Answer: v = 2π2 Kme2 Z / nh
Explanation:
The formula for velocity of an electron in the nth orbit is given as,
v = 2π2 Kme2 Z / nh
v = velocity
K = 1/(4πε0)
m= mass of an electron
e = Charge on an electron
Z= atomic number
h= Planck’s constant
n is a positive integer.
How many GL are there in 8.52 x 10^10 fl oz?
Answer:
2.52 x 10^10
Explanation:
1 Gl = 33814022600 fl Oz = 3.38 x 10^10 fl oz
x = 8.52 x 10^10 fl oz
8.52 x 10^10 = 3.38 x 10^10x
x = 8.52 x 10^10 / 3.38 x 10^10
x = 2.52071005917 = 2.52 x 10^10
x = 2.52 x 10^10
a sample of lead has a mass of 150.0 g what amount of lead in moles does the sample contain
Answer:
0.723 mol
Explanation:
Mole -
Moles is denoted by given mass divided by the molecular mass ,
Hence ,
n = w / m
n = moles ,
w = given mass ,
m = molar mass .
From the information of the question ,
w = 150.0 g
As we known the molar mass of lead is -
m = 207.2 g/mol
Hence , the value for the sample of mole can be calculated by using the above formula ,
n = w / m
putting the respective values ,
n = 150.0 g / 207.2 g/mol = 0.723 mol
Final answer:
A 150.0 g sample of lead contains 0.724 moles, calculated by dividing the mass of the sample by lead's atomic mass of 207.2 g/mol.
Explanation:
The question asks for the calculation of the number of moles of lead in a 150.0 g sample. Using the atomic mass of lead (207.2 g/mol), which is the average atomic mass considering all its naturally occurring isotopes, the calculation is straightforward.
First, the mass of the lead sample is divided by lead's atomic mass to find the number of moles:
Moles of lead = mass of lead sample / atomic mass of lead = 150.0 g / 207.2 g/mol
Therefore, 0.724 moles of lead are present in a 150.0 g sample.
The half-lives for the forward and reverse reactions that are first order in both directions are 24ms and 39 ms, respectively. Calculate the corresponding relaxation time (s) for the return to equilibrium after a temperature jump. Please enter your answer with two significant figures (unit: s).
Explanation:
The given data is as follows.
[tex](t_{\frac{1}{2}})_{1}[/tex] = 24 ms,
[tex](t_{\frac{1}{2}})_{2}[/tex] = 39 ms,
where, [tex](t_{\frac{1}{2}})_{1}[/tex] = half-life for the forward reaction
[tex](t_{\frac{1}{2}})_{2}[/tex] = half-life for the backward reaction
It is known that the formula for first-order reaction is as follows.
[tex]t_{\frac{1}{2}} = \frac{0.693}{K}[/tex]
Therefore,
[tex]K_{1} = \frac{0.693}{(t_{\frac{1}{2}})_{1}}[/tex]
= [tex]\frac{0.693}{24 ms}[/tex]
= 0.0289 [tex]ms^{-1}[/tex]
[tex]K_{2} = \frac{0.693}{(t_{\frac{1}{2}})_{2}}[/tex]
= [tex]\frac{0.693}{39 ms}[/tex]
= 0.0178 [tex]ms^{-1}[/tex]
Hence, formula for the relaxation time is as follows.
[tex]\tau = \frac{1}{K_{1} + k_{2}}[/tex]
= [tex]\frac{1}{(0.0289 + 0.0178) ms^{-1}}[/tex]
= 21.41 ms
Thus, we can conclude that the corresponding relaxation time(s) for the return to equilibrium after a temperature jump is 21.41 ms.
Determine whether each carbohydrate is best described as a monosaccharide, a disaccharide, or a polysaccharide
Answer options from an alternative source
fructose lactose starch glucose celluloseAnswer:
fructose -monosaccharide lactose - disaccharide starch - polysaccharideglucose - monosaccharide cellulose - polysaccharideExplanation:
Monosaccharides are carbohydrates that are the simplest form of a sugar. They cannot be further broken down into smaller carbohydrates, and represent the basic building block for carbohydrates. Monosaccharides can form disaccharides, which are the sugar formed when two monosaccharides join together, or polysaccharides, which are chains of monosaccharides.
Carbohydrates can be categorized as monosaccharides, disaccharides, or polysaccharides based on the number of sugar units they contain. Monosaccharides have one, disaccharides have two, while polysaccharides have multiple sugar units.
Explanation:The type of carbohydrate is determined by the number of sugar units it contains. Monosaccharides consist of one sugar unit, examples being glucose and fructose. Disaccharides consist of two sugar units, with lactose and sucrose being examples. Polysaccharides contain many sugar units, with examples including starch and cellulose.
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The density of SiO2 is 2.27 g cm-3. Given that its structure is amorphous, calculate the number of molecules per unit volume, in nm-3. Compare your result with (a) and comment on what happens when the surface of an Si crystal oxidizes. The atomic masses of Si and O are 28.09 and 16,respectively
Answer:
Explanation:
Oxidation is defined as the reaction of oxygen and a substrate which could be a metal, non-metal etc. Pure Silicon can be found to be too reactive and hence forms alloys with non-metals.
Therefore, oxidation of silicon will form a layer of silicon dioxide on the surface of the silicon and hence, the crystal Silicon structure is partly lost with the formation of an amorphous SiO2. An example of a feasible oxidation of silicon is thermal oxidation which follows the equation:
Si + 2H2O -> SiO2 + 2H2
Si + O2 -> SiO2
Final answer:
The number of SiO2 molecules per unit volume in nm-3 is calculated to be 22.8 molecules per nm³ based on the density and molar mass of SiO2. This calculation reveals the considerable volume expansion that occurs when the surface of a Si crystal oxidizes to form SiO2, potentially impacting semiconductor properties.
Explanation:
To calculate the number of SiO2 molecules per unit volume in nm-3, we first need to find the molar mass of SiO2. The atomic masses of Si and O are 28.09 and 16, respectively. Thus, the molar mass of SiO2 is 28.09 + 2(16) = 60.09 g/mol.
Given the density of SiO2 is 2.27 g/cm3, we can calculate the number of moles in 1 cm3 as follows:
Number of moles = density / molar mass = 2.27 g/cm3 / 60.09 g/mol = 0.0378 mol/cm3.Since 1 mol contains Avogadro's number of molecules (6.022 x 1023 molecules/mol), the number of molecules in 1 cm3 is 0.0378 mol/cm3 x 6.022 x 1023 = 2.28 x 1022 molecules/cm3.Converting cm3 to nm3, where 1 cm3 equals 1 x 1021 nm3, the number of molecules per nm3 is (2.28 x 1022) / (1 x 1021) = 22.8 molecules/nm3.Regarding the effect of surface oxidation on a Si crystal, the expansion of volume during the transformation from Si to SiO2 implies that the material becomes less densely packed with increased volume. Given that 0.44 Å of Si is used to obtain 1.0 Å of SiO2, this indicates that the oxidation process introduces more space within the structure due to the larger volume of SiO2 compared to Si. This expansion could affect the electrical and mechanical properties of silicon components, particularly in semiconductor applications, where precise control of material properties is essential.
A lithium atom starts from rest at a position x = xo and falls toward zinc atom with an acceleration that depends on their separation as a(x) = 4Eϵ/m { 12 (σ^12/σ^13) -6 (σ^6/σ^7) where ϵ, m, and σ are positive constants, and the zinc atom stays fixed at position x = 0, Assume that xo > 2^(1/6)σ. a. Find an expression for how the velocity of the moving lithium atom depends on x. (It will also depend on ϵ, m, xo and σ) b. What is the distance of closest approach of the the two atoms (in terms of σ and xo)?
Answer:
Please refer to the attachment for answers.
Explanation:
Please refer to the attachment for explanation
A reaction in which a substance reacts with oxygen, emitting heat and forming oxygen-containing compounds is an example of a(n):
A) acid-base reaction.
B) combustion reaction.
C) precipitation reaction.
D) gas evolution reaction.
Answer: B) combustion reaction.
Explanation:
A) acid-base reaction: When an acid reacts with a base, to form metal salt and water, this type of reaction is Acid Base reaction.
Example: [tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]
B) combustion reaction: When a hydrocarbon reacts with oxygen to produce carbon dioxide and water, this type of reaction is combustion reaction.
[tex]CH_4+2O_2\rightarrow CO_2+2H_2O[/tex]
C) precipitation reaction: a reaction in which aqueous solution of two compounds on mixing react to form an insoluble compound which separate out as a solid are called precipitation reactions.
[tex]Na_2SO_4(aq)+BaCl_2(aq)\rightarrow BaSO_4(s)+NaCl(aq)[/tex]
D) gas evolution reaction: a reaction in which one of the product is formed as a gas.
[tex]CaCO_3(s)\rightarrow CaO(s)+CO_2(g)[/tex]
Predict whether each of the following bonds is ionic, polar, covalent, or nonpolar covalent:
a) Si--O;
b) K--Cl;
c) S--F;
d) P--Br;
e) Li--O;
f) N--P.
Predict whether each of the following bonds is no polar covalent, polar covalent, or ionic
Bond. Electro negativity Type of bond
Si- O
k-Cl
I-I
C-H
a) Si--O: Polar Covalent
b) K--Cl: Ionic
c) S--F: Polar Covalent
d) P--Br: Polar Covalent
e) Li--O: Ionic
f) N--P: Covalent
a) Si--O: Polar Covalent. Silicon (Si) and oxygen (O) have different electronegativities, causing unequal sharing of electrons. The oxygen atom attracts electrons more strongly, resulting in a partial negative charge on oxygen and a partial positive charge on silicon.
b) K--Cl: Ionic. Potassium (K) and chlorine (Cl) have significantly different electronegativities. K transfers an electron to Cl, forming K⁺ and Cl⁻ ions held together by electrostatic attraction.
c) S--F: Polar Covalent. Sulfur (S) and fluorine (F) have distinct electronegativities, leading to unequal electron sharing. F pulls electrons more, inducing partial charges on both atoms.
d) P--Br: Polar Covalent. Phosphorus (P) and bromine (Br) have differing electronegativities, causing uneven electron distribution and partial charges on the atoms.
e) Li--O: Ionic. Lithium (Li) and oxygen (O) have a significant electronegativity difference. Li loses an electron to O, resulting in Li⁺ and O²⁻ ions, held together by electrostatic forces.
f) N--P: Covalent. Nitrogen (N) and phosphorus (P) have similar electronegativities, allowing for equal electron sharing in a covalent bond.a) Si--O: Polar Covalent.
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A reaction was performed in which 1.500 g of camphor was reduced by an excess of sodium borohydride to make 1.036 g of isoborneol. Calculate the theoretical yield and percent yield for this reaction.
Answer: The percent yield of the reaction is 68.16 %.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
For camphor:Given mass of camphor = 1.500 g
Molar mass of camphor = 152.23 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of camphor}=\frac{1.500g}{152.23g/mol}=9.85\times 10^{-3}mol[/tex]
The chemical equation for the reaction of camphor and sodium borohydride follows:
[tex]\text{Camphor}+NaBH_4\rightarrow \text{Isoborneol}[/tex]
As, sodium borohydride is present in excess. It is an excess reagent. So, camphor is the limiting reagent because it limits the formation of products.
By Stoichiometry of the reaction:
1 mole of camphor produces 1 mole of isoborneol
So, [tex]9.85\times 10^{-3}mol[/tex] of camphor will produce = [tex]\frac{1}{1}\times 9.85\times 10^{-3}mol=9.85\times 10^{-3}mol[/tex] of isoborneol
Now, calculating the mass of isoborneol from equation 1, we get:Molar mass of isoborneol = 154.25 g/mol
Moles of isoborneol = [tex]9.85\times 10^{-3}[/tex] moles
Putting values in equation 1, we get:
[tex]9.85\times 10^{-3}mol=\frac{\text{Mass of isoborneol}}{154.25g/mol}\\\\\text{Mass of isoborneol}=(9.85\times 10^{-3}mol\times 154.25g/mol)=1.52g[/tex]
To calculate the percentage yield of isoborneol, we use the equation:[tex]\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]
Experimental yield of isoborneol = 1.036 g
Theoretical yield of isoborneol = 1.52 g
Putting values in above equation, we get:
[tex]\%\text{ yield of isoborneol}=\frac{1.036g}{1.52g}\times 100\\\\\% \text{yield of isoborneol}=68.16\%[/tex]
Hence, the percent yield of the reaction is 68.16 %.
What is the minimum number of moles of sodium borohydride required to fully reduce 0.55 grams of benzophenone? Enter only the number with two significant figures.
Answer:
see explanation below
Explanation:
In this case, is pretty easy. This is a reduction reaction to form the respective alcohol.
Now for each mole of benzophenone that it's present, reacts with 1 mole of Sodium borohydryde, so, all we need to do, is to calculate the moles of benzophenone presents and these, would be the same moles of NaBH4 so:
moles Benzophenone : m/MM
The molar mass of benzophenone reported is 182.22 g/mol so:
moles Benzophenone = 0.55/182.22 = 3.02x10⁻³ moles
so the moles of NaBH₄ = 3.02x10⁻³ moles
A chemist measures the amount of bromine liquid produced during an experiment. He finds that 1.33 g of bromine liquid is produced. Calculate the number of moles of bromine liquid produced. Round your answer to 3 significant digits.
Answer:
8.32×10⁻³ moles of liquid Br₂ were produced.
Explanation:
You have the mass of bromine liquid produced and you must calculate the moles. Therefore you divide mass / molar mass Br
Bromine is a diatomic molecule, Br₂ so molar mass is 159.8 g/mol
1.33 g / 159.8 g/mol = 8.32×10⁻³ moles
How much heat (kJ) is absorbed by 229.1 g of water in order for the temperature to increase from 25.00∘C to 32.50∘C?
Q2) Calculate the amount of heat required to raise the temperature of a 34 g sample of water from 9 ∘C to 23 ∘C.
Answer:
(Q1) 9.42 kJ.
(Q2) 1.999 kJ
Explanation:
Heat: This is a form of Energy that brings about the sensation of warmth.
The S.I unit of Heat is Joules (J).
The heat of a body depend on the mass of the body, specific heat capacity, and temperature difference. as shown below
Q = cm(t₂-t₁) ........................ Equation 1
(Q1)
Q = cm(t₂-t₁)
Where Q = amount of heat absorbed, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature.
Given: m = 229.1 g = 0.2991 kg, t₁ = 25.0 °C, 32.50 °C
Constant: c = 4200 J/kg.°C
Substituting into equation 1
Q = 0.2991×4200(32.5-25)
Q = 1256.22(7.5)
Q = 9421.65 J
Q = 9.42 kJ.
Hence the heat absorbed = 9.42 kJ
(Q2)
Q = cm(t₂-t₁)
Where Q = amount of heat required, c = specific heat capacity of water, m = mass of water, t₁ = initial temperature, t₂ = final temperature.
Given: m = 34 g = 0.034 kg, t₁ = 9 °C, t₂ = 23 °C
Constant: c = 4200 J/kg.°C
Q = 0.034×4200(23-9)
Q = 142.8(14)
Q = 1999.2 J
Q = 1.999 kJ.
Thus the Heat required = 1.999 kJ
To calculate the amount of heat absorbed by water, you can use the formula Q = mcΔT.
Explanation:To calculate the amount of heat absorbed by water in order for the temperature to increase, you can use the formula:
Q = mcΔT
where Q is the heat absorbed, m is the mass of water, c is the specific heat capacity of water, and ΔT is the change in temperature.
For the first question, the specific heat capacity of water is 4.18 J/g⋅°C. Substitute the given values into the formula to calculate the heat absorbed.
For the second question, you can follow the same steps using the given mass, specific heat capacity, and change in temperature.
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What is the frequency of green light that has a wavelength of 543 nm? (c = 3.00 x 10⁸ m/s)
Answer:
ν = 5.53 x 10⁶ Hz
Explanation:
The frequency of a radiation, ν ,is inversely propotional to its wavelength, and is given by:
ν = c/λ where
ν = frequency
c: speed of light, 3 x 10⁸ m/s
λ: wavelength in m
Think of frequency as the number of waves per second.
We can directly compute the answer by first converting the wavelength to m for unit consistency and then plugging the values.
1 m = 10⁹ nm
543 nm x ( 1 m / 10⁹ nm ) = 5.43 x 10⁻⁷ m
ν = c/λ = 3 x 10⁸ m/s / 5.43 x 10⁻⁷ m = 5.53x 10¹⁴ s⁻¹
In the metric system the unit s⁻¹ is called Hertz.
ν = 5.53 x 10¹⁴ Hz
The frequency of green light with a wavelength of 543 nm is approximately 5.52 x 10^14 Hz.
Explanation:The frequency of electromagnetic waves can be calculated using the equation: frequency = speed of light / wavelength. In this case, we have a wavelength of 543 nm and the speed of light is 3.00 x 10^8 m/s. First, we need to convert the wavelength to meters. There are 1 x 10^9 nm in a meter, so the wavelength is 543 x 10^-9 m. Plugging these values into the equation, the frequency of the green light is approximately 5.52 x 10^14 Hz.
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Compounds in a and b were named incorrectly. On a sheet of paper draw the molecule that fits the given description. From the structure you drew determine the correct IUPAC name. Write the correct IUPAC name in the blank.
a) 4-methyl-3-propylheptane
(I answered 4-ethyl-3-methylheptane and it was incorrect)
b) 2-ethyl-6,6,6-trimethylhexane
Answer:
a. 4—ethyl—5—methyloctane
b. 2,2,6—trimethyloctane
Explanation:Please see attachment for explanation
4-hydroxypentanal reacts with one equivalent of methanol to form a cyclic acetal.
Draw curved arrows to show the movement of electrons in this step of the reaction mechanism.
Answer:
Explanation:
The equation is given as:
CH3CHOHC2H4CHO + CH3OH --> CYCLIC ACETAL + H2O
This above equation is carried out in the presence of a strong acid. There are five mechanisms employed and they are:
Step 1:
Initial formation of the hemiacetal which takes several steps
Step 2:
Addition of a proton. The hemicetal is protonated on the hydroxyl group (-OH group)
Step 3:
As seen a bond is broken to give the H2O molecule and a resonance stabilized cation.
The carbonyl group on the cation is enriched with the oxygen-18 got from the H2O molecule as seen in the mechanism.
Step 4:
An attraction occurs between electrophile and nucleophile i.e the stabilised cation and the lone paids of the methanol.
Step 5:
Finally, a proton (+) is removed from the molecule by a lone pair of electron on the methanol.
Attached are the Steps 1 - 5 mechanism below
If the metabolic rate of eggs at 25oC is 0.3 ml O2/hr and their metabolic rate at 35oC is 0.6 ml O2/hr, what is the Q10
Answer:
Q₁₀ = 2
Explanation:
The Q₁₀ can be calculated by the following equation:
[tex] Q_{10} = \frac{R_{2}}{R_{1}}^{10^{\circ} C/(T_{2}-T_{1})} [/tex]
where R: is the rate and T: is the temperature
With R₁=0.3 ml O₂/h, R₂=0.6 ml O₂/h, T₁=25 °C and T₂=35 °C, the Q₁₀ is:
[tex] Q_{10} = \frac{0.6 ml O_{2}/h}{0.3 ml O_{2}/h}^{10^{\circ} C/(35 -25)^{\circ} C} = 2 [/tex]
Therefore the Q₁₀ temperature coefficient of eggs is 2.
I hope it helps you!
What is the name of this molecule?
Η Η Η
Η
Η
Η
H-C-C-C-C- C- C-H
Η Η Η Η Η Η
Ο
Pentane
Ο
B. 2-pentane
C. Hexyne
D. Hexane
Answer: The name of the above compound is Hexane
Explanation: The Formula for Homolougous series i.e Alkane family is CnH2n+2
The number of the Carbon above is 6 and the number of the Hydrogen is 14.
That means it corroborates with the above formula for the alkame family
C6H(2×6)+2 =C6H12+2
Final answer is C6H14
From the number 6 means "Hex" with the family name "ane"
The name results to Hexane
g Isopropyl methyl ether is slightly soluble with water because the oxygen atom of ethers with or fewer carbon atoms can form a few hydrogen bonds with water.
True/False
Answer:
True
Explanation:
The isopropyl methyl ether is a polar molecule because its dipole moment is different from 0. The ether is formed by a molecule of oxygen between carbons, in this case, the oxygen is bonded to an isopropyl, which has 3 carbons, and to a methyl, with only one carbon, so, the dipole, which is the polar difference between the atoms, will be stronger in the isopropyl bond.
Because of that, the oxygen will have a partial negative charge. The water is also a polar substance, and "like dissolve like". Because water has a dipole in the hydrogen and in the oxygen, the hydrogen of it may bond with the oxygen of the ether, forming a hydrogen bond, which is strong.
Deprenyl is an enzyme inhibitor that helps prevent the metabolism of dopamine in the brain. The chemical formula of Deprenyl is C13H17NHCl. The appropriate dose for treating Parkinson’s disease is 100 μg/(day*kg body weight). For a 70 kg
Answer:
0.007 g of deprenyl dose is required fro the patient with body mass of 70 kilograms.
Explanation:
The dose for treating Parkinson’s disease = 100 μg/kg body weight
Mass of patient's body = 70 kg
Amount of dose of deprenyl required = 100 μg/kg × 70 kg = 7,000 μg
1 μg = 0.00001 g
7,000 μg = 7,000 × 0.000001 g = 0.007 g
0.007 g of deprenyl dose is required fro the patient with body mass of 70 kilograms.
Deprenyl is a chemical compound used as a treatment for Parkinson's disease. It works by inhibiting the enzyme that breaks down dopamine, increasing dopamine levels in the brain. The appropriate dose for treating Parkinson's disease with Deprenyl is 100 μg/day per kg of body weight.
Explanation:Deprenyl is a chemical compound with the formula C13H17NHCl. It is an enzyme inhibitor that helps prevent the metabolism of dopamine in the brain. Deprenyl is commonly used as a treatment for Parkinson's disease, a neurodegenerative disorder characterized by a loss of dopaminergic neurons.
Deprenyl works by inhibiting the enzyme monoamine oxidase-B (MAO-B), which is responsible for breaking down dopamine in the brain. By preventing the breakdown of dopamine, Deprenyl helps to increase dopamine levels, which can alleviate symptoms of Parkinson's disease.
The appropriate dose of Deprenyl for treating Parkinson's disease is 100 μg/day per kg of body weight. For example, for a 70 kg individual, the appropriate dose would be 7000 μg or 7 mg per day.
Draw the structures of the starting materials needed to make 2-methylhept-3-yne in the spaces provided. The starting materials may be any bromoalkane having five carbons or fewer.
Answer: answered
Explanation:
In an aqueous solution of a certain acid the acid is 4.4% dissociated and the pH is 3.03. Calculate the acid dissociation constant Ka of the acid. Round your answer to 2 significant digits.
Answer:
4.1x10⁻⁵
Explanation:
The dissociation of an acid is a reversible reaction, and, because of that, it has an equilibrium constant, Ka. For a generic acid (HA), the dissociation happens by:
HA ⇄ H⁺ + A⁻
So, if x moles of the acid dissociates, x moles of H⁺ and x moles of A⁻ is formed. the percent of dissociation of the acid is:
% = (dissociated/total)*100%
4.4% = (x/[HA])*100%
But x = [A⁻], so:
[A⁻]/[HA] = 0.044
The pH of the acid can be calcualted by the Handersson-Halsebach equation:
pH = pKa + log[A⁻]/[HA]
3.03 = pKa + log 0.044
pKa = 3.03 - log 0.044
pKa = 4.39
pKa = -logKa
logKa = -pKa
Ka = [tex]10^{-pKa}[/tex]
Ka = [tex]10^{-4.39}[/tex]
Ka = 4.1x10⁻⁵
To calculate the acid dissociation constant Ka, use the pH to find the hydrogen ion concentration [H+], then determine the initial concentration of the acid before dissociation, and finally calculate Ka using the formula [H+]^2 / initial concentration. The Ka value for the acid in question is approximately 4.1 × 10^-6.
Explanation:To calculate the acid dissociation constant Ka of the acid based on the given information, we can follow these steps:
First, determine the hydrogen ion concentration [H+] using the pH value. The pH is the negative logarithm of the hydrogen ion concentration. Since the pH is 3.03, [H+] = 10-3.03.Next, calculate the initial concentration of the acid before dissociation. The acid is 4.4% dissociated, which means that 4.4% of the initial concentration has turned into hydrogen ions and its conjugate base. If we denote the initial concentration as C, then the concentration of [H+] is 0.044 × C.Using the value of [H+], we can solve for C. C = [H+] / 0.044.Finally, the Ka value is calculated by dividing the concentration of the hydrogen ions by the initial concentration, which is [H+]^2 / C.Let's perform the calculations:
[H+] = 10-3.03 = 9.33 × 10-4 MC = 9.33 × 10-4 M / 0.044 = 2.12 × 10-2 MKa = (9.33 × 10-4 M)^2 / 2.12 × 10-2 M = 4.1 × 10-6Therefore, the acid dissociation constant Ka for the acid is approximately 4.1 × 10-6.
You need to make 10 mL of 2 mg/mL solution of protein and you have 25 mg/mL solution. How much protein solution and water do you need to mix in order to make the required solution?
Answer:
The protein solution needed is 0.8mL and the water needed 1000mL
Explanation:
C1 = 2 mg/mL
V1 = 10 mL
C2 = 25 mg/mL
V2 =?
C1V1 = C2V2
2 x 10 = 25 x V2
V2 = 20/ 25
V2 = 0.8mL
The protein solution needed is 0.8mL and the water needed 1000mL
Are the bonds in each of the following substances ionic, nonpolar covalent, or polar covalent?
(a) S8
(b) RbCl
(c) PF3
(d) SCl2
(e) F2(f) SF2
Answers :
Solution of each part is given below.
Explanation:
a) [tex]S_8[/tex] non polar covalent ( because each sulphur atom shares electron and the net dipole moment is zero.)
b) RbCl ionic ( Rb have good tendency to donate electron and chlorine is too electro negative therefore they make strong ionic bond.)
c) [tex]PF_3[/tex] polar covalent ( because of triagonal pyramidal geometry and strong electronegativity of F atom it is polar and covalency is due to the share of electron with each F atom.)
d) [tex]SCl_2[/tex] polar covalent ( because of tetrahedral geometry and sharing of electrons between S and Cl.)
e) [tex]F_2[/tex] non polar covalent ( because of linear geometry they are non polar and bond between them is formed due to sharing electrons.)
f) [tex]SF_3[/tex] polar covalent ( because of T- shape geometry they are non polar and due to sharing of electrons they are polar covalent.)
Hence, this is the required solution.
The nature or type of bonds formed by molecules and compounds are greatly influenced by the chemical properties of the element.
Data;
S8RbClPF3SCl2F2SF2Bonds in the CompoundsThe chemical properties of an element often affects how it bonds with other elements to form a compound. In this case, we have several compounds given.
S8: This is a non-polar covalent molecule.
RbCl: This is an ionic compound because it consists of very strong electropositive and electronegative elements.
PF3: This is a polar covalent compound due to the nature of phosphorous.
SCl2: This is a polar covalent compound
F2: This is a non-polar covalent compound
Sf3: This is a polar covalent compound
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How many electrons move past a fixed reference point every tttd = 1.25 psps if the current is iii = 4.8 μAμA ? The charge on a single electron is about â1.6Ã10â19Câ1.6Ã10â19C .
Answer:
38 electrons
Explanation:
From Faraday's first law of electrolysis which states that during electrolysis, the mass of a substance deposited at the electrode is proportional to the quantity of electricity passing through it. Mathematically , M ∝ Q
but M = zQ and from electricity, Q =It, hence the equation becomes M = zIt.
where M = Mass of substance deposited in g, and Q =Quantity of electricity in coulombs(C)
I = current in ampere(A)
t = time in seconds
z = Chemical Equivalent in g/C
hence, given t = 1.25 ps and i = 4.8 μA
Using Q = It = 1.25 ps × 4.8 μA , converting the ps (pico secs) to secs and micro ampere to ampere, Q = 1.25 × 10-12s × 4.8 × 10-6A = 6 × 10-18C
From 1 mole of electron is equal to the quantity of charge which is also equal to 96500C/mol,
Hence, number of moles of electrons = 6 × 10-18C / 96500C/mol
number of moles = 6.218 ×10-5 × 10-18 = 6.218 × 10-23moles
Recalling that, number of moles = number of electrons / Avogadro's constant and Avogardos constant = 6.023 × 10raised to the power of 23/mol
number of electrons = number of moles × 6.023 × 1023/mol
number of electrons = 6.218 × 10-23moles × 6.023 × 1023/mol = 37.50 which is approximately 38
Hence 38 electrons moved past the fixed reference point.
To calculate the number of electrons that move past a fixed reference point, use the formula: Number of electrons = (Current × Time × Charge on a single electron) / Electron charge. Plugging in the given values, the number of electrons is approximately 1.875 × 10^10 electrons.
Explanation:To calculate the number of electrons that move past a fixed reference point, we can use the formula:
Number of electrons = (Current × Time × Charge on a single electron) / Electron charge
Plugging in the given values, we have:
Number of electrons = (4.8 μA × 1.25 ps × 10^-12 C) / (1.6 × 10^-19 C)
Simplifying the expression, we find that the number of electrons is approximately 1.875 × 10^10 electrons.
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Imagine that you are given the mass spectra of these two compounds, but the spectra are missing the compound names.
Which peaks occur in one isomer but not the other isomer?
That is, which peaks could be used to distinguish one isomer from the other?
The structures of the isomers and the m/z values of their peaks are not given in the question. The complete question is provided in the attachment
Answer:
Compound 2 (2,5-dimethylhexane) will not have the peaks at 29 and 85 m/z
Explanation:
The fragmentation of molecules by electron ionization of mass spectrometer occurs according to Stevenson's Rule, which states that "The most probable fragmentation is the one that leaves the positive charge on the fragment with the lowest ionization energy". This is much like the Markovnikov's Rule in organic chemistry which has predicted the formation of most stable carbocation and the addition of hydrogen halide to it.
The mass spectra of compound 1 (2,4-dimethylhexane) will contain all the m/z values mentioned in the question. Each peak indicate towards homologous series of fragmentation product of the compound 1. The first peak can be attributed to ethyl carbocation (m/z = 29), with the increase of 14 units the next peak indicates towards propyl carbocation (m/z = 43) and onwards until molecular ion peak of 114 m/z.
Compound 2 (2,5-dimethylhexane) structure shows that the cleavage of C-C bond will not yield a stable ethyl and hexyl carbocation. Hence, no peaks will be observed at 29 and 85 m/z. The absence of these two peaks can be used to distinguish one isomer from the other.
Nitrogen forms a number of compounds with oxygen, for example, Nitrous oxide, N2O is 63.65% by mass.
A second compound, which contains two atoms of nitrogen per molecule, is 36.86% N by mass. How many oxygen atoms are in the second compound? Write your answer as a whole number.
Answer: there are 3 atoms of oxygen in the compound, and the compound is N2O3
Explanation:Please see attachment for explanation
The nitrogen-containing compound is 36.86% nitrogen by mass, and after calculating, it is determined that the compound contains three oxygen atoms.
Explanation:The question asks how many oxygen atoms are in a nitrogen-containing compound given that the compound is 36.86% nitrogen by mass and contains two nitrogen atoms per molecule. To find out, we start by using the percent composition of nitrogen to determine the total molecular mass of the compound. Nitrogen has an atomic mass of 14.01 amu, and since there are two nitrogen atoms, that contributes 28.02 amu to the molecular mass. Since nitrogen makes up 36.86% of the compound by mass, we calculate the total molecular mass of the compound by dividing the mass of nitrogen in the compound by the percentage of nitrogen (28.02 amu / 0.3686), which equals approximately 76 amu as the molar mass of the compound.
Now we subtract the mass contributed by nitrogen from the total molecular mass to find the mass of oxygen in the molecule (76 amu - 28.02 amu). This leaves approximately 47.98 amu for the oxygen atoms. Oxygen has an atomic mass of approximately 16 amu, so by dividing the mass of oxygen by the atomic mass of oxygen (47.98 amu / 16 amu), we find there are about 3 oxygen atoms in the molecule.
Therefore, the second compound contains three oxygen atoms, and you would write the answer as a whole number: 3.
A solution was made by dissolving 25 g of potassium malonate K2C3H2O4 (MM=180.2 g/mol) in water. The total volume of that solution is 455 ml.
a) calculate the pH of that solution
b) calculate the concentration of malonic acid (H2C3H2O4) in that solution
c) what would happen to concentration of malonic acid (increase or decrease in the above solution if pH is decreased by addition of 12 M HCL?
Explain your answer using net ionic equations and Le chatelier's principle.
Answer:
a) pH = 9.8
b) 2.2 x 10⁻⁸ = [ H₂C₃H₂O₄ ]
c) decrease
Explanation:
The equilibriums involved in this question are:
C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + OH⁻ (1) Kb₁ =[HC₃H₂O₄⁻][OH⁻]/[C₃H₂O₄²⁻ ]
HC₃H₂O₄⁻ + H₂O ⇄ H₂C₃H₂O₄ +OH⁻ (2) Kb₂=[ H₂C₃H₂O₄]/[OH⁻]/[HC₃H₂O₄⁻]
The kas for malonic acid, H₂C₃H₂O₄, from reference tables are:
Ka (H₂C₃H₂O₄ )= 1.4 x 10⁻³
Ka ( HC₃H₂O₄⁻ ) = 2.0 x 10⁻⁶
a) We can calculate the Kbs for the conjugate bases of the weak malonic acid from Kw = Ka x Kb
Kb (C₃H₂O₄²⁻) = 10⁻¹⁴ / 2.0 x 10⁻⁶ =5.0 x 10⁻⁹
Kb (HC₃H₂O₄⁻)= 10⁻¹⁴ / 1.0 x 10⁻³ = 7.1 x 10⁻¹²
Given the magnitudes of the Kbs ( Kb₂ is approximately 1000 times Kb1 ) , to calculate pOh we can neglect the contribution from (2). We then treat this problem as any equilibrium:
[K₂C₃H₂O₄] = 25 g/180.2 g/mol / 0.455 L = 0.30 M
Conc C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + 0H⁻
I 0.30 0 0 0
C -x +x +x
E 0.30 - x x x
Kb (C₃H₂O₄²⁻) = [ HC₃H₂O₄⁻ ] [OH⁻]/ [ C₃H₂O₄²⁻] = x² / 0.30 - x ≅ x² /0.30
x² /.030 = 5.0 x 10⁻⁹ ⇒ x = √(0.30 x 5.0 x 10⁻⁹ ) = 7.1 x 10⁻⁵ = [ÒH⁻]
(Verifying our approximation was good 7.1 x 10⁻⁵ / 0.30 = 2.4 x 10⁻⁴ so our approximation checks)
pOH = -log 7.1 x 10⁻⁵ = 4.2
pH = 14 -4.2 = 9.8
b) To answer this part we take equilibrium (2 ) and set up our usual ICE table to solve for the concentration of malonic acid:
Conc (M) HC₃H₂O₄⁻ + H₂O ⇄ H₂C₃H₂O₄ + OH⁻ (2)
I 7.1 x 10⁻⁵ 0 0
C -x +x +x
E 7.1 x 10⁻⁵ -x x x
7.1 x 10⁻⁵ - x ≅ 7.1 x 10⁻⁵
[ H₂C₃H₂O₄ ] [OH⁻] / [HC₃H₂O₄⁻] = Kb₂ = 7.1 x 10⁻¹² = x² / 7.1 x 10⁻⁵
x = √(7.1 x 10⁻¹² x 7.1 x 10⁻⁵) = 2.2 x 10⁻⁸ = [ H₂C₃H₂O₄ ]Again our approximation checks since [HC₃H₂O₄⁻] is almost 1000 times [ H₂C₃H₂O₄ ]
c) From eqn (1) :
C₃H₂O₄²⁻ + H₂O ⇄ HC₃H₂O₄⁻ + OH⁻
The salt K₂C₃H₂O₄ will react completely with the added acid, thereby decreasing the C₃H₂O₄²⁻ concentration, and according to Le Chateliers principle the system will shift to the left and the OH⁻ at equilibrium will decrease ( as also does [HC₃H₂O₄⁻] ) therefore the pOH will increase and the pH will decrease ( less OH⁻ higher pOH, smaller pH )
Final answer:
Calculate the pH of the solution, determine the concentration of malonic acid, and explain the impact of adding HCl on the concentration of malonic acid in the solution.
Explanation:
a) Calculate the pH of the solution:
Calculate the molarity of the potassium malonate solution.
Use the dissociation of K2C3H2O4 and the autoionization of water to find the concentration of OH- ions.
Convert the OH- concentration to pH using the formula pH = 14 - pOH.
b) Calculate the concentration of malonic acid:
Set up an equilibrium expression for the dissociation of malonic acid.
Use the pH calculated in part (a) to determine the concentration of malonic acid.
c) Impact of adding HCl:
The addition of HCl will shift the equilibrium towards the formation of malonic acid, leading to an increase in its concentration.
Based on the thermodynamic properties provided for water, determine the amount of energy released for 155.0 g of water to go from 39.0 °C to -36.5°C. Property Melting point Boiling point AHfus AHvap Cp (s) Value 0.0 100.0 6.01 40.67 37.1 75.3 33.6 Units oC kJ/mol kJ/mol J/mol.oc J/mol C mol oC Cp (g)
Answer : The amount of energy released will be, -88.39 kJ
Solution :
The process involved in this problem are :
[tex](1):H_2O(l)(39.0^oC)\rightarrow H_2O(l)(0^oC)\\\\(2):H_2O(l)(0^oC)\rightarrow H_2O(s)(0^oC)\\\\(3):H_2O(s)(0^oC)\rightarrow H_2O(s)(-36.5^oC)[/tex]
The expression used will be:
[tex]\Delta H=[m\times c_{p,l}\times (T_{final}-T_{initial})]+m\times (-\Delta H_{fusion})+[m\times c_{p,l}\times (T_{final}-T_{initial})][/tex]
where,
[tex]\Delta H[/tex] = heat available for the reaction = ?
m = mass of water = 155.0 g
[tex]c_{p,s}[/tex] = specific heat of solid water = [tex]2.01J/g^oC[/tex]
[tex]c_{p,l}[/tex] = specific heat of liquid water = [tex]4.18J/g^oC[/tex]
= enthalpy change for fusion = [tex]6.01kJ/mole=6010J/mole=\frac{6010J/mole}{18g/mole}J/g=333.89J/g[/tex]
Molar mass of water = 18 g/mole
Now put all the given values in the above expression, we get:
[tex]\Delta H=[155.0g\times 4.18J/g^oC\times (0-(39.0))^oC]+155.0g\times -333.89J/g+[155.0g\times 2.01J/g^oC\times (-36.5-0)^oC][/tex]
[tex]\Delta H=-88392.625J=-88.39kJ[/tex]
Therefore, the amount of energy released will be, -88.39 kJ
The total energy released when 155.0 g of water cools from 39.0 °C to -36.5°C is approximately -89.0 kJ, calculated by summing the energy changes for the liquid cooling, phase change, and solid cooling.
To calculate the amount of energy released when 155.0 g of water cools from 39.0 °C to -36.5°C, we first determine the heat released during the temperature drops above and below the freezing point, along with the energy released during the phase change from liquid to solid (freezing). We will use the provided thermodynamic properties, namely the specific heat capacities for liquid water (Cp = 75.3 J/mol°C) and solid water (Cp(s) = 37.1 J/mol°C), along with the enthalpy of fusion (AHfus = 6.01 kJ/mol).
The steps are as follows:
Convert the mass of water (155.0 g) to moles using the molar mass of water (18.015 g/mol).Calculate the heat released (q) in cooling the water from 39.0 °C to 0°C using the formula q = m⋅Cp⋅ΔT for liquid water.Calculate the energy released during the phase change using q = m⋅AHfus.Calculate the heat released in cooling the water from 0°C to -36.5°C using q = m⋅Cp(s)⋅ΔT for solid water.Add the energies from steps 2, 3, and 4 to find the total energy released.Now, let's calculate the values:
Number of moles (n) = 155.0 g / 18.015 g/mol = 8.605 molesq1 = m⋅Cp⋅ΔT = 8.605 mol × 75.3 J/mol°C × (0°C - 39.0°C) = -25727.3 Jq2 = m⋅AHfus = 8.605 mol × 6010 J/mol = -51709.05 Jq3 = m⋅Cp(s)⋅ΔT = 8.605 mol × 37.1 J/mol°C × (0°C - (-36.5°C)) = -11591.9 JThe total energy released is q1 + q2 + q3 = -25727.3 J - 51709.05 J - 11591.9 J = -89028.25 J
The total energy released when 155.0 g of water cools from 39.0 °C to -36.5°C is approximately -89.0 kJ.
An intravenous infusion contains 5 mg of zoledronic acid (RECLAST ) in 100 mL. If the infusion is to be administered in 15 minutes, how many (a) milligrams of zoledronic acid and (b) milliliters of infusion must be administered per minute? And (c), using a drip set that delivers 20 drops/milliliter, how many drops per minute must be infused?
Answer:
a) 0.33 mg/min
b) 6.67 mL/min
c) 133.4 drops/min
Explanation:
a) The mass flow indicates how much mass is flowing (in this case is being administrated) in a "piece" of time, thus, it's the total mass administrated by the total time:
mf = 5mg/15min
mf = 0.33 mg/min
So, 0.33 mg of the acid will be administrated per minute.
b) Now, we must calculate the volume flow, which is the total volume divided by the time:
Vf = 100mL/15 min
Vf = 6.67 mL/min
So, 6.67 mL of the infusion will be administrated per minute.
c) The drops flow, is the drop delivery ( 20 drops/mL) multiplied by the volume flow:
df = 20drops/mL * 6.67 mL/min
df = 133.4 drops/min
So, it must be infused 133.4 drops per minute.
Final answer:
To administer an intravenous infusion containing 5 mg of zoledronic acid in 100 mL over 15 minutes, 0.33 mg of zoledronic acid and 6.67 mL of infusion should be administered per minute. Using a drip set that delivers 20 drops/mL, the infusion should be given at a rate of 133.33 drops per minute.
Explanation:
An intravenous infusion contains 5 mg of zoledronic acid in 100 mL. To calculate the amount to be administered per minute:
(a) To find how many milligrams of zoledronic acid must be administered per minute: Convert 15 minutes to 1 minute: 5 mg x (1 minute / 15 minutes) = 5 mg / 15 = 0.33 mg/min
(b) To find how many milliliters of infusion must be administered per minute: 100 mL x (1 minute / 15 minutes) = 100 mL / 15 = 6.67 mL/min
(c) To calculate the drops per minute: Convert 6.67 mL/min x 20 drops/mL = 133.33 drops/min
A 45.30 g sample of solid mercury is initially at –59.00°C. If the sample is heated at constant pressure ( = 1 atm), kJ of heat are needed to raise the temperature of the sample to 30.00°C.
Answer:
0.165kJ
Explanation:
Formula to use for such a question is;
Energy = number of mole x molar gas constant x change in temperature
Number of mole = reacting mass of mercury / molar mass of mercury = 45.30/200.58 = 0.226moles
Change in temperature = final temperature - initial temperature = 30 - (-59) =30 + 59 = 89 Kelvin
E = nRT = 0.226 x 8.314 x 89
Energy = 165.35Joules
Energy in kJ = 165.35/1000 = 0.165kJ