1. 0.16 m Pb(CH3COO)2 A. Highest boiling point 2. 0.17 m NiBr2 B. Second highest boiling point 3. 8.8×10-2 m Al2(SO4)3 C. Third highest boiling point 4. 0.53 m Urea(nonelectrolyte) D. Lowest boiling point

Answer and Explanation :

Paramagnetic are those which has unpaired electrons and diamagnetic are those in which all electrons are paired.

(a) V³⁺

The electronic configuration is -  

[tex][Ar]3d^1[/tex]

The electrons in 3d orbital = 1 (Unpaired)

Thus, the ion is paramagnetic as the electrons are unpaired.

(b) Cd²⁺

The electronic configuration is -  

[tex][Kr]4d^{10}[/tex]

The electrons in 4d orbital = 10 (paired)

Thus, the ion is diamagnetic as the electrons are paired.

(c) Co³⁺

The electronic configuration is -  

[tex][Ar]3d^6[/tex]

The electrons in 3d orbital = 6 (Unpaired)

Thus, the ion is paramagnetic as the electrons are unpaired.

(d) Ag⁺

The electronic configuration is -  

[tex][Kr]4d^{10}[/tex]

The electrons in 4d orbital = 10 (paired)

Thus, the ion is diamagnetic as the electrons are paired.

Answer:

A. 11.1%

B. 0.0291

C. 1.57 M

D. 1.67 m

Explanation:

A.

Mass of KCl (solute): 28.0 g

Mass of water (solvent): 225 g

Mass of solution: 28.0 g + 225 g = 253 g

The mass percent of KCl is:

%KCl = (mass of KCl/mass of solution) × 100%

%KCl = (28.0 g/253 g) × 100%

%KCl = 11.1%

B.

The molar mass of KCl is 74.55 g/mol. The moles of KCl are:

28.0 g × (1 mol/74.55 g) = 0.376 mol

The molar mass of water is 18.02 g/mol. The moles of water are:

225 g × (1 mol/18.02 g) = 12.5 mol

The total number of moles is 0.376 mol + 12.5 mol = 12.9 mol.

The mole fraction of KCl is:

X(KCl) = moles of KCl / total moles

X(KCl) = 0.376 mol / 12.9 mol

X(KCl) = 0.0291

C.

The volume of the solution is 239 mL (0.239 L).

The molarity of KCl is:

M = moles of KCl / liters of solution

M = 0.376 mol / 0.239 L

M = 1.57 M

D.

The molality of KCl is:

m = moles of KCl / kilograms of solvent

m = 0.376 mol / 0.225 kg

m = 1.67 m

Answer:

The difference in the magnetic orientation influences the thermal stability of the allotropes of iron.

Explanation:

It is known that the allotropes of iron exist in three phases: α - phase, β- phase, and γ-phase. However, two prominent structures are the  α - phase and γ-phase. Now, let us look at the two phrases:

α - phase

This structure is a body-centered cube. It means that the unit cell structure resembles a cube. The lattice points are in the face of the cube. This subsequently affects the magnetic structure of the iron allotrope.

γ-phase

This allotrope has a lattice structure. It simply means that the structure has lattice points on the face of the cube. The structure generally affects the magnetic properties of the transitional metal; hence the stability of the γ-phase compared to α-phase.

Allotropes stable at high temperatures have higher enthalpies than those at low temperatures because they require more energy to maintain their structural bonds at these elevated temperatures. Hess's law and observations like the enthalpy differences in the thermite reaction further support this understanding in the context of energy changes and phases of matter.

The enthalpies of allotropes that are stable at high temperatures are higher than those stable at low temperatures because more energy is required to maintain the structure and bonding in the high-temperature allotrope. For example, in the case of iron, γ-Fe (gamma iron) has a higher enthalpy than α-Fe (alpha iron). This is due to the difference in bonding and structure at different temperatures. As temperature increases, thermal energy overcomes stronger bonds, resulting in allotropes with higher enthalpies at these temperatures.

Hess's law can illustrate this concept further. Considering the thermite reaction, the heat produced during the reaction of aluminum with iron(III) oxide indicates an exothermic reaction that causes the iron to melt. In general, transformations like changing phases from solid to liquid require energy, and allotropes that must retain more complex, less stable structures at higher temperatures inherently have higher enthalpies.

Moreover, substances with high melting and boiling points usually have strong bonds and interactions to maintain those phases, which means their reactions typically involve greater changes in enthalpy. This is why the enthalpy of vaporization is much greater than the enthalpy of fusion, and the same principle can be applied to allotropes stable at different temperatures. Allotropes stable at higher temperatures have structures that require more energy to maintain, hence their higher enthalpies.

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Explanation:

When we move across a period from left to right then there will occur an increase in electronegativity and also there will occur an increase in non-metallic character of the elements.

As calcium (Ca) is a group 2A element and rubidium (Rb) is a group 1A element. Hence, Rb being an alkali metal is more metallic in nature than calcium (alkaline earth metal).

Both magnesium (Mg) and radium (Ra) are group 2A elements. And, when we move down a group then as the size of element increases so, it becomes easy of the metal atom to lose an electron.

As a result, there occurs an increase in metallic character of the element. Hence, Radium (Ra) is more metallic in nature than magnesium (Mg).

Also, both bromine and iodine are group 17 elements. Since, both of them are non-metals and non-metallic character increases on moving down the group.

Therefore, bromine (Br) is more metallic than iodine.

In the context of the periodic table, metallicity increases further down a group and decreases from left to right across a period. Therefore, Rb, Ra, and I are expected to be more metallic than Ca, Mg, and Br respectively.

In an element, the metallicity increases as we go down a group (or column) on the periodic table, and decreases as we move from left to right across a period (or row). Therefore, based on the periodic table:

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Answer:

There are 0.0267 moles of oxygen in 0.658 grams of magnesium nitrate.

Explanation:

Mass of magnesium nitrate = m = 0.658 g

Molar mass of magnesium nitrate = M = 148 g/mol

Moles of magnesium nitrate = n

[tex]n=\frac{m}{M}=\frac{0.658 g}{148 g/mol}=0.004446 mol[/tex]

1 mole of magnesium nitrate has 6 moles of oxygen atoms. Then 0.004446 moles magnesium nitrate will have :

[tex]6\times 0.004446 mol=0.026676 mol\approx 0.0267[/tex]

There are 0.0267 moles of oxygen in 0.658 grams of magnesium nitrate.

Answer :  The condensed ground-state electron configuration for each is:

(a) [tex][Xe]6s^2[/tex]

(b) [tex][Ar]4s^23d^7[/tex]

(c) [tex][Kr]5s^14d^{10}[/tex]

Explanation :

Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom are determined by the electronic configuration.

Noble-Gas notation : It is defined as the representation of electron configuration of an element by using the noble gas directly before the element on the periodic table.

(a) The given element is, Ba (Barium)

As we know that the barium element belongs to group 2 and the atomic number is, 56

The ground-state electron configuration of Ba is:

[tex]1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^66s^2[/tex]

So, the condensed ground-state electron configuration of Ba in noble gas notation will be:

[tex][Xe]6s^2[/tex]

(b) The given element is, Co (Cobalt)

As we know that the cobalt element belongs to group 9 and the atomic number is, 27

The ground-state electron configuration of Co is:

[tex]1s^22s^22p^63s^23p^64s^23d^7[/tex]

So, the condensed ground-state electron configuration of Co in noble gas notation will be:

[tex][Ar]4s^23d^7[/tex]

(c) The given element is, Ag (Silver)

As we know that the silver element belongs to group 11 and the atomic number is, 47

The ground-state electron configuration of Ag is:

[tex]1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^14d^{10}[/tex]

So, the condensed ground-state electron configuration of Ag in noble gas notation will be:

[tex][Kr]5s^14d^{10}[/tex]

Here are the orbital diagrams and condensed ground-state electron configurations for Ba, Co, and Ag.

Orbital diagram and condensed ground-state electron configurations for (a) Ba, (b) Co, and (c) Ag:

(a) Barium (Ba) has an atomic number of 56. Its electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2, with 2 valence electrons in the 5s orbital. The orbital diagram can be represented as follows:
5s:[2]

(b) Cobalt (Co) has an atomic number of 27. Its electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7, with 7 valence electrons in the 3d orbital. The orbital diagram can be represented as follows:
3d:[7]

(c) Silver (Ag) has an atomic number of 47. Its electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^1 4d^10, with 1 valence electron in the 5s orbital. The orbital diagram can be represented as follows:
5s:[1]

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The change in energy of the system in the given reaction is -1045 kJ. This value is calculated using the first law of thermodynamics taking in account that the energy absorbed is lost by the system and the work done on the system is obtained.

In this chemical reaction, we are dealing with a process that involves heat absorption and work done on the system. Both these elements contribute to the change in energy of the system, denoted by ΔE.

The first law of thermodynamics states that ΔE = q + w, where 'q' represents heat and 'w' represents work. However, notice that the heat is absorbed by the surroundings, which means the system is losing that amount of heat, so q = -1.1 MJ = -1100 kJ (as 1MJ = 1000 kJ).

Also, the work is done on the system, so it's positive, and it's given in calories, we need to convert it into kilojoules (kJ), for that, use the conversion factor 1 cal= 0.004184 kJ, so w = 13.2 kcal * 4.184 = 55.23 kJ.

Plugging these values into thermodynamics equation, we get ΔE = -1100 kJ + 55.23 kJ = -1044.77 kJ. Thus, the change in energy of the system, ΔE, is -1045 kJ (rounded to 0 decimal places).

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Final answer:

To calculate the change in internal energy (ΔE) for the reaction, convert all values to kJ, then apply the formula ΔE = q + w. The answer is +1155 kJ, indicating energy absorption.

Explanation:

The question asks to calculate the change in internal energy (ΔE) for a chemical reaction where gaseous reactants form a liquid product. The energy absorbed by the surroundings is given as 1.1 MJ, and the work done on the system is 13.2 kcal. To find ΔE, we use the formula ΔE = q + w, where q is the heat absorbed by the system and w is the work done on the system.

First, convert all values to the same unit (kJ): Heat absorbed, q = 1.1 MJ = 1100 kJ; Work done, w = 13.2 kcal × 4.184 kJ/kcal = 55.23 kJ. Thus, ΔE = 1100 kJ + 55.23 kJ = 1155.23 kJ. Therefore, the change in internal energy for the reaction is +1155 kJ, indicating that the system absorbed energy.

The density of the unknown gas in a 2.85 L flask at 33 °C and 1.00 atm is approximately 0.93 g/L.

The question asks for the density of an unknown gas contained in a flask at given temperature and pressure conditions. To find the density (d) of the gas, we use the formula d = mass/volume. The mass of the gas is given as 2.65 g, and the volume of the flask is given as 2.85 L. Therefore, the density of the gas can be calculated as:

d = mass / volume

d = 2.65 g / 2.85 L

d = 0.9298 g/L

After performing the calculation, we find that the density of the gas is approximately 0.93 g/L at the given conditions of 33 °C and 1.00 atm.

The aldehyde group changes to ether group.

In the straight chain glucose molecule, there's the 6 carbon atoms attached with each other where there are several hydrogen and hydroxyl radicals attached. The C1 of glucose contains the aldehyde group and the C5 is the most reactive atom of glucose. In a solution, the lone pair of the oxygen atom of hydroxyl group of C5 attacks the electrophilic centre of C1, forming a carbon oxygen ether bond. This bond makes the double bonded oxygen weaker and one of the bond breaks forming oxygen radicle, which then attracts the hydrogen radicle emitted by the ether oxygen to form a hydroxyl group. This is how the ring structure forms in a solution.

Thus, the aldehyde group of glucose changes to ether group.

Answer:

The net work produced = -36737.52 J

The efficiency of the cycle = 72.2%

Explanation:

Given that :

The temperature of the hot reservoir [tex](T__H})[/tex] = 800 °C = (800+273)K

The temperature of the cold reservoir [tex](T__C})[/tex] = 25 °C (25+273)K

Pressure [tex](P__A})[/tex] =  0.2 bar

Pressure [tex](P_B})[/tex] =  60 bar

Rate constant (R) = 8.314

Determination of the efficiency of the cycle (η) is given by the formula:

(η) = [tex]1-\frac{T__C}{T__H}[/tex]

   = 1  - [tex]\frac{(800+273)K}{(25+273)K}[/tex]

   = 0.722

   = 72.2 %

∴ The efficiency of the cycle = 72.2 %

However, the heat given along the initial hot isothermal path [tex](Q__H})[/tex] is equal to the work done which is given by the equation;

[tex]Q__H}=nRT__H}In\frac{V_b}{V_a}[/tex]

[tex]Q__H}=nRT__H}In\frac{P_a}{P_b}[/tex]

substituting our data from the given parameters above; we have:

      [tex]= 1 * 8.314 * (800+273) *In (\frac{0.2}{60} )[/tex]

      = -50882.99 J

To determine the net work produced; we have:

[tex]W_{net}[/tex] = η[tex]Q__H[/tex]

       = 0.722 × (-50882.99 J)

       = -36737.52 J

∴ The net work produced = -36737.52 J

The net work produced and the efficiency of the cycle is:  [tex]{W_{net} = 111814.54 \text{ J}}[/tex], [tex]{\eta = 72.2\%}[/tex]

To solve this problem, we will use the principles of thermodynamics and the characteristics of a Carnot cycle. The net work produced by a Carnot cycle and its efficiency can be determined using the temperatures of the hot and cold reservoirs and the ideal gas law.

First, let's convert the temperatures from Celsius to Kelvin, which is necessary for the calculations:

- The temperature of the hot reservoir, [tex]\( T_{hot} \), is \( 800^\circ C + 273.15 = 1073.15 K \).[/tex]

- The temperature of the cold reservoir, [tex]\( T_{cold} \), is \( 25^\circ C + 273.15 = 298.15 K \).[/tex]

The efficiency of a Carnot cycle is given by the formula:

[tex]\[ \eta = 1 - \frac{T_{cold}}{T_{hot}} \][/tex]

Substituting the temperatures in Kelvin:

[tex]\[ \eta = 1 - \frac{298.15 K}{1073.15 K} \][/tex]

[tex]\[ \eta = 1 - 0.278 \][/tex]

[tex]\[ \eta = 0.722 \text{ or } 72.2\% \][/tex]

The net work produced in a Carnot cycle can also be expressed in terms of the heat added and the efficiency:

[tex]\[ W_{net} = Q_{in} \cdot \eta \][/tex]

where [tex]\( Q_{in} \)[/tex] is the heat added from the hot reservoir.

Since the process involves one mole of an ideal gas, we can use the specific heat capacity at constant volume, [tex]\( C_v \)[/tex], to find [tex]\( Q_{in} \)[/tex]:

[tex]\[ Q_{in} = n \cdot C_v \cdot (T_{hot} - T_{cold}) \][/tex]

For an ideal diatomic gas, [tex]\( C_v = \frac{5}{2}R \)[/tex], where [tex]\( R \)[/tex] is the ideal gas constant [tex](8.314 J/(mol\cdot K)).[/tex]

Substituting the values:

[tex]\[ Q_{in} = 1 \text{ mol} \cdot \frac{5}{2} \cdot 8.314 \text{ J/(mol\cdot K)} \cdot (1073.15 K - 298.15 K) \][/tex]

[tex]\[ Q_{in} = \frac{5}{2} \cdot 8.314 \text{ J/(mol\cdot K)} \cdot 775 \text{ K} \] \[ Q_{in} = 20 \text{ mol} \cdot 8.314 \text{ J/(mol\cdot K)} \cdot 775 \text{ K} \] \[ Q_{in} = 155027 \text{ J} \][/tex]

Now, we can calculate the net work produced:

[tex]\[ W_{net} = Q_{in} \cdot \eta \] \[ W_{net} = 155027 \text{ J} \cdot 0.722 \] \[ W_{net} = 111814.54 \text{ J} \][/tex]

Therefore, the net work produced by the Carnot cycle is approximately [tex]\( 111814.54 \text{ J} \)[/tex] and the efficiency of the cycle is [tex]\( 72.2\% \).[/tex]

The final answer for the net work produced and the efficiency of the cycle is: [tex]\[ \boxed{W_{net} = 111814.54 \text{ J}} \][/tex], [tex]\[ \boxed{\eta = 72.2\%} \][/tex]

The answer is: [tex]\eta = 72.2\%.[/tex]

Question in incomplete, complete question is:

Technetium (Tc; Z = 43) is a synthetic element used as a radioactive tracer in medical studies. A Tc atom emits a beta particle (electron) with a kinetic energy (Ek) of [tex]4.71\times 10^{-15}J[/tex] . What is the de Broglie wavelength of this electron (Ek = ½mv²)?

Answer:

[tex] 6.762\times 10^{-12} m[/tex] is the de Broglie wavelength of this electron.

Explanation:

To calculate the wavelength of a particle, we use the equation given by De-Broglie's wavelength, which is:

[tex]\lambda=\frac{h}{\sqrt{2mE_k}}[/tex]

where,

= De-Broglie's wavelength = ?

h = Planck's constant = [tex]6.624\times 10^{-34}Js[/tex]

m = mass of beta particle = [tex] 9.1094\times 10^{-31} kg[/tex]

[tex]E_k[/tex] = kinetic energy of the particle = [tex]4.71\times 10^{-15}J[/tex]

Putting values in above equation, we get:

[tex]\lambda =\frac{6.624\times 10^{-34}Js}{\sqrt{2\times 9.1094\times 10^{-31} kg\times 4.71\times 10^{-15}J}}[/tex]

[tex]\lambda = 6.762\times 10^{-12} m[/tex]

[tex] 6.762\times 10^{-12} m[/tex] is the de Broglie wavelength of this electron.

Answer:

z≅3

Atomic number is 3, So ion is Lithium ion ([tex]Li^+[/tex])

Explanation:

First of all

v=f*λ

In our case v=c

c=f*λ

λ=c/f

where:

c is the speed of light

f is the frequency

[tex]\lambda=\frac{3*10^8}{2.961*10^{16}}\\ \lambda=1.01317*10^{-8} m[/tex]

Using Rydberg's Formula:

[tex]\frac{1}{\lambda}=R*z^2*(\frac{1}{n_1^2}-\frac{1}{n_2^2})[/tex]

Where:

R is Rydberg constant=[tex]1.097*10^7[/tex]

z is atomic Number

For highest Energy:

n_1=1

n_2=∞

[tex]\frac{1}{1.01317*10^{-8}}=1.097*10^{7}*z^2*(\frac{1}{1^2}-\frac{1}{\inf})\\z^2=8.99\\z=2.99[/tex]

z≅3

Atomic number is 3, So ion is Lithium ion ([tex]Li^+[/tex])

Answer: The mass of urea needed is 12.89 grams

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

[tex]\pi=iMRT[/tex]

or,

[tex]\pi=i\times \frac{m_{solute}\times 1000}{M_{solute}\times V_{solution}\text{ (in mL)}}}\times RT[/tex]

where,

[tex]\pi[/tex] = osmotic pressure of the solution = 24.3 atm

i = Van't hoff factor = 1 (for non-electrolytes)

[tex]m_{solute}[/tex] = mass of urea = ? g

[tex]M_{solute}[/tex] = molar mass of urea = 60.1 g/mol

[tex]V_{solution}[/tex] = Volume of solution = 216 mL

R = Gas constant = [tex]0.0821\text{ L atm }mol^{-1}K^{-1}[/tex]

T = temperature of the solution = 298 K

Putting values in above equation, we get:

[tex]24.3atm=1\times \frac{m_{solute}\times 1000}{60.1\times 216}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 298K\\\\m_{solute}=\frac{24.3\times 60.1\times 216}{1\times 1000\times 0.0821\times 298}=12.89g[/tex]

Hence, the mass of urea needed is 12.89 grams

By using the formula for osmotic pressure and solving for the number of moles, we establish that approximately 12.74 grams of urea are required to generate an osmotic pressure of 24.3 atm in 216 mL of water at 298 K.

The problem deals with finding the mass of urea needed to generate a certain osmotic pressure. One can utilize the formula for osmotic pressure (Π = n/V * R * T) which is similar to the ideal gas law. In this formula, Π is your osmotic pressure (24.3 atm), n is the number of moles, V is the volume in liters (216 mL = 0.216 liters), R is the ideal gas constant (0.0821 L*atm/(K*mol)) and T is the temperature in Kelvin (298 K).

By solving for n (the number of moles), we obtain n = ΠV / RT = (24.3 atm * 0.216 L) / (0.0821 L atm/(K mol) * 298 K) which results in n = 0.212 moles.

Urea has a molar mass of 60.1 g/mol, so the mass of urea required is n * molar mass = 0.212 moles * 60.1 g/mol = 12.74 g. Thus, approximately 12.74 grams of urea are needed to generate an osmotic pressure of 24.3 atm in the given conditions.

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Answer: 67.8 %.

Explanation:

Okay, let us delve right into the solution to the question;

The balanced chemical reaction is given by the equation (1) below;

2 HCOONa + H2SO4 ---------> 2 CO + 2 H2O + Na2SO4. ----------------------------------------------------------------------------(1).

From the balanced chemical reaction in equation (1) above we can see that; 2 moles of HCOONa reacts with one moles of tetraoxosulphate acid, H2SO4 to produce 2 moles of carbonmonoxide,CO; 2 moles of water, H2O and 1 mole of sodium tetraoxosulphate, Na2SO4.

The parameters given from the question are; total atmospheric pressure, P(t) = 752 torr, volume of CO= 242 mL = 0.242 Litres.

STEP ONE : find the carbon monoxide,CO pressure; P(CO).

Using the formula below;

P(t) = P(CO) + P(H2O). Hence;

P(CO) = P(t) - P(H2O). Note that P(H2O)= 19.8 torr.

==>P(CO)= 752 torr - 19.8 torr = 732.2 torr.

STEP TWO: calculate the number of moles of Carbonmonoxide,CO.

Using the formula below;

Number of moles= pressure(P) × volume(v) / gas constant(R) × temperature (T).

That is, n= PV/RT.

n= 732 torr × 0.242 Litres/ 62.4 × 295.15.

= 9.62 × 10^-3 mol of CO.

STEP THREE:

2 moles of HCOONa = 2 moles of CO.

=> 2 moles of HCOONa = 2 moles of CO/ 2 moles of CO = 1 mol( HCOONa/ CO).

Then, 9.62 × 10^-3 mol of CO × 1 mol( HCOONa/ CO).

==> 9.62 × 10^-3 mol HCOONa × molar masss of HCOONa(68 grams/mol)

= 0.654 grams.

Therefore, the percentage of sodium formate in the original mixture = 0.654 grams/ 0.964 gram × 100 = 67.8 %.

The equation for the reaction of sodium with sulfuric acid is 2Na + H₂SO₄ → Na₂SO₄ + H₂.

The equation for the reaction of sodium with sulfuric acid is:

2Na + H₂SO₄ → Na₂SO₄ + H₂

In this reaction, sodium reacts with sulfuric acid to form sodium sulfate and hydrogen gas. This reaction is a displacement reaction where sodium replaces hydrogen in the sulfuric acid to form sodium sulfate and liberate hydrogen gas.

The balanced equation for the reaction is:

2Na(s) + H₂SO₄(aq) → Na₂SO₄(aq) + H₂(g)

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Final answer:

Paramagnetic ions are those with unpaired electrons, which can be found by looking at the electron configuration of Fe+ to Fe14+. The more unpaired electrons, the stronger the attraction to a magnetic field.

Explanation:

The student has asked which ions from Fe+ to Fe14+ are paramagnetic and which would be most strongly attracted to a magnetic field. An ion is considered paramagnetic if it has one or more unpaired electrons. To determine this, we can look at the electron configuration of each iron ion. Iron (Fe) has an electron configuration of [Ar] 4s2 3d6. When it loses electrons to become ionized (Fe+ to Fe14+), it loses them from its outermost shell first, which is the 4s shell, and then from the 3d shell. Paramagnetism increases with the number of unpaired electrons, so the ions with the highest number of unpaired electrons in the d shell will be most strongly attracted to a magnetic field.

Answer:

The age of the fossil be [tex]2.1987\times 10^{4} years[/tex].

Explanation:

Formula used :

[tex]N=N_o\times e^{-\lambda t}\\\\\lambda =\frac{0.693}{t_{\frac{1}{2}}}[/tex]

where,

[tex]N_o[/tex] = initial mass of isotope  C-14 = x

N = mass of the parent isotope left after the time, (t)  = 70.0% of x=0.07x

[tex]t_{\frac{1}{2}}[/tex] = half life of the isotope  C-14 = 5730 years

[tex]\lambda[/tex] = rate constant

Let the age of the fossil be t.

Now put all the given values in this formula, we get  t :

[tex]0.07x=x\times e^{-(\frac{0.693}{5730 years})\times t}[/tex]

[tex]t=2.1987\times 10^{4} years[/tex]

The age of the fossil be [tex]2.1987\times 10^{4} years[/tex].

Answer:

k = 6.31 x 10⁻³ min⁻¹

Explanation:

The equation required to solve this question is:

k = 0693 / t half-life

This equation is derived from the the equation from the radioctive first order reactions:

ln At/A₀ = -kt

where At is the number of isoopes after a time t , and A₀ is the number of of isotopes initially. The half-life is when the number of  isotopes has decayed by a half, so

ln(1/2) = -kt half-life

-0.693 = - k t half-life

t half-life = 109.8 min

⇒ k = 0.693 / t half-life = 0.693 / 109.8 min = 6.31 x 10⁻³ min⁻¹

The rate constant for the decomposition of Fluorine-18 is 0.00631 min⁻¹, calculated using the formula k = 0.693 / t₁/₂ where the half-life t₁/₂ is 109.7 minutes.

The decay of Fluorine-18 (¹8F) is described by first-order kinetics, which means the rate of decay is proportional to the amount of ¹8F present. The half-life of ¹8F is given as 109.7 minutes. To determine the rate constant (k) for the decomposition of Fluorine-18, we use the relationship between the half-life (t1/2) and rate constant for first-order reactions: k = 0.693 / t1/2. Substituting the given half-life into this equation, we get:

k = 0.693 / 109.7 min = 0.00631 min-1

This is the rate constant for the decomposition of Fluorine-18.

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Answer:

Macroscopic domain: Boiling point elevation, Henry's law, molarity, osmosis.

Microscopic domain: Hydrogen bond, ion-dipole attraction, nonelectrolyte, solvated ion.

Explanation:

A solution is composed of a solute (in high quantity) and one or more solute, which are dissolved in it. The properties of the solution can be characterized and measured in the macroscopic domain, or the microscopic domain when it's observed in the interactions with the molecules.

Boiling point elevation: It happens because the nonvolatile solvents interact with the solute, and so it will be difficult to boil it. The boiling point is a property of all the substance, and so, it can be noticed in the macroscopic domain.

Henry's law: States that the solubilization of a gas in a liquid depends on the partial pressure of the gas and by a proportional constant. Thus, the solubility of a gas is how much moles are dissolved in the volume of the solution, and so it's part of the macroscopic domain.

Hydrogen bond: It's an intermolecular interaction that happens in polar molecules that have bonds between hydrogen and a high electronegative element (N, O, or F). So, it's part of the microscopic domain.

Ion-dipole attraction: It's also an interaction that happens between an ion and a polar compound, so it's part of the microscopic domain.

Molarity: It represents how much moles of the solute is dissolved in the solution, so it's part of the macroscopic domain.

Nonelectrolyte: An electrolyte compound is the one which dissociates or ionizes, in the solvent, and because of that the solution can conduct electricity. A nonelectrolyte doesn't have this property. Because it depends on how the ions and molecules behave in solution, it's part of the microscopic domain.

Osmosis: Is the property of the solvent to go through a membrane from a side with fewer solutes (less concentrated) to another with more solute (high concentrated). So, it depends on the total amount of the solute, and so it's part of the macroscopic domain.

Solvated ion: A solvated ion is an ion that is surrounded by another ion, or by molecules, such water. So, it's part of the microscopic domain.

Answer:

478mL

Explanation:

We can obtain the molarity of a solution by:

Molarity = mole /Volume(L)

From the question,

Number of mole = 0.0526mol

Molarity = 0.110M

Volume =?

Volume = mole /Molarity

Volume = 0.0526/0.11 = 0.478L

But

1L = 1000mL

0.478L = 0.478 x 1000 = 478mL

Answer: The thickness of metal sheet is 1.93 mm

Explanation:

The metals sheet is in the form of cuboid.

To calculate the width of the metal sheet for the given volume, we use the equation to calculate the volume of cuboid, which is:

[tex]V=lbh[/tex]

where,

V = volume of metal sheet = [tex]45.5cm^3[/tex]  

l = length of metal sheet = 15.9 cm

b = width of metal sheet = 14.8 cm

h = height of metal sheet = ? cm

Putting values in above equation, we get:

[tex]45.5cm^3=15.9\times 14.8\times h\\\\h=\frac{45.5}{15.9\times 14.8}=0.193cm[/tex]

Converting this thickness into millimeters, we use the conversion factor:

1 cm = 10 mm

So, [tex]0.193cm\times \frac{10mm}{1cm}=1.93mm[/tex]

Hence, the thickness of metal sheet is 1.93 mm

To find the thickness (height) of the metal sheet, use the formula for volume and rearrange it to solve for the height.

To find the thickness (height) of the metal sheet, we can use the formula for volume. The formula for volume of a rectangular solid is:

Volume = Length * Width * Height

Given that the volume is 45.5 cm3, the length is 15.9 cm, and the width is 14.8 cm, we can rearrange the formula to solve for the height:

Height = Volume / (Length * Width)

Substituting the values, we have:

Height = 45.5 cm3 / (15.9 cm * 14.8 cm)

We can now calculate the height of the metal sheet in millimeters.

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Answer: hello dear, your question seems incomplete, but, chill out not to worry let me give you one or two things you need to know in order to be able to solve this kind of question in the nearest future, check this out!.

Explanation:

In order to kill parasites and to make the water the be safe from microoganisms, boiling is a great procedure for making sure this happens, that is to say is the act of purification of water. However, when you over-boil water it also depletes the amount of oxygen present in the water.

When you boil water for the purpose of killing germs/ parasites, the PURIFIED PART IS THE WATER VAPOUR, the LIQUID WATER STILL HAS THE DEAD PARASITES IN THEM. That is the reason why the process called DISTILLATION is more efficient in purifying water is more efficient than ordinary boiling of water.

The liquid water remaining in the container after the boiling would have also been purified though, but it will still contain dead contaminants, so, filtering can be done or one can drink the water like that.

Answer:

Explanation:

The given reaction is exothermic . So ΔH is negative .

Gas is evolving so work done by gas is positive or w is positive.

Change in internal energy that is ΔU is negative.

q = u - w

u is negative , w is positive so q is negative .

Answer:

 a) 1.866 × 10 ⁻¹⁹ J      b)   3.685 × 10⁻¹⁹ J

Explanation:

the constants involved are

h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s

Me of electron = 9.109 × 10 ⁻³¹ kg

speed of light = 3.0 × 10 ⁸ m/s

a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²

Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J

b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula

hv =   Φ + Ek

where Ek = 1.866 × 10 ⁻¹⁹ J

v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m

v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹

hv = 6.626 × 10⁻³⁴ m² kg/s ×  8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J

5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ

Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J

Final answer:

In the given reaction, 100 grams of calcium carbonate decomposed to form 56 grams of calcium oxide and 44 grams of carbon dioxide. This observation is in agreement with the law of conservation of mass.

Explanation:

The given reaction: CaCO3 → CaO + CO2

According to the reaction, 1 mole of CaCO3 decomposes to form 1 mole of CaO and 1 mole of CO2. The molar mass of CaCO3 is 100.09 g/mol. Therefore, the molar mass of CaO and CO2 should be the same, which is 56.08 g/mol. The given mass of CaCO3 is 100 g, so the moles of CaCO3 are:

(100 g / 100.09 g/mol) = 0.999 mol

Since 1 mole of CaCO3 decomposes to form 1 mole of CaO and 1 mole of CO2, the moles of CaO produced will be:

0.999 mol

The molar mass of CaO is 56.08 g/mol, so the mass of CaO produced will be:

(0.999 mol) * (56.08 g/mol) = 55.88 g

Therefore, the observed mass of CaO produced is 56 g, which is in agreement with the law of conservation of mass.

The reaction CaCO₃ → CaO + CO₂ illustrates 5. the Law of Conservation of Matter

The given reaction CaCO₃ → CaO + CO₂ demonstrates the Law of Conservation of Matter.

The combined mass of the products is 10 grams, which equals the mass of the reactant, thereby supporting the Law of Conservation of Matter.

Correct question is: In the reaction CaCO₃ → CaO + CO₂ 100 grams of calcium carbonate (CaCO₃) is observed to decompose upon heating into 56 grams of calcium oxide (CaO) and 44 grams of carbon dioxide (CO₂). This is an illustration of
1. the Law of Gravity
2. the Law of Conservation of Energy
3. the Law of Multiple Proportions
4. the conversion of matter into energy
5. thc Law of Conservation of Matter

Answer: The nitronium ion is a strong electrophile

Explanation:

The detailed mechanism of the reaction is shown in the images attached. The flow of electrons has been shown with arrows. HNO3 is first protonated by H2SO4 this protonated specie H2NO3+ now forms H2O and NO2+.

The nitronium ion is formed when concentrated sulfuric acid protonates nitric acid, which then loses water to produce the reactive electrophile NO2+ needed for electrophilic aromatic substitution reactions.

The formation of the nitronium ion (NO2+) from concentrated nitric acid in concentrated sulfuric acid is a crucial step in the electrophilic aromatic substitution mechanism. The process begins with the protonation of nitric acid by sulfuric acid, creating the nitronium ion and water. Specifically, sulfuric acid acts as a strong acid and protonates the nitric acid, which loses a water molecule and forms the nitronium ion. This positively charged electrophile is highly reactive and capable of attacking the electron-rich aromatic ring, initiating a substitution reaction.

In the context of aromatic substitutions, the nitronium ion is very strong and reactive enough to overcome the stability of the aromatic ring's delocalized electrons. Its formation is necessary because aromatic compounds don't readily react with partial positive electrophiles, making the full cation electrophile essential for the reaction to proceed.

Answer: The volume of the gas also gets double when number of moles are doubled.

Explanation:

The relationship of number of moles and volume at constant temperature and pressure was given by Avogadro's law. This law states that volume is directly proportional to number of moles at constant temperature and pressure.

The equation used to calculate number of moles is given by:

[tex]\frac{V_1}{n_1}=\frac{V_2}{n_2}[/tex]

where,

[tex]V_1\text{ and }n_1[/tex] are the initial volume and number of moles

[tex]V_2\text{ and }n_2[/tex] are the final volume and number of moles

We are given:

[tex]n_2=2n_1[/tex]

Putting values in above equation, we get:

[tex]\frac{V_1}{n_1}=\frac{V_2}{2n_1}\\\\V_2=\frac{2n_2\times V_1}{n_1}=2V_2[/tex]

Hence, the volume of the gas also gets double when number of moles are doubled.

Final answer:

Doubling the number of moles of a gas while keeping temperature and pressure constant will double the volume of the gas, in accordance with Avogadro's law.

Explanation:

When we double the number of moles of gas while keeping the temperature and pressure constant, according to Avogadro's law, the volume of the gas also doubles. This is because Avogadro's law states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of the gas. Therefore, if the amount of gas is doubled, the volume also doubles, assuming the gas behaves ideally.

Quantum numbers n, l, and ml are used to describe an electron's location in an atom. For n=2, l can be 0 or 1, and four orbitals exist. For l=3, ml can range from -3 to 3, providing seven orbitals.

In the realm of quantum mechanics, the values of the quantum numbers n, l, and ml tell us a lot about the electron's location in an atom. If the principal quantum number, n = 2, the angular momentum quantum number, l, can have values ranging from 0 to n-1. In this case, that means l can be 0 or 1. With this, the total number of orbitals (regions where you can most likely find an electron) possible at the n = 2 energy level is 4 (calculated as n2).

If the magnetic quantum number, l = 3, then, the magnetic quantum number ml can have values ranging from -l to +l, which means ml can range from -3 to 3. This produces a total of 7 orbitals possible at the l = 3 sublevel, each of which can hold two electrons.

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For n = 2, l can have values 0 and 1, with a total of 4 orbitals. For l = 3, ml ranges from -3 to 3, with 7 orbitals at the l = 3 sublevel.

The problem involves determining the possible values of different quantum numbers. When the principal quantum number n is 2, the angular momentum quantum number l can range from 0 to n-1, meaning l can have the values 0 and 1. The total number of orbitals possible at the n = 2 energy level is calculated by the formula n², thus the number is 4 orbitals.

If the angular momentum quantum number l is 3, the magnetic quantum number ml can range from -l to +l, meaning it can have values from -3 to 3 (-3, -2, -1, 0, 1, 2, 3). The total number of orbitals possible at the l = 3 sublevel is 2l+1, which is 7.

Answer:

The answer to the question is

The mass percentage of NaCl(s) in the mixture is 49.7%

Explanation:

The given variables are

mass of sample of mixture = 0.3146 g

Volume of AgNO₃ required to react comletely with the chloride ions = 45.70 mL

Concentration of the AgNO₃ added = 0.08765 M

The equations for the reactions oare

NaCl(aq) + AgNO₃ (aq) = AgCl(s) + NaNO₃(aq)

AgNO₃ (aq) + KBr (aq) → AgBr (s) + KNO₃

The equation for the reaction shows one mole of NaCl reacts with one mole of AgNO₃ to form one mole of AgCl

Thus 45.70 mL of 0.08765 M solution of AgNO₃ contains[tex]\frac{45.7}{1000} (0.08765) = 0.004 moles[/tex]

Therefore the sum of the number of moles of Br⁻ and Cl⁻

precipitated out of the solution =  0.004 moles

Thus if the mass of NaCl in the sample = z then the mass of KBr = y

However the mass of the sample is given as 0.3146 g which  means the molarity of the solution is 0.004 moles

given by

[tex]\frac{z}{58.44} + \frac{y}{119} = 0.004 moles[/tex]  and z + y = 0.3146

Therefore z = 0.3146 - y which gives

[tex]\frac{(0.3146-y)}{58.44} + \frac{y}{119} = 0.004 moles[/tex]

-8.7×10⁻³y +0.54×10⁻³ = 0.004

or 8.7×10⁻³y = 1.37769× 10⁻³

y = 0.158 g and z = 0.156 Thus the mass of NaCl = 0.156 g and the mass percentage = 0.156/0.3146×100 = 49.7% NaCl

The mass percentage of NaCl(s) in the mixture is 49.7%

Answer:

a) Approximate boiling point of HBr = -60.15 °C

b) Approximate boiling point of AsH₃ = -52.25 °C

Explanation:

Döbereiner stated that some elements could be arranged in groups of 3 similar elements ( known as "triads) , and the element of the middle ( elements are ordered with respect to their atomic mass) would have properties between the other 2 ( the average value)

a) In the first case the triad would be the halogen triad ( Cl , Br and I ) . And according to Döbereiner , the boiling point of HBr should be the average of HCl and HI . Therefore

Approximate boiling point of HBr = [(- 84.9°C) + (-35.4°C)]/2 = -60.15 °C

b) Simmilarly for  AsH₃ , PH₃ and SbH₃ , the boiling point of AsH₃ would be

Approximate boiling point of AsH₃ = [(- 87.4°C) + (-17.1°C)]/2 = -52.25 °C

Answer: option A. acidic

Explanation: acidic solution is characterized by the presence of Hydrogen ion.