Which would you expect to be the stronger nucleophile in a polar aprotic solvent?

If you substituted the carbonyl in the peptide bond with a C-F bond, the strands would get closer together.

All of the amino acids could form a hydrogen bond with another amino acid in the chain to stabilize the secondary structure of a b-pleated sheet.

Protein is composed of amino acid linked with peptide bond.

Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as fluorine (F), oxygen (O) and nitrogen (N) atoms.

In a beta-pleated sheet, hydrogen bonds are formed between carbonyl and amino groups of backbone (see picture below).

Fluorine atom has greater electronegativity than oxygen atom in carbony group, so the hydrogen bond with hydrogen atom is shorter and strands are closer.

Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

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Element x is unbibium has an average atomic mass of 122. 224 u and isotopic mass of the least abundant isotope is 237.03

Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons and the number of protons in a nucleus determines the element's atomic number on the periodic table called isotopes

Unbibium, also known as element 122 or eka-thorium, is the hypothetical chemical element in the periodic table with the placeholder symbol of Ubb and atomic number 122 and unbibium has two isotopes ³⁷⁴Ubb and ³⁷¹Ubb and this abundant isotope has an isotopic mass of 121. 560 u and a relative abundance of 63. 89% and the isotopic mass of the least abundant isotope is 237.03

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The minimum no of pins required by dual-op-amp is 8. Each op-amp has 2 input terminals(4 pins) and one output terminal(2 pins). Another 2 pins are required for power.

An operational amplifier is a high-gain, DC-coupled electronic voltage amplifier with differential input and typically single-ended output. An op amp in this setup generates an output potential (relative to circuit ground) that is typically 100,000 times greater than the potential difference between its input terminals. Operational amplifiers were first employed in analog computers to carry out mathematical operations in linear, non-linear, and frequency-dependent circuits.

The op amp's popularity as a component in analog circuits stems from its adaptability. By adopting negative feedback, the properties of an op-amp circuit, such as its gain, input and output impedance, bandwidth, etc., are defined by external components and have no influence on temperature coefficients or technical tolerance in the op amp itself.

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Volume of potassium hydroxide that can neutralise 25 cm³ of H2Z acid solution is 5cm³

The neutralization reaction is

H2Z + 2KOH → K2 H2Z + 2H2O

H2Z acid is diprotic acid as it has two ionizable hydrogens.

Thus, 1 mole of Z acid will neutralize 2 moles of KOH.

The number of moles of phosphorus acid present in 0.025 dm³ of 0.5 M aqueous solution is 0.1×

= 0.0025

They will neutralize 2×0.0025mol = 0.005 moles of KOH.

The molarity of KOH solution is 1.0 mol dm³

The volume of KOH solution required will be

1.0 × 0.005 = 0.005 dm³ = 5cm³

Hence, volume of KOH solution required will be 5 cm³.

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Answer:

2 single, 0 double, and 1 triple

Explanation:

H-C≡C-H

[tex]B_{1*2} H_{1*2} = B_{2} H_{2}[/tex]  is required its molecular formula.

First calculate the empirical formula and mass. Compare the molecular mass to the empirical mass to determine the molecular formula.

Empirical Formula

B: 6.444 g × 1 mol/ 7.078 g = 0.9104 mol

H: 1.803 g × 1 mol/1.980mol = 0.9106 mol

Calculate the mole ratios by dividing the moles of each element by the least number of moles.

B: 0.9104 mol/0.5961 mol = 1.5273

H: 0.9106 mol/0.5961 mol = 1.5276

The empirical formula is BH.

Calculate the empirical formula mass.

10.81 + (1 × 1.008) = 11.818

Molecular formula

30/11.818 = 2.5385 ≈ 2

Multiply the subscripts in the empirical formula by 2.

B₁ₓ₂[tex]H_{1}[/tex]ₓ₂ = B₂[tex]H_{2}[/tex]

This compound is diborane and its molar mass is 27.67 g/mol. If you go back and divide the molecular mass by the empirical mass, the result is 2.000. So B₂[tex]H_{2}[/tex]is the correct molecular formula. (27.67/ 11.818= 2.34).

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The responses that can form hydrogen bonds with water molecules are

II. CH₃COOH and IV. CH₃NH₂.

Acetic or ethanoic acid (CH₃COOH) has hydrogen atom bonded to an oxygen atom, so it can form hydrogen bonds with water molecules (see the picture below).

Methylamine (CH₃NH₂) has hydrogen atom bonded to a nitrogen atom, so it can form hydrogen bonds with water molecules.

Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.

Sodium (Na) and ethane can not form hydrogen bonds, because they do not have a hydrogen atom bonded to flourine (F), oxygen (O) and nitrogen (N) atoms.

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710 mL volume in ml of 0.3000 m nacl solution is required to produce 0.2150 moles of nacl.

Molar Concentration = number of moles/ volume

volume = number of moles/ molar concentration

volume = 0.2150/ 0.3000 = 0.71  L

volume required = 0.71 L = 0.71L× 1000 mL/L = 710 mL

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Answer:

4.34 times 10^24

Explanation:

number of atoms=7.2 times Avogadro's number

                           =7.2 times 6.02 times 10^23

                           =4.34 times 10^24

Answer:

Explanation: we will multiple the amount of moles to the Avogadro's number for example:                                                                                                        

                                     7.2*6*10 to the power 23

The Ka of the weak acid is 6.28 × 10⁻⁶.

Ka is the acid dissociation constant, which quantifies the extent of acid dissociation in water.

Balanced chemical reaction (dissociation) of an aqueous solution of a weak acid:

HA(aq) ⇄ H⁺(aq) + A⁻(aq)

pH = 2.708

c(H⁺) = 10⁻²°⁷⁰⁸

c(H⁺) = 1.96 × 10⁻³ M; concentration of hydrogen ions

c(H⁺) = c(A⁻); from balanced chemical reaction

c(HA) = 0.613 M - 1.96 × 10⁻³ M

c(HA) = 0.611 M; concentration of an acid in the solution

Ka = c(H⁺) × c(A⁻) / c(HA)

Ka = (1.96 × 10⁻³ M)² / 0.611 M

Ka = 6.28 × 10⁻⁶; the acid dissociation constant

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When 16.45 g sample of NaCl is dissolved in enough water to make 1.000 l of solution, the solution has a molarity equal to 0.2815 moles NaCl/L solution.

Molarity, or molar concentration, is defined as the number of moles of solute per liter of solution. It can be calculated using the formula given by:

M = n/v

where M = molarity

n = number of moles of solute

v = volume of solution

If the mass of the solute NaCl is 16.45 g, divide it with the molar mass of NaCl to get the number of moles of solute.

n = m/MM

n = 16.45 g/58.44 g/mol

n = 0.2814852841 moles NaCl

If 0.2814852841 moles NaCl is dissolved in enough water to make 1. 000 l of solution, solve its molarity.

M = n/v

M = 0.2814852841 moles NaCl/1.000 l solution

M = 0.2814852841 moles NaCl/L solution

M = 0.2815 moles NaCl/L solution

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The pressure is 8.81 cm of Hg.

The height of the water in the water barometer is h.

h = 883 cm = 8.83 m

The density of water at 20 ° C is p.

p = 998 g/cm³

The gravity of the earth is g.

g = 1 m/s²

The pressure is,

Pressure = Height × Density × Gravity

P = h × p × g

P = 8.83 × 9.98 × 1

P = 8.81 cm of Hg

Therefore, the pressure is 8.81 cm of Hg.

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The number of atoms present in reactants of the following chemical equation C₇H₁₆ + O₂ = CO₂ + H₂O is 7 atoms.

The number of atoms in a compound is shown in the chemical formula of the compound.

A chemical formula is a notation indicating the number of atoms of each element present in a compound.

According to this question, the chemical reaction between heptane and oxygen is given as follows:

C₇H₁₆ + O₂ = CO₂ + H₂O

The chemical formula of hexane shows that carbon has 7 atoms in the reactant side.

Therefore, the number of atoms present in reactants of the following chemical equation C₇H₁₆ + O₂ = CO₂ + H₂O is 7 atoms.

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The concentration of hydroxyl ion is 10^-9 M.

When an electrolyte is dissolved in water, it dissociates into ions.

In the above case, the ions are hydrogen (H+) and hydroxyl (OH-).

At a temperature of 298 K,

The ionic product(Kw of water is

Kw = [H+] [OH-] = 10^-14

Here [H+] = Concentration of hydrogen ions

[OH-] = Concentration of hydroxyl ions

Assuming that the above solution is at a temperature of 298 K, the ionic product(Kw) of water is

10^-14 = [10^-5] [OH-]

[OH-] = 10^-9.

Thus, the concentration of hydroxyl ions is 10^-9 M.

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The NaCl solution will have higher boiling point.

The temperature at which the vapour pressure equals the typical air pressure at sea level is known as the normal boiling point.

A molecular compound is [tex]C_{2} H_{6} O_{2}[/tex]. Meaning that it will continue to be in this state after dissolving:

[tex]C_{2} H_{6} O_{2}[/tex] ⇒ [tex]C_{6} H_{12} O_{6}[/tex] (aq)

Ionic materials include sodium chloride (NaCl). In other words, it will produce ions when it dissolves:

NaCl(s) ⇒ [tex]Na^{+}[/tex](aq) + [tex]Cl^{-}[/tex] (aq)

[tex]C_{2} H_{6} O_{2}[/tex] is a molecule and NaCl is an ionic substance. The boiling points of ionic compounds are higher than those of molecular molecules. NaCl will therefore have a higher boiling point.

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The volume of the sauce required is 529.76 mL

The volume has to do with the space that is occupied by an object. We can see that the unit that has been given for the spaghetti sauce is in the non standard unit of cups of tomato sauce. We are now asked to express this value in the metric unit of milliliter.

We have that;

1qt = 4 cups

x = 2.5 cups

x = 1qt  * 2.5 cups/4 cups

x = 0.56 qt

Also;

1q = 946 mL

0.56 qt =  0.56 qt * 946 mL/1q

= 529.76 mL

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The density of oxygen is 1.43 g/LC.

The periodic table's Group 16 (also known as the oxygen group) contains the nonmetallic chemical element oxygen (O). Oxygen is a colorless, odorless, and tasteless gas that is necessary for all living things. Animals take it up and then change it into carbon dioxide, which plants then use as a source of carbon and release the oxygen back into the atmosphere.

As well as reactions that remove elements from their combinations with one another, oxygen can react with nearly any other element to produce compounds. These reactions, which are frequently accompanied by the evolution of heat and light, are known as combustions. Water is the most significant component.

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Within a water molecule, the electrons spend most of their time attracted more closely to Oxygen atom.

An electron is a negatively charged subatomic particle that can exist either free or bonded to an atom (not bound). An atom has three primary types of particles: protons, neutrons, and the electron, which is bound to it. Together, protons, neutrons, and electrons make up the atom's nucleus.

In nature, electrons can be found both bound inside of atoms and unbound (free electrons). The part of an atom that is negatively charged is caused by electrons. Electrons revolve around the atomic nucleus, which is positively charged, in an atom. In solids, electrons serve as the main conductor of current.

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It is necessary to couple some biochemical reactions because individually some biochemical reactions have +ΔG and coupling them together makes helps to make the overall reaction -ΔG.

Reactions that have a positive value of Gibbs free energy, require additional energy to complete, which can be obtained when it is coupled with the hydrolysis of ATP.

Also, the biochemical reaction which has a negative value of ΔG is non-spontaneous in nature. For those to become spontaneous, the value of ΔG should be negative. The coupling of reaction makes their Gibbs free energy negative and makes them spontaneous.

Therefore it is necessary to couple biochemical reactions to the hydrolysis of ATP.

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The molar mass is 151 g/mol.

The Raout's law is used to describe the relationship between the partial pressures of the solution and that of the solute. Given that we have the partial pressure of the pure solvent is 0.2630 atm and the partial pressure of the solution is 0.2474 atm

Using Raout's law;

Psolution = Psolvent * mole fraction

Number of acetone = 25.00 g/58.08 g/mol = 0.43 moles

Number of substance =  4.231 g/ MM

Where MM = molar mass

0.2474 atm = 0.2630 atm * Moles of acetone/Total number of moles

Let the Moles of substance be x

0.2474 atm = 0.2630 atm *  0.43/0.43 + x

0.2474  = 0.113/0.43 + x

0.2474(0.43 + x) = 0.113

0.106 + 0.2474x =  0.113

0.2474x = 0.113 - 0.106

x = 0.113 - 0.106/0.2474

x = 0.028

Then;

x = 4.231 / MM

0.028 =  4.231 / MM

MM = 4.231 / 0.028

MM = 151 g/mol

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Answer:

Reducing Plastic Waste and Pollution

Explanation:

If I were a scientist I would begin working on reducing the number of plastics that are left in landfills and other wastelands. The first solution that comes to mind is cloning a type of melee worm that feeds off of plastic and styrofoam rather than rotting foods and compost. This would be an extremely positive contribution to society because it would keep the earth from being filled with garbage.

Answer:

This collision makes the electron in the cathode free. These electrons undergo collision with neutral atoms of the gas and ionize them to form ions. The positive ions thus produced move toward the oppositely charged cathode and electrons move towards the anode

The pH of the resulting solution formed by mixing HCl in water is 2.40.

The term pH, which stands for the potential of hydrogen, refers to a measurement of a substance's concentration of hydrogen ions (also known as protons). The pH of a solution provides important clues about its chemical makeup. Nutrient availability, biological function, bacterial behavior, and chemical behavior can all be impacted by pH.

pH = -log[H+], where [H+] is the concentration of H+ ions, is the formula used to determine the pH of any solution. The concentration of H+ ions is equal to the concentration of HCl because HCl is a strong acid and exhibits full dissociation.

Given mass of HCl = 0.45 g

Volume of solution = 2.0 L

We calculate the concentration of H⁺ ions as below:

M = n/V, where

V = volume

n = no. of moles

And no. of moles will be calculated as:

n = W/M, where

W = given mass

M = molar mass

Moles of 0.45 g of HCl = 0.45 g / 36.5g/mol = 0.0123mol

Now we put all these values in the above equation of concentration as:

M = 0.0123mol / 2.0L = 0.0061 M

We will put these values of concentration of H⁺ ions in the pH equation as:

pH = -log(0.006) = 2.22

Hence, 2.22 is the value of pH.

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BaCl2 + CuSO4 → BaSO4 + CuCl2

In the beaker, we would find both reactants and products.

The term reaction has to do with an interaction between reactants to give products. Sometimes, there is only a single reactant as we can see in the equation written as follows; [tex][Cu(H_{2} O)_{6} ]^{2+} ------- > [Cu(H_{2} O)_{5} (OH^-)]^+ + H^+[/tex]

In this case, a hydrogen ion leaves one of the water ligands to yield the species on the left hand side of the reaction equation. The double arrow in the reaction implies that this is a reversible reaction. A reversible reaction is one that could go either forward or backwards.

In a state of dynamic equilibrium, we always have the reactants and the products in the beaker. This is because, reactants are being converted to products and products to reactant at the same rate.

Hence in the beaker, we would find both reactants and products.

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7.8×10⁻² moles of water were in the sample of the salt

m(NiCl₂·6H₂O) = 3.5 g; mass of a hydrous salt

m(NiCl₂) = 2.1 g; mass of an anhydrous salt

m(H₂O) = m(NiCl₂·6H₂O) - m(NiCl₂)

m(H₂O) = 3.5 g - 2.1 g

m(H₂O) = 1.4 g; mass of water

M(H₂O) = 18 g/mol; the molar mass of water

n(H₂O) = m(H₂O) ÷ M(H₂O)

n(H₂O) = 1.4 g ÷ 18 g/mol

n(H₂O) = 0.078 mol; amount of water in the sample

The mole is an SI unit which measures the number of particles in substance. One mole is equal to 6.022·10²³ atoms.

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The final temperature of the water is 64.59°C.

Given,

Heat (Q) = 3.31 x 103 J

Mass of water (m) = 18.5 gm

Initial temperature (Ti) = 22°C

Final temperature =?

Specific heat - The heat required to raise the temperature of a substance by one-degree Celcius. The relation between heat and temperature change is Q = m × c × ΔT.

where Q = heat energy

m = mass of the substance

c = specific heat of the substance

ΔT = change in temperature

Now, we will use the same formula to calculate the final temperature of the water-

Q = m × c × ΔT

Q = m × c × ( final temperature - initial temperature)

3.31 x 103 = 18.5 x 4.2 x (final temperature - 22)                  

(Specific heat of water (c) = 4.2 J/g degrees Celcius)

3.31 x 103 = 77.70 x (final temperature - 22)

3.31 x 103 / 77.70 = final temperature - 22

33100/777 = final temperature - 22

42.59 = final temperature - 22

Final temperature= 42.59 + 22 = 64.59°C

Hence, the final temperature of the water is  64.59°C.

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Dissolve the naphthalene in minimum amount of hot methanol and hot filter the suspension. Impure samples of naphthalene can be purified by sublimation.

Certain organic substances change directly from the solid to the gaseous state when heated, without going through the liquid state. This process is called sublimation. In this process, the naphthalene generated becomes smoke and impurities remain. Steam can be cooled by condensation. This method is very useful for separating volatile solids from non-volatile solids.

Impure sublimable organic compounds are placed in a porcelain dish and covered with perforated filter paper. Place a cotton-plugged funnel on top of the filter paper to prevent organic compound vapors from escaping. A porcelain bowl is gently heated.

Organic compounds sublimate and vapor rises through the holes in the filter paper into the funnel. Because the funnel is cooler than the bowl, vapors condense on the cool walls of the funnel to form pure crystals of organic compounds.

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There are 2.05×[tex]10^{25}[/tex] titantium atoms in the cube.

STEP 1. Converting inches to cm

length in cm = 2.81 in*(2.54cm/1 in)

length in cm =7.1374

STEP 2: Determining mass of cube from the density

density = mass/volume

mass = density * volume

mass = 4.50 g/cm^2*(7.1374 cm) ^3

mass = 1635.18 g

STEP 3: Converting mass of titanium cube to number of atoms

no. of. Ti. atoms = 1636.18 g Ti * ( [tex]\frac{1 mol Ti}{47.867 g}[/tex]) ([tex]\frac{6.022*10^{23} atoms}{1 mol Ti}[/tex])

no. of. Ti. atoms = 2.058*10^25 atoms

Since the given values have 3 significant figures, the final answer must be:

no. of. Ti. atoms = 2.05*10^25 Ti atoms.

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