A chemist measures the energy change during the following reaction: 1. This reaction is:______. a. endothermic. b. exothermic. 2. Suppose 70.1 g of NO2 react. Will any heat be released or absorbed? A. Yes, absorbed. B. Yes, released. C. No. 3. If you said heat will be released or absorbed, calculate how much heat will be released or absorbed?

Explanation:

We know that molarity is the number of moles of solute present in liter of solution.

Mathematically,   Molarity = [tex]\frac{\text{no. of moles}}{\text{volume in liter}}[/tex]

As molarity is dependent on volume and volume of a solution or substance is dependent on temperature. So, with increase in temperature there will occur a decrease in volume of the solution. As a result, molarity will increase as it is inversely proportional to volume.

Hence, molarity of both the solutions will be different as temperature of both the solutions is different.

In order to obtain changes for the solution with temperature we need to get the molarity for both the solutions.

It is the concentration of a solution measured as the number of moles of solute per liter of solution.

It is given by:

[tex]\text{Molarity} = \frac{\text{Number of moles}}{\text{volume}}[/tex]

Hence, Molarity of both the solutions will be different as temperature of both the solutions is different.

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For calculating mass of solution, you need to know the concentration of the -ethyltoluene in the solution and the desired amount of -ethyltoluene. Use the mass percentage to calculate the mass of the solution needed.

The question asks for the mass of solution the chemistry student should use to obtain a certain amount of -ethyltoluene for an experiment. To calculate the mass, we need to know the concentration of the -ethyltoluene in the w/w solution and the desired amount of -ethyltoluene.

Let's assume the concentration of the -ethyltoluene in the solution is given as a mass percentage. If the desired mass of -ethyltoluene is known, we can use the mass percentage to calculate the mass of the solution needed.

For example, if the desired mass of -ethyltoluene is 10 grams and the mass percentage of -ethyltoluene in the solution is 5%, then the mass of the solution needed would be:

Mass of solution = 10 grams / (5% / 100%) = 200 grams

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Answer:

See picture for answer

Explanation:

First to all, an aldehyde is a carbonated chain with a Carbonile within it chain. It's call aldehyde basically because the C = O is always at the end of the chain. When the C = O is on another position of the chain, is called a ketone.

Now, in this exercise we have an aldehyde with 5 carbons, so the first carbon is the C = O. The remaining four carbon belong to the chain. however, we need to have a branched chain in this molecular formula.

If this the case, this means that the longest chain cannot have 5 carbons. It should have 4 carbons as the longest chain. The remaining carbon, would one branched.

In this case, we only have two possible ways to have an aldehyde with a branched chain, and 4 carbons at max. One methyl in position 2, and the other in position 3.

The remaining aldehyde with branched chain, cannot have 4 carbons as longest, it should have 3 carbons with longest chain and 2 carbons as radicals (In this case, methyl). In this way, we just have all the aldehyde with this formula and at least one branched chain. The other possible ways would be conformers or isomers of the first three.

See picture for the structures of these 3 aldehydes, and their names.}

The question is incomplete, here is the complete question:

Calculate the pH at of a 0.10 M solution of anilinium chloride [tex](C_6H_5NH_3Cl)[/tex] . Note that aniline [tex](C6H5NH2)[/tex] is a weak base with a [tex]pK_b[/tex] of 4.87. Round your answer to 1 decimal place.

Answer: The pH of the solution is 5.1

Explanation:

Anilinium chloride is the salt formed by the combination of a weak base (aniline) and a strong acid (HCl).

To calculate the pH of the solution, we use the equation:

[tex]pH=7-\frac{1}{2}[pK_b+\log C][/tex]

where,

[tex]pK_b[/tex] = negative logarithm of weak base which is aniline = 4.87

C = concentration of the salt = 0.10 M

Putting values in above equation, we get:

[tex]pH=7-\frac{1}{2}[4.87+\log (0.10)]\\\\pH=5.06=5.1[/tex]

Hence, the pH of the solution is 5.1

The pH of the solution is 5.1.

Anilinium chloride refers to the salt that should be created by the combination of a weak base (aniline) and a strong acid (HCl).

here the following equation should be used.

ph = 7-1/2(pkb+ logc)

here pkb = negative logarithm of the weak base i.e. aniline = 4.87

And, C = concentration of the salt = 0.10 M

Now the ph should be

= 7-1/2(4.87 + log(0.10))

= 5.1

Hence, The pH of the solution is 5.1.

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The electric potential due to ammonia at a point away along the axis of a dipole is 1.44 [tex]\times[/tex] 10^-5 V.

Explanation:

Given that 1 D = 1 debye unit = 3.34 × 10-30 C-m.

Given p = 1.47 D = 1.47 [tex]\times[/tex] 3.34 [tex]\times[/tex] 10^-30 = 4.90 [tex]\times[/tex] 10^-30.

            V = 1 / (4π∈о)  [tex]\times[/tex]  (p cos(θ)) / (r^2)

where p is a permanent electric dipole,

           ∈ο is permittivity,

            r is the radius from the axis of a dipole,

            V is the electric potential.

        V = 1 / (4 [tex]\times[/tex] 3.14 [tex]\times[/tex] 8.85 [tex]\times[/tex] 10^-12)  [tex]\times[/tex] (4.90 [tex]\times[/tex] 10^-30 [tex]\times[/tex] 1) / (55.3 [tex]\times[/tex] 10^-9)^2

        V  = 1.44 [tex]\times[/tex] 10^-5 V.

Answer:

Explanation: i)  Mass per capacity of the tant = (0.15015/100100) kg/L = 0.0000015 kg/L

Amount salt of concentrated salt left = ( 0.03003 - 0.0000015) kg/L = 0.0300285 kg/L

∴  mass of salt in the tank = 0.0300285 kg/L X 77 L/min = 2.31 kg

ii) Capacity of tank at 0.01001 kg/L: 2.31 kg/0.01001 kg/L = 230.77 L

∴ time taken for the concentration of the salt = 230.77/(77 L/min) = 3 minutes.

Answer:

Part A:

Order: K<Rb<Cs

Part B:

Order: O<C<Be

Part C:

Order:CL<S<K

Part D:

Order:Mg<Ca<K

Explanation:

Atomic Size:

It is the distance from the center to atom to the valance shell electron. It is very difficult to measure the atomic size because there is definite boundary of atom.

Trend:

Moving from top to bottom in a group, Atomic Size increases.

Moving from left to right in a period, Atomic size generally decreases.

On the basis of above trend we will solve our question:

Part A:

All elements belong to Group 1:

Moving from top to bottom in a group, Atomic Size increases.

Order: K<Rb<Cs

Part B:

All elements belong to 2nd Period:

Moving from left to right in a period, Atomic size generally decreases.

Order: O<C<Be

Part C:

S belongs to 3rd Period, K, Cl belong to 4th period

Order:CL<S<K

Part D:

Mg is above Ca in group 2 and K is before Ca in 4th period

From trends described above:

Order:Mg<Ca<K

Final answer:

Each set is arranged in order of increasing atomic size, reflecting the trend that atomic size increases down a group and decreases across a period.

Explanation:

Arranging each set in order of increasing atomic size based on their positions in the periodic table:

(a) K, Rb, Cs

(b) Be, C, O

(c) Cl, S, K

(d) Mg, Ca, K

Atomic size typically increases from top to bottom within a group and decreases from left to right across a period. So in each set, the element located further down a group will be larger, and the element on the farther left of a period will be smaller.

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

(a) [tex][Ar]4s^23d^{2}[/tex]

(b) [tex][Ne]3s^23p^5[/tex]

(c) [tex][Ar]4s^23d^{3}[/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, Ti (Titanium)

As we know that the titanium element belongs to group 4 and the atomic number is, 22

The ground-state electron configuration of Ti is:

[tex]1s^22s^22p^63s^23p^64s^23d^{2}[/tex]

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

[tex][Ar]4s^23d^{2}[/tex]

There are 4 number of valence electrons shown in orbital diagram.

(b) The given element is, Cl (Chlorine)

As we know that the chlorine element belongs to group 17 and the atomic number is, 17

The ground-state electron configuration of Cl is:

[tex]1s^22s^22p^63s^23p^5[/tex]

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

[tex][Ne]3s^23p^5[/tex]

There are 7 number of valence electrons shown in orbital diagram.

(c) The given element is, V (Vanadium)

As we know that the vanadium element belongs to group 5 and the atomic number is, 23

The ground-state electron configuration of Ti is:

[tex]1s^22s^22p^63s^23p^64s^23d^{3}[/tex]

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

[tex][Ar]4s^23d^{3}[/tex]

There are 5 number of valence electrons shown in orbital diagram.

To draw valence shell electron configurations and orbital diagrams for Ti, Cl, and V, you place electrons in orbitals according to the electron configuration up to the penultimate shell. Titanium's valence shell configuration is [Ar]3d2 4s2, Chlorine's is [Ne]3s2 3p5, and Vanadium's is [Ar]3d3 4s2.

In high school chemistry, understanding electron configurations is fundamental. Here's how you can predict valence shell electron configurations and draw orbital diagrams for titanium (Ti), chlorine (Cl), and vanadium (V).

Titanium has an atomic number of 22. Its electron configuration up to the penultimate shell is [Ar]3d2 4s2. To show the valence electron configuration:

Chlorine has an atomic number of 17. Its electron configuration up to the penultimate shell is [Ne]3s2 3p5. For the valence electrons:

Vanadium has an atomic number of 23. Its electron configuration up to the penultimate shell is [Ar]3d3 4s2. For its valence shell:

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Explanation:

Compounds having same molecular formula but different structural and spatial arrangement are isomers.

Three isomers are possible for dibromomethene.

In one structure (IUPAC name: 1,1-dibromomethene), both the bromine atoms are attached to one carbon atom.

In another two structures (Cis and trans), two bromine atoms are attached to two different carbon atoms.

In Cis 1,2-dibromomethene, two bromine atoms are present on the same side.

Whereas in Cis 1,2-dibromomethene, two bromine atoms are present on the opposite side and hence, does not have net dipole moment.

Answer: The solubility product of the given salt is [tex]7.63\times 10^{-5}[/tex]

Explanation:

To calculate the molarity of solution, we use the equation:

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

Moles of salt = 0.0410 mol

Volume of solution = 1.00 L

Putting values in above equation, we get:

[tex]\text{Molarity of solution}=\frac{0.0410mol}{1.00L}=0.0410M[/tex]

The given chemical equation follows:

[tex]AB_3(s)\rightleftharpoons A^{3+}(aq.)+3B^-(aq.)[/tex]

1 mole of the [tex]AB_3[/tex] salt produces 1 mole of [tex]A^{3+}[/tex] ions and 3 moles of [tex]B^-[/tex] ions

So, concentration of [tex]A^{3+}\text{ ions}=(1\times 0.0410)M=0.0410M[/tex]

Concentration of [tex]B^{-}\text{ ions}=(3\times 0.0410)M=0.123M[/tex]

Expression for the solubility product of  will be:

[tex]K_{sp}=[A^{3+}][B^-]^[/tex]

Putting values in above equation, we get:

[tex]K_{sp}=(0.0410)\times (0.123)^3\\\\K_{sp}=7.63\times 10^{-5}[/tex]

Hence, the solubility product of the given salt is [tex]7.63\times 10^{-5}[/tex]

The Ksp of the salt AB₃ at 25°C is 7.63×10^(-7).

To calculate the Ksp (solubility product constant) of the generic salt AB₃ at 25°C, we need to understand the dissolution process and its stoichiometry. The dissolution of AB₃ in water can be represented as:

AB₃ (s) ⇌  A^(3+) (aq) + 3 B^(−) (aq)

Given that 0.0410 mol of AB₃ is soluble in 1.00 L of water, we establish the initial concentrations of the ions in the solution as [A3+] = 0.0410 M and [B−] = 3×0.0410 M = 0.123 M. The Ksp for AB₃ can be calculated using the formula:

Ksp = [A^(3+)][B^(−)]3 = (0.0410)(0.123)³

After calculating, we find that Ksp = 7.63×10^(-7). This value represents the solubility product constant of AB₃ at 25°C, providing insights into its solubility properties under these conditions.

Answer:

[tex]t=147.24\ min[/tex]

Explanation:

Given that:

Half life = 30 min

[tex]t_{1/2}=\frac{\ln2}{k}[/tex]

Where, k is rate constant

So,  

[tex]k=\frac{\ln2}{t_{1/2}}[/tex]

[tex]k=\frac{\ln2}{30}\ min^{-1}[/tex]

The rate constant, k = 0.0231 min⁻¹

Using integrated rate law for first order kinetics as:

[tex][A_t]=[A_0]e^{-kt}[/tex]

Where,  

[tex][A_t][/tex] is the concentration at time t

[tex][A_0][/tex] is the initial concentration

Given that:

The rate constant, k = 0.0231 min⁻¹

Initial concentration [tex][A_0][/tex] = 7.50 mg

Final concentration [tex][A_t][/tex] = 0.25 mg

Time = ?

Applying in the above equation, we get that:-

[tex]0.25=7.50e^{-0.0231\times t}[/tex]

[tex]750e^{-0.0231t}=25[/tex]

[tex]750e^{-0.0231t}=25[/tex]

[tex]x=\frac{\ln \left(30\right)}{0.0231}[/tex]

[tex]t=147.24\ min[/tex]

Answer:

The van't Hoff factor of the solute is 1.51

Explanation:

Step 1: Data given

Molality = 0.710 molal

The aqueous solution freezes at − 2.00°C

Freezing point depression constant of water = 1.86 °C/m

Step 2: Calculate the van't Hoff factor

ΔT = i*Kf * m

⇒ with ΔT = The difference between the feezing point of pure and solution = 2.00°C

⇒ i the van't Hoff factor = TO BE DETERMINED

⇒ Kf = Freezing point depression constant of water = 1.86 °C/m

⇒ m = the molality of the solution = 0.710 molal

2.00 = i * 1.86 * 0.710

i = 1.51

The van't Hoff factor of the solute is 1.51

Final answer:

To find the van't Hoff factor for a solution that freezes at − 2.00°C with a molality of 0.710m, the van't Hoff factor, i, is approximately calculated as 1.52, indicating dissociation into multiple particles.

Explanation:

To calculate the van't Hoff factor, i, for the solute in a 0.710 m aqueous solution that freezes at − 2.00 ℃, we use the formula for freezing point depression, ΔTf = iKfm, where ΔTf is the freezing point depression, Kf is the molal freezing-point depression constant for the solvent (water in this case, with a value of − 1.86°C/m), and m is the molality of the solution. First, understand that the freezing point of pure water is 0°C, and the solution's freezing point is − 2.00°C, so the depression, ΔTf, is 2.00°C. To find the van't Hoff factor, i, rearrange the equation to i = ΔTf / (Kfm). Substituting the values gives us i = 2.00 °C / (− 1.86°C/m × 0.710 m) = 2.00°C / − 1.32°C = − 1.52. However, since i should be a positive value and considering the potential rounding or measurement error, the magnitude is taken yielding i approximately equal to 1.52, reflecting the number of particles the solute dissociates into in solution.

Answer:

(a) 5s. n = 5. Sublevel s, l = 0. Number of orbitals = 1

(b) 3p. n = 3. Sublevel p, l = 1. Number of orbitals = 3

(c) 4f. n =4. Sublevel f, l = 3. Number of orbitals = 7

Explanation:

The rules for electron quantum numbers are:

1. Shell number, 1 ≤ n

2. Sublevel number, 0 ≤ l ≤ n − 1

So,

(a) 5s. n = 5, shell number 5. Sublevel s, l = 0. Number of orbitals = 2l +1 = 1

(b) 3p. n = 3, shell number 3. Sublevel p, l = 1. Number of orbitals = 2l +1 = 3

(c) 4f. n =4, shell number 4. Sublevel f, l = 3. Number of orbitals =  2l +1 = 7

The 5s sublevel has n=5 and l=0 with 1 orbital, the 3p sublevel has n=3 and l=1 with 3 orbitals, and the 4f sublevel has n=4 and l=3 with 7 orbitals.

For the sublevels given, the corresponding quantum numbers and the number of orbitals are as follows:

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Final answer:

The reaction enthalpy (ΔHrxn) for the combustion of stearic acid is -10500 kJ/mol. When 206 grams of stearic acid are combusted, 7602 kJ of heat is released.

Explanation:

Calculating ΔHrxn for the Combustion of Stearic Acid

The combustion reaction for stearic acid (C₁₈H₃₆O₂) can be written as follows:

C₁₈H₃₆O₂(s) + 26O₂(g) → 18CO₂(g) + 18H₂O(l)

To calculate the reaction enthalpy (ΔHrxn), we use the sum of the enthalpies of formation (ΔHf) of the products minus the sum of ΔHf of reactants:

ΔHrxn = [18(ΔHf of CO₂) + 18(ΔHf of H₂O)] - [ΔHf of stearic acid + 26(ΔHf of O₂)]

Since ΔHf for elemental oxygen (O₂) is zero, we simplify the equation to:

ΔHrxn = [18(-394 kJ/mol) + 18(-242 kJ/mol)] - (-948 kJ/mol)

ΔHrxn = (-7092 kJ/mol + -4356 kJ/mol) - (-948 kJ/mol)

ΔHrxn = -11448 kJ/mol + 948 kJ/mol

ΔHrxn = -10500 kJ/mol

To find the heat (q) released when 206 g of stearic acid reacts, we first convert the mass of stearic acid to moles using its molar mass (284.48 g/mol):

Moles of stearic acid = 206 g / 284.48 g/mol = 0.724 mol

Then, multiply the moles by the ΔHrxn:

q = 0.724 mol * -10500 kJ/mol

q = -7602 kJ

Therefore, 7602 kJ of heat is released in the combustion of 206 g of stearic acid.

Answer:

The analytical concentrations of thiocyanate ions:

[tex][SCN^-]=0.00012 mol/L[/tex]

The analytical concentrations of ferric ions:

[tex][Fe^{3+}]=0.063 mol/L[/tex]

Explanation:

[tex]Moles (n)=Molarity(M)\times Volume (L)[/tex]

1) Moles of sodium thiocyanate  = n

Volume of sodium thiocyanate solution = 5.00 mL = 0.005 L

(1 mL = 0.001L)

Molarity of the sodium thiocyanate = [tex]4.8\times 10^{-4} M[/tex]

[tex]n=4.8\times 10^{-4} M\times 0.005 L=2.4\times 10^{-6}mol[/tex]

1 mole of sodium thiocyanate has 1 mol of thiocyante ions.

So, moles of thioscyanate ions in [tex]2.4\times 10^{-6}mol[/tex]  of NaSCN.

[tex]=1\times 2.4\times 10^{-6}mol=2.4\times 10^{-6}mol[/tex]

2) Moles of ferric nitrate = n'

Volume of ferric nitrate solution = 2.00 mL = 0.002 L

Molarity of the ferric nitrate = 0.21 M

[tex]n'=0.002 M\times 0.21 L=0.00042 mol[/tex]

1 mole of ferric nitrate has 3 moles of ferric ions.

So number of moles of ferric ions in 0.00042 moles of ferric nitrate is :

[tex]3\times 0.00042 mol=0.00126 mol[/tex]

Volume of nitric acid = 13.00 mL

Total volume by adding all three volumes of solutions = V

V = 5.00 mL + 2.00 mL + 13.00 mL = 20.00 mL = 0.020 L

The analytical concentrations of thiocyanate ions:

[tex][SCN^-]=\frac{2.4\times 10^{-6}mol}{0.020 L}=0.00012 mol/L[/tex]

The analytical concentrations of ferric ions:

[tex][Fe^{3+}]=\frac{0.00126 mol}{0.020 L}=0.063 mol/L[/tex]

Based on the data provided, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.

The concentration of a solution is calculated using the formula below:

The moles of the ions are first determined:

moles of NaSC N⁻  in 5.00 mL in 4.8 * 10⁻⁴ is calculated below:

moles of NaSC N⁻  = 0.005 * 4.8 * 10⁻⁴

moles of NaSC N⁻  = 2.4 * 10⁻⁶ moles

1 mole NaSC N ⁻  produces 1 mole SC N⁻

moles of SC N⁻ = 2.4 * 10⁻⁶ moles

moles of Fe(NO₃)₃ in 2.00 mL in 0.21 M solution is calculated below;

moles of Fe(NO₃)₃ = 0.002 * 0.21

moles of Fe(NO₃)₃ = 4.2 * 10⁻⁴ moles

1 mole Fe(NO₃)₃ produces 1 mole Fe³⁺

moles of Fe³⁺ = 4.2 * 10⁻⁴ moles

Total volume of solution = 0.002 + 0.005 + 0.013

Total volume of solution = 0.020 L

Concentration of SC N⁻ = 2.4 * 10⁻⁶/0.020

Concentration of Fe³⁺ = 4.2 * 10⁻⁴/0.02

Therefore, the analytical concentrations of SC N⁻ and Fe³⁺ in the solution is 1.2 * 10⁻⁴ M and 2.4 * 10⁻² M.

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Answer:

The question requires the value of the initial temperature which is found to be 60.266 °C ≅ 60.3 °C

Explanation:

To solve this question we list out the given variables as follows

Mass of water = 3110 g

Heat energy absorbed = 5.19 × 10⁵ J

Heat Energy required to raise the temperature of water to boiling point =

ΔH = m×C×Δθ where

m = mass of waster = 3110 g = 3.11 kg

C = specific heat capacity of water = 4.2 J/g°C

Δθ = Temperature change = T₂ - T₁ and

T₂ = 100°C which is the normal boiling point temperature of water

Hence 5.19 ×10⁵ J = 3110 g × 4.2 J/g°C ×Δθ

from where Δθ = (5.19 ×10⁵ J)/(13062 J/°C) = 39.73 °C

But Δθ = T₂ - T₁ = 100 °C- T₁ = 39.73 °C then

T₁ = -100 °C - 39.73 °C = 60.266 °C

Hence the initial temperature of the water is 60.266 °C

Final answer:

The initial temperature of the water can be calculated using the specific heat of water (4.184 J/g °C) and the amount of heat absorbed (5.19×10^5 J) before boiling.

Explanation:

The specific heat of water is a critical concept in thermodynamics and is essential for solving problems involving temperature changes. To calculate the initial temperature of the water, we utilize the specific heat capacity, which for water is 4.184 J/g °C. The amount of heat required to raise the temperature of a given mass of water is determined by this specific heat capacity.

For instance, using the information provided, if water absorbs 5.19×105 J of heat, we can set up an equation to find the initial temperature (Tinitial) before it began to boil. Using the formula q = mcΔT, where 'q' is the heat absorbed, 'm' is the mass, 'c' is the specific heat capacity, and 'ΔT' is the change in temperature, we find:

5.19×105 J = (3110 g)(4.184 J/g°C)(100°C - Tinitial)

This equation can be solved for Tinitial to find the initial temperature of the water.

Answer:

94.3 grams

Explanation:

MW of C2HF3O2 is 114g/mol

MW of oxygen in C2HF3O2 is 32g/mol

% composition of oxygen in C2HF3O2 = 32/114 × 100 = 28.1%

Mass of oxygen = 26.5 grams

Mass of trifluoroacetic acid = 26.5/0.281 = 94.3 grams

In the given question, 185.39 g is the mass of the trifluoroacetic acid sample.

Mass is a measure of the amount of matter in an object. The standard metric unit of mass is the kilogram (kg) and grams (gm).

To calculate the mass of the trifluoroacetic acid sample, we need to determine the molar mass of trifluoroacetic acid and then use the given mass of oxygen to find the mass of the entire compound.

The molar mass of trifluoroacetic acid ([tex]\rm C_2HF_3O_2[/tex]) can be calculated by summing the atomic masses of its constituent elements:

Molar mass of [tex]\rm C_2HF_3O_2[/tex] = (2 × 12.01 g/mol) + (1 × 1.01 g/mol) + (3 × 18.99 g/mol) + (2 × 16.00 g/mol)

= 112.03 g/mol

Now, we can use the given mass of oxygen (26.5 g) to find the mass of the entire trifluoroacetic acid sample.

mass (g) = (26.5 g) / (molar mass of O)

mass (g) = (26.5 g) / (16.00 g/mol)

mass (g) = 1.65625 mol

Finally, we can convert moles to grams using the molar mass of trifluoroacetic acid:

mass (g) = 1.65625 mol × 112.03 g/mol

mass (g) = 185.39 g

Therefore, the mass of the trifluoroacetic acid sample is approximately 185.39 g.

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To find the number of photons per second that illuminate a book from a 75-W bulb, calculate 5% of the bulb's power for light, take 10% of that for the light on the book, then divide by the energy per photon. The result is approximately 1.04 x 10¹⁸ photons per second.

The student's question is about determining the number of photons per second that shine on a chemistry text from a 75-Watt incandescent bulb, with only 5% of the bulb's power output converting to light and just 10% of that light illuminating the book.

To calculate this, we first determine the total light power output by taking 5% of the bulb's power, which gives us 3.75 Watts (0.05 times 75 W). Next, we need to calculate the power that actually falls on the book, which is 10% of the light power output, or 0.375 Watts. The energy per photon can be calculated using the formula E = (hc)/λ, where 'h' is Planck's constant, 'c' is the speed of light, and 'λ' is the wavelength. For 550 nm (550 x 10-9 meters), the energy per photon is approximately 3.61 x 10⁻¹⁹ Joules. Finally, to find the number of photons per second, we divide the light power on the book by the energy per photon: 0.375 J/s times 1 photon/3.61 x 10⁻¹⁹ J, resulting in approximately 1.04 x 10¹⁸ photons per second.

Answer:

The transmittance is the amount of energy that a body goes through in a certain amount of time without being absorbed and the absorbance is the amount of light that is absorbed by a solution.

There is no difference between absorptivity and molar absorptivity because the two terms express the same idea, because molar absorptivity is the absorbance of a solution per unit path length and concentration, so that the absorbance is proportional to concentration.

Final answer:

Transmittance is the percentage of light that passes through a sample, absorbance is the logarithmic measure of light absorption, and molar absorptivity is an intrinsic constant correlating absorbance to concentration. Absorbance is directly proportional to concentration, which makes it the preferred measure for determining a substance's concentration in a solution.

Explanation:

The terms transmittance, absorbance, and molar absorptivity are key concepts in spectrophotometry, each describing different aspects of how light interacts with a sample.

Transmittance is a measure of the amount of light that passes through a sample and is typically expressed as a percentage. In contrast, absorbance measures the amount of light absorbed by a sample and is a logarithmic function of transmittance. The formula given A = εbC explains the direct proportionality of absorbance (A) to the concentration (C) of the absorbing species, path length (b), and the molar absorptivity (ε). Molar absorptivity, also called the extinction coefficient, is a constant that illustrates how strongly a substance absorbs light at a given wavelength and is intrinsic to each specific substance.

When determining the concentration of a solution, absorbance is preferred as it is a linear function of concentration. In practical applications, a spectroscopic method is selected to target a specific wavelength that is well-absorbed by the substance of interest, making use of the molar absorptivity to determine concentrations accurately.

Answer:

0.2 and 0.1

Explanation:

Thin Layer Chromatography (TLC) is a type of separation technique which involves a stationary phase (an adsorbent medium) and a mobile phase (a solvent medium), and is used to separate mixtures of non-volatile compounds based on their relative attractions to either phases, which is determined by their polarity.

The more a compound binds to the adsorbent medium, the slower it moves up the TLC plate. Compounds that are polar tend to move up the TLC plate slower than non-polar compounds, resulting in a lower Rf value for polar compounds and a higher Rf value for non-polar compounds.

Rf (Retention factor) = distance moved by compound/solute

                                     distance moved by the solvent front

Rf values of 0.3 and 0.1 gives a difference of 0.2

Rf values of 0.8 and 0.6 gives a difference of 0.2

Rf values of 0.5 and 0.8 gives a difference of 0.3

Rf values of 0.2 and 0.1 gives a difference of 0.1, therefore the smallest separation between compounds is the one with Rf values of 0.2 and 0.1.

Let us label the options in the questions as follows:

Question:

A compound forms between magnesium cation and phosphate anion. Select ALL statements that are TRUE. Group of answer choices

A. The chemical formula of the compound is Mg₃(PO₄)₂.

B. The compound is a covalent compound.

C. The most stable form of a magnesium ion has a charge of 2+

D. This compound ONLY contains ionic bonds.

Answer:

Options A and C

Explanation:

Let us explore all the options,

A. The formula, Mg₃(PO₄)₂, satisfies the charges of both the magnesium (Mg²⁺) and the phosphate ions (PO₄²⁻). Mg²⁺ has three ions, which means the positive charge will be 6 +.  The phosphate ions has a negative charge of 3, so two ions of phosphate can counter the six positive charges in the compound. So, the statement is true

B. The compound is not covalent, as Mg²⁺ and PO₄²⁻ ions are bounded by electrostatic forces. So, the statement is false

C. The stable charge of Mg is 2+. Mg is a s block element in the third period. It does not have any empty inner d orbital. Which makes 2+ oxidation state the most stable. So, the statement is true

D. The phosphate group is composed of phosphorous atom covalently bonded to four oxygen atoms. Hence, the compound DOES NOT contain ONLY ionic bonds. So, the given statement is false

The compound forms between magnesium cation and phosphate anion have the chemical formula of the compound is Mg3(PO4)2 and the most stable form of a magnesium ion has a charge of 2+.

The correct options are (A) The chemical formula of the compound is Mg3(PO4)2, (C) The most stable form of a magnesium ion has a charge of 2+.

Thus, the correct options to follow the statements are (A) and (C).

Learn more about magnesium phosphate, here:

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Answer:

Carbon Dioxide = CO2

Explanation:

The synthesis of Malachite is seen in the chemical formula:

CuSO 4 . 5H2O(aq) + 2NaCO3(aq) --> CuCO 3 Cu(OH) 2 (s) + 2Na 2 SO 4 (aq) + CO 2 (g) + 9H 2 O(l)

The bubbles mentioned in the question hints that our interest is the compounds in their gseous phase  (g).

Upon examining the chemical equation, only CO2 is in the gaseous state and hence the only one that can be formed as bubbles,

The bubbles formed when sodium carbonate is added to the solution of copper sulfate are composed of carbon dioxide (CO2).

When sodium carbonate (Na2CO3) is added to a solution of copper sulfate (CuSO4), bubbles of carbon dioxide (CO2) are formed. The balanced chemical equation for this reaction is:

Na2CO3 + CuSO4 → CuCO3 + Na2SO4

So, the composition of the bubbles formed is carbon dioxide (CO2).

Answer:

a. 5.9 × 10⁻³ M/s

b. 0.012 M/s

Explanation:

Let's consider the following reaction.

2 N₂O(g) → 2 N₂(g) + O₂(g)

a.

Time (t): 12.0 s

Δn(O₂): 1.7 × 10⁻² mol

Volume (V): 0.240 L

We can find the average rate of the reaction over this time interval using the following expression.

r = Δn(O₂) / V × t

r = 1.7 × 10⁻² mol / 0.240 L × 12.0 s

r = 5.9 × 10⁻³ M/s

b. The molar ratio of N₂O to O₂ is 2:1. The rate of change of N₂O is:

5.9 × 10⁻³ mol O₂/L.s × (2 mol N₂O/1 mol O₂) = 0.012 M/s

Answer:

Bromine (35) 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p⁵

Magnesium(12) 1s2 2s2 2p6 3s²

Selenium (34) 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p4

Explanation:

In the SPDF electronic configuration, the S orbital can accommodate maximum of 2 electrons,

The P orbital has maximum of 6 electrons

The D orbital has maximum of 10 electrons

The F orbital has maximum of 14 electrons

Bromine with atomic number 35 belongs to group seven(7) period four (4) it ground state electron configuration is 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p⁵

Magnesium with atomic number 12 belongs to group one, period two(2), it ground state electron configuration is 1s2 2s2 2p6 3s²

Selenium has atomic number of 34, it belongs to group six(6), period four(4) it electronic configuration is 1s²2s²2p63s²3p⁶3d¹⁰ 4s² 4p4

The ground-state electron configurations for Br (Bromine), Mg (Magnesium), and Se (Selenium) are respectively: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵ (for Br); 1s² 2s² 2p⁶ 3s² (for Mg); And 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ (for Se).

The ground-state electron configuration refers to the most stable arrangement of electrons around the nucleus of an atom. Here are the ground-state electron configurations for the following atoms:

In each case, the superscript indicates the number of electrons in each energy level. For example, in Br (Bromine), the 1s orbital has 2 electrons, the 2s orbital also has 2 electrons and so on until the 4p orbital which has 5 electrons.

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Answer: The mass of fluoride ions that must be added will be [tex]8.943\times 10^6g[/tex]

Explanation:

The equation used to calculate the volume of cylinder is:

[tex]V=\pi r^2h[/tex]

where,

r = radius of the reservoir= [tex]\frac{d}{2}=\frac{4.30\times 10^2m}{2}=215m[/tex]

h = height of the reservoir = 56.03 m

Putting values in above equation, we get:

[tex]\text{Volume of reservoir}=(3.14)\times (215)^2\times 56.03\\\\\text{Volume of reservoir}=8.13\times 10^6m^3[/tex]

[tex]1m^3=1000L[/tex]

So, [tex]8.13\times 10^6m^3=8.13\times 10^9L[/tex]

Mass of water reservoir = [tex]8.13\times 10^9kg[/tex]    (Density of water = 1 kg/L )

We are given:

Concentration of fluoride ion in the drinking water = 1.10 ppm

This means that 1.10 mg of fluoride ion is present in 1 kg of drinking water

Calculating the mass of fluoride ion in given amount water reservoir, we use unitary method:

In 1 kg of drinking water, the amount of fluoride ion present is 1.10 mg

So, in [tex]8.13\times 10^9kg[/tex] of drinking water, the amount of fluoride ion present will be = [tex]\frac{1.10mg}{1kg}\times 8.13\times 10^9kg=8.943\times 10^9mg[/tex]

1 g = 1000 mg

So, [tex]8.943\times 10^9mg\times \frac{1g}{1000mg}=8.943\times 10^6g[/tex]

Hence, the mass of fluoride ions that must be added will be [tex]8.943\times 10^6g[/tex]

Final answer:

To achieve a fluoride concentration of 1.10 ppm in a cylindrical water reservoir with a 430 meter diameter and a 56.03 meter depth, 90.035 grams of fluoride ion (F−) must be added.

Explanation:

To calculate the amount of F− needed to attain a concentration of 1.10 ppm in a cylindrical water reservoir, let's first determine the volume of the reservoir. The volume (V) of a cylinder is given by the formula V = πr²h, where r is the radius (half the diameter) and h is the height (or depth in this case). Given a diameter of 4.30 × 10² m and a depth of 56.03 m, the radius r = 2.15 × 10² m.

So, the volume V = π(2.15 × 10² m)²(56.03 m) = π(4.6225 × 10´ m²)(56.03 m) = 8.185 × 10· m³. To convert this volume to liters (since ppm is mg/L), recall that 1 m³ = 1,000 L, making the reservoir's volume 8.185 × 10· m³ × 1,000 = 8.185 × 10±0 L.

With a target fluoride concentration of 1.10 ppm (− or mg/L), the mass (m) of F− required is:

m = concentration × volume = 1.10 mg/L × 8.185 × 10±0 L = 90,035 mg, or 90.035 g.

Thus, to achieve a fluoride concentration of 1.10 ppm in the water reservoir, 90.035 grams of F− must be added.

Answer:

(a) Amount remaining after 15 days = 27 mg

(b) Amount remaining after t days = [216(0.5)^t/5] mg

Explanation:

Nt = No(0.5)^t/t1/2

No (initial amount) = 216 mg, t = 15 days, t1/2 (half-life) = 5 days

N15 (amount remaining after 15 days) = 216(0.5)^15/5= 216(0.5)^3 = 216 × 0.125 = 27 mg

(b) Nt (amount remaining after t days) = 216(0.5)^t/5

Answer:

(a). 27 mg, (b). N = 216 (1/2)^ (t/5 days).

Explanation:

From the question, we are given that the half-life of bismuth-210, 210Bi = 5 days, a sample mass = 216 mg, the amount remaining after 15 days= ???(unknown).

Using the equation (1) below we can solve for the amount remaining after 15 days.

N= N° (1/2)^(t/th).-------------------------(1).

Where N = is the amount remaining, N° = is the initial amount, t= is time and th= half life.

Therefore,amount remaining, N = 216mg (1/2)^(15 days/5 days).

=====> Amount remaining, N =216 mg (1/2)^3.

=====> Amount remaining, N= 216 mg × 0.125. = 27 mg.

OR

We can solve it by using; 1/2 M°. Where M° is the initial mass.

Therefore, after 5 days, 1/2 × 216 = 108 mg remains.

After 10 days, 1/2 × 108 mg = 54 mg remains.

After 15 days; 1/2 × 54 mg = 27 mg remains.

(b). We are to find the amount remaining after time, t.

The amount remaining after time,t ==> N= N° (1/2)^(t/th)

===> N = 216 (1/2)^ (t/5 days).

With this we can calculate the amount of the sample at particular time if the time is given.

Given the pKa values of serine's α‑carboxyl and α‑amino groups, the carboxyl group is fully ionized and carries a -1 charge while the amino group carries a +1 charge at a pH of 8.80. Therefore, the total net charge on serine at this pH is zero.

Your question asks to calculate the average net charge on the amino acid serine at a pH of 8.80, given the pKa values for the α‑carboxyl group (2.21) and the α‑amino group (9.15). This is related to the concept of acid dissociation constants (pKa) and buffer solutions in chemistry.

At a pH of 8.80, the pH is higher than the pKa of the α‑carboxyl group but lower than the pKa of the amino group. For the α‑carboxyl group whose pKa is 2.21, the pH is significantly higher. This means, it is fully ionized and carries a -1 charge.

On the other hand, the α‑amino group has a pKa of 9.15, which is higher than the pH of 8.80. This means it is predominantly in its protonated form and carries a +1 charge.

Therefore, the total charge on serine at this pH is the sum of the charges of the α‑carboxyl group and the α‑amino group, which is -1 + 1 = 0. Hence, the average net charge of serine in a solution with pH 8.80 is zero.

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Here is the complete question:

Calculate the energy released in the following fusion reaction. The masses of the isotopes are: 14N (14.00307 amu), 32S (31.97207 amu), 12C (12.00000 amu), and 6Li (6.01512 amu).

¹⁴N + ¹²C + ⁶Li ⇒   ³²S

Answer:

68.7372 × 10⁻¹⁶ kJ

Explanation:

Given that the reaction;  ¹⁴N + ¹²C + ⁶Li ⇒   ³²S

To calculate for the energy released; we need to determine the mass defect  (md) of the reaction and which is given as :

Mass defect (md) = [mass of reactants] -[mass of product]

Mass defect (md) = [ ¹⁴N + ¹²C + ⁶Li ] - [ ³²S ]

Mass defect (md) = [ 14.00307 + 12.00000 + 6.01512 ] amu - [ 31.97207 ] amu

Mass defect (md) = 32.01819 - 31.97207

Mass defect (md) = 0.04612 amu

Having gotten the value of our Mass defect (md);  = 0.04612 amu

We know that if 1 amu ⇒ 931.5 Mev of energy

∴ 0.04612 amu = 0.04612 × 931.5 Mev of energy

                         = 42.96078  Mev of energy

where M = million = 10⁶

1 ev = 1.6 × 10⁻¹⁹ Joules

∴  42.96078  Mev of energy = 42.96078 × 10⁶ ×  1.6 × 10⁻¹⁹ J

                                               =  68.7372 × 10⁻¹³ J

                                              =  68.7372 × 10⁻¹⁶ kJ

Hence; the  energy released in the above  fusion reaction = 68.7372 × 10⁻¹⁶ kJ.

The Energy released in the fusion reaction is approximately 6.87 × 10⁻¹² J

Step 1: Determine the total mass of the reactants and products

The given reaction is:

[tex]\[ \text{14N} + \text{12C} + \text{6Li} \rightarrow \text{32S} \][/tex]

The masses of the isotopes are:

[tex]\( \text{14N} = 14.00307 \, \text{amu} \)[/tex]

[tex]\( \text{12C} = 12.00000 \, \text{amu} \)[/tex]

[tex]\( \text{6Li} = 6.01512 \, \text{amu} \)[/tex]

[tex]\( \text{32S} = 31.97207 \, \text{amu} \)[/tex]

Total mass of the reactants:

[tex]\[ \text{Mass of reactants} = \text{Mass of 14N} + \text{Mass of 12C} + \text{Mass of 6Li} \][/tex]

[tex]\[ \text{Mass of reactants} = 14.00307 \, \text{amu} + 12.00000 \, \text{amu} + 6.01512 \, \text{amu} \][/tex]

[tex]\[ \text{Mass of reactants} = 32.01819 \, \text{amu} \][/tex]

Mass of the products:

[tex]\[ \text{Mass of products} = \text{Mass of 32S} = 31.97207 \, \text{amu} \][/tex]

Step 2: Calculate the mass defect

The mass defect (\( \Delta m \)) is the difference between the total mass of the reactants and the total mass of the products:

[tex]\[ \Delta m = \text{Mass of reactants} - \text{Mass of products} \][/tex]

[tex]\[ \Delta m = 32.01819 \, \text{amu} - 31.97207 \, \text{amu} \][/tex]

[tex]\[ \Delta m = 0.04612 \, \text{amu} \][/tex]

Step 3: Convert the mass defect into energy

To convert the mass defect into energy, we use Einstein’s equation [tex]\( E = \Delta m c^2 \).[/tex]

First, we need to convert the mass defect from atomic mass units (amu) to kilograms (kg). The conversion factor is:

[tex]\[ 1 \, \text{amu} = 1.66053906660 \times 10^{-27} \, \text{kg} \][/tex]

So,

[tex]\[ \Delta m = 0.04612 \, \text{amu} \times 1.66053906660 \times 10^{-27} \, \text{kg/amu} \][/tex]

[tex]\[ \Delta m \approx 7.656 \times 10^{-29} \, \text{kg} \][/tex]

Now, using [tex]\( c = 3 \times 10^8 \, \text{m/s} \),[/tex] we find the energy released:

[tex]\[ E = \Delta m c^2 \][/tex]

[tex]\[ E = 7.656 \times 10^{-29} \, \text{kg} \times (3 \times 10^8 \, \text{m/s})^2 \][/tex]

[tex]\[ E = 7.656 \times 10^{-29} \, \text{kg} \times 9 \times 10^{16} \, \text{m}^2/\text{s}^2 \][/tex]

[tex]\[ E \approx 6.87 \times 10^{-12} \, \text{J} \][/tex]

Complete question is - Calculate the energy released in the following fusion reaction - [tex]\[ \text{14N} + \text{12C} + \text{6Li} \rightarrow \text{32S} \][/tex].  The masses of the isotopes are: 14N (14.00307 amu), 32S (31.97207 amu), 12C (12.00000 amu), and 6Li (6.01512 amu).

Answer:

The final volume will be 5.80 L

Explanation:

Step 1: Data given

Number of moles gas = 0.140 moles

Volume of gas = 2.78 L

Number of moles added = 0.152 moles

Step 2: Calculate the final volume

V1/n1 = V2/n2

⇒ with V1 = the initial volume = 2.78 L

⇒ with n1 = the initial number of moles = 0.140 moles

⇒ with  V2 = The new volume = TO BE DETERMINED

⇒ with n2 = the new number of moles = 0.140 + 0.152 = 0.292 moles

2.78/0.140 = V2 /0.292

V2 = 5.80 L

The final volume will be 5.80 L

Answer : The pH of the solution is, 5.22

Explanation :

First we have to calculate the moles of acetic acid and sodium acetate.

[tex]\text{Moles of acetic acid}=\text{Concentration of acetic acid}\times \text{Volume of acetic acid}=0.01M\times 0.025L=0.00025mol[/tex]

and,

[tex]\text{Moles of sodium acetate}=\text{Concentration of sodium acetate}\times \text{Volume of sodium acetate}=0.03M\times 0.025L=0.00075mol[/tex]

Now we have to calculate the concentration of acetic acid and sodium acetate in 1 L of solution.

[tex]\text{Concentration of acetic acid}=\frac{\text{Moles of acetic acid}}{\text{Volume of solution}}=\frac{0.00025mol}{1L}=0.00025M[/tex]

and,

[tex]\text{Concentration of sodium acetate}=\frac{\text{Moles of sodium acetate}}{\text{Volume of solution}}=\frac{0.00075mol}{1L}=0.00075M[/tex]

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

[tex]pH=pK_a+\log \frac{[Salt]}{[Acid]}[/tex]

[tex]pH=pK_a+\log \frac{[\text{Sodium acetate}]}{[\text{Acetic acid}]}[/tex]

[tex]pK_a[/tex]  of acetic acid = 4.74

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

[tex]pH=4.74+\log (\frac{0.00075}{0.00025})[/tex]

[tex]pH=5.22[/tex]

Thus, the pH of the solution is, 5.22

To find the pH of the solution, calculate the concentration of the acetic acid and sodium acetate. Convert the volume of acetic acid and sodium acetate to liters. Use the Henderson-Hasselbalch equation to find the pH of the buffer solution.

To determine the pH of the solution, we need to calculate the concentration of the acetic acid and its conjugate base, sodium acetate. First, convert the volume of acetic acid and sodium acetate to liters. The concentration of acetic acid is 0.01 M (10 mM), and the concentration of sodium acetate is 0.03 M (30 mM). Next, calculate the moles of acetic acid and sodium acetate using the equation moles = concentration x volume. The moles of acetic acid are 0.01 moles, and the moles of sodium acetate are 0.03 moles. The solution contains a weak acid (acetic acid) and its conjugate base (sodium acetate), which makes it a buffer solution. To find the pH of a buffer solution, we need to use the Henderson-Hasselbalch equation: pH = pKa + log ([base]/[acid]). The pKa of acetic acid is 4.74. Substitute the values into the equation: pH = 4.74 + log (0.03/0.01) = 4.74 + log(3) = 4.74 + 0.48 = 5.22. Therefore, the pH of the 1-L solution is 5.22.

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