Answers section 4.2 structure of the nuclear atom 1. a sulfur-32 atom contains 16 protons, 16 neutrons, and 16 electrons. what is the mass (in grams) of a sulfur-32 atom? 2. the mass of a neutron is 1.67 x 10-24 g. approximately what number of neutrons would equal a mass of one gram?

To solve for the number of molecules, we need to first find the number of moles. Assuming ideal gas, we use the formula:

n = PV / RT

where P is pressure = 780 mmHg, V is volume = 300 mL = 0.3 L, T is temperature = 135°C = 408.15 K, R is gas constant = 62.36367 L mmHg / mol K

n = (780 mmHg) (0.3 L) / (62.36367 L mmHg / mol K) (408.15 K)

n = 9.19 x 10^-3 mol

Using Avogadros number, we calculate the number of molecules.

molecules = 9.19 x 10^-3 mol * 6.022 x 10^23 molecules / mol

molecules = 5.54 x 10^21 molecules

[tex]\boxed{{5{.4 \times 1}}{{\text{0}}^{{\text{21}}}}\;{\text{molecules}}}[/tex] of nitrogen are present in a 300 mL container at 780 mm Hg and [tex]135\;^\circ{\text{C}}[/tex].

Further Explanation:

An ideal gas contains a large number of randomly moving particles that are supposed to have perfectly elastic collisions among themselves. It is just a theoretical concept and practically no such gas exists. But gases tend to behave almost ideally at a higher temperature and lower pressure.

Ideal gas law is considered as the equation of state for any hypothetical gas. Here, we assume nitrogen to be an ideal gas. So the expression for the ideal gas equation of nitrogen is as follows:

[tex]{\text{PV}} = {\text{nRT}}[/tex]                                    ......(1)

Here, P is the pressure of nitrogen.

V is the volume of nitrogen.

T is the absolute temperature of nitrogen.

n is the number of moles of nitrogen.

R is the universal gas constant.

Rearrange equation (1) to calculate the number of moles of nitrogen.

[tex]{\text{n}} = \frac{{{\text{PV}}}}{{{\text{RT}}}}[/tex]        ......(2)

Firstly, the temperature is to be converted into K. The conversion factor for this is,

[tex]{\text{0 }}^\circ {\text{C}} = {\text{273 K}}[/tex]

So the temperature of nitrogen is calculated as follows:

[tex]\begin{aligned}{\text{Temperature}}\left( {\text{K}}\right)&=\left({135 + 273} \right)\;{\text{K}}\\&=408\;{\text{K}}\\\end{aligned}[/tex]

Also, the volume is to be converted into L. The conversion factor for this is,

[tex]{\text{1 mL}}={\text{1}}{{\text{0}}^{ - 3}}{\text{ L}}[/tex]

So the volume of nitrogen is calculated as follows:

[tex]\begin{aligned}{\text{Volume}}\left({\text{L}}\right)&=\left({{\text{300 mL}}} \right)\left({\frac{{{{10}^{ - 3}}{\text{L}}}}{{{\text{1 mL}}}}}\right)\\&=0.3\;{\text{L}}\\\end{aligned}[/tex]

The pressure of nitrogen is 780 mm Hg.

The volume of nitrogen is 0.3 L.

The temperature of nitrogen is 408 K.

The universal gas constant is 62.36367 L mmHg/mol K.

Substitute these values in equation (2).

[tex]\begin{aligned}{\text{n}}&=\frac{{\left({{\text{780 mm Hg}}}\right)\left({{\text{0}}{\text{.3 L}}} \right)}}{{\left({{\text{62}}{\text{.3637 L mm Hg/K mol}}}\right)\left( {{\text{408 K}}}\right)}}\\&={\text{0}}{\text{.009196 mol}}\\&\approx {\text{0}}{\text{.009 mol}}\\\end{aligned}[/tex]

According to Avogadro law, one mole of any substance contains  [tex]{\text{6}}{\text{.022}}\times{\text{1}}{{\text{0}}^{{\text{23}}}}[/tex] molecules.

So the number of molecules of nitrogen is calculated as follows:

[tex]\begin{aligned}\text{Number of molecules of nitrogen}&=\left(0.009\text{ mol}\right)\left(\dfrac{6.022\times 10^{23}\text{molecules}}{1\text{mol}}\right)\\&=5.4198\times 10^{21}\text{ molecules}\\&\bf \approx5.4\times 10^{21}\text{\bf molecules} \end{aligned}[/tex]

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Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Ideal gas equation

Keywords: ideal gas, pressure, volume, absolute temperature, equation of state, hypothetical, universal gas constant, moles of nitrogen, 780 mm Hg, pressure of nitrogen, 780 mm Hg, volume of nitrogen, 0.3 L, temperature of nitrogen, 408 K, universal gas constant, 62.36367 L mmHg/mol K.

The pH of a 4.5 × 10^-4 M Ba(OH)2 solution is calculated by first determining the hydroxide ion concentration, which is doubled due to the two hydroxide ions provided by Ba(OH)2, and then calculating the pOH followed by subtracting from 14 to get the pH value of approximately 10.95.

Calculating the pH of Barium Hydroxide Solution

For the calculation of the pH of a 4.5 × 10-4 M barium hydroxide (Ba(OH)2) solution, it is crucial to consider that barium hydroxide is a strong base which dissociates fully in water. As Ba(OH)2 provides two moles of hydroxide ions for each mole of the substance dissolved, the hydroxide ion concentration will be twice the concentration of Ba(OH)2, which is 9 × 10-4 M (2 × 4.5 × 10-4 M).

To find the pOH of the solution, we take the negative logarithm of the hydroxide ion concentration: pOH = -log (9 × 10-4) = 3.045757491. To find the pH, subtract the pOH from 14: pH = 14 - 3.045757491, which simplifies to approximately pH = 10.95. This is a basic solution, as expected from barium hydroxide.

In laboratory settings, remember to use proper safety precautions, the correct form of chemicals, accurate measuring tools, and the appropriate methods to adjust the pH of solutions, such as adding acid or base. Moreover, for precise results, correctly label solutions and calibrate equipment such as pH meters as necessary.

Answer:

Angle between the carbon-sulfur bond and the carbon-nitrogen bond in the thiocyanate ion[tex]SCN^-[/tex] is 180°.

Explanation:

The hybridization of carbon atom is sp hybridized. The shape of the sp hybridized carbon is linear which means that angle between sulfur carbon a bond and carbon nitrogen bond is 180 °.

Where as [tex]sp^3[/tex] hybridized carbon has tetrahedral shape with an angle of 109.5°.

Where as [tex]sp^2[/tex] hybridized carbon has trigonal planar with an angle of 120°.

Potential energy is the stored energy present in an object due to its position. The energy of the ball after reduction will be 0.98 joules due to the conversion of potential energy into kinetic energy.

Potential is the stored amount of energy possessed by an object relevant to its height or position, whereas kinetic energy is due to the motion possessed by the object.

According to the conservational energy, the potential energy will be equivalent to the kinetic energy and is calculated as,

Given,

m = 0.5 kilograms

g = 9.8  m/s²

h = 2.0 - 1.8 = 0.2m

ΔPE = -ΔKE

mgh = -ΔKE

0.5 x 9.8 (1.8 - 2) = -ΔKE

-0.98 J = -ΔKE

Therefore, kinetic energy is 0.98 J.

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The triple bond is present in hydrocarbons alkyne.The shape of a molecule with triple bond is linear shape. Therefore, option B is correct.

The triple bond contain three covalent bond. A covalent bond of bond order is 3, it is consisting of six electrons. Therefore, one pair in a sigma bond and the other pairs in pi bonds present in it.

Alkynes are hydrocarbons in which carbon-carbon triple bonds are present. Their general formula is CnH2n-2 for molecules with one triple bond. Atoms form triple bonds with one another by sharing three pairs of electrons.

Triple-bonded carbons are sp-hybridized, and they have linear shapes. And its bond angle is 180° to each other.

Thus, The shape of a molecule with triple bond is linear shape, option B is correct.

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A tsunami is a sequence of ocean waves that often originate from the massive volume of water being moved by an underwater earthquake or volcanic eruption.

Undersea disturbance: An underwater earthquake frequently serves as a tsunami's first cause. Strong seismic waves can be produced when tectonic plates in the Earth's crust move or clash.

Displacement of water: The ocean floor frequently moves vertically during an underwater earthquake. A significant volume of water above the bottom is displaced when it rises or falls. This abrupt movement triggers the development of a tsunami.

Tsunami wave generation: Waves propagate outward from the disturbance's epicenter as a result of the water's displacement. These waves have large wavelengths and are initially rather modest, thus they can travel hundreds of kilometres over the ocean.

Wave propagation: The tsunami waves may move quickly, frequently topping hundreds of kilometres per hour, as they spread across the ocean. Yet, they are difficult to spot in the open ocean because to their typically tiny height, which is frequently less than a metre.

Approaching shallow water: The behaviour of tsunami waves alters drastically as they get closer to shallow coastal regions. The waves are slowed down by the shallower water, and the energy that was once dispersed along the wavefront is now concentrated in a smaller area.

Amplification of wave height: The tsunami wave is compressed when it approaches shallow water, raising the height of the wave. The wave may develop into a massive wall of water from a lengthy, almost unnoticeable swell. One of the riskiest characteristics of a tsunami is the abrupt rise in wave height.

Inundation: The tsunami may inflict extensive destruction when it reaches the coast. The wave's strong momentum and substantial water volume have the potential to flood low-lying coastal communities, destroy buildings, and completely destroy anything in its path.

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The BF3 molecule forms a trigonal planar configuration because boron, the central atom, is surrounded by three fluorine atoms. As a result, the bond angles in this molecule are exactly 120 degrees.

The bond angles in a BF3 molecule, or boron trifluoride, are determined by its molecular structure. This molecule is arranged in a trigonal planar configuration, and hence the bond angles are exactly 120 degrees.

Let's dive a bit deeper - in geometry any three points in a plane can form an equilateral triangle if they are equidistant from each other. Similarly, in BF3 molecule, the boron atom is at the center and the three fluorine atoms are located at the corners of an equilateral triangle.

Since all angles in an equilateral triangle are 60 degrees and the bond angle is the angle between two consecutive sides, it is twice as much, or 120 degrees.

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The bond angles in BF3 are 120°; the molecule's geometry is trigonal planar and highly symmetrical, resulting in a dipole moment of zero. BF3 also tends to bond with a fluoride ion to form BF4-, which is more stable.

The value of the bond angles in BF3 is 120°, which corresponds to the molecular geometry known as trigonal planar. Each fluorine atom is positioned at the vertices of an equilateral triangle around the central boron atom, and all bonds are equal in length, and the molecule is highly symmetrical.

Additionally, BF3 has a net dipole moment of zero due to this symmetry. However, BF3 often forms a bond with a fluoride ion, resulting in the formation of BF4−, which completes boron's octet and is more stable.

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The formula weight of a compound is simply equal to the total molar mass.

The molar mass of each elements are:

Mg = 24.305 g/mol

N = 14.0067 g/mol

O = 15.999 g/mol

So the total molar mass is:

formula weight = 24.305 + 2 (14.0067) + 6 (15.999)

formula weight = 148.3 g/mol

Final answer:

The formula weight of magnesium nitrate, Mg(NO3)2, is 148.341 g/mol when calculated using the atomic weights of magnesium, nitrogen, and oxygen and summing them up according to the numbers of atoms in the compound.

Explanation:

The formula weight of magnesium nitrate, Mg(NO3)2, is calculated by adding together the atomic weights of all the atoms in the compound.

The atomic weight of magnesium (Mg) is 24.305 g/mol, nitrogen (N) is 14.007 g/mol, and oxygen (O) is 15.999 g/mol. Given that there are two nitrate groups, we multiply the weights of nitrogen and oxygen accordingly.

Therefore, the formula weight of magnesium nitrate is 148.341 g/mol, expressed to four significant figures with the appropriate units (g/mol).

Inside the framework of electrochemistry, the Nernst equation is used to calculate the theoretical cell voltage difference. The Nernst equation shows the variation of cell potential from its standard state and uses the ion concentration values of cell #5 and cell #3.

The calculation of the theoretical cell voltage difference between cells #5 and #3 can be understood within the context of electrochemistry where the Nernst equation becomes a cornerstone.

The Nernst equation, written as Ecell = Ecell - (0.0257/n)*logQ, explains the variations in redox potentials (cell potentials) from the standard state values, where n denotes the number of electrons transferred, and Q represents the reaction quotient. This equation is used in practice to calculate Ecell, the potential of a redox system, which differs from its standard state value.

First, you'll need to know the ion concentration values for cells #3 and #5. Then, input those values into the expression. After computing, the resulting value represents the theoretical cell voltage difference between cells #5 and #3.

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The ionization energies are related to metallic character. The elements which have low ionization energies tend to behave more metallic. The first ionization energy is the best indication of whether an element behaves as a metal or nonmetal. It can also be used to compare the metallic character of two metals. The ionization energy of manganese is 717 kJ/mol and that of silver is 731 kJ/mol. The ionization energy ionization energy of manganese is smaller than that of silver so it can easily lose electron and undergo chemical reaction. The ionization energy of silver is more therefore it will take time to lose electron and undergo oxidation. Hence, as per the book, manganese is more metallic than silver

Final answer:

The claim that Si in SiH₄ does not follow the octet rule due to an unusual oxidation state of hydrogen is false; both silicon and hydrogen follow their expected oxidation states and the octet rule is satisfied for silicon.

Explanation:

The statement “The Si in SiH₄ does not follow the octet rule because hydrogen is in an unusual oxidation state” is false. In the molecule SiH₄, silicon follows the octet rule as it is surrounded by four hydrogen atoms (each providing one electron for bonding), resulting in silicon having eight electrons in its valence shell.

The oxidation state of hydrogen in this compound is +1, which is the usual oxidation state for hydrogen when it is bonded to nonmetals. Hence, the silicon atom in silane (SiH₄) completes its octet by forming four single bonds with four hydrogen atoms, with no need for lone pairs on the hydrogen atoms since hydrogen's valence shell is full with just two electrons.

In summary, SiH₄ is a molecule where both silicon and hydrogen atoms follow common oxidation states of +4 and +1, respectively, and the octet rule is satisfied for the silicon atom.

Answer is: Solid is represented when pulled slowly, liquid when pulled fast, gas when pulled vigorously.

For example, nitrogen molecules have weakest intermolecular bonds in gas phase and move fast and without order.

Cooling is change from liquids to solids. In solid state (for example ice) movement of molecules is more slow than movement of molecules in liquids (for example water).

In solid, molecules are closely packed, stiff and do not changes of shape or volume. Solid object (for example iron) does not take on the shape of its container.  

Liquids have definite volume, but no fixed shape.  

Gases (for example nitrogen and neon) not have definite volume and fixed shape, it depends on its container.

Answer:

Solid is represented when pulled slowly, liquid when pulled fast, gas when pulled vigorously.

Explanation:

Hello,

The three states of matter could be distinguished via their molecular both arrangement and movement, in such a way, solids have an organized assembly of molecules that slightly and slowly move with respect to their equilibrium position, that is why the solid is represented when the string is pulled slowly, besides of their well-defined shape.

Secondly, liquids have a widespread longer distance between molecules and faster molecular movements which cause the liquid to have an indefinite shape, thus, the liquid is represented when the string is pulled fast.

Finally, the molecular arrangement in gases is "messy" as long as the molecules are in constant rapid motion causing both the crashing to each other and the indefiniteness of their shape. In such a way the gas is represented when the string is pulled vigorously.

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The time required by an electromagnetic wave having a speed equal to that of light to travel a distance of 2.08 × 10⁸ km is 693. 3 seconds.

Transmission of wave is the movement of waves from one medium to the other. Waves are the propagation of energy or matter. Waves are associated with certain wavelength and frequency.

The speed of an electromagnetic wave is equal to the speed of light, that is 3 × 10⁵ m/s. The time taken by a wave to cover a distance is dependant on the distance and air resistance.

It is given that the distance between moon and earth is 2.08 × 10⁸ km. The speed of light energy is 3 × 10⁵ m/s. Thus the time to cover this distance is calculated as follows:

Time = distance / speed

        = 2.08 × 10⁸ km / 3 × 10⁵ m/s

        = 693.3 seconds.

Hence, the television pictures from mars will take 693.3 seconds to reach earth.

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