Answer:
3.90 L
Explanation:
The reaction between NH₄I and Pb(NO₃)₂ is a double replacement reaction, so, the ions will dissociate and change in the two substances. The ions are NH₄⁺, I⁻, Pb⁺², and NO₃⁻, so the reaction is:
2NH₄I + Pb(NO₃)₂ → PbI₂ + 2NH₄NO₃
Thus, by the stoichiometry of the reactions, 2 moles of NH₄I are necessary to react with 1 mol of Pb(NO₃)₂. According to Proust's law, the proportion of the reaction must be kept so:
2 moles/1 mol = n NH₄I/n Pb(NO₃)₂
The number of moles of Pb(NO₃)₂ that will react is the concentration multiplied by the volume in L, so:
n Pb(NO₃)₂ = 0.280 * 0.905 = 0.2534 mol
2/1 = n NH₄I/0.2534
n NH₄I = 0.5068 mol
The volume of NH₄I is:
n NH₄I = 0.130 *V
0.5068 = 0.130V
V = 3.90 L
The thermite reaction, used for welding iron, is the reaction of Fe3O4 with Al. 8 Al (s) + 3 Fe3O4 (s) ⟶ 4 Al2O3 (s) + 9 Fe (s) Δ H° = -3350. kJ/mol rxn. Because this large amount of heat cannot be rapidly dissipated to the surroundings, the reacting mass may reach temperatures near 3000. °C. How much heat (in kJ) is released by the reaction of 19.3 g of Al with 63.2 g of Fe3O4?
The reaction of 19.3 g of aluminum with 63.2 g of ferric oxide is exothermic, releasing 2395.25 kJ of heat. Aluminum is the limiting reagent in the reaction.
The limiting reagent is the reactant that is used up completely in the reaction. To determine the limiting reagent, compare the ratio of the moles of each reactant to the stoichiometric coefficients in the balanced chemical equation. The reactant with the smaller ratio is the limiting reagent.
1: Calculate the number of moles of each reactant.
Moles of aluminum = 19.3 g / 27 g/mol = 0.715 mol
Moles of ferric oxide = 63.2 g / 231.5 g/mol = 0.272 mol
2: Determine the limiting reagent.
The ratio of moles of aluminum to moles of ferric oxide is 0.715 mol / 0.272 mol = 2.63. The stoichiometric ratio of aluminum to ferric oxide in the balanced chemical equation is 8:3. Since 2.63 is less than 8/3, aluminum is the limiting reagent.
3: Calculate the amount of heat released.
q = -3350 kJ/mol * 0.715 mol = -2395.25 kJ
4: Interpret the answer.
The amount of heat released is -2395.25 kJ. This means that the reaction releases 2395.25 kJ of heat.
The amount of heat released by the reaction of 19.3 g of Al with 63.2 g of Fe_3O_4 is -2395.25 kJ.
A 0.5 kg block of aluminum (caluminum=900J/kg⋅∘C) is heated to 200∘C. The block is then quickly placed in an insulated tub of cold water at 0∘C (cwater=4186J/kg⋅∘C) and sealed. At equilibrium, the temperature of the water and block are measured to be 20∘C.
0.5 kg block of aluminum (caluminum=900J/kg⋅∘C) is heated to 200∘C. The block is then quickly placed in an insulated tub of cold water at 0∘C (cwater=4186J/kg⋅∘C) and sealed. At equilibrium, the temperature of the water and block are measured to be 20∘C.
If the original experiment is repeated with a 1.0 kg aluminum block, what is the final temperature of the water and block?
A. less than 20∘C
B. 20∘C
C. greater than 20∘C
Answer:
Option C is correct
Explanation:
Increase in the mass of aluminium block would increase the heat capacity of block isothermaly before immersed in water at 0° so heat available for transfer is higher so equilibrium temperature of system would increase.
(a) The first step in ozone formation in the upper atmosphere occurs when oxygen molecules absorb UV radiation of wavelengths ≤ 242 nm. Calculate the frequency and energy of the least energetic of these photons. (b) Ozone absorbs light having wavelengths of 2200 to 2900 Å, thus protecting organisms on Earth’s surface from this high-energy UV radiation. What are the frequency and energy of the most energetic of these photons?
Answer:
a) f = (1.24 × 10^15) Hz and E = (8.214 × 10^-19) J
b) f = (1.36 × 10^15) Hz; E = (9.035 × 10^-19) J
Explanation:
a) The least energetic photons have the highest wavelength. That is, the wavelength of the least energetic photons is equal to the upperlimit of the wavelength inequality given.
λ = 242nm = 2.42 × 10⁻7 m
v = fλ; f = v/λ; v = 3×10^8 m/s
f = (3×10^8)/(2.42×10^-7)
f = (1.24 × 10^15) Hz
E = hf; h = planck's constant = (6.62607004 × 10^-34) Js
E = 6.626 × 10^-34 × 1.24 × 10^15
E = (8.214 × 10^-19) J
b) The photons with the least wavelength in the range provided are the most energetic ones.
λ = (2200 × 10^-10) m = (2.2 × 10^-7) m
v = fλ; f = v/λ; v = 3×10^8 m/s
f = (3×10^8)/(2.2×10^-7)
f = (1.36 × 10^15) Hz
E = hf; h = planck's constant = (6.62607004 × 10^-34) Js
E = 6.626 × 10^-34 × 1.36 × 10^15
E = (9.035 × 10^-19) J
QED!
In ozone formation, least energetic photons having wavelength 242 nm have frequency ≈ 1.24 x 10^15 Hz and energy ≈ 8.2 x 10^-19 J. The most energetic photons that ozone absorbs, with a wavelength of 2200 Å, have a frequency of ≈ 1.36 x 10^15 Hz and energy of ≈ 9.02 x 10^-19 Joules.
Explanation:(a) The frequency (ν) of a photon is given by the formula: ν = c / λ, where c is the speed of light (3.00 x 10^8 m/s) and λ is wavelength. For the least energetic photons (wavelength of 242 nm), we would convert the wavelength to meters (242 nm = 242 x 10^-9 m). Applying the formula: ν = 3.00 x 10^8 m/s / 242 x 10^-9 m, we get ν ≈ 1.24 x 10^15 Hz.
The energy (E) of a photon is given by the formula: E = hν, where h is Planck’s constant (6.63 x 10^-34 Js). So, E = 6.63 x 10^-34 Js x 1.24 x 10^15 Hz, which gives us E ≈ 8.2 x 10^-19 Joules.
(b) For the most energetic of these photons, they have the shortest wavelength (2200 Å = 2200 x 10^-10 m). Using similar calculations as above: ν ≈ 1.36 x 10^15 Hz and E ≈ 9.02 x 10^-19 Joules.
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The orange color of carrots and orange peel is due mostly to β-carotene, an organic compound insoluble in water but soluble in benzene and chloroform. Describe an experiment to determine the concentration of β-carotene in the oil from orange peel.
Answer:
First Method: Vacuum Distillation and Chromatographic separation of the remains that were precipitated out from the peel.
Second Method: Extraction of components from orange peels by help of precipitation procedures that are mostly done In Situ. Those components can be recovered using the saponification process. Then these are examined under UV light spectroscopy. Now, the existence and extent of carotenoids can be determined by checking the levels of anti-oxidants.
A thermos contains 80.0g of water at 23.4 degrees C. Suppose 0.200 moles of KCl are dissolved in the water. What will be the final temperature of the solution? Assume that there is no energy transfer between the solution and the thermos, and that the specific heat is 4.184J/g*degrees C. Also, the delta H of solvation for KCl at 25 degrees C is 17.1 kJ/mol.
Answer:
32.04°C will be the final temperature of the solution.
Explanation:
Moles of potassium chloride = 0.200 mol
MAs sof KCl= 0.200 mol × 74.5 g/mol= 14.9 g
Enthalpy of solvation of potassium nitrate =
[tex]\Delta H_{solv}=17.1 kJ/mol[/tex]
Energy released when 0.200 moles of KCl is dissolved in water = Q
[tex]Q=17.1kJ/mol\times 0.200 mol=3.42 kJ=3420 J[/tex]
(1 kJ = 1000 J)
Heat released on dissolving 0.200 moles of KCl is equal to heat absorbed by water = Q
Mass of solution , m= 80.0 g +14.9 g = 94.9 g
Specific heat of water = c = 4.184 J/g°C
Initial temperature of the water = [tex]T_1=23.4^oC[/tex]
Final temperature of the water = [tex]T_2=?[/tex]
[tex]Q=m\times c\times (T_2-T_1)[/tex]
[tex]3420 J=94.9g\times 4.184 J/g^oC\times (T_2-23.4^oC)[/tex]
[tex]T_2=32.04^oC[/tex]
32.04°C will be the final temperature of the solution.
Given that D(H-H) and D(F-F) in H2 and F2 are 436 and 158kJ mol-1, estimate the bond dissociation enthalpy of H-F using a simple additivity rule. Compare the answer with the experimental value of 570kJ mol-1
Explanation:
Equation of the reaction:
H2(g) + F2(g) --> 2HF(aq)
1/2H2(g) + 1/2F2(g) --> HF(aq)
D(H-H) in H2 = 436 kJ/mol
D(F-F) in F2 = 158kJ/mol
ΔH bond breakage (dissociation):
1/2 mol H-H bonds = (1/2 X 436) kJ
= 218 kJ
1/2 mol F-F bonds = (1/2 X 158) kJ = = 80 kJ
Total = 218 + 80 = 298 kJ
ΔH bond formation:
1 mol H-F bonds = - 570 kJ
= DHreactant - DHproduct
ΔH°f = 298 kJ + -570 kJ = -272 kJ
Question 20 It takes 614./kJmol to break a carbon-carbon double bond. Calculate the maximum wavelength of light for which a carbon-carbon double bond could be broken by absorbing a single photon. Be sure your answer has the c
The maximum wavelength of light that can break a carbon-carbon double bond by absorbing a single photon is calculated to be 1940 nm. This is done by converting the energy required to break the bond to J/particle, and then using this to find the wavelength using the equation E=h*c/λ.
Explanation:To find the maximum wavelength of light that can break a carbon-carbon double bond by absorbing a single photon, it is necessary to convert the energy required to break the bond from kJ/mol to energy per photon and then use that to calculate the wavelength. Using the relation between energy and wavelength given by the formula E=h×c/λ, where E is Energy, h is Planck's constant (6.626 x 10⁻³⁴ Js), c is the speed of light and λ is the wavelength.
First, convert the energy required to break the bond to J/particle by converting kJ to J (1kJ = 1000J) and then dividing by Avogadro's number (6.022 x 10²³). Thus, E = 614.4 kJ/mol × 1000 J/kJ / 6.022 x 10²³ particles/mol = 1.02 x 10⁻¹⁹ J/particle.
Then, rearrange the formula to solve for λ. We get λ = h × c/E. Substituting values (h = 6.626 x 10⁻³⁴ Js, c = 3.00 x 10⁸ m/s, and E = 1.02 x 10⁻¹⁹ J) gives λ = 1.94 x 10⁻⁶ meters or 1940 nm.
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The maximum wavelength of light for which a carbon-carbon double bond could be broken by absorbing a single photon is 341 nm.
Explanation:To calculate the maximum wavelength of light for which a carbon-carbon double bond could be broken by absorbing a single photon, we need to use the formula E = hc/λ, where E is the energy of the photons, h is Planck's constant (6.63 x 10^-34 J·s), c is the speed of light (3.0 x 10^8 m/s), and λ is the wavelength of light in meters.
First, we need to convert the bond energy from kJ/mol to J/molecule by multiplying it by Avogadro's number (6.02 x 10^23). So, the bond energy is 614 x 10^3 J/mol. Next, we can rearrange the formula to solve for λ:
λ = hc/E = (6.63 x 10^-34 J·s)(3.0 x 10^8 m/s)/(614 x 10^3 J/mol)
Calculating this expression gives us a value of λ = 3.41 x 10^-7 m, or 341 nm. Therefore, the maximum wavelength of light for which a carbon-carbon double bond could be broken by absorbing a single photon is 341 nm.
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Write the full electron configuration of the Period 2 element with the following successive IEs (in kJ/mol):
IE₁ = 801
IE₂ = 2427
IE₃ = 3659
IE₄ = 25,022
IE₅ = 32,822
Answer:
Boron (B) is the element whose IE matches with our data.
Electronic Configuration of boron: [tex]1s^22s^22p^1[/tex]
Explanation:
Ionization Energy (IE):
It is the minimum amount of energy which is required to remove the lose electron. If the electron is closer to the nucleus then greater amount of energy is required to remove the electron.
If we look from left to right in a period, ionization energy increases due stability of valance shell.
From the data given to us:
IE₁ = 801
IE₂ = 2427
IE₃ = 3659
IE₄ = 25,022
IE₅ = 32,822
Boron (B) is the element whose IE matches with our data.
Electronic Configuration of boron: [tex]1s^22s^22p^1[/tex]
Boron has 5 electrons (3 in valance shell) that's why it has 5 Ionization Energies.
Only certain electron transitions are allowed from one energy level to another. In one-electron species, the change in the quantum number l of an allowed transition must be ±1. For example, a 3p electron can drop directly to a 2s orbital but not to a 2p. Thus, in the UV series, where nfinal = 1, allowed electron transitions can start in a p orbital (l = 1) of n = 2 or higher, not in an s (l = 0) or d (l = 2) orbital of n = 2 or higher. From what orbital do each of the allowed electron transitions start for the first four emission lines in the visible series (nfinal = 2)?
Final answer:
The first four lines of the Balmer series involve electron transitions from 3p to 2s, 4p to 2s, 5p to 2s, and 6p to 2s orbitals.
Explanation:
The Balmer series involves electron transitions from higher energy levels to the second principal energy level (n=2), producing visible spectral lines. For the first four lines of the visible emission spectrum in the Balmer series, the allowed transitions must follow the selection rule Δl = ±1. Therefore, these transitions can only start from orbitals with l=1, which are the p orbitals.
For nfinal = 2, the corresponding ni initial energy levels for the first four visible emission lines are:
3p (n=3, l=1) to 2s (n=2, l=0)4p (n=4, l=1) to 2s (n=2, l=0)5p (n=5, l=1) to 2s (n=2, l=0)6p (n=6, l=1) to 2s (n=2, l=0)After doing an experiment, a chemist determines the Rf value of a compound to be 4. He also notes that the solvent travelled 4 cm on the plate. What can you conclude about this experiment
Answer:
We can conclude that the Rf of that compound has a ratio of 4. It means that the solute has a ratio value of 4 times than that of solvent. As we can see that it has traveled 4 cm , this data is useful in determination of the compound in a mixture when compared with Rf values of other compounds.
When the excited electron in a hydrogen atom falls from to , a photon of blue light is emitted. If an excited electron in falls from , which energy level must it fall to so that a similar blue light (as with hydrogen) is emitted? Prove it.
Answer:
n = 3 for similar blue light
Explanation:
The principle applied here is energy levels and energy changes. There are different energy levels depending on the value of the integer as explained by Max planck - a german physicist in 1900, Max planck claimed that electrons in an atom were presumed to be oscillating with a frequency f, then there enrrgy will be given by the plancks equation ; E =hf, where h is the plancks constant.
In general energy of each level can be written as E =nhf
The Tris/Borate/EDTA buffer (TBE) is commonly made as a 5x solution. What volumes of 5x TBE and water are required to make 500 mls of a 0.5x solution which is often used in electrophoresis?
Answer:
50 ml (5x TBE) + 540 ml (water)
Explanation:
To prepare 0.5x TBE solution from 5x TBE solution we need to use the following dilution formula:
C1 x V1 = C2 x V2, where:
- C1, V1 = Concentration/amount (start), and Volume (start)
- C2, V2 = Concentration/amount (final), and Volume (final)
* So when we applied this formula it will be:
5 x V1 = 0.5 x 500
V1= 50ml
- To prepare 0.5x we will take 50ml from 5x and completed with 450ml water and the final volume will going to be 500ml.
What is the mass of cyclohexane solvent, in kg, if 9.76 mL are used and the cyclohexane has a density of 0.779 g/mL?
Answer:
0.0076kg
Explanation:
To get the mass, we use the relation among density, mass and volume.
Mass = density * volume
Here mass? , density = 0.779g/ml , volume = 9.76ml
Mass = 9.76 * 0.779 = 7.60g
Answer is wanted in kg so we divide by 1000. This is 7.60/1000 = 0.0076kg
Prior to hosting an international soccer match, the local soccer club needs to replace the artifical turf on their field with grass turf. The grass turf will cost $ 9.75 per square meter. If the field is 0.102 km by 0.069 km, how much will it cost the club to add the grass turf to their field?
It will cost the soccer club $68,618.50 to add the grass turf to their field for the international soccer match.
Given: Length = 0.102 km = 0.102 km × 1000 m/km = 102 m
Width = 0.069 km = 0.069 km × 1000 m/km = 69 m
The area of the field: Area = Length × Width
Area = 102 m × 69 m = 7038 sq. meters
The area by the cost of the grass turf per square meter:
Cost = Area × Cost per square meter
Cost = 7038 sq. meters ×$9.75/sq. meter = $68,618.50
Therefore, it will cost the soccer club $68,618.50 to add the grass turf to their field for the international soccer match.
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Specify the l and ml values for n = 4.
Answer : The specify the l and ml values for n = 4 are:
At l = 0, [tex]m_l=0[/tex]
At l = 1, [tex]m_l=+1,0,-1[/tex]
At l = 2, [tex]m_l=+2,+1,0,-1,-2[/tex]
At l = 3, [tex]m_l=+3,+2,+1,0,-1,-2,-3[/tex]
Explanation:
There are 4 quantum numbers :
Principle Quantum Numbers : It describes the size of the orbital. It is represented by n. n = 1,2,3,4....
Azimuthal Quantum Number : It describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For l = 0,1,2,3... the orbitals are s, p, d, f...
Magnetic Quantum Number : It describes the orientation of the orbitals. It is represented as m_l. The value of this quantum number ranges from [tex](-l\text{ to }+l)[/tex]. When l = 2, the value of [tex]m_l[/tex] will be -2, -1, 0, +1, +2.
Spin Quantum number : It describes the direction of electron spin. This is represented as [tex]m_s[/tex]The value of this is [tex]+\frac{1}{2}[/tex] for upward spin and [tex]-\frac{1}{2}[/tex] for downward spin.
As we are given, n = 4 then the value of l and ml are,
l = 0, 1, 2, 3
At l = 0, [tex]m_l=0[/tex]
At l = 1, [tex]m_l=+1,0,-1[/tex]
At l = 2, [tex]m_l=+2,+1,0,-1,-2[/tex]
At l = 3, [tex]m_l=+3,+2,+1,0,-1,-2,-3[/tex]
When measuring water using the graduated pipette, the mass of beaker and the water is 23.670 g. If the empty beaker weighs 13.712 g. What is the volume of water measured assuming a density of 0.9982071 g/mL.
Answer:
The volume of water measured is 10mL
Explanation:
Given;
Mass of mass of beaker and the water = 23.670 g
Mass of empty beaker = 13.712 g
Then, mass of water only = Total mass of of beaker and the water minus Mass of empty beaker
mass of water only = 23.670 g - 13.712 g = 9.958 g
Density = mass/volume
Given density of water = 0.9982071 g/mL
Density of water = Mass of water/ Volume of water
Then, Volume of water = Mass of water/Density of water
Volume of water = 9.958 g/0.9982071 g/mL
Volume of water = 9.975886 mL ≅ 10mL
Therefore, The volume of water measured is 10mL
Draw the partial (valence-level) orbital diagram, and write the symbol, group number, and period number of the element:
(a) [Ar] 4s²3d⁵
(b) [Kr] 5s²4d²
Answer:
a) The element is Manganese (Mn)
b) The element is Zirconium (Zr)
Explanation:
The step by step analysis and explanation is as shown in the attachment
Lithium has two naturally occurring isotopes, 6Li and 7Li . The atomic weight of lithium is 6.941. Which of the following statements concerning the relative abundance of each isotope is correct? A) The abundance of 7Li is greater than 6Li. B) The abundance of 7Li is less than 6Li. C) The abundance of 6Li is equal to the abundance of 7Li. D) Not enough data is provided to determine the correct answer. E) Based on the atomic mass, only 7Li occurs naturally.
Answer: The abundance of Li-7 isotope is higher as compared to Li-6.
Explanation:
Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
[tex]\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i[/tex]
We are given:
Two isotopes of lithium :
Li-6 and Li-7
Average atomic mass of lithium= 6.941
As, the average atomic mass of lithium is closer to the mass of isotope Li-7. This means that the relative abundance of Li-7 is higher as compared to Li-6.
Percentage abundance of Li-7> Percentage abundance of Li-6 isotope
The atomic weight of lithium is closer to the mass number of 7Li, indicating that 7Li is more abundant than 6Li in nature. Thus, the correct answer is A) The abundance of 7Li is greater than 6Li.
Explanation:The atomic weight of lithium, being 6.941, is closer to 7 than 6. Consequently, this indicates that most naturally occurring lithium is of the heavier 7Li isotope. So, in terms of relative abundance, 7Li is indeed more prevalent than 6Li. This means the correct answer would be option A) The abundance of 7Li is greater than 6Li. Therefore, based on the atomic weight of lithium, we can conclude that the abundance of 7Li is greater than 6Li.
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Define shielding and effective nuclear charge. What is the connection between the two?
Answer:
The relation between the shielding and effective nuclear charge is given as
[tex]Z_{eff} = Z -S[/tex]
where s denote shielding
z_{eff} denote effective nuclear charge
Z - atomic number
Explanation:
shielding is referred to as the repulsion of an outermost electron to the pull of electron from valence shell. Higher the electron in valence shell higher will be the shielding effects.
Effective nuclear charge is the amount of net positive charge that valence electron has.
The relation between the shielding and the effective nuclear charge is given as
[tex]Z_{eff} = Z -S[/tex]
wheres denote shielding
z_{eff} denote effective nuclear charge
Z - atomic number
A 5.21 mass % aqueous solution of urea (CO(NH2)2) has a density of 1.15 g/mL. Calculate the molarity of the solution. Give your answer to 2 decimal places.
Answer:
Molarity is 0.99 M
Explanation:
5.21% by mass, is a sort of concentration which shows the mass of solute in 100 g of solution.
Molarity is a sort of concentration that indicates the moles of solute in 1 L of solution (mol/L)
Let's find out the volume of solution by density.
Solution density = Solution mass / Solution volume
1.15 g/mL = 100 g / Solution volume
Solution volume = 100 g / 1.15 g/mL → 86.9 mL
We must have the volume of solution in L, so let's convert it.
86.9 mL / 1000 = 0.0869 L
Now, we have to determine the moles of solute (urea)
5.21 g . 1 mol / 60 g = 0.0868 moles
Mol/L = Molarity → 0.0868 moles / 0.0869L = 0.99 M
Answer:
[tex]\large \boxed{\text{1.00 mol/L}}[/tex]
Explanation:
Molar concentration = moles/litres
So, we need both the number of moles and the volume.
1. Volume
Assume a volume of 1 L.
That takes care of that.
2. Moles of urea
(a) Mass of solution
[tex]\text{ Mass of solution} = \text{1000 mL} \times \dfrac{\text{1.15 g solution}}{\text{1 mL}} = \text{1150 g solution}[/tex]
(b) Mass of urea
[tex]\text{Mass of urea} = \text{1150 g solution}\times \dfrac{\text{5.21 g urea}}{\text{100 g solution}} = \text{59.92 g urea}[/tex]
(c) Moles of urea
[tex]\text{Moles of urea} = \text{59.92 g urea} \times \dfrac{\text{1 mol urea}}{\text{60.06 g urea}} = \text{1.00 mol urea}[/tex]
3. Molar concentration
[tex]\text{Molar concentration} = \ \dfrac{\text{1.00 mol}}{\text{1 L}} = \textbf{1.00 mol/L}\\\text{The molar concentration of the urea is $\large \boxed{\textbf{1.00 mol/L}}$}[/tex]
Beta (β) sheets are a type of secondary structure in proteins. A segment of a single chain in an antiparallel β sheet has a length of 80.5 Å . How many residues are in this segment?
Answer:
Explanation:
The structural repeating unit of beta sheet is 7 anstrom/2 aminoacids. So,
[tex]\frac{80.5 Angstrom}{3.5} = 23 aminoacids[/tex]
If a segment of a single chain in an antiparallel beta sheet has a length of 80.5 angstrom, then there will be 23 residues in this segment.
To find the number of residues in an 80.5 Å long segment of an antiparallel beta-pleated sheet, divide the total length by the length of one residue (3.5 Å per residue), which gives approximately 23 residues.
Explanation:The student asked how many residues are in a segment of a single chain in an antiparallel beta-pleated sheet with a length of 80.5 Å. To determine the number of amino acid residues in the segment, we can use the typical amino acid residue length in a ß-pleated sheet, which is approximately 3.5 Å per residue in an extended conformation. This measurement considers the distance hydrogen bonds can span between the carbonyl oxygen and amino hydrogen along the peptide chain in the secondary structure.
By dividing the total length of the chain (80.5 Å) by the length of one residue (3.5 Å), you can calculate the number of residues:
Number of residues = Total length ÷ Length per residue
Number of residues = 80.5 Å ÷ 3.5 Å/residue
Number of residues ≈ 23 residues
This calculation does not account for slight variations that may occur in different proteins or specific contexts, but it provides a general estimate for the number of amino acids in a segment of a beta sheet.
(a) which of these gases would you expect to have the largest van der waals constant a? H2, HF, F2******** (b) which of these gases would you expect to have the largest van der waals constant b? H2, HCL, CL2
In the given gases, HF should have the largest van der Waals constant a because of its stronger intermolecular forces, and Cl2 should have the largest van der Waals constant b due to its larger molecular size.
Explanation:The van der Waals constants (a) and (b) are indicative of the strength of the forces between molecules, and the physical size of the molecules in a given gas, respectively.
(a) In the selection of H2, HF, F2, we would expect the molecule with the strongest intermolecular forces to have the largest van der Waals constant a. That would be HF because when comparing these gases, HF has permanent dipole-dipole interaction which is stronger than the London dispersion forces in H2 and F2.
(b) For the gases H2, HCl, Cl2, we would expect the molecule with the largest physical size to have the largest van der Waals constant b. In this case, Cl2 is the largest molecule and thus would have the largest van der Waals constant b under normal conditions.
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The volume of a single tungsten atom is 1.07×10-23 cm3. What is the volume of a tungsten atom in microliters?
Answer: 1.07×10^-20microlitre
Explanation:
1cm3 = 1000microlitres
1.07×10^-23 cm3 of tungsten = 1.07×10^-23 x 1000 = 1.07×10^-20microlitre
The volume of a single tungsten atom in microliters is 1.07x10^-17 µL. This is found by multiplying the given volume in cubic centimeters by the conversion factor of 1,000,000 µL/cm³.
Explanation:The volume of a single tungsten atom is 1.07×10-23 cm3. One cubic centimeter (cm3) is equal to 1,000,000 microliters (µL). To convert the volume from cubic centimeters to microliters, we need to multiply the original value by the conversion factor. Therefore, the volume of a tungsten atom in microliters will be 1.07×10-23 cm3 * 1,000,000 µL/cm3, which equals to 1.07×10-17 µL. Hence, the volume of a tungsten atom in microliters is 1.07×10-17 µL.
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CH3CH2OH(l) 3O2(g) Classify each chemical reaction: reaction type of reaction (check all that apply) combination precipitation single replacement combustion double replacement acid-base decomposition combination precipitation single replacement combustion double replacement acid-base decomposition combination precipitation single replacement combustion double replacement acid-base decomposition combination precipitation single replacement combustion double replacement acid-base decomposition
Answer:
Reaction I is a COMBINATION REACTION - A reaction that involves the mixing of two or more elements to form a single product.
Reaction II is COMBUSTION REACTION - A reaction that involves Oxygen to produce carbon(iv)oxide and water vapor
Reaction III is DOUBLE DISPLACEMENT REACTION - A reaction that involves the exchange of radicals.
Reaction IV is a COMBUSTION REACTION
Explanation:
Reaction I is a COMBINATION REACTION - A reaction that involves the mixing of two or more elements to form a single product.
Reaction II is COMBUSTION REACTION - A reaction that involves Oxygen to produce carbon(iv)oxide and water vapor
Reaction III is DOUBLE DISPLACEMENT REACTION - A reaction that involves the exchange of radicals.
Reaction IV is a COMBUSTION REACTION
Attached is the reactions I - 1V
The given chemical equation CH3CH2OH(l) + 3O2(g) represents a combustion reaction where CH3CH2OH reacts with oxygen to produce carbon dioxide and water.
Explanation:Based on the given chemical equation, CH3CH2OH(l) + 3O2(g), the reaction is a combustion reaction. Combustion reactions involve the rapid combination of a fuel (in this case, CH3CH2OH) with oxygen (O2) to produce heat, light, and new products. In a combustion reaction, a fuel is oxidized and reacts with oxygen to form carbon dioxide and water.
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How are measurements of paramagnetism used to support electron configurations derived spectroscopically? Use Cu(I) and Cu(II) chlorides as examples.
Answer:
Paramagnetism is dependent on the unpaired electron in the last orbital . In this regard, Cu(I) chloride is paramagnetic whereas Cu(II) chloride is not.
Explanation:
Paramagnetism is the property of materials/components which makes them attracted them weekly to the magnetic field.
It is related to electronic configuration, such that it depends on the unpaired electron in the last orbital possess the property.
On basis of this property, Cu(I) chloride is paramagnetic while Cu(II) chloride is non paramagnetic. This is because Cu(I) chloride contains an unpaired electron in the last orbital whereas Cu(II) chloride does not have any unpaired electron.
Answer:
Explanation:
Paramagnetism is a type of magnetism whereby materials are weakly attracted to an externally applied magnetic field and then form internal, induced magnetic fields in the direction of the applied magnetic field. They are attracted to magnetic fields and have magnetic moment induced by the applied field is linear in the field strength. Paramagnetic materials include elements such as Oxygen,
Aluminium etc. and maybe some compounds like FeO etc.
Paramagnetism occurs due to the presence of unpaired electrons in an atom, so atoms with incompletely filled atomic orbitals are paramagnetic, there are exceptions such as copper exist and this is due to their spin, unpaired electrons have a magnetic dipole moment and act like tiny magnets. They have a magnetic permeability slightly greater than 1. External magnetic field causes the electrons spin to align parallel to the field hence, causing a net attraction. Paramagnetic materials include aluminium, oxygen, titanium, and iron oxide (FeO).
From the example,
Cu(I) and Cu(II)
Electronic configuration
Cu(I) - [Ar] 3d10
Cu(II) - [Ar] 3d9
[Ar] - 1s2 2s2 2p6 3s2 3p6 4s2
Therefore, Cu(I) is Paramagnetic while Cu(II) is not Paramagnetic (diamagnetic).
Suppose a helium-3 nuclide transforms into a helium-4 nuclide by absorbing a proton and emitting a positron. Complete the nuclear chemical equation below so that it describes this nuclear reaction.
Answer: The nuclear equation for the conversion of He-3 nuclide to He-4 nuclide is given above.
Explanation:
Nuclear reaction are defined as the reactions in which nucleus of an atom is involved.
Positron emission is defined as the emission process in which positron particle is emitted. In this process, a proton gets converted to neutron and an electron neutrino particle.
[tex]_Z^A\textrm{X}\rightarrow _{Z-1}^A\textrm{Y}+_{+1}^0e[/tex]
The chemical equation for the reaction of He-3 with a proton follows:
[tex]_2^3\textrm{He}+_1^1\textrm{H}\rightarrow _2^4\textrm{He}+_{+1}^0e[/tex]
Hence, the nuclear equation for the conversion of He-3 nuclide to He-4 nuclide is given above.
The nuclear equation where a helium-3 nuclide transforms into a helium-4 nuclide by absorbing a proton and emitting a positron is written as ³He + ¹H → ⁴He + e⁺. This ensures that mass and charge are conserved in the reaction.
Explanation:To complete the nuclear chemical equation where a helium-3 nuclide (³He) transforms into a helium-4 nuclide (⁴He) by absorbing a proton (¹H) and emitting a positron (e⁺), we must ensure that both mass and charge are conserved in the reaction. In this case, the equation can be represented as:
³He + ¹H → ⁴He + e⁺
The mass number on the left side of the equation is 3 (from helium-3) plus 1 (from the proton), totaling 4, which matches the mass number of helium-4 on the right side of the equation. The atomic number (number of protons) is also conserved through this reaction: 2 (from helium-3) + 1 (from the proton) equals 2 (from helium-4) + 1 (from the emitted positron), with positrons having a positive charge but no atomic number associated.
30 mL of 0.25 M acetic acid are titrated with 0.05 M KOH. What is the pH after addition of 75 mL KOH? Group of answer choices
Answer:
The PH of the mixture is 4.74
Explanation:
The number of millimoles of acetic acid is calculated using the formula:
No of millimoles= Molarity * Volume( in ml)
= 0.25M * 30ml = 7.5 moles
Number of millimoles of KOH is calculated using:
Number of millimoles = Molarity * Volume ( in ml)
=0.05M * 75ml
= 3.75 moles
The PH of the solution is derived using:
pH = pKa + log [salt] / acid
= [tex] -log [ 1.8 * 10^5 ] + log [ 3.75 mmoles/ 3.75 mmoles] [/tex]
=4.74
What is the difference in height between the top surface of the glycerin and the top surface of the alcohol? Suppose that the density of glycerin is 1260 kg/m3 and the density of alcohol is 790 kg/m3.
Here is the full question
Glycerin is poured into an open U-shaped tube until the height in both sides is 20 cm. Ethyl alcohol is then poured into one arm until the height of the alcohol column is 10 cm. The two liquids do not mix.
What is the difference in height between the top surface of the glycerin and the top surface of the alcohol? Suppose that the density of glycerin is 1260 kg/m3and the density of alcohol is 790 kg/m3.
Express your answer in two significant figures and include the appropriate units (in cm)
Answer:
ΔH ≅ 3.73 cm
Explanation:
The pressure inside a liquid is known as hydrostatic pressure and which is represent by the formula:
P = ρ × g × h
where;
ρ is the density of the fluid
g is the gravitational constant
h is the height from the surface
From the question above;
For glycerine; we have:
density of glycerine = 1260 kg/m³
gravitational constant = 9.8 m/s²
height = ???
∴
[tex]P_{(g)= 1260kg/m^3}*9.8m/s^2*h_g[/tex] ----- equation (1)
On the other hand for alcohol:
density of alcohol is given as = 790 kg/m³
gravitational constant = 9.8 m/s²
height = 10 cm
∴
[tex]P_{(a)= 790kg/m^3*9.8m/s^2*10[/tex] ----------- equation (2)
if we equate equation 1 and 2 together; we have
[tex]P_{(g)= P_{(a)[/tex]
[tex]1260kg/m^3}*9.8m/s^2*h_g = 790kg/m^3*9.8m/s^2*10cm[/tex]
Making [tex]h_g[/tex] the subject of the formula, we have :
[tex]h_g= \frac{ 790kg/m^3*9.8m/s^2*10cm}{1260kg/m^3*9.8m/s^2}[/tex]
[tex]h_g[/tex] = 6.269 cm
The difference in the height denoted by ΔH can therefore be calculated as:
ΔH [tex]= H_a-H_g[/tex]
ΔH [tex]= 10cm - 6.269cm[/tex]
ΔH = 3.731 cm
ΔH ≅ 3.73 cm (to two significant figures)
Suppose you want to test the results of a transformation by growing Escherichia coli cells in LB medium containing ampicillin as the antibiotic for selection. Ampicillin at a concentration of 100 µg/mL will kill cells that do not contain an ampicillin resistance gene, but will allow the growth of cells that have been transformed with this gene. The concentrated stock of ampicillin is 100 mg/mL. How many microliters of the ampicillin stock should you add to 50 mL of LB for a bacterial culture?
Answer:
50.0 μL
Explanation:
When a dilution is done, the mass of the solute (in this case the ampicillin) remains constant, following the Lavoiser's law that the mass is conserved. The mass is the concentration (C) multiplied by the volume (V), so if 1 is the stock solution, and 2 is the bacterial culture after the addition of the antibiotic:
m1 = m2
C1*V1 = C2*V2
C1 = 100 mg/mL = 100000 μg/mL (1 mg = 1,000μg)
C2 = 100 μg/mL
V2 = 50 mL + V1 = 50000μL + V1 (V1 in μL)
100000*V1 = 100*(50000 + V1)
1000V1 = 50000 + V1
999V1 = 50000
V1 = 50.0 μL
How many orbitals in an atom can have each of the following designations: (a) 5f; (b) 4p; (c) 5d; (d) n = 2?
Answer: (a) seven orbitals, (b). 3 orbitals, (c). 5 orbitals and (d). 4 orbitals.
Explanation:
In order to solve this question we need to know how to explain the behaviour of electrons in atoms,and what we need to know is what is called the quantum numbers. There are four different kinds of quantum numbers and they are;
(1). Principal quantum numbers: the principal quantum number is denoted by the letter 'n'. It is used to describe the orbitals' energy. It has the values of n=1,2,3,4,...
(2). The spin quantum numbers: the spin quantum numbers is denoted by m(s). The 's' in the parenthesis is in subscript. It has the values of +1/2 and -1/2.
(3). Azimuthal quantum numbers: this is denoted by ℓ and it is used to explain orbital angular momentum and orbital shape. It has the values of ℓ= 0,1,2,3,....n-1.
Note that => ℓ = 0; we have a s-subshell,sphere shape.
ℓ = 1; p-subshell, dumb bell shape.
ℓ=2; d- subshell, double dumb bell shape.
ℓ= 3; f - subshell, multiple lobes.
(4). Magnetic quantum number: it is denoted by m(l) where the 'l' in the parenthesis is in subscript.
===> NOTE: there are (2ℓ + 1 ) orbitals in a subshell, also, there are n^2 number of orbitals in a shell.
Having known all that above, let us jump right in to the solution.
(a). From above we can see that; there are (2ℓ + 1 ) orbitals' in a subshell, also, f= ℓ= 3.
Therefore, the number of orbitals in 5f = 2 ℓ + 1 = (2×3) + 1 = 6+1 = 7 orbitals for 5f.
(b). 4p, the numbers of orbitals in 4p is; p= ℓ= 1=> 4 ℓ + 1 = (2×1) + 1 = 2+1 = 3 orbitals for 4p.
(c). 5d, the numbers of orbitals' in 5d is; d= ℓ= 2 = (2×2) + 1 = 4 + 1 = 5 orbitals for 5d.
(d). For n= 2, the numbers of orbital is ; n^2. Where the n given is 2. Therefore, 2^2= 2×2 = 4 orbitals in n=2.
An orbital refers to a region in space where electrons can be found.
An orbital refers to a region in space where there is a high probability of finding an electron. Orbitals that posses the same amount of energy are called degenerate orbitals.
The number of orbitals in an atom that can have the following designations are shown below;
5f - seven orbitals can have this designation because the f orbital is seven fold degenerate.4p - three orbitals can have this designation because the p orbital is three fold degenerate5d - five orbitals can have this designation because the d orbital is five fold degeneraten = 2 - the total number of orbitals in an energy level is given by n^2. Hence there are four orbitals that has the designation n =2Learn more: https://brainly.com/question/1527403