A chemist determines by measurements that moles of fluorine gas participate in a chemical reaction. Calculate the mass of fluorine gas that participates. Be sure your answer has the correct number of significant digits.

Answer:

The mole fraction of hexane is 0.6204

Explanation:

Obs: X hex = 1 - X pen

Ptot = P pen + P hex

Ptot = X pen P pen + X hex P hex ---> applying X hex = 1 - X pen

X pen = (Ptot - P hex) / (P pen - P hex)

X pen = (255 - 151) / (425 - 151) = 0.3795

X hex = 1 - X pen

X hex = 1 - 0.3795 = 0.6204

Answer:

Make a graph

Explanation: edge 2021

Answer:

For the first question the products elute slower. The answer to the second question is it would not be a good option as an eluent

Explanation:

Solvents are classified into polar and nonpolar. While in polar solvents, the distribution of the electronic cloud is asymmetric; therefore, the molecule has a positive and a negative pole. Low molecular weight alcohols such as methanol belong to this type.

While in apolar solvents, the distribution of the electronic cloud is symmetric; Therefore, these substances lack a positive and negative pole in their molecules. Some solvents such as hexane.

The miscibility of methanol (polar solvent) in hexane (apolar solvent) is low, miscibility is the main reason for not using this mixture as eluent.

Answer:

Molality = 18.5 m

Explanation:

Let's analyse data. We want to determine molality which means mol of solute / 1kg of solvent. (Hence we need, the moles of solute and the mass of solvent in kg)

12.83 M means molarity → mol of solute in 1L of solution

Density refers always to solution → Mass of solution / Volume of solution

1L = 1000 mL

We can determine the mass of solution with density

0.9102 g/mL = Mass of solution / 1000 mL

Mass of solution = 0.9102 g/mL . 1000 mL → 910.2 g

Let's convert the moles of solute (NH₃) to mass

12.83 mol . 17.03 g/ 1 mol = 218.5 g

We can apply this knowledge:

Mass of solution = Mass of solvent + Mass of solute

910.2 g = Mass of solvent + 218.5 g

910.2 g - 218.5 g = 691.7 g → Mass of solvent.

Let's convert the mass in g to kg

691.7 g . 1kg / 1000 g = 0.6917kg

We can determine molalilty now → 12.83 mol / 0.6917kg

Molality = 18.5 m

To determine the molality of a 12.83 M NH3 solution with a density of 0.9102 g/mL, calculate the mass of NH3 per liter using molarity and molar mass, find the mass of the solution using volume and density, subtract the mass of NH3 to find the mass of water, and finally divide the moles of NH3 by the mass of water in kilograms.

To find the molality (m) of an aqueous solution of ammonia (NH3) with a molarity (M) of 12.83 and a density of 0.9102 g/mL, we need to calculate the number of moles of NH3 per kilogram of water. Molality is defined as moles of solute per kilogram of solvent (water). First, we determine the mass of NH3 in 1 liter of solution, considering the molarity and the molar mass of NH3 (17.03 g/mol). Using the density of the solution, we then calculate the mass of the solution and subtract the mass of the ammonia to find the mass of water.

Here's the step-by-step calculation:

This approach allows us to determine molality, which is essential for understanding the colligative properties of the solution.

Answer:

74.344 kJ.

Explanation:

Below is an attachment containing the solution.

Answer:

12.96 seconds

Explanation:

Assuming the reaction follows a first order

Rate = K[NOBr] = change in concentration of NOBr/time

K = 0.556 L mol^-1 s^-1

Change in concentration of NOBr = 0.32M - 0.039M = 0.281M

0.281/t = 0.556×0.039

t = 0.281/0.021684 = 12.96 seconds

It will take approximately 40.48 seconds for the concentration of NOBr to decrease from 0.32 M to 0.039 M.

To determine how long it will take for the concentration of NOBr to decrease from 0.32 M to 0.039 M, we need to use the integrated rate law for a second-order reaction:

For a second-order reaction:

1 / [A]₁ = kt + 1 / [A]₀

Where:

Now, let's rearrange and solve for time (t):

(1 / [A]₁) - (1 / [A]₀) = kt

[1 / 0.039 M] - [1 / 0.32 M] = (0.556 L mol⁻¹ s⁻¹) * t

25.64 - 3.125 = 0.556t

22.515 = 0.556t

t = 22.515 / 0.556

t ≈ 40.48 seconds

Final answer:

The rate law and the Arrhenius equation help calculate the ratio of rate constants for reactions with similar frequency factors. In this case, with identical frequency factors, the ratio of the rate constants is 1.

Explanation:

The rate law for a reaction:

rate = k[A] [B]

The Arrhenius equation:

k = Ae(-Ea/RT)

For the given question:

Given k1 and k2 are the same, k1/k2 = 1.

The ratio of rate constants depends on the exponential term in the Arrhenius equation, specifically the difference in activation energies. If the activation energies are very close, the ratio [tex]\( \frac{k_1}{k_2} \)[/tex] will be close to 1, indicating similar rate constants for the two reactions at 25 °C.

The ratio of reaction rate constants [tex](\(k_1/k_2\))[/tex] for two reactions with similar frequency factors can be expressed using the Arrhenius equation, which relates the rate constant (k) to temperature. The Arrhenius equation is given by:

[tex]\[ k = A \cdot e^{-\frac{E_a}{RT}} \][/tex]

Where:

- ( k ) is the rate constant,

- ( A) is the frequency factor (pre-exponential factor),

- ( E_a ) is the activation energy,

- ( R ) is the gas constant (8.314 J/(mol·K)),

- ( T ) is the temperature in Kelvin.

Assuming the frequency factors[tex](\( A_1 \) and \( A_2 \))[/tex] are the same, the ratio of rate constants [tex](\( \frac{k_1}{k_2} \))[/tex] can be simplified to the ratio of the exponential term:

[tex]\[ \frac{k_1}{k_2} = e^{-\frac{E_{a1} - E_{a2}}{RT}} \][/tex]

Given that the reactions are at 25 °C (298 K), the ratio [tex]\( \frac{k_1}{k_2} \)[/tex]will depend on the difference in activation energies [tex](\( E_{a1} - E_{a2} \)).[/tex]

The question provides us with the chemical formula for an unknown compound, and values for moles of oxygen and calcium. However, to solve this problem, we need to have the number of moles for phosphorus, not calcium. Without this, it's impossible to proceed further and derive a concrete answer.

The task requires us to find the accurate value of x in the chemical formula P2Ox. To do this, we consider that the unknown compound is composed entirely of phosphorus (P) and oxygen (O), but not calcium (Ca). Calcium seems to be irrelevant for this particular problem.

In the formula P2Ox, '2' is the stoichiometric index for phosphorus and 'x' for oxygen. However, we are not given the moles of phosphorus, which makes the problem unsolvable with the information provided.

Ideally, we would divide the number of moles of oxygen by the number of moles of phosphorus to find the value of 'x', but since the moles of phosphorus are not provided, we are unable to proceed further with the provided information.

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Answer : The percentage composition of carbon, hydrogen and sulfur in a compound is, 38.8 %, 9.6 % and 51.6 % respectively.

Explanation :

To calculate the percentage composition of element in sample, we use the equation:

[tex]\%\text{ composition of element}=\frac{\text{Mass of element}}{\text{Mass of sample}}\times 100[/tex]

Given:

Mass of carbon = 1.94 g

Mass of hydrogen = 0.48 g

Mass of sulfur = 2.58 g

First we have to calculate the mass of sample.

Mass of sample = Mass of carbon + Mass of hydrogen + Mass of sulfur

Mass of sample = 1.94 + 0.48 + 2.58 = 5.0 g

Now we have to calculate the percentage composition of a compound.

[tex]\%\text{ composition of carbon}=\frac{1.94g}{5.0g}\times 100=38.8\%[/tex]

[tex]\%\text{ composition of hydrogen}=\frac{0.48g}{5.0g}\times 100=9.6\%[/tex]

[tex]\%\text{ composition of sulfur}=\frac{2.58g}{5.0g}\times 100=51.6\%[/tex]

Hence, the percentage composition of carbon, hydrogen and sulfur in a compound is, 38.8 %, 9.6 % and 51.6 % respectively.

Answer: The number of molecules of carbon dioxide gas are [tex]2.815\times 10^{21}[/tex]

Explanation:

To calculate the molar solubility, we use the equation given by Henry's law, which is:

[tex]C_{CO_2}=K_H\times p_{CO_2}[/tex]

where,

[tex]K_H[/tex] = Henry's constant = [tex]0.034mol/L.atm[/tex]

[tex]C_{CO_2}[/tex] = molar solubility of carbon dioxide gas

[tex]p_{CO_2}[/tex] = pressure of carbon dioxide gas = 0.250 atm

Putting values in above equation, we get:

[tex]C_{CO_2}=0.034mol/L.atm\times 0.250atm\\\\C_{CO_2}=8.5\times 10^{-3}M[/tex]

To calculate the number of moles for given molarity, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]

Molarity of carbon dioxide = [tex]8.5\times 10^{-5}M[/tex]

Volume of solution = 0.550 L

Putting values in above equation, we get:

[tex]8.5\times 10^{-3}M=\frac{\text{Moles of }CO_2}{0.550L}\\\\\text{Moles of }CO_2=(8.5\times 10^{-3}mol/L\times 0.550L)=4.675\times 10^{-3}mol[/tex]

According to mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

So, [tex]4.675\times 10^{-3}[/tex] moles of carbon dioxide will contain = [tex](6.022\times 10^{23}\times 4.675\times 10^{-3})=2.815\times 10^{21}[/tex] number of molecules

Hence, the number of molecules of carbon dioxide gas are [tex]2.815\times 10^{21}[/tex]

Answer:

2.8 *10^21 molecules CO2 are dissolved in the 0.550 L water

Explanation:

Step 1: Data given

Volume of water = 0.550 L

Temperature = 25.0 °C

Pressure of CO2 = 0.250 atm

The Henry’s constant for CO2 and water at 25 °C = 0.034 M/atm

Step 2: Henry's law

C(CO2) = Kh * p(CO2)

⇒ with C(CO2) = the molar solubility of CO2

⇒ with Kh = Henry's constant = 0.034 M/atm = 0.034 mol/(L * atm)

⇒ with p(CO2) = the pressure of CO2 = 0.250 atm

C(CO2) = 0.034 mol/(L*atm) * 0.250 atm

C(CO2) = 0.0085 mol /L

Step 3: Calculate moles CO2

Moles CO2 = volume * molar solubility CO2

Moles CO2 = 0.550 L * 0.0085 mol/L

Moles CO2 = 0.004675 moles

Step 4: Calculate molecules of CO2

Molecules CO2 = moles * Number of Avogadro

Molecules CO2 = 0.004675 * 6.022 *10^23 / mol

Molecules CO2 = 2.8 *10^21 molecules

2.8 *10^21 molecules CO2 are dissolved in the 0.550 L water

Answer : The amount of formaldehyde permissible are, [tex]5.4\times 10^{-6}g[/tex]

Explanation : Given,

Density of air = [tex]1.2kg/m^3=1.2g/L[/tex]     [tex](1kg/m^3=1g/L)[/tex]

First we have to calculate the mass of air.

[tex]\text{Mass of air}=\text{Density of air}\times \text{Volume of air}[/tex]

[tex]\text{Mass of air}=1.2g/L\times 6.0L[/tex]

[tex]\text{Mass of air}=7.2g[/tex]

Now we have to calculate the amount of formaldehyde.

Permissible exposure level of formaldehyde = 0.75 ppm = [tex]\frac{0.75g\text{ of formaldehyde}}{10^6g\text{ of air}}[/tex]

Amount of formaldehyde in 7.2 g of formaldehyde = [tex]7.2g\times \frac{0.75g\text{ of formaldehyde}}{10^6g\text{ of air}}[/tex]

Amount of formaldehyde in 7.2 g of formaldehyde = [tex]5.4\times 10^{-6}g[/tex]

Thus, the amount of formaldehyde permissible are, [tex]5.4\times 10^{-6}g[/tex]

The study of the chemical and bonds is called chemistry.

The correct answer is  [tex]5.4*10^{-6[/tex]

All the data is given in the question. therefore

Hence, the correct answer to the question is [tex]5.4*10^{-6[/tex].

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Answer : The formic acid pressure is, 99 torr

Explanation :

The given chemical reaction is:

                            [tex]HCOOH(g)\rightarrow CO_2(g)+H_2(g)[/tex]

Initial pressure        a                   0              0

At time 't'                (a-x)                 x              x

According to the Dalton's law,

[tex]P_{Total}=P_{HCOOH}+P_{CO_2}+P_{H_2}[/tex]

[tex]P_{Total}=(a-x)+x+x=a+x[/tex]    .........(1)

As we are given that:

Initial pressure = a = 220 torr

[tex]P_{Total}=319torr[/tex]

Now put the value of 'a' in equation 1, we get:

[tex]P_{Total}=a+x[/tex]

[tex]319torr=220torr+x[/tex]

[tex]x=99torr[/tex]

Thus, the formic acid pressure is, 99 torr

Answer:

(a)  7.11 x 10⁻³⁷ m

(b)  1.11 x 10⁻³⁵ m

Explanation:

(a)  The de Broglie wavelength is given by the expression:

λ = h/p = h/mv

where h is plancks constant, p is momentum which is equal to mass times velocity.

We have all the data required to calculate the wavelength, but first we will have to convert the velocity to m/s, and the mass to kilograms to work in metric system.

v = 19.8 mi/h x ( 1609.34 m/s ) x ( 1 h / 3600 s ) = 8.85 m/s

m = 232 lb x ( 0.454 kg/ lb ) = 105.33 kg

λ = h/ mv = 6.626 x 10⁻³⁴ J·s / ( 105.33 kg x 8.85 m/s ) = 7.11 x 10⁻³⁷ m

(b) For this part we have to use the uncertainty principle associated with wave-matter:

ΔpΔx > = h/4π

mΔvΔx > = h/4π

Δx = h/ (4π m Δv )

Again to utilize this equation we will have to convert the uncertainty in velocity to m/s for unit consistency.

Δv = 0.1 mi/h x ( 1609.34 m/mi ) x ( 1 h/ 3600 s )  

     = 0.045 m/s

Δx = h/ (4π m Δv ) = 6.626 x 10⁻³⁴ J·s / (4π x 105.33 kg x 0.045 m/s )

     = 1.11 x 10⁻³⁵ m

This calculation shows us why we should not be talking of wavelengths associatiated with everyday macroscopic objects for we are obtaining an uncertainty of 1.11 x 10⁻³⁵ m for the position of the fullback.

This question discusses the fundamentals quantum mechanics. It asks about the de Broglie wavelength and uncertainty principle of a football player treating as a particle. The de Broglie wavelength can be calculated using Planck's constant and momentum, and the uncertainty can be determine using the uncertainty principal formula.

In this question, we're asked about two core principles in quantum mechanics: the de Broglie wavelength and the uncertainty principle. As such, we're essentially treating the football player as both a particle and a wave, which is a fundamental concept of quantum mechanics.

Let's address the points one by one.

(a) The de Broglie wavelength of a particle is given by λ=h/p. Where h is Planck's constant (6.62607015 × 10-34 m2 kg / s) and p is momentum. The momentum of a player can be calculated as mass x velocity. Convert the player's mass from lbs to kg and speed from mi/h to m/s. Substitute these values into the equation to get the de Broglie wavelength.

(b) The uncertainty principle states that the more precisely the momentum of a particle is known, the less precisely its position can be known, and vice versa. In this case, we're given the uncertainty in the player's speed (which contributes to an uncertainty in his momentum, and thus in his position). By using the uncertainty principal formula Δx=Δp*h/4π, where Δx represents the position uncertainty and Δp is the momentum uncertainty. Using the figures provided in the question, you can calculate the position uncertainty.

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Answer:

Explanation:

The period law state that when elements are listed in order of their atomic numbers, the elements fall into recurring groups, so that there is a recurrence of similar properties at regular intervals.

Na and K in the periodic table fall into the same group, this is because they both have one electrons in their outermost shell.

Na 11 -1s2 2s2 2p6 3s1

K 19 - 1s2 2s2 2p6 3s2 3p6 4s1

They share similar chemical and physical properties. Na and K are very reactive metals, they can loose/donate their outermost electron to non metals in other to attain stable octet state.

The form ionic compound when they react with non metals.

Answer:Hydrogen is placed such because it exhibits some similar characteristics of both group1 and group VII elements.

Explanation:

The reason why hydrogen is similar to group 1 metals:

#It has same valence electron and inorder achieve octet state it can lose that electron and forms H+ ion

#It acts as a good reducing agent similar to group1 metals

#It can also halides

Similarity to halogens:

#hydrogen can also gain one electron to gain noble gas configuration. It can combine with other non metals to form molecules with covalent bonding.

#It exists as diatomin molecule,H2

#Have the same electronegativity nature

#its reaction with other metal

Answer:

pKa = 7.2

Explanation:

When pH=pKa=2.0, there are equal amounts of the X carboxyl group and its ionized form.

Then, (75 mL * 0.10 M) 7.5 mmol of OH⁻ are added, so all 5 mmol of X-COOH converts into X-COO⁻. Then the remaining (7.5 - 5) 2.5 mmol of OH⁻ react with the second ionizable group of X

Number of X-COO⁻ = 5mmol (from the beginning) + 5mmol (from X-COOH that reacted) - 2.5 mmol (from the OH⁻ remaining) = 7.5 mmol

Because the total number of X compound moles did not change, we have (10 - 7.5) 2.5 mmol of the conjugate base of X-COO⁻.

Now we have all required data to solve this problem using Henderson-Hasselbach's equation:

pH = pKa + log [A⁻]/[HA]

6.72 = pKa + log (2.5/7.5)

pKa = 7.2

Answer:

[tex]pK_a[/tex]  = 7.20

Explanation:

Given that our Molarity of X(unknown compound)= 0.10 M

Volume of X = 100 ml = 0.1  L

Molarity  = [tex]\frac{number of moles of X}{Volume of X}[/tex]

Number of moles of X = Molarity × Volume of X

= 0.1 M × 0.1 L

= 0.01 mol

[tex]pK_a[/tex] = [tex]pH[/tex]

∴[tex][H^+][/tex] =[tex][HA][/tex]    (this literaly implies and point out that the beginning the amount of carboxyl group and the second ionizable group must be equal.)

Having said that,

Number of moles of carboxyl group in X = [tex]\frac{0.01mol}{2}[/tex]

= 0.005 mol

When 75 ml of 0.10 M NaOH is added to 100 ml of a 0.10 M solution of X;

we have the number of moles of NaOH that is being added as:

Molarity × volume of NaOH

= 0.1 M × 0.075 L

= 0.0075 mol

From the question, if NaOH molecules thoroughly dissociate the carboxyl group of X.

The excess NaOH can be calculated as:

Excess of (NaOH) = Number of moles of NaOH added - Number of moles of carboxyl group in X

Excess of (NaOH) = 0.0075 -0.005 = 0.0025 mol

∴ Applying Henderson-Hesselbalch equation; it will be easier to determine the [tex]pK_a[/tex] for second group:

[tex]pK_a[/tex]  = [tex]pH[/tex] [tex]-\frac{log[A]}{HA}[/tex]

       = 6.72 - log[tex](\frac{0.0025}{0.0075})[/tex]

       = 6.72 - log (0.333)

       = 6.72 + 0.477

[tex]pK_a[/tex]  = 7.197

≅ 7.20

Answer:

-2.80 × 10³ kJ/mol

Explanation:

According to the law of conservation of energy, the sum of the heat absorbed by the bomb calorimeter (Qcal) and the heat released by the combustion of the glucose (Qcomb) is zero.

Qcal + Qcomb = 0

Qcomb = - Qcal [1]

We can calculate the heat absorbed by the bomb calorimeter using the following expression.

Qcal = C × ΔT = 4.30 kJ/°C × (29.51°C - 22.71°C) = 29.2 kJ

where,

C: heat capacity of the calorimeter

ΔT: change in the temperature

From [1],

Qcomb = - Qcal = -29.2 kJ

The internal energy change (ΔU), for the combustion of 1.877 g of glucose (MW 180.16 g/mol) is:

ΔU = -29.2 kJ/1.877 g × 180.16 g/mol = -2.80 × 10³ kJ/mol

Answer:

(a) n = 2, l = 0 ⇒ sublevel s, ⇒ ml = 0, number of orbitals = 1

(b) n = 3, l = 2 ⇒ sublevel d, ⇒ ml = 0, ±1, ±2, number of orbitals = 5

(c) n = 5, l = 1 ⇒ sublevel p, ⇒ ml = 0, ±1, number of orbitals = 3

Explanation:

The rules for electron quantum numbers are:

1. Shell number, 1 ≤ n,

2. Subshell number, 0 ≤ l ≤ n − 1, from s, p, d, f, g, h...

3. Orbital energy shift, -l ≤ ml ≤ l

4. Spin, either -1/2 or +1/2

In our case

(a) n = 2, l = 0 ⇒ sublevel s

-l ≤ ml ≤ l ⇒ ml = 0, number of orbitals = 1

(b) n = 3, l = 2 ⇒ sublevel d

-l ≤ ml ≤ l ⇒ ml = 0, ±1, ±2, number of orbitals = 5

(c) n = 5, l = 1 ⇒ sublevel p

-l ≤ ml ≤ l ⇒ ml = 0, ±1, number of orbitals = 3

The first pair of quantum numbers (n, l) represents the 2s sublevel with 1 orbital. The second pair represents the 3d sublevel with 5 orbitals. The third pair represents the 5p sublevel with 3 orbitals.

The information given refers to quantum numbers in the quantum mechanical model of the atom, a fundamental concept in high school physics and chemistry. This model explains the behavior of electrons in atoms.

(a) For n = 2 and l = 0, the sublevel designation is 2s. The permissible ml value is 0 and there is 1 orbital.
(b) For n = 3 and l = 2, the sublevel designation is 3d. The permissible ml values range from -2, -1, 0, 1, 2 and there are 5 orbitals.
(c) For n = 5 and l = 1, the sublevel designation is 5p. The permissible ml values are -1, 0, 1 and there are 3 orbitals.

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Explanation:

Case 1.  When circumference of cylinder is 27.94 cm and its height is 21.59 cm. Therefore, we will calculate the radius of cylinder as follows.

            Circumference = [tex]2 \pi r[/tex]

                        27.94 cm = [tex]2 \times 3.14 \times r[/tex]

                         r = 4.45 cm

Now, we will calculate the volume of cylinder as follows.

              Volume = [tex]\pi r^{2}h[/tex]

                            = [tex]3.14 \times (4.45 cm)^{2} \times 21.59 cm[/tex]

                            = [tex]1342.46 cm^{3}[/tex]

Case 2.  When circumference of cylinder is 21.59 cm and its height is 27.94 cm. Therefore, we will calculate the radius of cylinder as follows.

            Circumference = [tex]2 \pi r[/tex]

                        21.59 cm = [tex]2 \times 3.14 \times r[/tex]

                         r = 3.44 cm

Now, we will calculate the volume of cylinder as follows.

              Volume = [tex]\pi r^{2}h[/tex]

                            = [tex]3.14 \times (3.44 cm)^{2} \times 27.94 cm[/tex]

                            = [tex]1038.18 cm^{3}[/tex]

Answer:

56.06 g/mol is the molar mass

Explanation:

Vapor pressure lowering → P° - P' = P° . Xm

Where P° is vapor pressure of pure solvent

P' is vapor pressure of solution

Xm is the mole fraction (moles of solute / total moles)

Total moles = moles of solute + moles of solvent

Let's replace the data.

100 Torr - 87.7 Torr = 100 Torr . Xm

12.3 Torr = 100 Torr . Xm

0.123 = Xm

We know the moles of solvent because we know the molar mass from benzene and its mass in the solution. (mass / molar mass)

100 g / 78 g/mol = 1.28 moles

Let's build the equation where the unknown is the moles of solute

0.123 = moles of solute / moles of solute + 1.28 moles

0.123 (moles of solute + 1.28 moles) = moles of solute

0.123 moles of solute + 0.158 moles = moles of solute

0.158 = 1moles of solute - 0.123moles of solute

0.158 moles = 0.877 moles of solute

0.158 / 0.877 = moles of solute → 0.180

These moles corresponds to 10.1 g of the unknown, non volatile and non electrolyte X compound so:

molar mass (g/mol) → 10.1 g / 0.180 mol = 56.06 g/mol

To calculate the molar mass of the solute, we can use the formula: molar mass = (mass of solute / moles of solute). First, find the moles of solute using the relationship between the freezing point depression and the moles of solute. Next, calculate the molality of the solution using the given freezing point depression constant and mass of the solute, and use that to calculate the moles of solute. Finally, divide the mass of solute by the moles of solute to find the molar mass.

To calculate the molar mass of the solute, we can use the formula:

molar mass = (mass of solute / moles of solute)

We first need to find the moles of solute using the relationship between the freezing point depression and the moles of solute:

ΔTf = Kf * m

where ΔTf is the freezing point depression, Kf is the freezing point depression constant, and m is the molality of the solution.

In this case, we are given that the freezing point depression is 0.40°C, the freezing point depression constant of benzene is 5.12 K kg/mol, and the mass of the solute is 2 grams. We can use these values to calculate the molality of the solution:

m = (ΔTf / Kf)

m = (0.40°C / 5.12 K kg/mol)

m = (0.078125 mol/kg)

Now we can calculate the moles of solute:

moles of solute = (m * mass of solvent)

moles of solute = (0.078125 mol/kg * 0.1 kg)

moles of solute = 0.0078125 mol

Finally, we can calculate the molar mass:

molar mass = (mass of solute / moles of solute)

molar mass = (2 grams / 0.0078125 mol)

molar mass ≈ 256 g/mol

Therefore, the molar mass of the solute, X, is approximately 256 g/mol.

A couple purchases a house for $400,000.00. They pay 20% down at closing, and take out a mortgage of $320,000.00. The mortgage company offers them a 4.80% annual rate with monthly compounding. The mortgage will require monthly payments for the next 30 years.

What will be the monthly payment on this mortgage?

Answer:

$ 1678.91

Explanation:

Given that;

Cost of purchasing a house = $400,000.00

Down payment =20%

Mortgage Value (MV) = $320,000.00

Annual rate offered by the mortgage company = 4.80% yearly i.e 0.4 per month

Duration of the Mortgage Loan (n) =  30 years which is equivalent to 360 months.

if we represent the monthly repayment with MR ,To calculate the monthly repayment MR;we have;

MV = MR × [tex](\frac{1}{i})*[1-(\frac{1}{(1+i)^{n}} )}][/tex]

where i = 0.004 (4.8 % annually expressed as 0.48, divided by 12 monthly payments per year)

∴

[tex]320,000.00[/tex] = [tex]MR[/tex] [tex]*(\frac{1}{0.004})*[1-(\frac{1}{1+0.004)^{360}}})][/tex]

320,000.00 = MR × 190.60

Monthly repayment (MR) = $ 1678.90870933

Monthly repayment (MR) ≅ $ 1678.91

Answer:

a.A pure substance is made up of only 1 type of particle

Explanation:

When a substance is pure, it has only one type of particle. These particles maybe molecules, ions or atoms linked in a definite way throughout the substance. If a substance contains different particles, it cannot be regarded as a pure substance because its properties will be observed as a compromise of the individual properties of its different components.

The statement that accurately describes a pure substance is that it is made up of only one type of particle. Both elements and compounds can be considered as pure substances.

The correct statement to describe a pure substance is:

a. A pure substance is made up of only 1 type of particle.

This means that a pure substance is only made up of identical atoms if it is an element, or identical molecules if it is a compound. Therefore, both elements and compounds can be considered as pure substances, contradicting options c and d. It also contradicts option b because a pure substance is not made up of more than one type of particle.

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Explanation:

Lithium, sodium and potassium are all group 1A elements and when we move down a group then there occurs an increase in atomic size of the elements. As lithium is the smallest and potassium being the largest so, when each of them will lose an electron and obtain a positive charge then size of lithium will further decrease.

Therefore, ions are ranked according to their increase in size as follows.

                      [tex]Li^{+} < Na^{+} < K^{+}[/tex]  

When an atom tends to gain electrons then it acquires a negative charge. This means that size of the atom increases.  

So, more is the negative charge present on an atom more will be its atomic size. Therefore, correct order of increasing size for [tex]Se^{2-}, Rb^{+}, Br[/tex] is as follows.

                      [tex]Br < Rb^{+} < Se^{2-}[/tex]

Similarly, order of increasing size of [tex]O^{2-}, F^{-}, N^{3-}[/tex] is as follows.

                    [tex]F^{-} < O^{2-} < N^{3-}[/tex]

The root-mean-square speed for diatomic oxygen at 50°C can be calculated using the formula Urms =

oot(3RT/M), where R is the gas constant, T is the temperature in Kelvin, and M is the molar mass of oxygen. Multiplication options presented in the question are incorrect and should not be used.

To calculate the root-mean-square speed (Urms) for diatomic oxygen at a given temperature, we use the formula derived from the kinetic theory of gases:

Urms =

oot(3RT/M)

Where:

The student provides information that diatomic hydrogen has a particular Urms value at 50°C (which needs to be converted to Kelvin by adding 273.15, resulting in 323.15K). However, to find the Urms for oxygen directly, we will use the molar mass of oxygen (32.00 g/mol or 0.032 kg/mol) and the same temperature in Kelvins:

Urms =

oot(3  imes 8.314  imes 323.15 / 0.032)

Calculating the above will give us the correct Urms for oxygen, the presented multiplication options (16)(2000 m/s), etc., are misleading and should not be used for this calculation.

To calculate the percent dissociation of benzoic acid, use the ionization constant and the initial concentration, then quantifying the degree of dissociation by how much H+ ion concentration is produced. A simplified approach is given assuming low degree of ionization, typical of weak acids.

The question asks for the percent dissociation of benzoic acid, which is a chemistry concept. To calculate percent dissociation, you need the ionization constant of the acid (Ka), which you can lookup in the ALEKS Data resources, and the concentration of the acid, which is given as 2.4mM.If the Ka for benzoic acid is x, then the equilibrium expression for the dissociation of C6H5CO2H into ions is [C6H5CO2-][H+]/[C6H5CO2H] = x. Solve this equation to find the concentration of H+ ions. Once you calculate the concentration of H+ ions, the percent dissociation is ([H+]/initial concentration of the acid) x 100%.This is a simplified approach, assuming the degree of ionization is less than 5%, as it is with weak acids in relatively dilute solutions. If this assumption is not valid, a quadratic equation would need to be used.

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Answer:

[tex]n=2.59\times 10^{16}[/tex] photons

Explanation:

[tex]E=n\times \frac{h\times c}{\lambda}[/tex]

Where,  

n is the number of photons

h is Plank's constant having value [tex]6.626\times 10^{-34}\ Js[/tex]

c is the speed of light having value [tex]3\times 10^8\ m/s[/tex]

[tex]\lambda[/tex] is the wavelength of the light

Given that, wavelength = 514 nm = [tex]514\times 10^{-9}\ m[/tex]

Energy = 10.0 mJ = 0.01 J ( 1 mJ = 0.001 J )

Applying the values as:-

[tex]0.01=n\times \frac{6.626\times 10^{-34}\times 3\times 10^8}{514\times 10^{-9}}[/tex]

[tex]\frac{19.878n}{10^{17}\times \:514}=0.01[/tex]

[tex]n=2.59\times 10^{16}[/tex] photons

The number of grams of sodium chloride in the solution is 3.43 g.

The number of grams of sodium chloride in the solution can be calculated using the molar mass and molarity.

First, we need to calculate the number of moles of NaCl in the solution. Using the given molarity (0.470 M) and volume (125.0 mL) of the solution, we can use the formula:

moles = molarity × volume (in L)

Therefore, moles of NaCl = 0.470 mol/L × 0.125 L = 0.05875 mol NaCl

Next, we can use the formula mass of NaCl (58.44 g/mol) to calculate the mass:

mass = moles × formula mass

Therefore, mass of NaCl = 0.05875 mol × 58.44 g/mol = 3.43 g NaCl

Answer:

option D is correct

D. This solution is a good buffer.

Explanation:

TRIS (HOCH[tex]_{2}[/tex])[tex]_{3}[/tex]CNH[tex]_{2}[/tex]

if TRIS is react with HCL it will form salt

(HOCH[tex]_{2}[/tex])[tex]_{3}[/tex]CNH[tex]_{2}[/tex] + HCL ⇆   (HOCH[tex]_{2}[/tex])[tex]_{3}[/tex]NH[tex]_{3}[/tex]CL

Let the reference volume is 100

Mole of TRIS is =  100 × 0.2 = 20

Mole of HCL is =  100 × 0.1 = 10

In the reaction all of the HCL will Consumed,10 moles of the salt will form

and 10 mole of TRIS will left

hence , Final product will be salt +TRIS(9 base)

H = Pk[tex]_{a}[/tex] + log (base/ acid)

8.3 + log(10/10)

8.3

The correct statements are that the resulting solution is a good buffer and the ratio of [conjugate base]/[conjugate acid] is [0.1 M]/[0.1 M]. The majority of TRIS is not in the acid form in the solution.

If equal volumes of 0.1 M HCl and 0.2 M TRIS are mixed together, the excess TRIS will react with HCl forming its conjugate acid (TRIS-HCl) and reducing the concentration of HCl. Since we started with more TRIS, half of it will remain unreacted and exist as the base (TRIS), while the other half will form the conjugate acid (TRIS-HCl). Therefore, the concentrations of the conjugate base and the conjugate acid will both be 0.1 M.

So, the statement C. The ratio of [conjugate base]/[conjugate acid] is [0.05 M]/[0.05 M] is incorrect. The correct ratio is 0.1 M/0.1 M.

The pKa of TRIS is 8.30 meaning that it can act as a buffer at around pH 8.30. Since the solution consists of equal concentrations of a weak base and its conjugate acid, it will indeed create a buffer solution. Consequently, D. This solution is a good buffer is correct.

The statement E. The majority of TRIS will be in the acid form in the solution is not correct. The base and acid forms are in equal amounts.

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Answer:

a. Zero unpaired electron

b. 3 unpaired electrons

c. Zero unpaired electron

d. 1 unpaired electron

Explanation:

a. 2A(2) has configuration => 1s2. Since the s-orbital is completely filled, Therefore it has zero unpaired electrons

b. 5A(15) has configuration =>

1s2 2s2 2p6 3s2 3p3

Since the p-orbital is not completely filled, It has 3 unpaired electrons

c. 8A(18) has configuration =>

1s2 2s2 2p6 3s2 3p6

Since the p-orbital is completely filled, therefore it has zero unpaired electrons

d. 3A(13) has configuration =>

1s2 2s2 2p6 3s2 2p1

Since the p-orbital is not completely filled, therefore it has 1 unpaired

Answer:

(a) 2A(2) - it has 2 valence electrons

(b) 5A(15) -

Explanation:

A)To determine the number of unpaired electrons for atoms in group 2A (2)

Using beryllium (it belongs to group 2A) as an example

The atomic number of Be is 4

The electronic configuration is 1s²2s²

The highest principal quantum number is 2, therefore all electrons with n=2 are valence/unpaired electron

Beryllium has 2 valence/unpaired electrons, this applies to all other elements in this group

Therefore group 2A atoms have 2 unpaired electrons  

B) To determine the number of unpaired electrons for atoms in group 5A(15)

Using Nitrogen as an example

The atomic number of Nitrogen is 7

The electronic configuration  is 1s²2s²2p³

The highest principal quantum number for nitrogen is 2, therefore all electrons with n=2 are valence/unpaired electrons

Nitrogen has 2+3= 5 valence/unpaired electrons, this applies to all other elements in this group

Therefore, group 5A atoms have 5 unpaired electrons

C) To determine the number of unpaired electrons for atoms in group 8A(18)

Using Neon as an example

The atomic number of Neon is 2

The electronic configuration of Neon is 1s²2s²2p⁶3s²3p⁶

The highest principal quantum number for 3, therefore all electrons with n=3 are valence/unpaired electrons

Neon has 2+6 = 8 valence/unpaired electrons,this applies to all other elements in this group except Helium whose number of unpaired electrons is 2

Therefore, group 8A atoms have 8 unpaired electrons

D) To determine the number of unpaired electrons for atoms in group 3A(13)

Using Aluminium as an example

The atomic number of Aluminium is 13

The electronic configuration of Neon is 1s²2s²2p⁶3s²3p¹

The highest principal quantum number for 3, therefore all electrons with n=3 are valence/unpaired electrons

Neon has 2+1 = 3 valence/unpaired electrons,this applies to all other elements in this group

Therefore, group 3A atoms have 3 unpaired electrons

Note: The number of valence electrons of atoms in a group is the same as the group number that the atom belongs to

Answer: The empirical formula for the given compound is [tex]Fe_2O_3[/tex]

Explanation:

We are given:

Mass of Fe = 4.166 g

Mass of O = 1.803 g

To formulate the empirical formula, we need to follow some steps:

Moles of Iron =[tex]\frac{\text{Given mass of Iron}}{\text{Molar mass of Iron}}=\frac{4.166g}{55.85g/mole}=0.0746moles[/tex]

Moles of Oxygen = [tex]\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{1.803g}{16g/mole}=0.113moles[/tex]

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0746 moles.

For Iron = [tex]\frac{0.0746}{0.0746}=1[/tex]

For Oxygen = [tex]\frac{0.113}{0.0746}=1.5[/tex]

Converting the mole ratio into whole number by multiplying with '2'

Mole ratio of Fe = (1 × 2) = 2

Mole ratio of O = (1.5 × 2) = 3

The ratio of Fe : O = 2 : 3

Hence, the empirical formula for the given compound is [tex]Fe_2O_3[/tex]

Answer:

The complete answer is in the diagram.