Calculate the molarity of 80.0 ml of a solution that is 0.92 % by mass nacl. assume the density of the solution is the same as pure water.

In the given question, the molecules that are polar are [tex]\rm SO_2[/tex] and [tex]\rm CH_2Cl_2[/tex]. The correct answer is option 2 and option 3, respectively.

A molecule is a chemical entity that is formed by two or more elements, which are chemically bonded together.

A molecule is polar if it has a net dipole moment, which means that the electron distribution is not symmetrical around the molecule.

- [tex]\rm SO_2[/tex] is a bent molecule with a sulfur atom bonded to two oxygen atoms. The sulfur-oxygen bonds are polar due to the electronegativity difference between sulfur and oxygen. The molecule is not symmetrical, and the partial charges do not cancel out, so  [tex]\rm SO_2[/tex] is polar.

- [tex]\rm CH_2Cl_2[/tex] is a tetrahedral molecule with a carbon atom bonded to two hydrogen atoms and two chlorine atoms. The carbon-hydrogen bonds are nonpolar, but the carbon-chlorine bonds are polar. The molecule is not symmetrical, and the partial charges do not cancel out, so  [tex]\rm CH_2Cl_2[/tex] is polar.

Therefore, [tex]\rm SO_2[/tex] and [tex]\rm CH_2Cl_2[/tex] are the molecules that are polar and [tex]\rm CO_2[/tex] and [tex]\rm PCl_3[/tex] are nonpolar. Option 2 and 3 are the correct answer, respectively.

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Airbags always fill evenly to reduce the force on vehicle occupants during a crash, protecting them from serious injuries.

Airbags always fill evenly because they are designed to reduce the force on vehicle occupants in a crash. When an impact occurs, a reaction is triggered that rapidly produces nitrogen gas, filling the airbag. The force of the impact is spread out over a larger surface area and a longer time, which reduces the force exerted on the occupants and minimizes serious injuries.

For example, when a car comes to a sudden stop, the momentum change experienced by the occupants is the same whether an airbag is deployed or not. However, if the force acts over a larger time, as it does with an airbag, the force will be much less and the occupants will be better protected.

A. The complete balanced chemical reaction is:

PbS  +  1.5 O2  --->  PbO  +  SO2

B. First let us convert mass of PbS into number of moles. The molar mass of PbS is 239.3 g/mol, hence:

moles PbS = 29.9 g/ (239.3 g/mol) = 0.125 mol

From the reaction, we need 1.5 moles of O2 for every 1 mole of PbS, therefore:

moles O2 = 0.125 mol * 1.5 = 0.1875 mol

The molar mass of O2 is 32 g/mol, hence the mass is:

mass O2 = 0.1875 mol * 32 g/mol = 6 grams O2

C. Converting mass to number of moles:

moles PbS = 65.0 g/ (239.3 g/mol) = 0.2716 mol

From the reaction, we can produce 1 mole of SO2 for every 1 mole of PbS, therefore:

moles SO2 = 0.2716 mol

The molar mass of O2 is 64 g/mol, hence the mass is:

mass SO2 = 0.2716 mol * 64 g/mol = 17.38 grams SO2

D. First let us convert mass of PbO into number of moles. The molar mass of PbO is 223.2 g/mol, hence:

moles PbO = 128 g/ (223.2 g/mol) = 0.573 mol

From the reaction, we need 1 mole of PbS for every 1 mole of PbO, therefore:

moles PbS = 0.573 mol

The molar mass of PbS is 239.3 g/mol, hence the mass is:

mass PbS = 0.573 mol * 239.3 g/mol = 137.23 grams PbS

The balanced equation for the combustion of lead(II) sulfide in oxygen is 2 PbS + 3 O₂ → 2 PbO + 2 SO₂. Calculations show the grams of oxygen required for 29.9 g of PbS, grams of SO₂ produced from 65.0 g of PbS, and grams of PbS used to produce 128 g of PbO.

Detailed steps, molar masses, and ratios are provided for clarity.

A. Balanced Equation:
The combustion of lead(II) sulfide (PbS) in oxygen (O₂) produces lead(II) oxide (PbO) and sulfur dioxide (SO₂). The balanced chemical equation is:

2 PbS + 3 O₂ → 2 PbO + 2 SO₂

B. Calculating Oxygen Required:
First, find the molar mass of PbS:

Moles of PbS in 29.9 grams:

From the balanced equation, 2 moles of PbS require 3 moles of O2, therefore:

Molar mass of O₂ = 32 g/mol

C. Calculating Sulfur Dioxide Produced:
Moles of PbS in 65.0 grams:

The balanced equation shows a 1:1 molar ratio between PbS and SO₂:

Molar mass of SO₂ = 32 + (2*16) = 64 g/mol

D. Calculating Lead II Sulfide Used:
Mass of PbO = 128 grams

Using the balanced equation's 1:1 molar ratio between PbS and PbO:

Final answer:

A hypothetical universal solvent that could dissolve anything would lead to significant practical and biological problems, as it would destroy containers and structures, potentially leading to chaos. Water is often termed the 'universal solvent' because of its ability to dissolve many substances, crucial for life processes; however, it cannot dissolve nonpolar substances like oils.

Explanation:

If a “universal solvent” could dissolve anything, it would pose significant challenges in everyday life. Such a solvent would not differentiate between materials, making it impossible to contain or store it as it would dissolve any container. Furthermore, the structural integrity of everything around us, including our own bodies, relies on the stability of materials not dissolving or breaking down on contact with solvents. Therefore, a true universal solvent could potentially dissolve buildings, roads, and other infrastructure. Our own cells, which require a water-based solution to keep the necessary biochemical reactions occurring, would also be unable to maintain their structure, leading to life-threatening situations.

Water is often described as the “universal solvent” because it dissolves more substances than any other liquid. However, this label is a relative term because while water is excellent at dissolving a wide range of substances due to its polarity and ability to form hydrogen bonds, it cannot dissolve nonpolar substances like oils. Water's solvent properties are essential for life; it dissolves vital nutrients and minerals, facilitates chemical reactions in the body, and allows for the transport of substances in biological systems.

Final answer:

To find the number of moles of calcium carbonate in a 20.0g sample, divide the mass of the sample by the molar mass of CaCO3, which is approximately 100.09 g/mol. The calculation shows there are about 0.1998 moles in the sample.

Explanation:

To calculate the number of moles of calcium carbonate (CaCO3) in a 20.0g sample, we use the molar mass of CaCO3. The molar mass of CaCO3, which is the mass of one mole of calcium carbonate, is the sum of the atomic masses of one calcium (Ca), one carbon (C), and three oxygen (O) atoms.

That gives us a molar mass of approximately 40.08 (Ca) + 12.01 (C) + 3 × 16.00 (O) = 100.09 grams per mole.

To find the number of moles, we divide the mass of our sample by the molar mass:

Number of moles = Mass of sample ÷ Molar mass

For a 20.0g sample:

Number of moles of CaCO3 = 20.0 g ÷ 100.09 g/mol = 0.1998 moles

Therefore, there are 0.1998 moles of calcium carbonate in a 20.0g sample of limestone.

The correct answer is C. I hope thus helps

Answer:

Option B

Explanation:

The electron configuration of an isolated sulfur atom is 1s²2s²2p⁶3s²3p⁴, with a total of 16 electrons. Its valence electrons, which are crucial for chemical reactions, are the six electrons in the 3s and 3p orbitals. Elements with similar electron configurations are grouped together in the periodic table due to their analogous chemical properties.

The electron configuration of an isolated sulfur (S) atom is 1s²2s²2p⁶3s²3p⁴. Here, the superscripts represent the number of electrons in each orbital. Elemental sulfur has 16 electrons in total. The first two electrons occupy the 1s orbital, the next two occupy the 2s orbital, six fill the 2p orbital, and the remaining six are in the 3rd energy level with two in the 3s orbital and four in the 3p orbital.

These electron configurations are key to understand the chemical behavior of atoms, as electrons in the outer shells (also known as valence electrons) participate in chemical reactions. For sulfur, the valence electrons are the ones in the 3s and 3p orbitals, making a total of 6 valence electrons.

The electron configuration also helps us understand the placement of elements in the periodic table, since elements with similar electron configurations tend to exhibit similar chemical properties and are grouped together in the same column.

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The electron configuration of a sulfur atom (S) is 1s²2s²2p⁶3s²3p⁴. This representation describes the arrangement of electrons around the nucleus in atomic orbitals. It follows the Pauli Exclusion Principle and the Hund’s Rule.

The electron configuration of an isolated sulfur atom is represented by the order of filled electron shells. The sulfur atom, which is atom number 16 on the periodic table, has an electron configuration of 1s²2s²2p⁶3s²3p⁴. This means that there are 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, 6 electrons in the 2p subshell, 2 electrons in the 3s subshell, and 4 electrons in the 3p subshell.

An electron configuration illustrates how electrons are arranged around the atomic nucleus. The format used includes the energy level (n), the type of orbital (s, p, d, f), and a superscript to indicate the number of electrons in that specific sphere. This configuration abides by the Pauli’s Exclusion Principle stating that no two electrons in an atom can have the same set of four quantum numbers.

Each atomic orbital can host a maximum of two electrons. These orbitals fill based on increasing energy level, often visualized through an electron configuration chart or the aufbau diagram. The atom tries to fill or half fill, its subshells to maintain stability, a condition known as Hund’s Rule.

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The wavelength of an electron is [tex]\boxed{{\text{a}}.1.99\times{{10}^{-10}}{\text{m}}}[/tex]

Further Explanation:

de Broglie wavelength:

The de Broglie equation is used to calculate the wavelength from the given values of mass and velocity. It is specially applied to neutral atoms, elementary particles, and molecules. The de Broglie equation is as follows:

[tex]\lambda=\frac{h}{{mv}}[/tex]

Here, m is the mass in kilogram, h is the Planck’s constant whose value is equal to [tex]6.626\times{10^{-34}}{\text{ J}}\cdot {\text{sec}}[/tex], λ is the de Broglie wavelength in meters, and v is the velocity in meter per second.

The velocity of a given electron is [tex]3.66\times{10^6}{\text{ m/s}}[/tex].

The mass of a given electron is [tex]9.11\times{10^{-28}}\,{\text{g}}[/tex].

Mass of an electron in kilogram is calculated as follows:

[tex]\begin{aligned}{\text{Mass}}\left({{\text{kg}}}\right)&={\text{Mass}}\left({\text{g}}\right)\times\left( {\frac{{1{\text{kg}}}}{{1000{\text{ g}}}}}\right)\\&=\left({9.11\times{{10}^{-28}}\,{\text{g}}}\right)\times\left({\frac{{1{\text{ kg}}}}{{1000{\text{ g}}}}}\right)\\&=9.11\times{10^{-31}}\,{\text{kg}}\\\end{aligned}[/tex]

Substitute [tex]6.626\times{10^{-34}}{\text{J}}\cdot {\text{sec}}[/tex] for h, [tex]9.11\times{10^{-31}}\,{\text{kg}}[/tex] for m, and [tex]3.66\times{10^6}{\text{m/s}}[/tex] for v in equation (1) to calculate the value of de Broglie wavelength (λ).

[tex]\begin{aligned}\lambda&=\frac{h}{{mv}}\\&=\frac{{\left( {6.626\times{{10}^{-34}}{\text{ J}}\cdot {\text{sec}}}\right)}}{{\left({9.11 \times{{10}^{-31}}\,{\text{kg}}}\right)\left({3.66\times{{10}^6}{\text{m/s}}}\right)}}\\&=1.9872\times{10^{-10}}{\text{m}}\\&\approx1.99\times{10^{-10}}{\text{m}}\\\end{aligned}[/tex]

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1. Balanced chemical equation: https://brainly.com/question/1405182

2. Identification of all of the phases of the reaction: https://brainly.com/question/8926688

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Atomic structure

Keywords: de Broglie equation, m, h, v, wavelength, electron, velocity, mass, planck’s constant, kilogram and 1.99*10-10 m.

The 4 indicators that a chemical reaction has taken place are:

A change in color, temperature, formation of a precipitate and evolution of a gas.

There are four main indicators that a chemical reaction has taken place:

1. A change in color: This is the most common indicator of a chemical reaction. When two substances react, they often produce new substances with different colors. For example, when iron rusts, it changes from a shiny silver color to a dull orange color.

2. A change in temperature: Some chemical reactions release heat, while others absorb heat. If you notice a change in temperature, it's a good indication that a chemical reaction has taken place. For example, when you mix baking soda and vinegar, the reaction releases heat, and the mixture will become warm.

3. The formation of a precipitate: A precipitate is a solid that forms when two liquids are mixed. If you see a solid forming in a solution, it's a good indication that a chemical reaction has taken place. For example, when you mix silver nitrate and sodium chloride, a white precipitate of silver chloride will form.

4. The evolution of a gas: Some chemical reactions produce gases. If you see bubbles forming in a solution, it's a good indication that a gas is being produced. For example, when you mix baking soda and vinegar, carbon dioxide gas is produced, and you will see bubbles forming in the solution.

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Alkali metals are stored in kerosene or mineral oil to prevent contact with air and moisture, preserving their reactivity and preventing them from reacting with moisture and oxygen in the air. The high reactivity of alkali metals requires them to be prepared by electrolysis of alkali metal compounds.

Alkali metals are stored in kerosene or mineral oil because they are highly reactive and can react with moisture and oxygen in the air. Storing them under kerosene or mineral oil creates a barrier that prevents contact with air and moisture, thereby preserving their reactivity. The high reactivity of alkali metals also means that they are never found free and must be prepared by electrolysis of alkali metal compounds.

Final answer:

Alkali metals are stored in kerosene or mineral oil due to their high reactivity with air and moisture, to prevent violent reactions that can occur upon contact with these substances.

Explanation:

Alkali metals such as lithium, sodium, and potassium are incredibly reactive substances due to their tendency to lose their lone valence electron. Because of this high reactivity, they can react violently with both moisture and oxygen in the air. To prevent these dangerous reactions, these metals are stored under kerosene or mineral oil. These substances are used because they are non-polar and do not contain water, providing a barrier that prevents alkali metals from coming into contact with air and moisture. For example, when potassium, a very reactive alkali metal, combines with oxygen in a combustion reaction, the balanced chemical equation is 4 K(s) + O₂(g) → 2 K₂O(s). This reaction can be violent, illuminating the need for careful storage.

Sugar is a compound made of carbon, hydrogen and oxygen.

Answer: The correct option is B.

Explanation:

An element is the simplest substance which cannot be divided further and is made up from only one type of atoms. Example: oxygen, nitrogen etc.

A compound is defined as a substance which is formed by the combination of two or more elements in a fixed ratio. Example: [tex]CO_2,H_2O[/tex] etc.

A mixture is formed by the combination of elements or compounds in a non-uniform ratio. Example: Salt in water

Option A: Steel is a alloy of 96% iron, carbon and many other elements. This is a homogeneous mixture of more than 2 elements. Hence, it is considered as a mixture because elements are not present in a fixed ratio.

Option B: Formula for sugar is [tex]C_{12}H_{22}O_{11}[/tex]. This is a compound made from the elements: Carbon, Hydrogen and Oxygen in a fixed ratio of 12 : 22: 11. Hence, it is considered as a compound.

Option C: Air is a mixture of many gases. Gases present in air are nitrogen, oxygen, argon , carbon dioxide etc. These gases are not present in fixed ratio.

Option D: Nitrogen is the simplest unit of substance. It is considered as an element.

Hence, the correct option is B.

The bond energy per mole for breaking all the bonds of O2 is approximately 496 kJ/mol.

The bond energy per mole for breaking all the bonds of oxygen, O2, can be determined using the concept of bond energy. Bond energy is the energy required to break a specific covalent bond in one mole of gaseous molecules. For a diatomic molecule like O2, the bond energy, DO-O, is the standard enthalpy change for the endothermic reaction:

O2 (g) → 2O (g)

This value for DO-O has been measured to be approximately 496 kJ/mol.

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To calculate the moles of aluminum chloride produced from chlorine gas, use the balanced chemical equation and the molar mass of chlorine.

To calculate the moles of aluminum chloride produced from chlorine gas, we need to use the balanced chemical equation for the reaction between aluminum and chlorine:

2Al + 3Cl2 → 2AlCl3

From the equation, we can see that 3 moles of chlorine gas react with 2 moles of aluminum to produce 2 moles of aluminum chloride.

First, we need to determine the moles of chlorine gas present in 21.0 g. Using the molar mass of chlorine (35.45 g/mol), we can convert grams to moles:

21.0 g Cl2 × (1 mol Cl2 / 35.45 g Cl2) = 0.593 mol Cl2

Now we can use the mole ratio from the balanced equation to calculate the moles of aluminum chloride:

0.593 mol Cl2 × (2 mol AlCl3 / 3 mol Cl2) = 0.395 mol AlCl3

Therefore, from 21.0 g of chlorine gas, approximately 0.395 moles of aluminum chloride can be produced.

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With excess aluminum and 21.0 g of chlorine gas, you can produce 0.197 moles of aluminum chloride (AlCl₃).

To determine the moles of AlCl₃ produced from 21.0 g of Cl2, first calculate moles of Cl₂ , then use the balanced equation to find moles of AlCl₃ .

You will produce 0.197 moles of AlCl₃ from the given amount of Cl₂ .

To determine how many moles of aluminum chloride AlCl₃ can be produced from 21.0 grams of chlorine gas Cl₂ , we need to follow these steps:

Therefore, with excess aluminum and 21.0 g of chlorine gas, you can produce 0.197 moles of aluminum chloride (AlCl₃).

A chemical change is evidence by the formation of new substances, the release of gases, and changes in color, temperature, or odor.

A chemical change, also known as a chemical reaction, is characterized by the production of one or more new substances that are different from the original substances. Some evidence of a chemical change include:

Formation of new substances: For example, the formation of rust from iron, oxygen, and water is a chemical change because rust is a different kind of matter.

Release of gases: Explosions, like the explosion of nitroglycerin, produce gases that are different from the original substance.

Changes in color, temperature, or odor: Chemical reactions may result in noticeable changes, such as color changes when cooking or rotting food.

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