The elements of heavy metals are used to absorb electrons in electron-dense stains.
What are heavy metals?A heavy metals are generally defined as metals with relatively high densities, atomic weight and atomic number.
They toxic and poisonous in nature. They occurs naturally and are very essential to life.
Arsenic, cadmium, lead, copper, nickel and mercury are the most commonly used heavy metals.
Electron staining means to absorb heavy metals of high scattering power to biological specimens which exhibit a small scattering power for electrons.
Thus, the elements of heavy metals are used to absorb electrons in electron-dense stains.
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which indicator is most appropriate for the titration of acetic acid with naoh? the ka for ch3co2h is 1.8×10−5. explain the reasoning for your answer:
An endpoint is observed using a phenolphthalein indicator when titrating CH3COOH against NaOH.
What is phenolphthalein ?Phenolphthalein is a shorthand notation for the chemical compound C20H14O4, which is frequently written as "HIn," "HPh," "phph," or just "Ph." In acid-base titrations, phenolphthalein is commonly employed as an indicator. It is a member of the group of colors known as phthalein dyes.
For use in studies, phenolphthalein is typically dissolved in alcohols because it is only marginally soluble in water. It is a weak acid that can dissolve and lose H+ ions. The double-deprotonated phenolphthalein ion is fuchsia, whereas the nonionized phenolphthalein molecule is colorless.
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if you have a properly adjusted flame, which is pale blue, what is observed if the gas control valve is slightly closed
When there is less natural gas, a luminous flame will appear.
A luminous flame is one that produces more light from a fuel source with inefficient combustion. In other words, there is not enough oxygen available for stoichiometric combustion when combustion occurs. For more effective combustion, this emits light that is more in the yellow-orange range of the visible light spectrum as opposed to a more blue-nearly colorless region.
An acetylene torch is a good illustration of luminous falme because the first ignition is normally carried out in the presence of only acetylene, which produces a very sooty, bright, yellowish-red flame. The flame receives more of the necessary oxygen for effective combustion when the oxygen valve is opened, and the flame changes color to blue.
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at a particular temperature, the solubility of co₂ in water is 0.13 m when the partial pressure is 1.5 atm. what partial pressure (in atm) of co₂ would give a solubility of 0.080 m?
The partial pressure of CO₂ which will give a solubility of 0.080 m is 0.93 atm, at a particular temperature.
Using Henry's Law,
Henry's law states that, solubility of a gas in a liquid is directly proportional to the partial pressure of gas and mole fraction of gas is proportional to partial pressure of the gas.
It is expressed as -
Sgas = Kh Pgas
where,
Sgas = Solubility of
Kh = Henry's law constant
Pgas = Partial pressure of gas
Putting the values in the above expression,
Sgas = Kh Pgas
0.13 M = Kh x 1.5 atm
Kh = 0.13 M
1.5 atm
Kh = 0.086
For partial pressure,
Sgas = Kh Pgas
0.080 M = 0.086 x Pgas
Pgas = 0.080 = 0.93 atm
0.086
Partial pressure of CO₂ is 0.93 atm
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Is the correlation between time spent studying each day positive or negative?
Answer:
Positive.
Explanation:
The slope is positive and increasing, thus meaning there is a positive correlation between time spent studying each day and performance.
Which element has similar properties to neon (Ne)?
O Chlorine (CI)
O Selenium (Se)
O Krypton (Kr)
O Bromine (Br)
Answer:
Krypton
Explanation:
They're both inert gases
10.0g of potassium iocide is dissolved in 50.0g of water. Calculate the percent mass of the solute in the solution
Answer:
100/6% =16.67%
Explanation:
16.67%
What is the difference between the mass number of an isotope and its atomic number?the number of isotopesthe number of protonsthe number of neutronsthe number of electrons
Atomic mass refers to an element's average weight, whereas mass number refers to the number of nucleons.
The phrases "atomic mass" and "mass number," which are used in chemistry, have different meanings. The average weight of an element is one, while the number of nucleons in the atom's nucleus is another.Atomic weight is another name for atomic mass. The weighted average mass of an atom in an element is known as its atomic mass, and it depends on the relative abundance of its isotopes in nature.The total number of protons and neutrons in the nucleus of an atom is counted to determine the mass number.There are three naturally occurring isotopes of hydrogen, each of which has a unique mass number.1H has a proton and a mass number of 1, while 2H has a proton and a neutron. 1 proton and 2 neutrons make up 3H, which has a mass number of 3. 1H makes up 99.98% of all hydrogen. 1 It is coupled with 2H and 3H to produce a total hydrogen atomic mass of 1.00784 g/mol.The protium isotope of hydrogen, which has a single proton, is the only one in which the atomic number and mass number are the same.Learn more about Isotopes here:
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How much carbon (C) is in 1.41 × 10^22 atoms
of carbon?
Answer in units of mol.
Taking into account the definition of Avogadro's Number, 0.02341 moles of carbon are 1.41×10²² atoms of carbon.
Avogadro's NumberAvogadro's Number is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.
Amount of moles of carbonYou can apply the following rule of three: if 6.023×10²³ atoms are contained in 1 mole of carbon, then 1.41×10²² atoms are contained in how many moles of carbon?
amount of moles of carbon= (1.41×10²² atoms × 1 mole)÷ 6.023×10²³ atoms
amount of moles of carbon= 0.02341 moles
Finally, 0.02341 moles of carbon are 1.41×10²² atoms of carbon.
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someone pls explain how I do this work
Answer:
Explanation:
Element #of protons Mass #. # of electrons Atomic #. Neutron
Se. 34. 78.96. 34 34 45
Si. 14. 28. 14. 14 14
H. 1. 1. 1 1 0
Ca. 20. 40.078. 20. 20. 21
Fe. 26. 56. 26. 26. 30
Na. 11. 23. 11. 11. 12
Calcium oxide is used to remove the pollutant so2 from smokestack gases. the overall reaction is:____.
Calcium oxide is used to remove the pollutant so2 from smokestack gases. the overall reaction is:
CaO(s)+SO2(g)+ 1/2 O2(g)CaSO4(s)
What is calcium oxide?
Calcium oxide (CaO), commonly referred to as quicklime or burnt lime, maybe a widely used chemical compound. it's a white, caustic, alkaline, crystalline solid at temperature.
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2. 3.80 km to meters
T
2.380km= 2e+3m.
A kilometer is a unit of measurement, as is the mille. It additionally translated as 10,000-steps meters, creating a strolling aim that, thru the decades, by some means has become embedded in our global awareness and fitness trackers. however contemporary exceptional science suggests we do now not need to take 10,000 steps an afternoon, which is ready five miles, for the sake of our health or toughness.
The CDC recommends that on foot 10,000 steps a day is sufficient to stay in a suitable form, but the general public needs to hit 20,000 steps as a part of their fitness desires. if you need to try the 20000 steps a day weight reduction, you can expect notable results: decreased belly fat, progressed sleep, boosted immune response, and so on. As excellent as it sounds, taking walks 20000 steps a day of weight loss has its cons. They include emotions of tiredness and starvation, plus it steals a big chew of your day.
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HELP ME FLOCABULARY
help me please
Answer:
a
Explanation:
potential energy is something that could happen but haven't yet
What is the boiling point of the automobile radiator fluid prepared by mixing 1.09 l of ethylene glycol (hoch2ch2oh, density = 1.114 g/ml) with 1.16 l of water (density = 1.000 g/ml)?
Final temp = 108.05.
What is Density? The relationship between a substance's mass and the amount of space it occupies is known as its density (volume). The density of a substance is determined by the mass, size, and arrangement of its atoms. Density (D) is defined as the product of a substance's mass and volume.For instance, a block of the harder, lighter element gold (Au) will be denser than a block of the heavier element lead (Pb) (Au). Styrofoam blocks are less dense than bricks. Mass per unit volume serves as its definition.Definition of density: A material's density is determined by how closely it is packed. As the mass per unit volume, it has that definition.What is the boiling point of the automobile radiator fluid prepared by mixing 1.09 l of ethylene glycol (hoch2ch2oh, density = 1.114 g/ml) with 1.16 l of water (density = 1.000 g/ml)?
Delta T = 1*.52*1000*1.114*1000/1160*62
=8.05 deg C
final temp = 108.05
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Cells taken from a frog and a human are placed in a salt solution. The frog cells swell and burst o
while the human cells shrink. Explain these results.
If the frog cells swell and burst while the human cells shrink means that the solution will be hypotonic for frog cells while for human cells the solution will be hypertonic.
Why do these changes happen?These changes will occur because in the frog cell there will be higher concentrations of ions than in the extracellular space, so water will enter the cell by osmosis to equalize the concentrations of the cells. While in the human cell there will be a lower concentration of ions than outside the cell, for this reason the water leaves it in order to equalize the concentrations both inside and outside the cell. Being then the hypotonic solution for the frog cell and hypertonic for the human cell.
Therefore, we can confirm that if the frog cells swell and burst while the human cells shrink means that the solution will be hypotonic for frog cells while for human cells the solution will be hypertonic.
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The resting potential of a neuron that is submerged in a solution with zero extracellular potassium will __________________ because __________________________.
The answer would be for this question will be hyperpolarize; the driving force for potassium to exit the cell increases.
The resting potential of a neuron that is submerged in a solution with zero extracellular potassium will hyperpolarize because the driving force for potassium to exit the cell increases.
Hyperpolarization is the process in which the membrane potential looks good on more negative at a specific spot on the neuron's membrane where as depolarization is when the membrane potential became less negative.
At this point at which the neuron is hyperpolarized, in the middle of –70 mV and –75 mV. After hyperpolarization the potassium passage encloses and the natural permeability of the neuron to sodium and potassium permits the neuron to come back to its recline potential of –70 mV.
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Coach is used to activate carboxylic acids. what type of compound is formed between coach and a carboxylic acid?
The type of compound is formed between coach and a carboxylic acid alcohol + carboxylic acid → ester + water.
How carboxylic acids are formed?
A acid is produced after the acidic hydrolysis of esters and carboxylates are produced after the basic hydrolysis of an ester.
What are the functional group of alcohol and carboxylic acid?
Alcohols contain the hydroxyl functional group and may be primary, secondary, or tertiary. Ethers are compounds with an oxygen atom bonded to 2 alkyl groups. Aldehydes and ketones contain the carbonyl functional group
Can a compound be a acid and an alcohol?
Esters are represented by the formula RCOOR', where R and R' are hydrocarbon groups. The ester, which is compound derived from a carboxylic acid and an alcohol in which the OH of the acid is replaced by an OR group, looks somewhat sort of a n ether and also somewhat like a carboxylic acid.
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Which of the following describes Rutherford’s model of the atom?
A. Solid sphere like a marble but unique to the element it makes
B. Numerous positive charges floating around in a sea of negative charge (plum pudding)
C. Positive nucleus surrounded by a blob of negative charges
D. Positive nucleus surrounded by electrons in circular orbits
E. Positive nucleus surrounded by electron orbitals with complex 3-D shapes and assigned energies.
Answer: C. Positive nucleus surrounded by a blob of negative charges
a sample of oxygen gas that occupies 0.679 m3 exerts a pressure of 36 kpa at a temperature of 293 k (absolute temperature measured on the kelvin scale). find the value of k (in kpa · m3) in the given model.
The value of k is 24.44 kPa[tex]m^{3}[/tex] using the given model of pressure and volume .
Given data,
P= 36kPa
V = 0.679[tex]m^{3}[/tex]
According to the given model,
P = k/V
where, P = pressure in kPa
V = volume occupied by gas
k = proportionality constant
Plugging in the values in the respective model we get,
P = k/V
36 = k/0.679
k = 24.44 kPa[tex]m^{3}[/tex]
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"4s2 is the amount of energy in the atom"
Using the terms energy level, sub level, number of electrons explain WHY this misconception is incorrect and what "4", "s" and "2" represent in electron configurations.
The shell is spherically symmetrical orbital and two electrons are found in the N shell of the atom.
What is electron configurations?The electron configuration is defined as the manner in which the electrons are arranged in an atom. The electron present in an atom are arranged in subshells and shells. The shells are choose according to the principal quantum number in which the subshells are taken by the orbital quantum number.
The orbital in which the electron is found has a direct relation to the energy of the electron.
Thus, we concluded that the "4s^2" refers that it is spherically symmetrical orbital and the two electrons are found in the N shell of the atom.
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Chemists use the letters of the alphabet as what for the elements?
Answer:
As a Symbol
Explanation:
7. When an astronaut travels from the Earth to the Moon, which of their physical properties changes: mass or weight?
Explain why one property changes but the other does not.
Answer:
the weight
Explanation:
becouse the moon has less mass then earth the gravitational attraction on the Moon is much less than it is on Earth since the moon has less mass this means if you where to go to the moon your mass will stay the same but your weight will change
hope it helps
Suppose the United States adopted the international standard for
letter-sized paper. Explain at least two things that might result from this change
Answer:
. In the United States, a standard letter-sized piece of paper is 8.5 inches wide by 11 inches long. The international standard for a letter-sized piece of paper is different. The international standard is based on SI units: 21.0 cm wide by 29.7 cm long. a. Convert 21.0 cm to inches. Show your dimensional analysis setup. b. Convert 29.7 cm to inches. Show your dimensional analysis setup. c. State the dimensions, in inches, of the international standard for a letter-sized piece of paper. d. Which piece of paper is longer: a U.S. letter-sized piece of paper, or an international letter-sized piece of paper? e. Suppose the United States adopted the international standard for letter-sized paper. Explain at least two things that might result from this change
Igneous rock is where new rock is formed from molten
Answer:
Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface.
Explanation:
How to find the substrate concentration of the master mix?
The master mix now contains: 0.16 mL of 10 µM ethanol, 0.2 ml of 10 µM NAD, and 0.54 mL buffer. The substrate concentration of the master mix is
a = 0.0016 mM
This is further explained below.
How do find the substrate concentration of the master mix?Generally, Ethanol is acting as the substrate for this master mixture.
The following formula is used in order to determine the amount of ethanol that is included in the master mix:
CiVi= CfVf
Ci equals the starting concentration of ethanol, which is equal to 10 muM. 0.16 milliliters is equal to the volume of ethanol that was consumed initially.
Cf = final concentration, often known as the amount of ethanol present in the master mix = a Vf = final volume, which also refers to the final volume of the master mix = 1 milliliter
Introducing the values into the equation:
CiVi= CfVf
10 uM X 0.16 ml = a X 1 ml
a = (10 uM X 0.16 ml ) / 1ml
a = 1.6 uM
a = 1.6/ 1000 mM ... ( 1\muM = 1/1000 mM )
a = 0.0016 mM
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failure to mix a specimen containing an anticoagulant by inverting the sealed specimen container several times after collection of the specimen
Failure to mix a specimen containing an anticoagulant by inverting the sealed specimen container several times after collection of the specimen is due to the clots in specimen.
Clots in specimen or clotted specimen refers to an abruptly clotted blood specimen in which clotting occurs in that tube which contains anticoagulant. A specimen is clotted when the anticoagulant in the tube is not adequately mixed.
To mix and ensure adequate anticoagulation of the specimen, tube filled with the blood has to be inverted 8 - 10 times immediately, so that clots in specimen do not occur.
Specimen is supposed to be mixed immediately to ensure that anticoagulant in the tube has been fully dissolved with the specimen, which in return maintains the effective anticoagulant-to-specimen ratio and provides a specimen free from any clots.
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What form of carbamate is used mainly as an herbicide? a. carbaryl b. metam sodium c. thiocarbamate d. dithiocarbamate e. none of these is correct.
The form of carbamate mainly used as a herbicide is dithiocarbamate.
The esters of carbamic acid is are known as Carbamate compounds. They are mainly used as insecticides and referred as N-methylcarbamate. The general formula for RHNCOOR'. Carbamate compounds are highly soluble in water, polar and are chemically reactive. Carbamates can be easily hydrolyzed, they have low level of persistence in soil as well as water.
Dithiocarbamates are the small group of organic molecules. They have been extensively used in agricultural industry for more than 50 years. They have strong chelating ability for inorganic species and have anti-oxidant property. Molecular weight of dithiocarbamate is 171.26.
Carbon disulfide with ammonium or either primary/secondary amine gives Dithicarbamates in presence of NaOH or amine. The reaction is an exothermic reaction.
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How many moles of sucrose (m = 342.3 g/mol) are there in 25 ml of a 0.551 g/l solution of sucrose?
Molarity of sucrose = 0.116 M .
Volume of solution = 0.5 liter
Mass of sucrose in gram = 20 gram
Molar mass of sucrose 342.3 g/mol
Molarity of sucrose
Computation:
Mole of sucrose = Mass of sucrose in gram / Molar mass of sucrose
Mole of sucrose = 20 / 342.3
Mole of sucrose = 0.058 (Approx.)
Molarity of sucrose = Mole of sucrose / Volume of solution
Molarity of sucrose = 0.058 / 0.5
Molarity of sucrose = 0.116 M
What is Molarity ?A substance's molarity (M) is the volume of solution in which it is present. The amount of a solute in moles per liter of a solution is known as molarity. A solution's molar concentration is another name for molarity.
The amount of solute in one mole per liter of solution is known as molarity. For instance, when table salt is dissolved in water, the solute is salt, and the solution is water. 58.44 grams make up one mole of sodium chloride. One molar solution, often known as 1M, is created when 58.44 grams of sodium chloride are dissolved in one liter of water.
The quantity of solute in one mole of solution per liter is known as molarity.
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Destabilization that occurs in a molecule when two non bonded atoms are too close together is called?
Destabilization that occurs in a molecule when two non bonded atoms are too close together is called Van der Waals repulsion.
When two non bonded atoms come close together then in such situation there are two types of forces that come into play.
First one is Van der Waal attractive forces and the second one is van der Waal repulsion forces.
Van der Waal attractive forces are the forces of attraction between the electronic cloud of one atom/molecule with the nucleus of the other atom/molecule and van der Waal repulsive forces are the force of repulsion between the electronic cloud of the both the atoms/molecules and the repulsion between the nucleus of both the atoms/molecules.
Attractive forces causes stabilization whereas repulsive forces causes destabilization.
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What is the molar solubility of marble (i.e., [ca2 ][ca2 ] in a saturated solution) in normal rainwater, for which ph=5.60ph=5.60 ?
the molar solubility of marble (i.e., [ca2 ][ca2 ] in a saturated solution) in normal rainwater, for which Ph=5.60ph=5.60 is 0.0142.
What do you mean by saturated solution?A saturated solution is a solution that contains maximum amount of solute that can be dissolved under the condition at which the solution exists.
In chemistry, after studying solutions and properties of solution, one can understand that a solution can reach a status of saturation. This state is when solution has reached a point in which no more solute can be added. Addition of solute after this point would result in solid precipitate or gas being released. Such mixture is called a saturated solution.
Ksp of(CaCO3)= 4.5 x 10 -9
Ka1 for (H2CO3) = 4.7 x 10^-7
Ka2 for the (H2CO3) = 5.6 x 10 ^-11
1) The equation 1 for Ksp = 4.5 x 10^-9
CaCO3(s)→ Ca +2(a q) + CO3-2(a q)
2) The equation 2 for Ka1 = 4.7 x 10^-7
H2CO3- + H2O → HCO3- + H3O+
3) equation 3 for Ka2 = 5.6 x 10^-11
HCO3-(a q) + H2O(l) → CO3-2 (a q) + H3O+(a q)
so, form the equation 1& 2&3 we can get the overall equation:
CaCO3(s) + H+(a q) → Ca2+(a q) + HCO3-(a q)
note: you could get the overall equation by adding the equation 1 to the inverse of equation 3 as the following:
when inverse of equation 3 is :
CO3-2 (a q) + H3O+ (a q) ↔ HCO3- (a q) + H2O(l) Ka2^-1 = 1.79 x 10^10
when we add it to the equation 1
CaCO3(s) ↔ Ca2+(a q) + CO3-2(a q) Ksp = 4.5 x 10^-9
∴ overall equation will be as we have mentioned before:
when H3O+ = H+
CaCO3(s) + H+(a q) ↔ Ca2+ (a q) + HCO3-(a q) K= 80.55
from overall equation:
∴K = [Ca2+][HCO3-] / [H+]
when we have [Ca2+] = [HCO3-] we can assume both = X
∴K = X^2 / [H+]
when we have the PH = 5.6 we can get [H+]
PH = - ㏒[H+]
5.6 = -㏒[H]
∴[H] = 2.5 x 10^-6
so, by the substitution on K expression:
∴ 80.55 = X^2 / (2.5 x10^-6)
∴X = 0.0142
∴[Ca2+] = X = 0.0142.
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how are the balanced or unbalanced forces related to rotational motion?
Answer: When the forces are balanced, neither of the teams, but if the rope moves away in a particular direction or if a team wins, then the forces applied by both teams are unbalanced. Practically anything that moves is a result of the exertion of unbalanced forces on it.
Explanation:
The balanced or unbalanced forces are related to rotational motion by the occurrence of the constant and altered changes in the speed of the object.
What is Rotational motion?Rotational motion may be defined as a type of motion that involves the movement of an object along an axis in a circular path with a common angular velocity.
Balanced forces maintain the state of an object at a constant speed. It means that its velocity remains unchanged during the course of the time interval. While unbalanced forces stimulate the alteration in the velocity of an object. It either reduces or enhances the initial speed of an object.
Therefore, the balanced or unbalanced forces are related to rotational motion by the occurrence of the constant and altered changes in the speed of the object.
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