapor pressure of the solution can be calculated using Raoult's law:

P_solution = X_water * P_water

where P_water is the vapor pressure of pure water at the given temperature. Substituting the given values, we get:

P_solution = 0.9292 * 23.56 torr = 21.87 torr

Therefore, the vapor pressure of the NaCl solution is approximately 21.87 torr.

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Acetone is an organic solvent that is widely used in a variety of laboratory and industrial processes. In this experiment, its purpose is to extract a desired product from a sample.

Organic refers to anything made or grown without the use of synthetic chemicals, pesticides, or genetic engineering. It is a term used to describe a holistic approach to farming and production practices that emphasize the use of natural ingredients and processes. Organic foods, for example, are grown without the use of chemical fertilizers, herbicides, or pesticides, while organic textiles are made with natural fibers, such as cotton and wool, that have been grown without the use of synthetic fertilizers or pesticides.

The process begins by heating the sample in a round bottom flask. As the sample is heated, the desired product boils off and can be collected in a condenser. In order to enhance the separation process and ensure that the product does not become contaminated, acetone is added to the flask.

In order to use acetone correctly, the sample must be heated to the appropriate temperature. A thermometer should be used to ensure that the sample has reached the desired temperature. The acetone should then be added to the flask in small increments.

Once the acetone has been added, the sample should be stirred gently. This helps to ensure that the acetone is evenly distributed throughout the sample and that it has had the chance to dissolve any of the desired product.

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Red, white, and platelet counts and types, as well as their distribution throughout the blood, are all revealed by CBC. The results of CMP-14 testing reveal the level of blood proteins and sugar.

Why would someone utilize a CMP blood test?

A blood test called the complete metabolic panel (CMP) provides medical professionals with knowledge about the body's electrolyte levels, including sodium and potassium, as well as the kidney and liver's function.

What conditions can a CMP identify?

A CMP can help your doctor identify specific problems including diabetes, renal disease, and hypertension when combined with other tests and data from a clinical evaluation.

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Answer:

true

Explanation:

The internal energy change for the reactions would be -2850 J.

The sign of heat is interpreted as being positive when heat is absorbed and as being negative when heat is expelled.

Work done during the expansion and compression processes is viewed negatively and positively, respectively.

According to the First law of thermodynamics,

Δ U = q + w

where, Δ U be the internal energy

q be the heat absorbed or released = -2290 J

w be the work done = 560 J

simplifying the values in above equation, we get:

Δ U = (-2290) + (-560)

Δ U = -2850 J

Hence, the internal energy change for the reaction would be -2850 J.

Therefore, the correct answer is option 1) –2850 J.

The complete question is:

A sample of octane burns releasing 2290 J of heat to the surroundings, and the gases produced expands against a piston to do 560 joules of work. Calculate the internal energy change for this reaction.

1- –2850 J

2- –1730 J

3- –2290 J

4- +1730 J

5- +2850 J

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At the same temperature and pressure, equal volume of gases contains the same number of molecules is a true statement.

This statement is known as Avogadro's Law, which states that equal volumes of gases, at the same temperature and pressure, contain the same number of molecules (or moles) regardless of their chemical nature or physical properties.

This means that if we compare two different gases occupying the same volume at the same temperature and pressure, they will contain the same number of molecules.

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The number of the molecules of water are needed to completely hydrolyze the polymer that is ten monomers long is the 9 molecules of water.

A polymer can be defined as the macromolecule which is essentially is the combination of the many subunits. The Polymers will be break down into the monomers is called as the hydrolysis of the polymer, which is the reaction in which the water molecule will be  utilize during the breakdown.

One water molecule is use to break the each bond present between the two adjacent monomers in the  polymer during the hydrolysis. The ten-monomer of the long polymer that comprises the nine bonds because the two adjacent monomers are joined through the bond. Therefore, the nine water molecules are required to hydrolyze the ten monomers long polymer.

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2.8 grams of NaCl are in 14.3 L of a 2.38 M solution of NaCl." The molarity is defined as the number of moles of solute present in 1 liter of solution.

The term molarity is defined as the number of moles of solute present in 1 liter of solution.Molarity is also known as the molar concentration of a solution.

Given:

Volume of solution = 14300 mL

Molarity of sodium chloride = 2.38 M

Molar mass of sodium chloride (NaCl) = 59 g/mole

2.38 = mass of NaCl × 1000 / 59g × 14300

mass of NaCl = 2.38 × 59g × 14300 / 1000

= 2.8 grams

Thus, 2.8 grams of NaCl are in 14.3 L of a 2.38 M solution of NaCl.

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Iron (Fe) does NOT fit in the pattern in column 7 because Iron is a metal.

What are the characteristics of Iron (Fe)?

1. Iron (Fe) is a silvery-gray metal that is very malleable and ductile.

2. It has a melting point of 1538 °C (2798 °F) and a boiling point of 2862 °C (5164 °F).

3. It is the most abundant element in the Earth's crust, making up about 5.6% of its mass.

4. It is magnetic, and it is an important component of steel and other alloys.

5. Iron is also an essential element for biological processes, and it is necessary for the formation of hemoglobin in red blood cells.

Iron is not an element in column 7 of the periodic table because it is a transition metal, which is found in columns 3-12. Column 7 contains the halogens (Group 17), which are non-metallic elements. Allow (iron) had different properties (to oxygen and sulfur) and it ignore electrons.

Therefore, Iron is a metal is the answer.

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The alcohol mentioned above generates carbon dioxide in Methanol per mole burnt.

Methanol is a substance with the chemical formula CH3OH. The simplest alcohol, it is a colorless, flammable, light, volatile liquid with a distinct odor that is gentle and sweeter than ethanol.

It functions as an antifreeze, fuel, and solvent for ethyl alcohol while a polar liquid at room temperature. With the help of oxygen and sunlight, methanol is converted into carbon dioxide and water.

Burning methanol in the air produces carbon dioxide and water:

2CH3OH + 3O2 - 2CO2 + 4H20

A methanol flame appears to be practically colorless. To prevent colorlessness on the nearly undetectable fire when burning methanol, precautions should be taken.

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The assertion is accurate. The ionization potential is the amount of energy needed to expel an electron from an isolated atom or molecule. Each additional electron eliminated causes an increase in ionization energy.

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The greater the orbital overlap in a bond, the weaker the bond is a false statement.

In fact, the opposite is true: the greater the orbital overlap in a bond, the stronger the bond. Orbital overlap refers to the degree to which the orbitals of two atoms participating in a covalent bond interact with each other, with a greater degree of overlap leading to a stronger bond.

This is because the shared electrons spend more time between the nuclei of the bonded atoms, and the resulting electrostatic attraction between the positive nuclei and negative electrons is stronger. The strength of a covalent bond is also influenced by other factors, such as the electronegativity of the atoms involved and the bond length.

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The strongest types of bonds are ionic bonds, covalent bonds, hydrogen bonds, and van der waals forces.

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Molar mass of the benzoic acid is approximately 122.12 g/mol.

The chemical formula of benzoic acid is C₇H₆O₂. To calculate its molar mass, we need to find the atomic masses of each element in the compound and then add them up based on the molecular formula.

The atomic masses of carbon (C), hydrogen (H), and oxygen (O) are 12.01 g/mol, 1.01 g/mol, and 16.00 g/mol, respectively.

The molar mass of benzoic acid can be calculated as follows:

Molar mass of benzoic acid = (7 x atomic mass of C) + (6 x atomic mass of H) + (2 x atomic mass of O)

Molar mass of benzoic acid = (7 x 12.01 g/mol) + (6 x 1.01 g/mol) + (2 x 16.00 g/mol)

Molar mass of benzoic acid = 122.12 g/mol

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