Answer:
1.146 x 10⁴ year.
Explanation:
The decay of carbon-14 is a first order reaction.The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.The integration law of a first order reaction is:kt = ln [A₀]/[A]
k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.
t is the time = ??? years.
[A₀] is the initial percentage of carbon-14 = 100.0 %.
[A] is the remaining percentage of carbon-14 = 1/4[A₀] = 25.0 %.
∵ kt = ln [Ao]/[A]
∴ (1.21 x 10⁻⁴ year⁻¹)(t) = ln (100.0%)/[25.0 %]
(1.21 x 10⁻⁴ year⁻¹)(t) = 1.386.
∴ t = 1.386/ (1.21 x 10⁻⁴ year⁻¹) = 1.146 x 10⁴ year.
The piece of fossilized wood is approximately 11,460 years old, based on its carbon-14 radioactivity being 1/4 that of new wood and using the known half-life of carbon-14 which is 5730 years.
A fossilized piece of wood has a carbon-14 radioactivity that is 1/4 that of new wood. Given that the half-life of carbon-14 is 5730 years, we can estimate the age of the fossil. For each half-life that passes, the amount of carbon-14 halves. If the wood has 1/4 the radioactivity, this means that two half-lives have passed, as (1/2)² = 1/4. Therefore, using the formula for carbon dating and the known half-life of carbon-14, we can calculate that the wood is approximately 2 times 5730 years old, which is 11,460 years old.
What type of reaction is created by starting a fire by igniting gasoline?
A physical reaction
A chemical reaction
A combustion reaction
An oxidation reaction
Answer:
Oxidation reaction
Explanation:
When flame comes in contact with gasoline in the presence of oxygen, combustion takes place. Oxidation reaction involves reacting oxygen with a compound. To stop fire, we can stop the oxidation process by adding carbon (iv) oxide since it does not support combustion. Hence the reason why CO2 is used to stop flames.
The anions formed from the atoms of the elements in family VIA should carry a +6 charge.
a. true
b. false
The answer would be true
Final answer:
The statement is false because elements in family VIA (Group 16) of the periodic table typically form anions with a -2 charge, not a +6 charge, as they tend to gain two electrons to achieve a noble gas electron configuration.
Explanation:
The statement that the anions formed from the atoms of the elements in family VIA should carry a +6 charge is false. Elements in Group 16 (family VIA) of the periodic table, also known as the chalcogens, include oxygen, sulfur, selenium, tellurium, and polonium. These elements typically have six valence electrons and tend to gain two electrons to achieve a stable electron configuration, similar to that of a noble gas. As a result, these elements form anions with a -2 charge, not a +6 charge.
An easy way to remember the typical charge of anions in this group is by considering the general trend on the periodic table: as you move from the right to the left, elements form anions with a negative charge equal to the number of groups moved left from the noble gases. Therefore, since Group 16 is two groups left of the noble gases, the typical anion charge for these elements would be 2-.
In the reaction of chlorine with calcium, explain which atom is oxidized.
Show ALL steps and work. I don't understand this.
Answer:
The atom is oxidized is Ca.
Explanation:
The oxidation-reduction reaction contains a reductant and an oxidant (oxidizing agent).The oxidation process is the process in which electrons are lost and produce positively charged ions.The reduction process is the process in which electrons is gained and negatively charge ions are produced.In the reaction of chlorine with calcium:Ca + Cl₂ → CaCl₂,
Ca loses 2 electrons and is oxidized to Ca²⁺. (Ca → Ca²⁺ + 2e).
Cl is gains 2 electrons in "Cl₂, oxidation state zero" and is reduced to Cl⁻. (Cl₂ + 2e → 2Cl⁻).
What is the best explanation for why electrolyte solutions conduct electricity?
The answer is: the presence of free-flowing ions. Explanation: ionic compounds dissociate in water forming a solution with free ions.
Corrosion is the process by which iron is oxidized by elemental oxygen. therefore oxygen is the (oxidizing / reducing) agent and (gives / accepts) electrons.
Answer:
Oxygen is the oxidizing agent and accept electrons
Explanation:
Corrosion is an example of a redox reaction which involves both reduction and oxidation process.During corrosion a metal loses electrons and becomes oxidized to form a metal ion. Therefore, oxygen is the oxidizing agent since it undergoes reduction by gaining electrons.Therefore, during corrosion of iron, iron is the reducing agent and gives electrons, while oxygen is the oxidizing agent and accepts the electrons.Methane reacts with oxygen to produce carbon dioxide water and heat.how many kcal are produced when 5.00 g of methane react
Answer:
= 66.33 kCal
Explanation:
The combustion of methane is given by the equation;
CH4(g) + 2O2(g) → CO2(g) + 2H2O(l); ΔH = -890.3 kJ/mol
The molar enthalpy of combustion of methane is -890.3 kJ/mol
This means 1 mole of CH4 yields 890.3 kJ/Mol
But, molar mass of methane is 16.04 g/mol
Therefore;
Heat produced by 5.0 g of methane will be;
= (5.0 g/ 16.04 g/mol)× 890.3 kJ/mol
= 277.525 kJ/mol
But; 1 kcal = 4.184 kJ
thus; = 277.525 /4.184
= 66.33 kCal
Final answer:
To determine the amount of heat produced when 5.00 g of methane reacts with oxygen, convert the given heat production for 2.50 g of methane to kcal, find the heat value per gram, and then multiply by the mass of methane used (5.00 g).
Explanation:
The question asks how many kilocalories are produced when 5.00g of methane (CH₄) is reacted with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O) and release heat. To find this, we can use the information provided: the combustion of 2.50 g of methane produces 125 kJ of heat. As 1 kcal is equivalent to 4.184 kJ, we can first convert 125 kJ of heat to kcal, which gives us 29.8 kcal (125 kJ / 4.184 kJ/kcal).
Since this amount of heat is produced by 2.50 g of methane, we can find the heat produced by 1 g by dividing 29.8 kcal by 2.5, which gives us 11.92 kcal/g. For 5.00g of methane, the heat produced would be 5 times 11.92 kcal/g, equating to 59.6 kcal.
what are the 5 phases of matter?
Answer:solid
liquid
gas
supercritical fluid
plasma
superfluidity in liquid helium (that is Bose-Einstein condensate property)
supersolidity in fermionic condensate like the potassium40
Hope this helps and i like your profile pic ;)
The five phases of matter are solids, liquids, gases, plasma, and Bose-Einstein condensates.
Each phase differs in the way its atoms and molecules behave and interact with one another, resulting in different properties and behaviors.
Here's a brief explanation of each of the five phases of matter:
Solids: Solid matter has a definite shape and volume. It is rigid and cannot be compressed.
Liquids: Liquid matter has a definite volume but takes the shape of the container it's in. It can flow and be poured.
Gases: Gaseous matter has neither a definite shape nor a definite volume. It can be compressed and expanded.
Plasma: Plasma is a high-energy state of matter in which atoms lose their electrons, resulting in a mix of free electrons and positively charged ions. It is the most common state of matter in the universe.
Bose-Einstein Condensates: Bose-Einstein condensates are formed at extremely low temperatures when a group of atoms behaves like a single entity, becoming indistinguishable from one another.
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The specific heat for liquid argon and gaseous argon is 25.0 J/mol·°C and 20.8 J/mol·°C, respectively. The enthalpy of vaporization of argon is 6506 J/mol. How much energy is required to convert 1 mole of liquid Ar from 5°C below its boiling point to 1 mole of gaseous Ar at 5°C above its boiling point?6631 J229 J6735 J125 J6610 J
Answer:
6,735 JExplanation:
The total energy required to convert 1 mole of liquid from 5°C below its boiling point to 1 mole of gaseous Ar at 5° above its boiling point may be calcualted in three stages:
Heating the liquid Ar from 5°C below its boling point to the boiling pointVaporizing the liquid Ar at its boiling temperatureHeating the gaseous Ar from its boiling point to 5°C above it.1) Energy to heat the liquid Ar from 5°C below its boling point to the boiling point:
Q₁ = m × C × ΔT = 1 mol × 25.0 J/mol°C × 5°C = 125 J2) Energy to vaporize the liquid Ar:
Q₂ = m × Latent heat of vaporization = 1 mol × 6506 J/mol = 6506 J3) Energy to heat the gaseous Ar 5°C above its boiling point:
Q₃ = m × C × ΔT = 1 mol × 20.8 J/mol°C × 5°C = 104 J4) Total energy (E)
E = Q₁ + Q₂ + Q₃ = 125 J + 6506 J + 104 J = 6735 J ← answerThe total energy required to convert 1 mole of liquid Argon from 5°C below its boiling point to 1 mole of gaseous Ar at 5°C above its boiling point is calculated through a multi-step process. The steps involve increasing the temperature of the liquid to its boiling point, vaporizing at the boiling point, and further heating the gas above the boiling point. The sum of these three steps yields a total required energy of 6735 J.
Explanation:This is a multi-step thermodynamics problem in chemistry that requires the use of specific heat, change in temperature, and enthalpy of vaporization. The energy required to convert 1 mole of liquid Argon from 5°C below its boiling point to 1 mole of gaseous Ar at 5°C above its boiling point can be found through the equation: q = m*c*ΔT, where q is the heat energy, m is the amount of Argon in moles, c is the specific heat, and ΔT is the change in temperature.
First, we need to raise the temperature of the liquid argon from 5°C below the boiling point to the boiling point. Using the specific heat for liquid argon, this gives us q1 = (1 mol)(25.0 J/mol·°C)(5°C) = 125 J.
Next, we have to provide the heat of vaporization to convert the liquid to gas at the boiling point, which gives us q2 = 6506 J/mol. Then we have to further heat the gas from the boiling point to 5°C above it. Using the specific heat for gaseous argon, this gives us q3 = (1 mol)(20.8 J/mol·°C)(5°C) = 104 J.
Adding these three energy amounts together, we find that total energy required is q_tot = q1 + q2 + q3 = 125 J + 6506 J + 104 J = 6735 J.
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How many moles of helium are 8.84×10^24 atoms of He?
Answer:
14.77 mol.
Explanation:
It is known that every 1.0 mole of compound or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms.Using cross multiplication:
1.0 mole of He contains → 6.022 x 10²³ atoms.
??? mole of He contains → 8.84 x 10²⁴ atoms.
∴ The no. of moles of He contains (8.84 x 10²⁴ atoms) = (1.0 mol)(8.84 x 10²⁴ atoms)/(6.022 x 10²³ atoms) = 14.77 mol.
When a solvent can dissolve no more of a solid solute at a specific temperature, we say the solution is______
The answer is Saturated
The solute is saturated when it can no longer absorb any more of a substance.
3 A2 + B2 >>> 2 units of product
3 AA + BB >>> 2 products
3 volumes + 1 volume >>> 2 volumes product
3 liters + 1 liter >>> 2 liters product
3 moles A2 + 1 mole B2 >>> 2 moles product
Click to get the correct formula for the product of the reaction.
options:
AB2
A2B
A3B
AB
Answer:
A₃B.
Explanation:
3 AA + BB → 2 products.
Any chemical reaction should obey the law of conservation of mass that the no. of reactants atoms is equal to the no. of products atoms.Herein, 6 atoms of A react with 2 atoms of B.So, the product should contain 6 atoms of A and 2 atoms of B.The reaction produces 2 units of the product, so the product unit must contain 3 atoms of A and 1 atom of B.Thus, the product unit is A₃B.The reaction is:
3AA + BB → 2A₃B.
atoms change their chemical identity as the number of protons in their nuclei change.
A. Nuclear Fission
B. Both
C. Nuclear Fusion
Answer:
B
Explanation:
Three identical flasks contain three different gases at standard temperature and pressure. flask a contains c2h6, flask b contains o3, and flask c contains nh3. which flask contains the largest number of molecules?
Answer:
All the three flasks contain the same number of molecules.Explanation:
According to Avogadro's principle, equal volume of gases at the same temperature and pressure will contain the same number of particles (atoms or molecules).
Therefore, being the three flasks identical, which includes that they have the same volumen, and being that they contain different gases at standard temperature and pressure, regardless of the chemical formula of each gas, by direct use of Avogadro's principle, they all will contain the same number of molecules.
The ideal gas equation, pV = nRT reflects this fact: if you isolate the ratio V/n, you get V/n = RT/p. Then, since RT/p (the right side) is constant, V/n is also constant, meaning that for a fixed volume the number of particles is constant, regardelss of the gas.
According to Avogadro's law, equal volumes of gas at the same temperature and pressure contain the same number of molecules. Therefore, all three flasks, despite containing different gases, would have the same number of molecules.
Explanation:The subject of your question pertains to the principles of chemistry, specifically related to Avogadro's law. According to Avogadro's law, equal volumes of different gases at the same temperature and pressure contain an equal number of molecules. Therefore, Flasks A, B, and C which contain C2H6, O3, and NH3 respectively, all at standard temperature and pressure, would each contain the same number of molecules. This principle applies regardless of the identity of the gas, as it is related to the behaviour of gases as outlined in the ideal gas law.
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Which grouping identifies chemical properties?A. Density, luster, boiling point B. Melting point, hardness, conductivity C. Malleability, ductility, texture D. Combustibility, flammability, reactivity
Answer:
option D. Combustibility, flammability, reactivity.Explanation:
Physical properties: characteristics of the matter that can be observed and measured by physical media, withoud changing the composition of the matter.
Typical examples of physical properties are: mass, volume, density, boiling point, melting point, hardness, specific heat.
Chemical properties: they are ability of the matter to change by decompositon or combination with other substances to produce one or more different substances. They cannot not be observed or measured without changing the composition of the orignal sample.Typical examples of chemical properties are reactivity with oxygen, reactivity with water, and any reactitivy in general.
Hence, applying those definitions to the set of choices you get:
A. Density, luster, boiling point (incorrect)
All of them are physical properties since they are observable and measurable without altering the composition of the sample.
B. Melting point, hardness, conductivity (incorrect)
They all are also physical properties. For example, melting point can be measured with a thermometer during the phase change.
C. Malleability, ductility, texture (incorrect)
Again, all physical properties. Ducitlity, for example, is the ability of the metals to form this wires.
D. Combustibility, flammability, reactivity (correct answer)
Combustibility: is the reaction with oxigen to form CO₂ and H₂OFlammability: is the ability to burn in flames, which is a chemical change.Reactivity: Already discussed.All these properties can only be measured by producing the correspondant chemical reaction (change), so they are chemical properties.
Answer:
The correct option is D
Explanation:
what is the total number of moles represented by 20 grams of CACO3
A. 0.1
B. 0.2
C. 1
D. 2
Answer:
B. 0.2.
Explanation:
We can use the relation:n = mass/molar mass
mass of CaCO₃ = 20 g, molar mass of CaCO₃ = 100.0869 g/mol.
∴ n = mass/molar mass = (20 g)/(100.0869 g/mol) = 0.1998 ≅ 0.2 mol.
So, the right choice is: B. 0.2.
Final answer:
To find the total number of moles in 20 grams of CaCO₃, calculate the molar mass of CaCO₃ and then use the formula for moles. The total number of moles in 20 grams of CaCO₃ is 0.2.
Explanation:
To calculate the total number of moles represented by 20 grams of CaCO₃, we first need to determine the molar mass of CaCO₃.
The molar mass of CaCO₃:
Ca: 40.08 g/mol
C: 12.01 g/mol
O: 16.00 g/mol
Adding these up gives a total molar mass of CaCO₃ as 100.09 g/mol.
Now, we use the formula:
Number of moles = Mass / Molar mass
Number of moles = 20 g / 100.09 g/mol = 0.2 moles
Therefore, 20 grams of CaCO₃ represents 0.2 moles.
An experiment with 55 co takes 47.5 hours. at the end of the experiment, 1.90 ng of 55-co remains. if the half-life is 18.0 hours, how many ng of 55-co were originally present?
Answer:
[tex]\boxed{\text{10.7 ng}}[/tex]
Explanation:
Let A₀ = the original amount of ⁵⁵Co .
The amount remaining after one half-life is ½A₀.
After two half-lives, the amount remaining is ½ ×½A₀ = (½)²A₀.
After three half-lives, the amount remaining is ½ ×(½)²A₀ = (½)³A₀.
The general formula for the amount remaining is:
A =A₀(½)ⁿ
where n is the number of half-lives
n = t/t_½
Data:
A = 1.90 ng
t = 45 h
t_½ = 18.0 h
Calculation:
(a) Calculate n
n = 45/18.0 = 2.5
(b) Calculate A
1.90 = A₀ × (½)^2.5
1.90 = A₀ × 0.178
A₀ = 1.90/0.178 = 10.7 ng
The original mass of ⁵⁵Co was [tex]\boxed{\text{10.7 ng}}[/tex].
In an electrolytic cell, is it a oxidation-reduction reaction? True or False.
Answer:
\boxed{\text{True}}
Explanation:
Consider the electrolysis of molten MgCl₂.
During electrolysis
Mg²⁺ gains electrons, so it is reduced. Cl⁻ loses electrons, so it is oxidized[tex]\rm Reduction: Mg^{2+} + 2e^{-} \longrightarrow Mg\\Oxidation: 2Cl^{-} \longrightarrow Cl_{2} + 2e^{-}\\Overall: MgCl_{2} \longrightarrow Mg + Cl_{2}\\\\\text{Electrolysis is a }\boxed{\textbf{redox reaction}}[/tex]
Because the the individual components of any mixture are not _____ to each other, the composition of those components can vary. Also, some of the _____ properties of the individual components are still noticeable
Answer:
Because the individual components of any mixture are not bonded to each other, the composition of those components can vary. Also, some of the physical properties of the individual components are still noticeable.
Explanation:
A mixture is a combination of two or more pure substances that are present in any proportion and each pure substance keeps its own physical and chemical properties.
As oppossite to mixtures, the compounds are pure substances formed by two or more different elements which are chemically bonded to each other. So, while in the compounds the components (elements) are bonded in a fixed proportion, and their composition cannot vary, in the mixtures each component may be present in any proportion, which means that the composition can vary.
Take, for example, the simple case of talc and iron particles.This is a mixture. Talc is not bonded to the iron particles, and so their proportion, the compositoin, can vary in any form. Aslo, both talc and iron particles keep their own physical properties: you can perfectly separate the mixture by using a magnet to attract the iron particles, because they have not lost their magnetic property (a physical one).
R-12 should be recycled instead of vented to the atmosphere because
A. recycling companies offer large financial incentives.
B. it has been proven to deplete the Earth's ozone layer.
C. R-12 is expensive.
D. R-12 is unstable.
I believe is B if not then it's A
Answer:
Option (B)
Explanation:
R-12 is known as the Dichloro-difluoro-methane and it is a colorless gas. It is was earlier used in the refrigerators, vehicles air conditioning, and aerosol spray. The use of this R-12 was found to be depleting the ozone layer which was not a positive effect on the earth. Due to this, the use of this gas was banned and alternative energy resources were used. Its products containing this R-12 gas were not expensive and they were stable enough.
Hence, the correct answer is option (B).
How is radiation absorbed?
a. by increasing the molecular vibrations of molecules
b. by converting atoms to ions
c. by breaking chemical bonds
d. all of the above
By increasing the molecular vibrations
Which of the following has the shortest wavelength?
Ultraviolet light
Visible violet light
Visible red light
Infrared light
Answer:
ultraviolet light is the shortest wavelength
Explanation:
Answer:
The correct answer is the first option: Ultraviolet light.
Explanation:
Hello!
Let's solve this!
The ultraviolet light is the one with the shortest wavelength. It is between visible light and x-rays. The place where this is seen is in the electromagnetic spectrum, which is the set of all electromagnetic waves.
Therefore, we conclude that the correct answer is the first option: Ultraviolet light.
Do valence electrons show a repeating or periodic pattern? Explain.
Answer:
Yes, valence electrons show a repeating or periodic pattern.Explanation:
It is precisely the repeating pattern of the valence electrons which is the responsible for the repeating pattern of the chemical properties: elements on a same group (column) of the periodic table have similar chemical properties because they have the same number of valence electrons.
The chemical changes (reactions) are the result of the interaction of the electrons of the elements, and, since the valence electrons are the outer most electrons, you can expect that it is the valence electrons which most influence the occurrence of the chemical reactions, which is what defines the chemical properties.
Here you have the pattern of the valence electrons shown by the representative elements on the periodic table:
Group number number of valence electrons
(column number)
1 1
2 2
13 3 (the ones digit of the column number)
14 4 (the ones digit of the column number)
15 5 (the ones digit of the column number)
16 6 (the ones digit of the column number)
17 7 (the ones digit of the column number)
18 8 (the ones digit of the column number)
The atomic mass of carbon is 12.01, sodium is 22.99, and oxygen is 16.00. What is the molar mass of sodium oxalate (Na2C2O4)?
Answer:
134g/mol
Explanation:
The table shows the characteristics of four substances after they are placed in water.
Substance
Ion concentration
Electrical conductivity
W
Medium
Good
X
Low
Poor
Y
High
Excellent
Z
None
None
Which compound is most likely the strongest electrolyte?
W
X
Y
Z
Answer:
Electrolytes are chemicals that break into ions (ionize) when they are dissolved in water. The positively-charged ions are called cations, while the negatively charged ions are called anions.
Strong electrolytes completely ionize in water. This means 100% of the dissolved chemical breaks into cations and anions.
Weak electrolytes partially ionize in water. Pretty much any dissociation into ions between 0% and 100% makes a chemical a weak electrolyte, but in practice, around 1% to 10% of a weak electrolyte breaks into ions.
If a substance doesn’t ionize in water at all, it’s a nonelectrolyte.
Explanation:
The substance that serves as a good electrolyte in the list is the substance labelled Y.
What is an electrolyte?An electrolyte is a solution that conducts electricity by the movement of ions in the solution. The high concentration of ions in the electrolyte implies that it has a good conductivity
Hence, the substance that serves as a good electrolyte in the list is the substance labelled Y.
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An electrolytic cell is based upon a nonspontaneous reaction; the Eocell for the reaction is _____.
greater than one
less than zero
equal to one
equal to zero
In an electrochemical cell in which the oxidation reaction is nonspontaneous the oxidation will not occur spontaneously at the anode and the reduction will not be spontaneous at the cathode. And according to the law for the calculation of the voltage potential of the electrochemical cell (Ecell):
Ecell = Eox. - Ere. where (Eox. is the potential of the oxidation at the anode and Ere. is the potential of the reduction at the cathode). The standard potential for an electrolytic cell is negative, because of the Ere. which is greater than Eox.
The answer is : less than zero.
which of the following correctly represents an ion pair and the ionic compound the ions form
a. Ca2-, F-, CaF2
b.Na+, Cl-, NaCl2
c. Ba2+, O2-, Ba2O2
d. Pb4+, O2-, Pb2O4
Answer:
It's a.
Explanation:
That would be Ca2+ , F- . We see in the compound CaF2 the signs balance to give a neutral compound, 2+ balances with 2-.
Answer: a. [tex]Ca^{2+}[/tex], [tex]F^-[/tex], [tex]CaF_2[/tex]
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
(a) calcium and fluorine: Here calcium is having an oxidation state of +2 called as [tex]Ca^{2+}[/tex] cation and fluorine [tex]F^{-}[/tex] is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral [tex]CaF_2[/tex]. called as calcium fluoride.
(b) sodium and chlorine: Here sodium is having an oxidation state of +1 called as [tex]Na^{+}[/tex] cation and chlorine [tex]Cl^{-}[/tex] is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral [tex]NaCl[/tex] called as sodium chloride.
(c) barium and oxygen : Here barium is having an oxidation state of +2 called as [tex]Ba^{2+}[/tex] cation and oxygen [tex]O^{2-}[/tex] is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral [tex]BaO[/tex] called as barium oxide.
(d) lead and oxygen : Here lead is having an oxidation state of +4 called as [tex]Pb^{4+}[/tex] cation and oxygen [tex]O^{2-}[/tex] is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral [tex]PbO_2[/tex] called as lead(IV) oxide.
a beaker contains 500ml of 12m potassium nitrate .what is the molarity of the new solution if 250 ml more water is added
Answer:
8.0 M.
Explanation:
It is known that the no. of millimoles after dilution is equal to the no. of millimoles before dilution.∴ (MV) of KNO₃ before dilution = (MV) of KNO₃ before dilution.
Before dilution:
M = 12.0 M, V = 500.0 mL.
After dilution:M = ??? M, V = 500.0 mL + 250.0 mL = 750.0 mL.
∴ M after dilution = (MV) before dilution / (V) after dilution = (12.0 M)(500.0 mL)/(750.0 mL) = 8.0 M.
A photon with a wavelength of less than 50.4 nm can ionize a helium atom.
What is the ionization potential of helium?
Answer in J
To find the ionization potential of an atom, you use the wavelength of light that causes the matter to ionize. This can be calculated using the Planck-Einstein relation where energy equals Planck's constant multiplied by light's frequency. Frequency is found using the speed of light equation which is then used in the Planck-Einstein equation to find the ionization potential.
Explanation:The question is asking for the ionization potential of a helium atom. Ionization potentials denote the energy required to remove an electron from an atom. It's given that the minimum wavelength of light that can ionize helium is 50.4 nm. The energy of a photon of light can be calculated using the Planck-Einstein relation, E=hν, where h is Planck's constant (6.626 x 10-34 Js) and ν is the frequency of the light. The frequency can be found from the speed of light equation, c=λν, rearranged to give ν=c/λ.
Substituting constants and the given wavelength, and converting m to nm:
ν = (3.00 x 108 m/s) / (50.4 x 10-9 m)
Therefore, E = (6.626 x 10-34 Js) x ν
This would yield the energy needed to ionize the helium atom and that value is the ionization potential of helium in Joules.
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Explain why the pbcl2 dissolved when water was added
PbCl2 would not dissolve because it is insoluble based on the solubility rules for substances that will dissolve in water. This compound would instead form a solid precipitate at the bottom of the container.
PbCl2 dissolves in water as it dissociates into Pb²+ and Cl¯ ions which attract polar water molecules. Just like potassium chloride, lead(II) chloride dissolves due to hydration of ions. Solubility of PbCl2 may increase with temperature.
Explanation:When PbCl2 is dissolved in water, it dissociates into ions Pb²+ and Cl¯. These ions interact with water molecules due to the presence of polar bonds in water. Just like potassium chloride (KCl) dissolves in water by getting hydrated, or attracting water molecules, lead(II) chloride (PbCl2) dissolves in a similar fashion. Water, being a polar molecule, is attracted by the charges on both lead(II) and chloride ions. This hydration of ions is an important factor in the dissolution of many solids into liquids.
Moreover, the solubility of various solids in water tends to increase with temperature. Hence, if the PbCl2 was added to warm water, it might have increased its solubility, enabling more of PbCl2 to dissolve.
However, it is important to note that certain compounds like PbCl2 have relatively low solubility in water, and may still leave some solid undissolved even after thoroughly mixing.
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What volume of 0.125 m kmno4 is required to yield 0.180 mol of potassium permanganate
Answer:
= 1.44 L
Explanation:
Molarity or concentration is given by the formula;
Molarity = moles/volume in L
Therefore;
Volume = moles/molarity
Number of moles = 0.180 moles
Molarity = 0.125 M
Thus;
Volume = 0.18 mol/ 0.125 M
= 1.44 L
= 1.44 L