Answer:
1. Ka = 8.16x10⁻⁵
2. pH = 2.40
Explanation:
1. The dissociation of a weak acid in water occurs as follows:
HA ⇄ H⁺ + A⁻
Ka = [H⁺] [A⁻] / [HA]
As 2% of the 0.20M solution is dissociated:
[H⁺] = [A⁻] = 0.20M * 2% = 0.004M -As H⁺ and A⁻ comes from the same reaction, their concentrations are the same
[HA] = 0.20M * 98% = 0.196M
Ka = (0.004)² / (0.196M) = 8.16x10⁻⁵
2. pH = -log [H⁺] = -log [0.004M]
pH = 2.40Calculate the energy change when an electron moves from n=5 to n=7. Explain/show work please.
Answer: E = 1.55 ⋅ 10 − 19 J
Explanation:
The energy transition will be equal to 1.55 ⋅ 10 − 1 J .
So, you know your energy levels to be n = 5 and n = 3. Rydberg's equation will allow you calculate the wavelength of the photon emitted by the electron during this transition
1 λ = R ⋅ ( 1 n 2 final − 1 n 2 initial ) , where λ - the wavelength of the emitted photon; R
- Rydberg's constant - 1.0974 ⋅ 10 7 m − 1 ; n final - the final energy level - in your case equal to 3; n initial - the initial energy level - in your case equal to 5. So, you've got all you need to solve for λ , so 1 λ =
1.0974 ⋅10 7 m − 1 ⋅ (.... −152
)
1
λ
=
0.07804
⋅
10
7
m
−
1
⇒
λ
=
1.28
⋅
10
−
6
m
Since
E
=
h
c
λ
, to calculate for the energy of this transition you'll have to multiply Rydberg's equation by
h
⋅
c
, where
h
- Planck's constant -
6.626
⋅
10
−
34
J
⋅
s
c
- the speed of light -
299,792,458 m/s
So, the transition energy for your particular transition (which is part of the Paschen Series) is
E
=
6.626
⋅
10
−
34
J
⋅
s
⋅
299,792,458
m/s
1.28
⋅
10
−
6
m
E
=
1.55
⋅
10
−
19
J
what is neutralisation reaction?
Answer:
In chemistry, neutralization or neutralisation (see spelling differences) is a chemical reaction in which acid and a base react quantitatively with each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution.
Answer:
A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7
Explanation:
A block of aluminum occupies a volume of 13.8 mL and weighs 43.3 g.
What is its density? Give answer with one decimal.
Answer:
3.1g/mL
Explanation:
density = mass/volume
= 43.3/ 13.8
= 3.1g/mL
Which of the following amino acid functional groups will influence the pKa of an amino acid residue the least if it is on an adjacent residue?A. -OH.B. -NH3.C. -CH3.D. -COOH.
Answer:
C. -CH3
Explanation:
The pKa (acid dissociation constant) of an amino acid residue is primarily influenced by the functional groups attached to the adjacent end of the amino acid chain. The acidity of a functional group depends on how electronegative the functional group is. In the given functional groups' list, the functional group with the least influence on the pKa of the amino acid is the alkyl substituent (-CH3), because they have the least electron-withdrawing capacity.
Draw two five carbon rings that share an atom.
which of the following tools can be used to measure mass? A.a graduated cylinder B. a triple beam balance C. a mercury thermometer D. a bathroom scale
Answer:
triple beam balance
Explanation:
The tool that can be used to measure mass is a triple beam balance. Therefore, the correct option is option B.
A graduated cylinder is used to determine a liquid's volume. A mercury thermometer is used to measure temperature. Weight is calculated on a bathroom scale and is a force rather than a mass. A typical scientific tool for calculating an object's mass is a triple beam balance.
It is composed of three beams with moveable weights that enable precise mass balancing and a pan on one end where the thing to be measured is placed. By comparing the placement of the weights on the beams to the appropriate scale, the mass of the object can be ascertained.
Therefore, the correct option is option B.
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The equilibrium concentrations of the reactants and products are [HA]=0.280 M, [H+]=4.00×10−4 M, and [A−]=4.00×10−4 M. Calculate the value of pKa for
Answer:
6.24
Explanation:
The following data were obtained from the question:
Concentration of HA, [HA] = 0.280 M,
Concentration of H+, [H+] = 4×10¯⁴ M
Concentration of A-, [A−] = 4×10¯⁴ M
pKa =.?
Next, we shall write the balanced equation for the reaction. This is given below:
HA <===> H+ + A-
Next, we shall determine the equilibrium constant Ka for the reaction. This can be obtained as follow:
Equilibrium constant for a reaction is simply the ratio of concentration of the product raised to their coefficient to the concentration of the reactant raised to their coefficient.
The equilibrium constant for the above equation is given below:
Ka = [H+] [A−] /[HA]
Concentration of HA, [HA] = 0.280 M,
Concentration of H+, [H+] = 4×10¯⁴ M
Concentration of A-, [A−] = 4×10¯⁴ M
Equilibrium constant (Ka) =
Ka = (4×10¯⁴ × 4×10¯⁴) / 0.280
Ka = 1.6×10¯⁷/ 0.280
Ka = 5.71×10¯⁷
Therefore, the equilibrium constant for the reaction is 5.71×10¯⁷
Finally, we shall determine the pka for the reaction as follow:
Equilibrium constant, Ka = 5.71×10¯⁷
pKa =?
pKa = – Log Ka
pKa = – Log 5.71×10¯⁷
pKa = 6.24
Therefore, the pka for the reaction is 6.24.
What is the pH of 500 mL of water after the addition of 1 mL of 2M NaOH?
Answer:
pH = 11.60
Explanation:
When we add a base, we are increasing [OH⁻], so the pH will be totally basic.
pH of water = 7
Basic pH > 7
We are adding 2 M . 1 mL = 2 mmoles
2 mmoles of OH⁻ are contained in 501 mL of total volume.
[OH⁻] = 2 mmol / 501 mL = 3.99×10⁻³ M
- log 3.99×10⁻³ M = 2.39 → pOH
pH = 14 - pOH → 11.61
Water equilibrium
2H₂O ⇄ H₃O⁺ + OH⁻ Kw = 1×10⁻¹⁴
NaOH → Na⁺ + OH⁻
Suppose you were to read about a scientific statement based on data from hundreds of years of research and observation that applies to a broad set of naturally occurring events. Would you consider it a hypothesis or a theory? a) hypothesis b) theory c) both d) neither
Answer:
theory
Explanation:
A theory has been tested and proven several times and oftentimes has a large amount of information, research, and evidence standing behind it.
Hope this helps! :)
2-methyl-2-pentene Spell out the full name of the compound.
Answer:
METHYL PENTENE or 2-METHYL PENT-2-ENE
Explanation:
The number 2 carbon carries the methyl group and the double bone is on the 2 carbon as well.
The chemical structure of the compound has been attached.
I hope this is what you were looking for.
4. In a chemical process, you need to force a compound to bond with a halogen, causing it to lose hydrogen. Which type of reaction do
you need to perform?
A. Halogenation
B. Hydrolysis
C. Reduction
D. Ammoniation
Answer:
Halogenation
Explanation:
Halogenation is a type of substitution reaction in which a hydrogen atom is replaced by a halogen atom in a molecule.
The molecule looses its hydrogen atom as the halogen is introduced into the molecule. This sort of reaction is very common in organic chemistry. Many hydrocarbons can be halogenated in the presence of light.
Cobalt has the chemical symbol Co and the atomic number 27. How many protons, neutrons, and electrons would be found in an atom of cobalt-58?
Answer:
COBALT
Explanation:
CO BALT COBALT
1. Isotonic saline requires a concentration of 0.85% NaCl. How much solid NaCl must be weighed out on the balance to prepare a bottle full containing 3500 ml?
Given :
Concentration of NaCl , [tex]c=0.85 \%[/tex] .
To Find :
Th amount of solid NaCl must be weighed out on the balance to prepare a bottle full containing 3500 ml .
Solution :
Concentration of NaCl is 0.85 % .
It means , 0.85 gm of NaCl in 100 ml of water .
So , amount of solid NaCl required to prepare 3500 ml solution is :
[tex]x=\dfrac{3500\times 0.85}{100}\ gm\\\\x=29.75\ gm[/tex]
Therefore , amount of solid NaCl required is 29.75 gm .
Hence , this is the required solution .
Select all the correct locations on the image. In this diagram, which subatomic particles have a negative charge?
Answer:
The correct answer is: (E), Electron.
Explanation:
There are three types of subatomic particles - protons (P) have a positive charge, neutrons (N) have zero charge, and electrons (E) have a negative charge.
Hope this helps!
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, electron is the subatomic particles that have a negative charge.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.
Therefore, electron is the subatomic particles that have a negative charge.
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How many particulars are present in 2 moles of water molecules?
Answer:
4 mole hydrozen and 2 mole oxyzen
Explanation:
If a 250mL beaker weighs 13.473g and the same beaker plus 2.2 mL of water weighs 15.346g. How much does the 2.2 mL of water, alone, weigh? Show your work for the calculation. Be sure to use significant figures.
Given :
A 250 ml beaker weighs 13.473 g .
The same beaker plus 2.2 ml of water weighs 15.346 g.
To Find :
How much does the 2.2 ml of water, alone, weigh .
Solution :
Now, mass of water is given by :
[tex]\text{Mass of water alone = Total mass - Mass of beaker alone}\\\\Mass =15.346-13.473\ g\\\\Mass =1.873\ g[/tex]
Therefore , mass of 2.2 ml of water alone is 1.873 g .
Hence , this is the required solution .
A chemical engineer must report the average volume of a certain pollutant produced by the plants under her supervision. Here are the data she has been given by each plant: What average volume should the chemical engineer report? Be sure your answer has the correct number of significant digits.
Answer:
[tex]V_{average}=15.34L[/tex]
Explanation:
Hello,
In this case, given the volumes of pollutants:
Macon 0.519 L
Ogiala 44.67 L
Pitt 0.826 L
The average he ought report is computed by adding them and subsequently dividing by three since there are three pollutants as shown below:
[tex]V_{average}=\frac{0.519L+44.67L+0.826L}{3} \\\\V_{average}=15.34L[/tex]
Regards.
A child has a small rubber ball that is filled with water and glitter. When the ball is bounced the glitter spreads around the inside of the toy then settles back at the bottom. The mixture inside the toy would be considered which of the following?
Homogeneous
Solution
Heterogeneous
Colloid
Answer:
Heterogeneous
Explanation:
A heterogeneous mixture is a non-uniform composition in which particles of far larger size are suspended in a phase and can be easily separated from each other. In a heterogeneous mixture, the gravity pulls the suspended particles down out of solution.
The given example is a heterogeneous mixture in which glitter particles are suspended inside the toy and settles back at the bottom due to gravity. The glitter particles can also easily separated from the toy.
Hence, the correct answer is "Heterogeneous".
There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. In the first step, calcium carbide and water react to form acetylene and calcium hydroxide:
CaC2(s) + 2H2O(l) → C2H2(g) + Ca(OH)2(s)ΔH = −414kJ
In the second step, acetylene, carbon dioxide and water react to form acrylic acid:
6C2H2(g) + 3CO2(g) + 4H2O(g) → 5CH2CHCO2H(g)ΔH = 132kJ
Calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water, and carbon dioxide from these reactions. Round your answer to the nearest kJ.
Answer:
ΔH = -470.4kJ
Explanation:
It is possible to sum 2 or more reactions to obtain the ΔH of the reaction you want to study (Hess's law). Using the reactions:
1. CaC2(s) + 2H2O(l) → C2H2(g) + Ca(OH)2(s)ΔH = −414kJ
2. 6C2H2(g) + 3CO2(g) + 4H2O(g) → 5CH2CHCO2H(g)ΔH = 132kJ
6 times the reaction 1.
6CaC2(s) + 12H2O(l) → 6C2H2(g) + 6Ca(OH)2(s)ΔH = −414kJ*6 = -2484kJ
This reaction + 2:
6CaC2(s) + 3CO2(g) + 16H2O(l) → + 6Ca(OH)2(s) + 5CH2CHCO2H(g) ΔH = -2484kJ + 132kJ = -2352kJ
As we want to calculate the net change enthalpy in the formation of just 1 mole of acrylic acid we need to divide this last reaction in 5:
6/5CaC2(s) + 3/5CO2(g) + 16/5H2O(l) → + 6/5Ca(OH)2(s) + CH2CHCO2H(g) ΔH = -2352kJ / 5
ΔH = -470.4kJComplete the following table for the three key subatomic particles.
Answer:
This question is incomplete without the table
Explanation:
The missing table is attached to this answer.
There are three subatomic particles found in an atom; protons, neutrons and electrons. The properties of the subatomic particles will be classified under the following subheadings (which are the empty columns/boxes in the attachment)
SYMBOL
The symbol of proton is "p⁺", the symbol of neutron is "n⁰" and the symbol of electron is "e⁻".
CHARGE
Looking at the symbol of the subatomic particles, one can guess the charge of each of the particles from the superscript.
Protons are positively charged, electrons are negatively charged while neutrons have no charge/electrically neutral.
The relative charge of proton is +1 while it's absolute charge is +1.60218 × 10⁻¹⁹
The charge of a proton was first determined by Ernest Rutherford using the gold-foil experiment
The relative charge of electron is -1 while it's absolute charge is -1.60218 × 10⁻¹⁹
The charge of an electron was first determined by R. Milikan using the oil-drop experiment
The relative charge and absolute charge of neutron is 0
The charge of a neutron was first determined by (or credited to) James Chadwick.
MASS
The relative mass (amu) of proton is 1.00727 while that of neutron is 1.00866. The relative mass (amu) of an electron is 0.00054858 while it's absolute mass (g) is 9.10939 × 10⁻²⁴.
The mass of an electron was first measured by J. J. Thomson.
The mass of a proton was first measured by (or credited to) Ernest Rutherford.
The mass of a neutron was first measured by James Chadwick.
LOCATION
The protons and neutrons are located inside the nucleus which is found in the centre of an atom while the electron(s) is/are found outside the nucleus but within the atom.
Categorize each molecule according to its hydrogen-bonding characteristics.a. CH3OCH3b. CH3CH2CH3c. CH3CH2NH2d. H2Oe. CH3OH
Answer:
H2O > CH3OH > CH3CH2NH2 > CH3OCH3 > CH3CH2CH3
Explanation:
Hydrogen bonding exists in molecules in which hydrogen is bonded to a highly electronegative element such as fluorine, chlorine, oxygen, sulphur, nitrogen etc.
Water has the highest degree of hydrogen bonding among the listed substances hence its very high boiling point, stemming from intermolecular hydrogen bonding. CH3CH2NH2 has a lesser degree of hydrogen bonding because nitrogen is less electronegative than oxygen.
Alcohols show significant hydrogen bonding in solution, the same applied to amines. However, ethers do not form hydrogen bonds with each other but they can form hydrogen bonds with other molecules such as alcohols and amines. Alkanes do not form hydrogen bonds at all.
Why does the lack of snow in the mountains make drought cycles worse
Answer:
lack of snow in the mountains makes drought cycles worse because mountains are a natural part of the water cycle.
Explanation:
Mountains play a critical part In the water cycle by capturing moisture in the air and it precipitates as snow and when it does this the snow will melt in the warmer seasons and flow down stream then following the rest of the water cycle if we didn't have this then the streams would run less and it would greatly disrupt the water cycle.
What are ions exactly?
Are atoms with an incomplete outer valence shell called ions?
Answer:
An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule. ... When an atom is attracted to another atom because it has an unequal number of electrons and protons, the atom is called an ION.
Explanation:
How many grams are in 160 pounds?
Answer:
72574.8
Explanation:
Thats what google says
I need help with this chemistry question talking about pure substances and mixtures?
The correct answer is A. The sample is not a heterogeneous mixture
Explanation:
A heterogeneous mixture includes two or more materials and these are not completely integrated. Due to this, in most cases, if a heterogeneous mixture is filtered it is possible to separate its parts. This did not occur when Ben filtered the substance, which shows it is likely the substance is not a heterogeneous mixture. Moreover, a heterogeneous mixture does not show uniformity in terms of appearance or properties, which shows this definitely not heterogenous and Ben can safely conclude this.
If a dog has a mass of 21.5kg, what is his mass in the following units?
What is the dogs mass in gram?
What is the dog mass in mg?
Answer: 21.5kg in grams is 21,500 grams
21.5kg in mg is 215,000,00
Explanation:
what is difference between paper and absorption chromatography
In partition chromatography, the stationary phase is in a liquid state. ... The difference between adsorption and partition chromatography is a separation of molecules occur based on the adsorption ability in adsorption chromatography while separation occurs based on the partition in partition chromatography
Indicate the direction of polarity of each of the covalent bonds by placing the appropriate delta notation next to each end of the bond. C-O, O-CL, O-F, C-N, C-L, S-H, S-CL
Answer:
C→O, O→Cl, O→F, C→N, C←Li, S ←H, S→Cl
Explanation:
The general convention for indicating polarity in molecules is that of showing the direction of polarity from the positive to the negative part of the bond. This is indicated in the answer by arrows that show the direction of the dipole.
The negative end of the dipole must be the more electronegative element while the positive end of the dipole is the less electronegative element, hence the answer shown above.
The delta notation, indicating the polarity of for the presented covalent bonds are:
δ+ C-O δ-δ- O-Cl δ+δ+ O-F δ-δ+ C-N δ-δ+ C-Cl δ-δ- S-H δ+δ+ S-Cl δ-Polar bonds are those in which atoms have different electronegativities.
The delta notation is used to indicate the direction of the polarity.
The atom with the greater electronegativity acquires a partial negative charge (goes with the symbol δ-), while the atom with the lesser electronegativity acquires a partial positive charge (goes with the symbol δ+).
Let's consider the following elements with their electronegativities.
C (2.5)O (3.5)Cl (3.0)F (4.0)N (3.0)S (2.5)H (2.1)The delta notation for the presented bonds are:
δ+ C-O δ-δ- O-Cl δ+δ+ O-F δ-δ+ C-N δ-δ+ C-Cl δ-δ- S-H δ+δ+ S-Cl δ-Learn more: https://brainly.com/question/2734316
Which of the following is a valid conversion factor:
10m/1dm
1mL/100L
100cg/1g
1cm^3/1L
What is the relationship between grams and cm³?
Answer:
1 gram
Explanation:
1 gram= weight of 1 cubic centimeter of pure water at temperature 4°C = 1000 milligrams = 0.001 kilogram