Answer:
it's used to measure intensity of radioactivity in a sample of material
A mixture is prepared using 27.00 mL of a 0.0758 M weak base (pKa=4.594) , 27.00 mL of a 0.0553 M weak acid (pKa=3.235) and 1.00 mL of 1.25×10−4 M HIn and then diluting to 100.0 mL, where HIn is the protonated indicator. The absorbance measured at 550 nm in a 5.000 cm cell was 0.1102 . The molar absorptivity (????) values for HIn and its deprotonated form In− at 550 nm are 2.26×104 M−1cm−1 and 1.53×104 M−1cm−1 , respectively. What is the pH of the solution?
Answer:
pH = 4.164
Explanation:
The first process is to find the initial moles for the base (B) & the acid (HA)
i.e.
[tex]= \dfrac{27 mL \times 0.0758 \ moles \ \ of \ B}{1000 \ mL}[/tex]
[tex]=0.0020466[/tex]
[tex]\simeq 2.047\times 10^{-3} \ moles \ of \ B[/tex]
[tex]= \dfrac{27 mL \times 0.0553 \ moles \ \ of \ HA}{1000 \ mL}[/tex]
[tex]=0.0014931[/tex]
[tex]\simeq 1.493\times 10^{-3} \ moles \ of \ HA[/tex]
The acid with base reaction is expressed as;
HA + B → A⁻ + HB⁺
to 1.493 × 10⁻³ 2.047 × 10⁻³ - -
- 1.493 × 10⁻³ 1.493 × 10⁻³ 1.493 × 10⁻³ 1.493 × 10⁻³
0 5.54 × 10⁻⁴ 1.493 × 10⁻³ 1.493 × 10⁻³
From observation; both the acid & base weak
Given that:
The pKa for base = 4.594
The pKa for acid = 3.235
Recall that;
pKa = -log Ka
So; Ka = [tex]\mathbf{10^{-Ka}}[/tex]
By applying this:
For Base; Ka = [tex]10^{-4.594}[/tex] = 2.5468 × 10⁻⁵
For Acid: Ka = [tex]10^{ -3.235}[/tex] = 5.821 × 10⁻⁴
After the reaction; we have the base with its conjugate acid & conjugate base of acid; Thus, since the conjugate acid of the base possesses a higher value of K, it is likely it would be the one to define the pH of the solution.
By analyzing the system, we have:
HB⁺ + H₂O ↔ B + H₃O⁺
[tex]\dfrac{1.493\times 10^{-3}}{0.1 \ L}[/tex] [tex]\dfrac{5.54\times 10^{-4}}{0.1 \ L}[/tex]
to 0.01493 M 0.00554 M
- x x x
0.01493 - x 0.00554 - x x
Thus;
[tex]2.5468 \times 10^{-5} = \dfrac{(0.00554 -x)\times x}{(0.01493-x)}[/tex]
Using the common ion effect;
0.00554 - x [tex]\simeq[/tex] 0.00554 &
0.01493 - x [tex]\simeq[/tex] 0.01493
∴
[tex]x = \dfrac{2.5468 \times 10^{-5} \times 0.01493}{0.00554}[/tex]
x = [H₃O⁺] = 6.8635 × 10⁻⁵
∴
pH = -log(6.8635 × 10⁻⁵)
pH = 4.164
A limited number of the many known elements comprise the largest portion of living matter. Group Elements A Calcium, Phosphorus, Oxygen, Sulfur B Cobalt, Hydrogen, Oxygen, Nitrogen C с Helium, Oxygen, Sulfur, Carbon Hydrogen, Oxygen, Nitrogen, Carbon 1 1 Which group of elements above comprises the largest portion of living matter? A Group A B Group B C Group C D Group D
Answer:
Explanation:
Hydrogen oxygen nitrogen and carbon
Based on details from "Thomas Edison: The Master of Improvement,” how did Joseph Swan and Thomas Edison differ?
Swan liked to experiment, while Edison did not.
Swan was very inventive, while Edison was not.
Swan invented a working lightbulb, while Edison did not.
Swan received a formal education, while Edison did not.
Answer:
The correct answer is D. Swan received a formal education, while Edison did not.
Explanation:
I did the Unit Test :)
"Thomas Edison: The Master of Improvement,” is about Thomas Edison. Joseph Swan received a formal education, while Thomas Edison did not. Thus, option D is correct.
Who was Thomas Edison?Thomas Edison was a known American inventor that invented the incandescent light bulb, the camera, phonograph, etc. He used electricity and worked very hard to invent the lightbulb. He received no formal education and believed in self-improvement.
He was a great inventor and fantastic improver that performed various experiments to invent the greatest inventions. Joseph Swan, on the other hand, was a physicist that developed the incandescent light bulb even before Edison.
He invented dry photographic plates and electric lightbulbs. He received proper formal education and sued Edison for the lightbulb patent infringement. He used carbon paper filaments, unlike Edison's metallic filaments in the bulb.
Therefore, in option D. both the scientists, Joseph Swan and Thomas Edison differed in receiving formal education.
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ln a particular genetic cross, the probability of the offspring having a certain trait is 3/4
Which percentage represents this probability?
O 25%
O 50%
O 75%
O 100%
Answer:
75%
Explanation:
3/4 is 75% if you multiply by 25
please help me i will give brain list
Answer:
a. pentane = C5H12
b. Heptane = C7H16
c. Hexyne = C6H10
d. Octene = C8H16
e. Nonane = C9H20
Hope it helps.
1-pentene
Molecular Formula C5H10
Condensed Structural FormulaCH2=CH(CH2)2CH3
Melting Point (°C)–138
Boiling Point (°C)30
2- heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16, and is one of the main components of gasoline (petrol).
Your skin is an important organ and has several functions. All of the functions below are performed by the skin EXCEPT
A)
makes vitamin D.
B
prevents-dehydration:
C)
maintains body temperature.
D)
works with bones to help you move.
Answer:D
Explanation:
Your skin makes vitamin D
Your skin prevents dehydration
And your skin maintains body temperature. So you are left with D
Answer:
The correct option is D.
works with bones to help you move
Explanation:
Skin is the outer layer of the body and it is the body's largest organ.
It protect the body from heat and other harmful substances.
It is comprises of three layers;
The Epidermis which is the outer layer.
The dermis which is a fibrous later that protect the Epidermis.
The subcutis is the subcutaneous layer that is beneath the dermis.
Function of the skin.
1. It's regulate body temperature
2. It's protect the body from heat and pathogenic entry.
3. It produces vitamin D
4. The skin allow sensations or feelings of touch, heat, and cold.
Therefore;
works with bones to help you move is wrong because it is the muscle that work with the bone.
How many moles are I 24.0x10^18 molecules NaOH?
Answer:
[tex] \huge 3.986 \times { 10}^{ - 5} \: \: mol \\ [/tex]
Explanation:
To find the number of moles in a substance given it's number of entities we use the formula
[tex]n = \frac{N}{L} \\[/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
[tex]n = \frac{24 \times {10}^{18} }{6.02 \times {10}^{23} } \\ \\ = 3.986 \times { 10}^{ - 5} \: \: mol[/tex]
Hope this helps you
Heeellllpppp ASAP ......
Answer:
I saw B, he vented SUS
Explanation:
Iodoethane Is the answer.
A log has a density of .8 g/cm³. What will happen to this log in freshwater, which has a density of 1.0 g/cm³?
It will sink.
It will float.
It will move deeper.
It will decrease in density.
Explanation:
Objects with a lower density will float while objects with a higher density will sink.
Since 0.8g/cm³ < 1.0g/cm³,
The log will float in freshwater.
the initial internal energy of a system is 43.5kj. it absorbs 8.3kj of heat while performing 3.5kj of work on the surroundings. what is its final internal energy?
Shows works to help me understand what I did wrong.
Answer:
[tex]U_2=48.3kJ[/tex]
Explanation:
Hello!
In this case, since the fist law of thermodynamics helps us to understand how the change in internal energy is defined in terms of the head added to the system and the work done by the system:
[tex]Q+W=\Delta U[/tex]
In such a way, since 8.3 kJ of heat are absorbed by the system, 3.5 kJ are done by the system and the initial internal energy is 43.5 kJ, the final internal energy turns out:
[tex]U_2=U_1+Q-W\\\\U_2=43.5kJ+8.3kJ+3.5kJ\\\\U_2=48.3kJ[/tex]
Best regards!
A chemical equation is balanced when the
subscripts of the reactants equal the subscripts of the products,
coefficients of the reactants equal the coefficients of the products,
products and reactants are the same chemicals,
same number of each kind of atom appears in the reactants and in the products,
same number of each kind of atom appears in the reactants and in the products
HELPPP PLEASEEE
is this
1: radiation
2: conduction
3: convection
This is an example of #2, conduction.
Conduction is the process where heat energy is transmitted through collisions between atoms or molecules.
What happens to molecular energy(heat) in water when water vapor becomes a liquid?
Group of answer choices
Water vapor gives up heat energy.
Water vapor absorbs heat energy.
As water's mass increases it absorbs energy.
Water vapor retains the same heat energy.
Answer:
Water vapor retains the same heat energy.
Answer:
water vapor gives up heat energy.
Explanation:
Took a quiz and got it right
Magnesium has a density of 1.738 g/cmº at 25°C. What is the mass of a block of
magnesium that has a volume of 743 cm??
Answer:
87.50g(1cm^3/1.1738g)=50.345 cm^3
Explanation:
volume units id in cubic centimeters
you have a friend who is using a recipe for flat from american cookbook you notice that he set your over temperature at 175F° what you advise him to do?
Answer:
I will give them advice, that do the power of flame low....
Explanation:
thanks.
A football player kicks a 0.94 kg football with a force of 2.4 N.
Calculate the acceleration of the football as the player kicks the ball. Round your answer to the nearest tenth of a m/s2.
The acceleration of the football is
Explanation:
Fnet = ma
Therefore a = Fnet/m = 2.4N/0.94kg = 2.45m/s².
Answer:
2.6 m/s2
Explanation:
Solids, liquids and gases are all
considered to be forms of matter.
Each of these take up space and also
exhibit what other significant
characteristic?
A. color
B. smell
C. texture
B. mass
Answer:
mass
Explanation:
hope this helps you!!
A sample is in the second half-life. What percent of the sample is stable at this point?
A. 12.5%
B. 25%
C. 50%
D. 75%
Answer:
75%
Explanation:
on edg :)
Which phrase describes one type of freshwater wetland?
2
acidic areas found in northern climates
reservoirs created by dams at the end of rivers
areas of high elevation that feed into river systems
small streams that flow into larger streams and wetlands
Answer:
The correct answer is D
Explanation:
Wetlands are environments that are either submerged under water or are frequently wet. Marshes, swamps, bogs, and fens are examples of freshwater wetlands. Here small streams flow into larger streams and wetlands. The correct option is D.
Ecosystems in freshwater wetlands are impacted by transient or ongoing flooding. They are essential habitats for fauna (including migratory species), play a significant role in the regulation of water flow and water quality to entire catchments, and offer shelter for fauna during droughts.
In tropical and subtropical areas, mangrove swamps are coastal wetlands. In brackish to saline tidal waters, they are distinguished by halophytic (salt-loving) trees, shrubs, and other plants.
Thus the correct option is D.
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Which element has the highest electronegativity?
Answer:
fluorine
Explanation:
has the highest electronegativity?
What is 797 mm hg to atm?
Answer:
797 mm hg = 1.04868 atm
Explanation:
1 atm = 760 mm hg
797 mm hg to atm is 1.0468 atm
Pressure is defined as the physical force exerted on an object. The force applied is perpendicular to the surface of objects per unit area.
There are many different types of units and prefixes that may be used in general practice to reflect pressure. Thus, it is ensured that all the measurements and their respective units are in the same framework when conducting pressure calculations.
Pascal is the SI unit of pressure, and is the basic pressure unit in the SI (the International System of Units) system.
Given,
Pressure = 797 atm
1 mm Hg = 0.00131579 atm
797 mm Hg = 0.00131579 × 797
= 1.04868 atm
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Which of the following elements has six valence electrons?
Be
B
C
N
O
In science why is it important to explain why the evidence supports your claim?
A biochemist carefully measures the molarity of magnesium ion in of cell growth medium to be . Unfortunately, a careless graduate student forgets to cover the container of growth medium and a substantial amount of the solvent evaporates. The volume of the cell growth medium falls to . Calculate the new molarity of magnesium ion in the cell growth medium. Be sure your answer has the correct number of significant digits.
Answer:
760 uM
Explanation:
A biochemist carefully measures the molarity of magnesium ion in 47, mL of cell growth medium to be 97 uM. Unfortunately, a careless graduate student forgets to cover the container of growth medium and a substantial amount of the solvent evaporates. The volume of the cell growth medium falls to 6.0 mL. Calculate the new molarity of magnesium ion in the cell growth medium Be sure your answer has the correct number of significant digits.
The problem here is that the amount of magnesium ion remains the same irrespective of the volume.
Amount of magnesium in the growth medium = molarity x volume
= 97 x [tex]10^{-6}[/tex] x 47 x [tex]10^{-3}[/tex] = 4.559 x [tex]10^{-6}[/tex]
Then, the volume reduced to 6.0 mL, the new molarity becomes;
molarity = mole/volume
= 4.559 x [tex]10^{-6}[/tex]/6 x [tex]10^{-3}[/tex] = 7.598333 x [tex]10^{-4}[/tex] M = 759.83333 uM
To the correct number of significant digits = 760 uM
How does adding a lone pair affect the position of existing atoms and lone pairs
Answer:
How does adding a lone pair affect the position of existing atoms and lone pairs? It decreases the angles between the atoms - the atoms are moving closer because they are being repelled further away from the lone pairs then they are from the other atoms
Explanation:
hope it helps!
what is the volume of a book that has a width of 10cm,a length that is 2 times the width,and a height that is half the width
width=10cm
length=2xwidth=2x10=20cm
height=width/2=10/2=5
V=w*l*h=10*20*5=1000cm^3
Answer:
1000cm^3
Explanation:
first collect what is known
width 10cm
length 2×width (2×10cm) =20cm
height width/2 (10cm/2) =5cm
now if we use the formula for finding volume of a cuboid that has length, width and height known;
V = l×w×h
= 20cm × 10cm × 5cm
= 1000cm^3
Which of the following elements in a nonmetal? *
Zinc (Zn)
O Barium (Ba)
Krypton (Kr)
Lithium (Li)
Answer:
Krypton (Kr)
Explanation:
Nonmetals are the elements that have opposing features and characteristics of metals. Nonmetals do not shine and are dull in appearance. They are bad conductors of heat and electricity. They are brittle and cannot be beaten into sheets. The density, melting and boiling points of the nonmetals are low. Krypton (Kr) is a non metal whose atomic number is 36.
Someone plz help me write notes (images attached)
Answer:
I'm not going to give you notes but I'm going to give you a tip for notes take what you think is the most important thing about the text and basically paraphrase it into your own words if that helps
tide occur in ocean but not in lake why
Answer:
Because while our lakes are Great, they're comparatively much smaller than oceans. And the gravitational pull isn't strong.
How is continental crust different from oceanic crust?
A: Oceanic crust is thicker and more dense.
B: Oceanic crust is thinner and more likely to sink.
C: Continental crust is thicker and more likely to sink.
D: Continental crust is more dense and lighter.
Answer:
b
Explanation:
google lol ur welcome
B: Oceanic crust is thinner and more likely to sink.