Answer:
Boron has different isotopes with different atomic masses. The relative atomic mass of boron, which is 9, is the average of the atomic masses of the isotopes
Explanation:
The relative atomic mass is indicated in terms of its heaviness compared to the parts of mass of carbon-12. The relative mass of boron is 9 means its mass relative to the mass of carbon -12 is 9 amu.
What is relative atomic mass ?The relative atomic mass of an element is the mass relative to the mass of carbon-12 or it can be defined as the number which indicates how many times the mass of one atom of the element is heavier in comparison to (1/12)th part of the mass of one atom of carbon-12.
Usually the mass number of an atom is the sum of number of protons and number of neutrons. But the actual mass or average atomic mass is not calculated in this way.
The actual mass is determined using mass spectroscopy. The relative atomic mass of every element is computed based on the mass of C-12 obtained from spectroscopic technique.
Thus the relative atomic mass of boron is calculated in a similar way and it is 9 amu.
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Calculate the average atomic mass of rubidium from the data below. Show your work.
Isotope
Rubidium-85
Rubidium-87
Mass
84.9118
86.9092
I
Percent abundance
72.2%
27.8%
Answer:
avg is 85.4678 atomic mass unit
The Mass of an empty bottle
is 4 kg if the mass When
filled with Cold water
12.5 kg Find
A. Mass of empty bottle.
Water has a 1 g/cm3 density. Weight of water in grammes when a bottle is completely filled with that amount of water.
Density bottle volume:
The empty density bottle weighs M1 = 4 kg.
Bottle weight plus water equals 12.5 kg Bottle weight plus water equals 12.5 kg Mass of water filling the density container to the top equals M2 — M1 (12.5—4=8.5 kg).
However, 1 g of water has a volume of 1 cc.
∴ water volume equals 8.5 cubic centimetres, or 8.5 ml, in a density bottle.
Define density.
The ratio between a substance's mass and volume is referred to as its density.
Volume/Mass = Density
The substance's mass per unit of volume is known as its density (volumetric mass density or specific mass). Although the Latin letter D may also be used, the sign most frequently used for density is (the lower case Greek letter rho). Mass divided by volume is the definition of density in mathematics: where is the density, m is the mass, and V is the volume.
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a sample of gas contains 1.75 moles at 37.8 °c in a volume of 3.61 l. if 2.67 moles of gas are added, what is the new volume (in l) assuming temperature and pressure do not change.
Using Avogadro’s law, the new volume of the gas is found to be 9.11L
Avogadro's law is a gas law that relates the volume of a gas to the amount of gas substance present. According to Avogadro's law, "equivalent volumes of all gases have the same number of molecules at the same temperature and pressure." Avogadro's law asserts that given the same temperature and pressure conditions, similar volumes of different gases contain an equal number of molecules.
Given:
V1 = 3.61L
n1 = 1.75 moles
n2 = 4.42 moles
To find:
V2 = ?
Formula:
V1/V2 = n1/n2
Calculation:
V2 = V1n2/n1
V2 = 3.61 x 4.42 / 1.75
V2 = 9.11L
Result:
The volume of the gas is found to be 9.11L
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a 25.00 ml sample of acetic acid containing phenolphthalein indicator is titrated with 0.1067 m naoh. the solution changes color after 30.07 ml naoh has been added. what is the concentration of the acetic acid before titration?
The concentration of the acetic acid before titration is 0.1283m
25 ml CH_3 COOH titrated with [tex]$0.1067 \mathrm{~m}$[/tex][tex]$\mathrm{NaOH}$[/tex] of [tex]$30.07 \mathrm{ml}$[/tex] where solution change colour, meany Equivalence point occurs. where
[tex]$$n_{\text {acid }}=n_{\text {base }}$$[/tex]
[tex]$\Rightarrow m_{\text {acid }} v_{\text {acid }}=m_{\text {base }} v_{\text {base}$[/tex]
[tex]$\left[\mathrm{CH}_3COO\mathrm{H}\right]=\frac{\left[\mathrm{NaOH}\right] \times V_{\mathrm{NaOH}}}{\mathrm{V}_{\mathrm{CHOOH}}}$[/tex]
[tex]$=\frac{(0.1067 \mathrm{~m}) \times(30.07 \mathrm{~ml})}{(25 \mathrm{ml})}$[/tex]
[tex]$=\frac{3.20847}{25} \mathrm{~m}$[/tex]
[tex]$=0.1283 \mathrm{~m}$[/tex]
Acetic acid, which has the molecular formula CH3COOH, is also referred to as ethanoic acid, ethylic acid, vinegar acid, and methane carboxylic acid. As a byproduct of fermentation, acetic acid gives vinegar its distinctive smell. About 4-6% of the acetic acid in vinegar is water.
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Classify each of the following examples as a physical change or a chemical change. Answer choices may be used more than once.
1. Physical change
Sugar dissolving in waterWater freezing into iceIn a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed.
2. Chemical change
Burning a candleRust forming on a carA chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed. It results when a substance combines with another to form a new substance.
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a 268 cm3 sample of an ideal gas at 18°c and 748 torr pressure is placed in an evacuated container of volume 648cm3 . to what centigrade temperature must the assembly be heated so that the gas will fill the whole chamber at 748 torr?
The temperature of the ideal gas that must be heated to maintain the pressure is 703.61 K.
We need to know about the ideal gas theory to solve this problem. The ideal gas is assumed that there is no interaction between particles in a gas. It can be determined by the equation
P . V = n . R . T
where P is pressure, V is volume, n is the number of moles gas, R is the ideal gas constant (8.31 J/mol.K) and T is temperature.
From the question above, we know that
The initial condition of the sample is
V1 = 268 cm³
T1 = 18⁰ C = 291 K
P1 = 748 torr
V2 = 648 cm³
P2 = 748 torr
When the initial and final pressure is the same, we can use the ratio of temperature and volume as
V1/T1 = V2/T2
268 / 291 = 648 / T2
T2 = 703.61 K
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Which model(s) represents a pure substance?
Answer:
models 1,2,3,4
hope it helps
What volume of gas is generated when 58. 0 l of oxygen gas reacts at stp according to the following balanced equation? assume that the reaction goes to completion and that no starting materials remain.
The volume of gas that is CO2 generated when 58.0 L of oxygen reacts at STP is 38.67 L.
At STP, Temperature is 0°C and Pressure is 1 atm. So in this condition the one mole of gas will occupy a volume of 22.4 L.
Since the given equation goes to completion as given in the question, the balanced chemical equation will be:
CH₃CH₂OH + 3O₂ ⇒ 2CO₂ + 3H₂O
From this we can calculate the mole ratio O2 to Co2 and that is 3:2.
From this we can find the volume of Co2,
Volume of CO₂ = 58 × ²/₃
Volume of CO₂ = 38.67 L
Hence the volume of gas that is CO2 generated when 58.0 L of oxygen reacts at STP is 38.67 L.
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What is a molecule dipole moment?
Answer:
the measure of net molecular polarity, which is the magnitude of the charge Q at either end of the molecular dipole times the distance r between the charges.
Explanation:
It is a separation of charge forming a positive and a negative end of a molecule
A molecule contains 3 atoms. It has 1 triple bond and 1 single bond. There are no lone pairs on any of the atoms. How many rheds are within the molecule?.
The given molecule has only 1 rhed – region of high electron density because of presence of one triple bond.
An electron density zone might be either bonding or non-bonding. Electrons in a covalent bond between two atoms are counted as one region, whether the link is single, double, or triple (or anything in between). The amount of lone pairs on the core atom is used to count non-bonding areas.
Double and triple bonds qualify as one high electron density region. A single unpaired electron counts as one high electron density region. One can utilize any of the resonance structures for molecules or ions that have resonance structures.
A high electron density atom or group indicates that some component of the molecular structure (such as resonance or inductive effects) is transferring negative charge towards this location in the molecule.
In the given molecule, A – B ≡ C
Only one triple bond is there and no lone pairs of electrons. Hence, only 1 rhed (region of high electron density) is present within the molecule.
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Eukaryotic cells contain a structure called the _______ which is distinct central organelle that contains the cells ____ material.
Eukaryotic cells are organelles with a developed nucleus. Eukaryotic cell contains a structure called cytoskeletal structure which is distinct central organelle that contains the cells genetic material DNA.
What is Eukaryotic cells?There are two type of cells based on the nucleus. If the cell is having a well developed nucleus it is called eukaryotic cells and the cell which have no developed nucleus is called prokaryotic cell.
Eukaryotic cells contains nucleus, cytoplasm, endoplasmic reticulum, lysosomes, mitochondria and ribosomes.
In eukaryotic cells contains a cytoskeletal structure inside cytoplasm consist of fibers, microtubules and filaments which make it strong.
The genetic material DNA is placed inside this cytoskeleton. Cytoskeleton provide perfect shape to the cell and helps to stimulate the cell movement.
Therefore, the special organelle contained in eukaryotic cells which contains the genetic material DNA.
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What is the law that is responsible for having the same number and type of atoms present in the reaction at the beginning and at the end?.
Answer-
The law of conservation of mass says that matter is not created or destroyed in a closed system. That means if we have a chemical reaction, the amount of each element must be the same in the starting materials and the products.
Hope it makes sense!
question content area which is the best description of how to dry a liquid with a drying agent? add the drying agent in small batches and observe the solution between each addition. keep adding drying agent until all of the liquid has been absorbed. add a large amount of drying agent and then swirl to see what happens
The best way to dry a liquid with a drying agent is to add it in small batches and observe the solution between each addition. It is also very helpful to swirl the mixture after each batch.
The ideal drying process involves using the least amount of drying agent possible. If too much of the reagent is used, a certain amount of the liquid being dried will be lost as it is adsorbed on the surface of the drying agent. The swirling in between each batch serves to check if enough of it has been added. The drying agent clumps together when it absorbs water, so when all the water has been absorbed, it will swirl free as a powder.
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How many more electrons can fit in the 2nd electron shell compared to the 1st?
6
2
8
10
THIS IS VERY URGENT IM OFFERING 60 POINTS AND ILL MAKE YOUR BRAINLIEST!!!
An isotope of the element iridium has a 77 protons and 115 neutrons in its nucleus.
Which of the following correctly represents this isotope?
A.115 over 77 Ir
B. 77 over 115 Ir
C. 192 over 77 Ir
D. 192 over 115 Ir
PLEASE HURRY :C
Answer: 192 over 77 Ir
Explanation:
Iridiums atomic mass is 192.217 and to get 192 you would add both protons and neutrons to get the atomic mass. When writing in isotope notation, the mass goes on top.
4. What trend in atomic radius occurs down a group on the periodic table?
rind on the periodic table?
Answer:Atomic radius gets bigger
Explanation:
Atomic radius bigger because not only do the atoms have more and more protons and neutrons, and thus more mass in general, there is also stronger shielding affect. Shielding affect is when electrons closer to the nucleus block the positive charge from reaching electrons farther from the nucleus, and thus those far electrons are not drawn towards the nucleus as strongly, and spread out more, increasing atomic radius.
What do we call the arrangement of elements with similar properties?
Answer:
the periodic table
Explanation:
Elements with similar properties are in columns called groups. Elements to the left of this line are metals. Elements in the same group of the periodic table have the same number of electrons in their outer shell. This gives them similar chemical properties.
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what is the solubility in moles/liter for aluminum hydroxide at 25 oc given a ksp value of 1.0 x 10-33. write using scientific notation and use 1 or 2 decimal places (even though this is strictly incorrect!)
The solubility in moles/liter for aluminum hydroxide at 25 degrees Celcius is 2.47×109 M
What is solubility?
The maximum amount of a substance that can be dissolved in a given volume of a solvent at a particular temperature is referred to as the substance's solubility. The solubility of a given solute-solvent combination is a quality that is unique to that combination; yet, the solubility of individual compounds can vary substantially.
Given that,
Temperature= 25 degrees Celcius
Ksp value= 1.0 X 10^-33
Al(OH)3(s) ==> Al3+(aq) + 3OH-(aq)
Ksp = [Al3+][OH-]3
Let x = [Al3+], then [OH-] = 3x
1.3x10-33 = (x)(3x)3
1.3x10-33 = 27x4
x4 = 4.8x10-35
x = 2.5X10-9 M = molar solubility of Al(OH)3
Hence, the answer rounded off to one decimal point since in decimal part .466 digits in 2nd and 3rd place (66) and greater than 50. the previous digit is converted to the next digit (4-5) Even if you want to give the answer up to two decimal points then the digit in 3rd place (6) is greater than (5) so the digit in 2nd decimal place converts to (67) the answer will be 2.47×109.
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What is the effect of applying an unbalanced force on an object?
Answer:
Unbalanced forces affect motion of objects by causing them to accelerate, decelerate or change direction.
A sample of nitrogen gas occupies a volume of 7.22 L at 60.0°C and 402 torr.
If the volume of the gas sample is decreased to 5.29 L, while its temperature is decreased to –4.0°C, the resulting gas pressure will be
The resulting gas pressure will be 512.08 torr.
By ideal gas law, PV = nRT
P = pressure
V = volume
n = number of mole of gas
R = gas constant
T = temperature
Using ideal gas law, P₁V₁/ T₁ = P₂V₂/ T₂
P₁= 402 torr
V₁ = 7.22 L
T₁ = 60.0°C
P₂ = ?
T₂ = 56° C
V₂ = 5.29 L
Put these values in formula, P₁V₁/ T₁ = P₂V₂/ T₂
P₂ = P₁V₁T₂/ T₁ V₂
P₂ = 402 torr ×7.22 L ×56° C / 60.0°C ×5.29 L
P₂ = 512.08 torr
Hence, the resulting gas pressure will be 512.08 torr.
The ideal gas equation is formulated as: PV = nRT.
In this equation, P refers to the pressure of the ideal gas, V is the volume of the ideal gas, n is the overall quantity of ideal gas this is measured in terms of moles, R is the universal gas constant, and T is the temperature.
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describe the reaction of glycolysis where electrons are removed from the carbon's originally present in glucose including the enzyme that catalyzes the reaction. does the reaction generate a reduced or an oxidized electron carrier?
The reaction where electrons are removed from carbon initially present in glucose is the formation of Glyceraldehyde-3-phosphate and Dihydroxyacetone phosphate.
Glycolysis is the process of the formation of glucose into 2 molecules of pyruvate. It is a cellular process, the molecule reduces in carbon number to form pyruvate thus electrons are removed in the fourth step of glycolysis. The reaction is:
Fructose-6-phosphate(6 carbon) →→→ Glyceraldehyde-3- phosphate(3 carbon) + Dihydroxyacetone phosphate (3 carbon)
This reaction occurs in the presence of the enzyme Fructose bisphosphate aldolase. The reaction generates a reduced electron carrier NAD⁺
Dihydroxyacetone phosphate further reverses into glyceraldehyde-3-phosphate, thus leading to the formation of 2 molecules of pyruvate(a 3-carbon molecule).
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which two characteristics describe a gas?
Answer:
gases have no definite volume and shape
What is the name of C4S3?
Answer:
Carbon trisulfide or tetracarbon trisulfide.
Explanation:
I don't know if this compound actually exists. The C is carbon and the S is sulfur. The carbon retains its name and is in first position in the name. A compound of sulfur is given the nickname "sulfide." The number of S atoms needs to be identified using the latin prefix "tri." The number of C atoms is often not identified in chemical naming, based on the irritating assumption that anyone looking at the three sulfurs would be able to determine that 3 carbons are necessary. But that is often not obvious, as in this case. So I prefer adding the latin prefix for 4 (tetra-) for the sulfur, to make it tetrasulfur trisulfice. {Try fitting that into a bottle}.
wich statement indicates that a chemical reaction has taken place
The correct answer of chemical reaction is option (C) an odor is produced by burning a sugar.
An odor is produced by burning a sugar is a statement which indicates that a chemical reaction has taken place.
A chemical reaction is a manner that leads to the chemical transformation of 1 set of chemical substances to some other. A chemical reaction is a technique in which one or extra materials, also called reactants, are converted to 1 or greater special materials, known as merchandise. substances are both chemical factors or compounds.
A chemical reaction is a system in which reactants react chemically and convert into merchandise by chemical transformation. as an example, breathing we inhale oxygen which reacts with glucose and produces carbon dioxide, water and energy.
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A molecule contains 3 atoms. It has 1 triple bond and 1 single bond. There are no lone pairs on any of the atoms. How many rheds are within the molecule?.
The central atom of the molecule has three electrons on its valence shell.
What is the valance shell electro pair repulsion theory?
The valance shell electron pair repulsion theory shows us the number of electron pairs that can be found on the valance shell of the central atom of the molecule. Recall that the shape of the molecule is determined by the number of electron pairs that can be found on the valance shell of the central atom of the molecule.
Hence, given the fact that the molecule contains 3 atoms. It has 1 triple bond and 1 single bond, we can be able to conclude that the molecule has three electron pairs on its valance shell.
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Which of the following is incorrect according to Dalton's atomic theory?
a) atoms of different elements can mix together and chemically combine to make new elements
b) atoms of the same element are identical
c) chemical reactions occur when atoms are rearranged in different combinations
d) all elements are made up of tiny particles called atoms
According to the given statement chemical reactions occur when atoms are rearranged in different combinations
The correct option is C.
Why is Dalton's Atomic Theory important?The fact that Dalton's atomic theory does not break a number of fundamental rules of chemical combination, including the law of definite proportions, the law of multiple proportions, and the law of conservation of mass, is one of its most significant advantages.
What are Dalton's atomic theory's four main aspects?All matter is composed of tiny, unique units called atoms.Atoms are unbreakable and undividable.An element's atoms all have the same weight and other characteristics.Various elements' atoms have different masses.To know more about Dalton's atomic theory visit:
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Explain why the ideas on atoms proposed
by Dalton constitute a theory, while the ideas pro-posed by Democritus do not
The ideas on atoms proposed by Dalton constitute a theory, while the ideas proposed by Democritus do not because Democritus' theories did not explain chemical behavior and were not supported by experimental findings.
Dalton's theories were scientifically based and did explain chemical behavior; his tests revealed that the ratios in which elements were mixed were whole numbers. Democritus' theories were in line with later scientific theories, but they did not account for chemical activity. Democritus' method was not based on science, so it also lacked experimental support.
According to the first section of Dalton's theory, all matter is composed of indivisible atoms. According to the second component of the theory, the mass and characteristics of every atom in a specific element are the same. Compounds, according to the third section, are combinations of two or more different kinds of atoms.
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21.0 g of hydrogen is mixed with 7.0 g of nitrogen. What is the maximum mass of ammonia that can be produced from this reaction?
HELP
21.0 g of hydrogen is mixed with 7.0 g of nitrogen then the maximum mass of ammonia that can be produced from this reaction is 8.51gram.
What is Limiting agent?
Limiting agent is reactant in a reaction which is in smallest amount, that is totally consumed when a chemical reaction is completed
The balanced reaction is
[tex]N_{2}+3H_{2}\rightleftharpoons 2NH_{3}[/tex]
moles of nitrogen= 7.0÷28=0.25
moles of hydrogen=21.0÷2.016=10.41
To know the limiting reagent we have to divide moles by stoichiometry
0.25÷1=0.25
10.41÷3=3.47
0.25 is lesser than 3.47 so Nitrogen is limiting reagent so reaction will run according this only
1 Moles of nitrogen=2 mole of ammonia
0.25 mole of nitrogen = 2×0.25=0.5 mole of ammonia
mass of ammonia= 0.5mole×Molar mass of ammonia
= 0.5×17.031
=8.51g
Thus the mass of ammonia formed is 8.51g
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Please help its due today
In the previous lesson you described the similarities and differences between the light signs in shops, such as the ones "open", "closed", and fireworks. Zooming in, what do you think is happening at the atomic level to explain these differences and similarities? Explain.
Atomic level to explain these differences and similarities are existing or occurring within an atom or atoms
Atomic level is the when photon are incident in the new medium and they are absorbed by the atom or electron and then remitted or converted to internal energy and here firework are colorful and neon are orange and when the electron run to lower energy level then they emit colored light and the neon never run out electrical energy is the sole resource that is consumed
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The work function of iron is 4.50 eV.
What frequency of light will create
photoelectrons with a KE of 1.88 eV?
Frequency of light that will create photoelectrons with a KE of 1.88 eV is 1.54 × [tex]10^{15}[/tex].
How to find frequency ?The frequency of a repeating event is the number of occurrences per unit of time. It is also known as temporal frequency to distinguish it from spatial frequency and ordinary frequency to distinguish it from angular frequency.
Frequency is defined as the number of waves that pass through a fixed point in one unit of time; it is also defined as the number of cycles or vibrations that a body in periodic motion goes through in one unit of time. The number of periods or cycles per second is defined as frequency. The hertz is the SI frequency unit (Hz). A hertz is one cycle per second.
Kinetic energy of photoelectrons = Planks constant × frequency - work function
KE = h ×f - Ф (h = planks constant = 6.62610 × [tex]10^{-34}[/tex]
1.88 + Ф = h × f
1.88 + 4.50 = h × f
f = 1.54 × [tex]10^{15}[/tex]
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