Hi there!
[tex]\large\boxed{\text{Visible Light.}}[/tex]
According to the diagram and the arrows, a drop from level 4 (n = 4) to level 2 (n = 2) produces orange visible light.
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The concentration ratio of conjugate acid to conjugate base for a 20 mM solution at pH 7.0 of an amino acid is 20:1.
Required:
a. What is the pK of the side chain?
b. What amino acid might this be?
Answer:
a. 8.3= pKa of the aminoacid
b. Cysteine
Explanation:
The pH of an acid can be obtained using the H-H equation:
pH = pKa + log [A-] / [HA]
Where pH is the pH of the buffer = 7.0
pKa is the pka of the conjugate acid = ?
[A-] / [HA] is the ratio between conjugate base and conjugate acid. As the ratio of conjugate acid to conjugate base = 20:1, the [A-] / [HA] = 1/20
Replacing:
7 = pKa + log 1/20
7 = pKa - 1.30
7+1.30 = 8.3 = pKa of the aminoacid
The only aminoacid with a side chain with pKa = 8.3 is:
Cysteine. Allowing its identification.
When 2-methyl-3-hexene is treated with Cl2 in methanol, three products are formed (neglecting stereoisomers). Draw curved arrows to show the movement of electrons in this step of the reaction mechanism.
Answer:
Explanation:
The structural formula of 2-methyl-3-hexene is drawn in the attached image below. After then, the three possible structures were drawn and the mechanism reaction.
From the mechanism shown, methanol deprotonates methoxide proton and neutralizes the positive charge to form methoxide. This is followed by the movement of electrons that takes place from the region of higher electron density to lower electron density.
A chemist measures the energy change
ΔH during the following reaction:
2NH3(g)→N2(g)+3H2(g)
ΔH=160kJUse the information to answer the following questions.This reaction is:__________.
a. endothermic
b. exothermic
Suppose 70.9 g of NH3 react. Will any heat be released or absorbed?
a. Yes, absorbed
b. Yes, released
c. No.
If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed. Round your answer to 3 significant digits.
Answer:
For (1): The correct option is (a)
For (2): The correct option is (a) and 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts.
Explanation:
There are 2 types of reactions that are classified based on enthalpy change:
Endothermic reactions: These are the reactions where heat is absorbed by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is positive for these reactions.
Exothermic reactions: These are the reactions where heat is released by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is negative for these reactions.
For (1):For the given chemical reaction:
[tex]2NH_3(g)\rightarrow N_2(g)+3H_2(g);Delta H=160kJ[/tex]
As the change in enthalpy or heat of the reaction is positive. Thus, the reaction is an endothermic reaction because heat is absorbed by the reaction.
For (2):When ammonia reacts, some amount of heat will be absorbed by the reaction. Thus, we can say the heat will be absorbed.
The number of moles is calculated by using the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of ammonia = 70.9 g
Molar mass of ammonia = 17 g/mol
Using equation 1:
[tex]\text{Moles of ammonia}=\frac{70.9g}{17g/mol}=4.17mol[/tex]
By stoichiometry of the reaction:
If 2 mole of ammonia reacts, the heat absorbed is 160 kJ
So, if 4.17 moles of ammonia reacts, the heat absorbed will be = [tex]\frac{160kJ}{2mol}\times 4.17mol=333.6kJ[/tex]
Hence, 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts
Which of the following two periods contain the same number of element?
A. 2 & 3
B.3 & 4
c. 4 & 6
D. 2 & 4
Answer:
4 and 6
Explanation:
Period 4 has 18 elements and so does period 6.
What does Gibbs free energy predict?
A. It predicts what the rate of the reaction will be.
B. It predicts how high the activation energy is.
C. It predicts if entropy will increase or decrease.
D. It predicts whether or not a reaction will be spontaneous.
Answer:
It predicts whether or not a reaction will be spontaneous.
Explanation:
The equation;
∆G= ∆H - T∆S enables us to obtain the Gibbs free energy of a chemical process.
The Gibbs free energy value tells us whether a chemical process will be spontaneous or not.
When;
∆G>0 the reaction is not spontaneous
∆G=0 the reaction is at equilibrium
∆G<0 the reaction is spontaneous
1. What is the difference between accidental discoveries and scientific investigations?
Answer:
the discovery will always need to be tested more where if you're investigating you should already be in a more controlled environment
The difference between accidental discoveries and scientific investigations are as follows.
Accidental discoveriesThe discovery which is occur accidentally, means something discovered intensely.Examples of accidental discoveries like, microwave, teflon, penicillin, plastic etc.Scientific investigationA process of finding of answers of the question by using various research method.There are various scientific investigation, like fair testing, modeling, pattern, seeking, identification and classifying etcExample of scientific investigation are plant experiment.To learn more about accidental discoveries,
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Determine whether methylcyclohexane contains a chiral center. _____ How many different substituents do you count at atom
Answer:
methylcyclohexane does not possess a chiral center
Explanation:
A molecule is said to possess a chiral center if one or more of the atoms in the molecule is bonded to four different atoms or groups.
If we look at methylcyclohexane, none of the carbon atoms in the molecule is bonded to four different atoms or groups hence the molecule contains no chiral centers and will not exhibit optical isomerism.
So, methylcyclohexane has a plane of symmetry thus it is an achiral molecule.
Balance the chemical equation below using the smallest possible whole number stoichiometric coefficients.
P4(s) + NaOH(aq) + H2O(l) -> Ph3(g) + Na2HPO3(aq)
Answer:
I used a,b c, d in the equation as substituted coefficients to find the unknown for each element of P, Na, O, H, and I got
P4(s) + 4NaOH(aq) + 2H20(l)---->2Ph3 +2Na2HPO3(aq).
which I think should be the answer.
Calculate the molality of a solution containing 22.75 g of glycerol (C3H8O3) in 79.6 g of ethanol (C2H5OH).
Answer:
3.11 mol/kg
Explanation:
Molality M = number of moles of solute, n/mass of solvent, m
To calculate the number of moles of glycerol (C₃H₈O₃) in 22.75 g of glycerol, we find its molar (molecular) mass, M',
So, M' = 3 × atomic mass of carbon + 8 × atomic mass hydrogen + 3 × atomic mass of oxygen
= 3 × 12 g/mol + 8 × 1 g/mol + 3 × 16 g/mol = 36 g/mol + 8 g/mol + 48 g/mol = 92 g/mol.
So, number of moles of glycerol, n = m'/M' where m' = mass of glycerol = 22.75 g and M' = molecular mass of glycerol = 92 g/mol
So, n = m'/M'
n = 22.75 g/92 g/mol
n = 0.247 mol
So, the molality of the solution M = n/m
Since m = mass of ethanol = 79.6 g = 0.0796 kg, substituting the value of n into the equation, we have
M = 0.247 mol/0.0796 kg
M = 3.11 mol/kg
So, the molality of the solution is 3.11 mol/kg.
what mass of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol
Answer: A mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.
Explanation:
Given: Mass of naphthalene = 25.0 g
Molality = 0.22 m
This means that 0.22 moles of solute is present per kg of solvent.
As 25.0 g of naphthalene is there that will be 25.0 g per 1000 g (1 kg) is equal to 0.025 kg.
Hence, moles of phenol are calculated as follows.
[tex]Molality = \frac{moles}{mass (in kg)}\\0.22 m = \frac{moles}{0.025 kg}\\moles = 0.0055 mol[/tex]
Also, molar mass of phenol is 94.11 g/mol. This means that 1 mole of phenol contains 94.11 g.
Therefore, mass contained by 0.0055 moles of phenol is as follows.
[tex]0.0055 mol \times 94.11 g/mol \\= 0.518 g[/tex]
Thus, we can conclude that a mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.
Which mechanisms is most significant in returning the ion concentrations to the resting state?
Answer:
Active transport by the Na+-K+ pump
Explanation:
Active transport by the Na+-K+ pump
Maintenance (and restoration) of the resting ion concentrations depends on the Na+-K+ pump. Once gated ion channels are closed, the combined action of the pump and ion leakage (particularly that of K+) establishes a resting membrane potential in a typical neuron of around âˆ'70 mV.
Suppose a 48. L reaction vessel is filled with 1.6 mol of Br2 and 1.6 mol of OCl2. What can you say about the composition of the mixture in the vessel at equilibrium
Answer:
There will be very little of BrOCl BrCl
Explanation:
Based on the equilibrium:
Br2(g) + OCl2(g) ⇄ BrOCl(g) + BrCl(g)
The equilibrium constant, Kc, is:
Kc = 1.58x10⁻⁵ = [BrOCl] [BrCl] / [Br2] [OCl2]
As Kc is <<< 1, in equilibrium, the concentration of products will remain lower regard to the concentration of the reactants. That means, right answer is;
There will be very little of BrOCl BrClhelp with the following would be greatly appreciated!
3. Does entropy increase or decrease in the following processes?
A. Complex carbohydrates are metabolized by the body, converted into simple sugars.
Answer: Increase
es-lesund
B. Steam condenses on a glass surface.
Answer:
decreare
-->
MgCl2(s)
C. Mg(s) + Cl2(g)
correct
Answer:
Answer:
hope it helps much as you can
4. If matter goes through a chemical change, are the physical properties likely to stay the same?
•
Please say yes or no and explain why.
Answer: If matter goes through a chemical change then the physical properties are not likely to stay the same.
Explanation:
When chemical composition of a substance changes during a chemical reaction then it is called a chemical change.
Chemical change always leads to the formation of new substances. Properties like chemical reactivity, combustion, rusting etc are chemical changes.
For example, [tex]N_{2} + 3H_{2} \rightarrow 2NH_{3}[/tex]
Here, [tex]NH_{3}[/tex] will have different chemical as well as physical properties as compared to [tex]N_{2}[/tex] and [tex]H_{2}[/tex].
As physical properties are the properties that cause change in state of a substance.
Properties like boiling point, state of substance etc are physical properties.
Thus, we can conclude that if matter goes through a chemical change then the physical properties are not likely to stay the same.
1. Show that heat flows spontaneously from high temperature to low temperature in any isolated system (hint: use entropy change that occurs during the process for your proof).
2. Work out the entropy change for the decomposition of mercuric oxide using mathematical and graphical arguments.
Answer:
1 ) Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
2) ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
Explanation:
1) To show that heat flows spontaneously from high temperature to low temperature
example :
Pick two(2) solid metal blocks with varying temperatures ( i.e. one solid block is hot and the other solid block is cold )
Place both blocks for time (t ) in an insulated system to reduce heat loss or gain to or from the environment
Check the temperature of both blocks after time ( t ) it will be observed that both blocks will have same temperature after time t ( first law of thermodynamics )
Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
2) Entropy change for Decomposition of mercuric oxide
2HgO (s) → 2Hg(l) + O₂ (g)
Δs = positive
there is transition from solid to liquid and the melting point of mercury ( the point at which reaction will take place ) = 500⁰C
hence ΔSdecomposition = S⁻ Hg - S⁻ HgO =
Δh of reaction = 181.6 KJ
Temp = 500 + 273 = 773 k
hence ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
An unknown weak acid with a concentration of 0.530 M has a pH of 5.600. What is the Ka of the weak acid
Answer:
Ka = 3.45x10⁻⁶
Explanation:
First we calculate [H⁺], using the given pH:
pH = -log[H⁺][H⁺] = [tex]10^{-pH}=10^{-5.6}[/tex] [H⁺] = 2.51x10⁻⁶ MTo solve this problem we can use the following formula describing a monoprotic weak acid:
[H⁺] = [tex]\sqrt{C*Ka}[/tex]We input the data that we already know:
2.51x10⁻⁶ = [tex]\sqrt{0.530*Ka}[/tex]And solve for Ka:
Ka = 3.45x10⁻⁶Determine whether each phrase describes carboxylic acids or esters.
a. Usually have a sour odor _____________
b. Notable for their pleasant fragrances ___________
c. Do not form hydrogen bonds amongst themselves and have higher vapor pressure _____________
d. Their reactions with base are known as neutralizations ____________
e. Their reactions with base are known as saponifications _____________
A chemist makes of nickel(II) chloride working solution by adding distilled water to of a stock solution of nickel(II) chloride in water.Calculate the concentration of the chemist's working solution. Round your answer to significant digits.
Answer:
0.0900 mol/L
Explanation:
A chemist makes 330. mL of nickel(II) chloride working solution by adding distilled water to 220. mL of a 0.135 mol/L stock solution of nickel(II) chloride in water. Calculate the concentration of the chemist's working solution. Round your answer to significant digits.
Step 1: Given data
Initial concentration (C₁): 0.135 mol/LInitial volume (V₁): 220. mLFinal concentration (C₂): ?Final volume (V₂): 330. mLStep 2: Calculate the concentration of the final solution
We prepare a dilute solution from a concentrated one. We can calculate the concentration of the working solution using the dilution rule.
C₁ × V₁ = C₂ × V₂
C₂ = C₁ × V₁/V₂
C₂ = 0.135 mol/L × 220. mL/330. mL = 0.0900 mol/L
Would 1 pound of peanut butter occupy more or less space than 1 pound of water?
PLEASE ANSWER THESE:
Question 4: Biological Molecules (5 points)
A. Pepsin is an enzyme used by the human body to break down food in the stomach.
i. Explain, in terms of a chemical reaction, how pepsin helps a person. (3 points)
ii. What are the building blocks of the pepsin macromolecule? (2 points)
Answer: the answer is A
Explanation: add me hope i helped
Imagine you are celebrating a birthday in December and need balloons. The temperature in the
store where you are purchasing the balloons is approximately 25°C and each balloon is filled
to a volume of 2 liters to obtain maximum pressure.
Use the gas laws to explain what will happen to the volume and pressure of the gas in the
balloon when go outside, where the temperature is 0°C. Include both Charles's Law
and Gay-
Lussac's Law in your answer.
ILL GIVE BRAINIEST PLEASE HELP
HELP ME PLEASE!!!!!!
I WANT IT AS PARAGRAPHHHHH NOT POINT AND ANSWER THIS TWO QUESTIONS AS 1 PARAGRAPH
One of the lab safety rules being violated is that Jodi doesn't have her hair tied up. She should have her hair tied up. Having her long hair not tied up or away from her face is a safety hazard. Jodi is also not wearing glasses, which is essential when working with chemicals. One of the Bunsen Burners aren't being used but it's on, which is a fire hazard.
Answer:
Jodi should wear her hair up to avoid a mishap, such as lighting her hair on fire. Then, instead of using a fire extinguisher on Jodi, Kimberly should use a fire blanket to prevent additional damage. Mac is preoccupied with a second flame and maybe Jodi without her safety goggles?
A buffer is prepared containing 0.75 M NH3 and 0.20 M NH4 . Calculate the pH of the buffer using the Kb for NH3. g
Answer:
pH=8.676
Explanation:
Given:
0.75 M [tex]NH_{3}[/tex]
0.20 M [tex]NH_{4}[/tex]
The objective is to calculate the pH of the buffer using the kb for [tex]NH_3[/tex]
Formula used:
[tex]pOH=pka+log\frac{[salt]}{[base]}\\[/tex]
pH=14-pOH
Solution:
On substituting salt=0.75 and base=0.20 in the formula
[tex]pOH=-log(1.77*10^{-5})+log\frac{0.75}{0.20}\\ =4.75+0.5740\\ =5.324[/tex]
pH=14-pOH
On substituting the pOH value in the above expression,
pH=14-5.324
Therefore,
pH=8.676
Which substance has nonpolar covalent bonds?
CO
NO2
H2
NaBr
Answer:
H2
Explanation:
Answer:
[tex]{ \bf{H _{2} }} \\ { \tt{hydrogen \: gas}}[/tex]
What evidence supports the law of conservation of energy?
Light energy is converted to chemical energy during photosynthesis.
Oxygen is made from the breakdown of carbon dioxide during photosynthesis.
Energy is absorbed by chlorophyll during photosynthesis.
The sun gives off light energy that is absorbed by plants.
Answer:
light energy is converted to chemical energy during photosynthesis.
Explanation:
Law of conservation of energy says: Energy can neither be created nor destroyed-only converted from one form of energy to another.
Answer:
A. Light energy is converted to chemical energy during photosynthesis.
Choose the correct statement. A) The cathode is the electrode where the oxidation takes place. B) The cathode is the electrode where the reduction takes place. C) Both oxidation and reduction may take place at the cathode, depending on the cell. D) The cathode is always positive
6. Which compound contains no ionic character?
Answer:
The compound which doesn't contains ionic character is HC, H-atom and CL- atom shares 1 electron a to form covalent bond....
What types of house are found in very cold regions
Answer:
the house found in a very cold are Igloos or the ice house
once a recrystallization is completed and filtered, what solvent would be suitable for transferring the leftover solids to filtration funnel
Answer:
To transfer leftover solids to the filtration funnel and wash out crystals after recrystallization, ice cold methanol should be used (the mother liquor used for recrystallization).
Explanation:
Hope this helped