Answer: A.
Explanation: A chemical reaction is a chemical change that occurs when two or more substances combine to form a new substance . Photosynthesis turns carbon dioxide and water into oxygen and carbohydrates, therefore a chemical change occurs.
Answer:
A. Because a new substance is formed.
Noble gases rarely ever react with other elements. Which rule below explains why?
Octet Rule
Hund's Rule
Aufbau Principle
Pauli Exclusion Principle
Answer:
A.Octet Rule
Explanation:
Because its orbital surface containes eight electrons
Answer:
Octet Rule
Explanation:
The octet rule talks about the tendency of atom to attain 8 electron in it outer shell. When an atom have fewer outer electrons than 8 they tend to easily react to form stable compounds. The atom that has it outer shell fully filled up are usually very stable and hardly go into a reaction. The octet rule is mostly involved with the s and p orbitals.
Noble gases like Neon and Argon have fully filled outer shell. The valency electron is 8. This fully filled valency shell is responsible for the stable nature of these noble gases. These noble gases find it hard to react with other elements. Example includes Neon and Argon which have atomic numbers of 10 and 18 respectively. The electronic configuration can be represented as follows:
Neon → 2 8
Argon → 2 8 8
The number of atoms in 5.78 mol NH4NO3. Show your work.
Answer:
3.481 x 10²⁴ atoms
Explanation:
Data Given:
Number of moles of NH₄NO₃ = 5.78 mol
Number of atoms of NH₄NO₃ = ?
Solution:
Formula used
no. of moles = no. of atoms / Avogadro's number
As we have to find no. of atoms
So, we have to rearrange the above equation
no. of atoms = no. of moles x Avogadro's number . . . . . (1)
Where
Avogadro's number = 6.022 x 10²³ atoms
Put values in above Equation 1
no. of atoms = 5.78 mol x 6.022 x 10²³ atoms/mol
no. of atoms = 3.481 x 10²⁴ mol
So,
no. of atoms in 5.78 mole NH₄NO₃ = 3.481 x 10²⁴ atoms
Answer:
The answer is 3.48 × 10²⁴
Explanation:
Avogadro's constant/number is used to get the actual number of particles (atoms or ions) in a molecule of a substance.
Avogadro's number is 6.022 × 10²³
To get the actual number of atoms in a substance: avogadro's constant is multiplied by the number of moles of the substance
Hence,
number of atoms = 5.78 × 6.022 × 10²³
number of atoms in 5.78 moles of NH₄NO₃ = 3.48 × 10²⁴
what is the oxidation number of sulfur in BaSO4?
The oxidation number of sulfur in BaSO₄ is +6.
Explanation:The oxidation number of sulfur in BaSO₄ can be calculated using the guidelines for assigning oxidation numbers.
Guideline 3 suggests that the oxidation number for oxygen is -2.
By using this oxidation number and the ion's formula, guideline 4 can be used to calculate the oxidation number for sulfur:
Let x be the oxidation number for sulfur.
Since there are 4 oxygen atoms in the compound, the sum of the oxidation numbers for the oxygen atoms is -8.
This means that x + (-8) = 0, which implies that x = +6.
Therefore, the oxidation number of sulfur in BaSO₄ is +6.
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The oxidation number of sulfur in BaSO₄ is +6.
The oxidation number of sulfur in BaSO₄ can be determined using the rules for assigning oxidation numbers and ensuring the sum of the oxidation numbers equals the charge on the molecule.
Here’s a step-by-step explanation:
Start by noting that barium (Ba) typically has an oxidation number of +2 in its compounds.Oxygen (O) typically has an oxidation number of -2.In BaSO₄, there are four oxygen atoms. Thus, the total oxidation number contributed by oxygen is:4 x (-2) = -8.
Since the compound BaSO₄ is neutral, the sum of the oxidation numbers in BaSO4 must be zero.Let the oxidation number of sulfur (S) be x. According to the sum rule, we have:(+2) + x + (-8) = 0.
Solving for x, we get: x = +6.Therefore, the oxidation number of sulfur in BaSO₄ is +6.
Juan inflates a balloon and then releases its end to let the balloon go free as air comes out. The balloon then flies around the room.
Answer:
This is because of Newton's third Law of motion :
For every action there is equal and opposite reaction .
Explanation:
When air is squeezed out from the balloon , the potential energy (Shape of balloon) is converted into Kinetic energy. This kinetic energy is possessed by fast moving air particles coming out from balloon.These air particles are pushed backward,so according to Newtons third law , the balloon should fly upward.
[tex]F_{AB} = - F_{BA}[/tex]
Answer:
According to Newton’s third law of motion, the balloon is pushed forward as the air is forced out.
Explanation:
Action, Reaction
What types of energy are involved in a chemical reaction?
is the energy required for a chemical reaction to take place, and
is the energy associated with
every substance.
Answer:
Enthaply
Explanation:
The Energy involved in a chemical reaction is the difference in the amounts of stored chemical energy between the products and the reactants. This stored chemical energy, or heat content, of the system is known as its enthalpy.
Answer:
The types of energy in chemical reactions are as follows: internal energy, enthalpy
Explanation:
The internal energy is the sum of all the energies, it is due to the positions and movements of the subatomic particles, atoms and molecules that constitute it, as well as to the unions between the atoms. In chemical reactions there is a variation in the internal energy of substances, classified as exothermic if they release energy in the form of heat, endothermic if they absorb energy in the form of heat.
On the other hand, the enthalpy of reaction is the heat absorbed or released in a chemical reaction at a constant pressure. It is defined as the subtraction between the sum of the enthalpies of the products and the sum of the enthalpies of the reagents.
What is the molarity (M) of the following solutions?
a. 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution
b. A 2.6 L solution made with 235.9 g of KBr
Answer:
The molarity (M) of the following solutions are :
A. M = 0.88 M
B. M = 0.76 M
Explanation:
A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.
Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)
= 27 + 3(16 + 1)
= 27 + 3(17) = 27 + 51
= 78 g/mole
[tex]Al(OH)_3[/tex] = 78 g/mole
Given mass= 19.2 g/mole
[tex]Mole = \frac{Given\ mass}{Molar\ mass}[/tex]
[tex]Mole = \frac{19.2}{78}[/tex]
Moles = 0.246
[tex]Molarity = \frac{Moles\ of\ solute}{Volume\ of\ solution(L)}[/tex]
Volume = 280 mL = 0.280 L
[tex]Molarity = \frac{0.246}{0.280)}[/tex]
Molarity = 0.879 M
Molarity = 0.88 M
B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr
Molar mass of KBr = 119 g/mole
Given mass = 235.9 g
[tex]Mole = \frac{235.9}{119}[/tex]
Moles = 1.98
Volume = 2.6 L
[tex]Molarity = \frac{Moles\ of\ solute}{Volume\ of\ solution(L)}[/tex]
[tex]Molarity = \frac{1.98}{2.6)}[/tex]
Molarity = 0.762 M
Molarity = 0.76 M
If atoms
energy during a change of state, they are pulled together by attractive forces and become more organized.
Answer:
If atoms lose energy during a change of state, they are pulled together by attractive forces and become more organized.
Explanation:
Change of state is the process by which substances pass from one state of agregation to another. The aggregation states are solid, liquid and gas. This state of aggregation depends on the cohesion forces that hold the particles together.
The change of state of substances consists of an exchange of energy. If it occurs when the body or system gives energy to the environment, the changes in state that occur are:
Solidification. Change of state from liquid to solid. Condensation. Change state from gas to liquid. Inverse sublimation. Change of state of gas directly to solid.Intermolecular forces are attractive forces between molecules. In the solid state, the intermolecular forces are relatively intense. In this case the molecules occupy a rigid position and have virtually no freedom to move. They only vibrate around the equilibrium positions. In the liquid state the intermolecular forces are not as strong as in the solid state, therefore, the particles have a certain freedom of movement. Liquids do not have a definite form, but take the form of the container that contains them. The molecules have limited movements of rotation, vibration and translation. Finally, in the gaseous state, the intermolecular forces between the particles are very weak, generating the particles great mobility. These particles tend to be great distances between them and there is no appreciable interaction between them.
Then it is possible to say that the intermolecular forces of attraction become stronger than before and become more organized and stable when the changes in the state of solidification, condensation and inverse sublimation occur.
Finally, If atoms lose energy during a change of state, they are pulled together by attractive forces and become more organized.
How do you know the strength of oxidizing/reducing agents in questions such as these ones? I know the answer for 37 is D but I don’t know why
Answer:
[tex]Pd^{2+}[/tex] is the strongest oxidizing agent .
Explanation:
It is said in the question that given reactions are spontaneous.
As [tex]Np^{3+}[/tex] oxidizes Ce to [tex]Ce^{3+}[/tex] we can say that [tex]Np^{3+}[/tex] is a stronger oxidizing agent than [tex]Ce^{3+}[/tex].
Similarly , [tex]Cd^{2+}[/tex] is stronger than [tex]Np^{3+}[/tex] (from first reaction).
From second reaction we can see that [tex]Pd^{2+}[/tex] is stronger than [tex]Cd^{2+}[/tex].
The order of oxidizing strength is [tex]Pd^{2+}[/tex] > [tex]Cd^{2+}[/tex] > [tex]Np^{3+}[/tex] > [tex]Ce^{3+}[/tex] .
To what pressure would you have to compress 48.0 L
of oxygen gas at 99.3 kPa in order to reduce its vol-
ume to 16.0 L?
Answer:
298 kPa
Explanation:
Data Given:
initial Volume of oxygen V1= 48.0 L
Final Volume of oxygen V2= 16.0 L
initial pressure of oxygen P1= 99.3 kPa
initial Pressure of oxygen P2= ?
Solution:
The Boyle's law formula will be applicable here at constant temperature
Boyle's law formula
P1V1 = P2V2
As we have to find final pressure so rearrange the equation
P2 = P1V1 /V2 ....................(1)
Put values in Equation 1
P2 = 99.3 kPa x 48 L /16 L
P2 = 298 kPa
So the final pressure will be 298 kPa
A hurricane warning has been issued in a location in Florida. What would people in the location most likely do? (2 points) Question 20 options: 1) turn on all major appliances in the house 2) remove fuel from their cars and generators 3) check and replenish emergency supplies 4) sit on the floor beside windows and doors
Answer:3 check and replenish emergency supplies
Explanation: This one is the only one that is not counter intuitive.
which alkali is used in Barium Sulfate ?
Answer:
Explanation:
Barium sulfate (or sulphate) is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and materials prepared from it.
Answer:
The barium
Explanation:
Barium is an alkaline earth metal that has toxic properties. It is the alkaline used in the composition of barium sulfate which is used as a contrast in stomach and intestine radiographs. This procedure presents no danger, as this sulfide is insoluble, that is, it will not be absorbed by the stomach.
Barium is a toxic chemical element, silvery in appearance, with a high melting point, which can be found in the mineral barite, not being found free in nature, due to its high reactivity.
A client is undergoing therapy in a whirlpool unit that has been plugged into an extension cord. What is this an example of?
Using extension or flexible cords improperly
Explanation:
A client undergoing therapy in a whirlpool unit plugged into an extension cord demonstrates a wrong and improper use of extensions and flexible cords. This is not a safe way to connect an electrical circuit.
Unless a Ground Fault Circuit Interrupter is used, the client is at a risk of suffering from electrocution. The Ground Fault Circuit Interrupter is able to detect leakages in the circuit and breaks it off.learn more:
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Using an extension cord with a whirlpool unit for therapy is an example of poor safety practices due to potential voltage drop and compromised earthing, which could result in the appliance not operating properly and raise electrical safety concerns.
A client undergoing therapy in a whirlpool unit that has been connected to an extension cord may be an example of poor safety practices in a health care setting. The use of an extension cord for a high-powered appliance such as a whirlpool may result in a reduced power output, leading to the appliance not operating correctly. This is because the voltage drop across the extension cord can be large, which decreases the voltage at the appliance, therefore reducing its effectiveness. Moreover, earthing or grounding may be compromised, which is essential for the safety of electrical appliances to prevent electric shocks.
The situation of a client being in a whirlpool unit connected to an extension cord can raise concerns about adherence to safety protocols. It is important for health care providers to ensure that all electrical safety requirements are met, including proper installation and usage of all therapeutic equipment. Electrical appliances should be properly earthed, and any form of makeshift extension cord usage should be carefully evaluated and generally avoided.
Describe the sampling method for determining population size
Answer:
Describe the sampling method for determining population size. The sampling method involves counting the total number of organisms in a certain area and then using that number to determine the total number of organisms in a larger area.
Explanation:
Balance this equation C6H14(g) + O2(g) → H2O(g) + CO2(g)
Answer:
2 C6H14 + 19 O2 = 12 CO2 + 14 H2O
Explanation:
Final answer:
The combustion of hexane (C6H14) is balanced by setting appropriate coefficients for CO2 and H2O to match the number of C and H atoms and then adjusting the O2 to balance the oxygen atoms, resulting in a balanced equation with equal numbers of each atom on both reactant and product sides.
Explanation:
To balance the chemical equation for the combustion of hexane (C6H14), we must ensure that the number of atoms for each element is the same on both the reactant and product sides. Given the unbalanced equation C6H14(g) + O2(g) → H2O(g) + CO2(g), we balance it step by step.
First, balance the carbon (C) atoms by setting the coefficient for CO2 equal to the number of C atoms in C6H14:
C6H14(g) + O2(g) → H2O(g) + 6CO2(g)
Next, balance the hydrogen (H) atoms by setting the coefficient for H2O equal to half the number of H atoms in C6H14:
C6H14(g) + O2(g) → 7H2O(g) + 6CO2(g)
Finally, count the number of oxygen (O) atoms in the products (6*2 for CO2 and 7 for H2O equals 19 O atoms) and balance it with the oxygen molecules (O2) in the reactants:
2C6H14(g) + 19O2(g) → 14H2O(g) + 12CO2(g)
This yields a balanced equation with 12 carbon atoms, 28 hydrogen atoms, and 38 oxygen atoms on each side.
Check your work to confirm that all atoms balance and that there are no fractional coefficients. The equation is now balanced.
I need help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer is C. 2-Pentene.
Answer:
C
Explanation:
This has diagonal lines, which indicates that it’s C.
How did early chemists determine which substances were elements?
(A) They knew how many protons were in the atoms.
(B) They knew how many electrons were in the outer shell of every atom.
(C) They knew what substances were mixtures.
(D) They knew which substances could not be broken down by chemical means.
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The correct answer would be option D
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They knew which substances could not be broken down by chemical means.
By definition, an element is the smallest part of a substance which has independent existence and can not be broken down by chemical means.
We must remember that the early chemists didn't have the luxury of the sophisticated equipment we have today many of which can literally "see through" a substance.
The had to depend on rather crude methods and instruments. Amidst all that, they still knew which substances could not be broken down by chemical means and those that could not. Those that could not be broken down by chemical means were labelled as elements and characterized.
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23. Which of the following describes ionic bonds?
a. lonic bonds are weak bonds between two water molecules
Electrons are shared between two atoms
C. Electrons are transferred from one atom to another
d. Protons are transferred from one atom to another
Answer:
b.Electrons are shared between two atoms.
Help..I asked this question before but I keep getting either between the two B or D and I would really like the correct answer. And if u don’t mind can u perhaps tell me how u searched or what exactly did u search to get the answer?...please and thank you
Answer: I think it’s C
Explanation:
Which of the following will NOT break down due to a chemical change?
1.H2O
2.Ne
3.N2O
4.HF
Answer:
2. Ne
Explanation:
Neon is an element. You cannot break down an element by chemical means.
1, 3, and 4 are wrong. They are all compounds, and compounds can be broken down by chemical means.
Neon will not break down due to a chemical change, therefore option (a) is correct .
What do you mean by the chemical change ?A chemical change is the change of one material into another, resulting in new materials with different properties .
Properties of chemical change -:
Some examples of chemical change are-
The formation of curd from milk through fermentation .Rusting of iron is a form of corrosion .Neon will not break down due to a chemical change, hence option (a) is correct .
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If 84 grams of sodium chloride reacts with an excess amount of magnesium oxide, how many grams of sodium oxide will be produced
Answer:
56.0g (3 s.f.)
Explanation:
Please see attached picture for full solution.
Which statement best describes the pH of pure water?
It is neutral because the concentration of hydronium ions equals that of hydroxide ions.
It is neutral because the pure liquid contains neither hydronium ions nor hydroxide ions.
It is acidic because it has a hydronium ion concentration of 1.0 x 10-7 M-
It is basic because it has a hydroxide ion concentration of 1.0 x 10-7M.
Mark this and return
I
Next
Submit
The pH of pure water is neutral because the concentration of hydronium ions equals that of hydroxide ions.
Answer: Option A
Explanation:
Water is one of the most important constituents of living being. It is said that there is no life without water. So that water need to neutral in nature to save life. Pure water is composed of hydronium [tex]H^{+}[/tex] and hydroxide [tex]\left(O H^{-}\right)[/tex] ions. It is known that hydronium ions are acidic in nature with concentration of [tex]1 \times 10^{-7} \mathrm{M} / \mathrm{L}[/tex].
Similarly, the hydroxide ions which are basic in nature will be in same concentration as that of hydronium ions. So, as the concentration of basic and acidic elements are equal with the same strength of pH, the combination of these ions lead to formation of pure water with the pH being neutral.
Consider the total ionic equation below.
2H⁺+ CrO²⁻₄+Ba²⁺+2OH⁻-->Ba²⁺+CrO²⁻₄+2H2O
What are the spectator ions in this equation?
H+ and OH-
H+ and Ba2+
CrO²⁻₄ and OH⁻
CrO²⁻₄ and Ba²⁺
Answer:
The spectator ions in this equation are :
CrO²⁻₄ and Ba²⁺
Explanation:
Spectator ions : These are the ions which are present in the solution but do not take part in chemical reaction.They are present as such in both reactant as well as product .
In this reaction,
1.H+ and OH- are combined and converted into water (H2O) : Changed to H2O
So , H+ and OH- are not Spectator ions
2.CrO²⁻₄ and Ba²⁺ are unchanged . Present as such in product and reactants
CrO²⁻₄ and Ba²⁺are Spectator ions
The spectator ions in this equation are CrO²⁻₄ and Ba²⁺. Therefore, option D is correct.
What is an ionic equation ?The term an ionic equations are defined as the chemical equations that show only ions that participate in a chemical reaction. In other words, the ions that react together in solution and form new substances. The other ions that don't participate are called spectator ions.
Spectator ions are defined as the ions which are present in the solution but do not take part in chemical reaction.They are present as such in both reactant and product .
In the given reaction,
1.H+ and OH- are mixed and converted into water (H2O)
So , H+ and OH- are not Spectator ions
2.CrO²⁻₄ and Ba²⁺ are unchanged . Present as such in product and reactants.
Therefore, CrO²⁻₄ and Ba²⁺ are Spectator ions
Thus, option D is correct.
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which of the following is a property of metals that is due to the delocalized electrons
A.transparency
B.dull Appearance
C.brittle
D.good conductor
Answer:
Good conductor
Explanation:
Metals form metallic bonds. They are also sometimes called 'a sea of electrons'. Basically, metal cations are surrounded by a sea of closely packed valence electrons. This close packing lets the particles of a metal interact much more efficiently and transfer heat or electric current efficiently. The valence electrons and metals ions are also moving to some extent, so besides being packed efficiently, they can also interact and collide to transfer electricity and heat.
This makes metals good heat and electric conductors.
The property of metals that is due to the delocalized electrons is good conductor. The correct option is D.
What property of metals is due to the delocalized electrons?Metals possess the property of being good conductors of electricity and heat, which is primarily due to the presence of delocalized electrons. Delocalized electrons are loosely bound and can move freely throughout the metal lattice. When a potential difference is applied, these mobile electrons can easily flow, carrying electric current with minimal resistance.
This property makes metals invaluable in electrical applications, such as wiring and electronic components. Additionally, the delocalized electrons are responsible for metals' high thermal conductivity, allowing them to efficiently transfer heat. However, this delocalization of electrons also leads to metals having a lustrous appearance (not dull), and they are generally malleable and ductile rather than brittle. Therefore, the correct answer is D. good conductor.
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Plants undergo photosynthesis to produce glucose according to the reaction below. What mass of water is required to produce 5.0g of glucose?
6CO2 + 6H2O --> C6H12O6 + 6O2
a. 3.0 g H2O
b. .50 g of H2O
c. 5.0 g H2O
d. 18 g H2O
Answer:
option a) 3 g
Explanation:
mass of Glucose = 5 g
Mass of H₂O = ?
Reaction Given:
6CO₂ + 6H₂O ----> C₆H₁₂O₆ + 6O₂
Solution:
First we have to find mass of glucose from balanced reaction.
So,
Look at the reaction
6CO₂ + 6H₂O -------> C₆H₁₂O₆ + 6O₂
6 mol 1 mol
As 6 mole of water (H₂O) give 1 mole of Glucose (C₆H₁₂O₆ )
Convert moles to mass
molar mass of C₆H₁₂O₆ = 6(12) + 12(1) + 6(16)
molar mass of C₆H₁₂O₆ = 72 + 12 + 96
molar mass of C₆H₁₂O₆= 180 g/mol
molar mass of H₂O = 2(1) + 16 = 18 g/mol
Now
6CO₂ + 6H₂O ---------> C₆H₁₂O₆ + 6O₂
6 mol (18 g/mol) 1 mol (180 g/mol)
108 g 180 g
108 g of water (H₂O) produce 180 g of glucose (C₆H₁₂O₆)
So
if 108 g of water (H₂O) produce 180 g of glucose (C₆H₁₂O₆) so how many grams of water (H₂O) will be required to produce 5 g of glucose (C₆H₁₂O₆).
Apply Unity Formula
108 g of water (H₂O) ≅ 180 g of glucose (C₆H₁₂O₆)
X g of water (H₂O) ≅ 5 g of glucose (C₆H₁₂O₆)
Do cross multiply
mass of water (H₂O) = 108 g x 5 g / 180 g
mass of water (H₂O) = 3 g
So 3 g of water is required to produce 5 g of glucose.
Name the following compound:
C5Si7
Answer:
Pentacarbon heptasilicide.
Explanation:
In order to name the following compound, we need to identify whether it is molecular or ionic.
Molecular compounds consist of non-metal atoms, while ionic compounds would have metal cations in their composition.
In the given compound, [tex]C_5Si_7[/tex], we have two non-metals, carbon and silicon, meaning we should follow the molecular compound naming rules. The rules involve using prefixes to state the number of individual atoms.
The two prefixes required here are 'penta' for 'five' to indicate 5 carbon atoms present and 'hepta' for 'seven' to indicate 7 silicon atoms present.
The first part of the name would be pentacarbon (notice that the standard name for the first element is used). The second part would be heptasilicide (notice that the second atom would have an ending of -ide followed by the standard beginning of silicon).
A plutonium atom undergoes nuclear fission. Identify the missing element in the nuclear equation.
230 pu
Answer:
[tex]_{92}^{226}U[/tex]
Explanation:
Let's firstly identify the atomic number (the number of protons) of Pu. This is done by referring to the periodic table and finding Pu. The atomic number of Pu is:
[tex]Z=94[/tex]
In order to identify the type of a nuclear decay, we need to find the N/Z ratio. This is the ratio between the number of neutrons and the atomic number of an isotope. The number of neutrons is found by subtracting the number of protons from the mass number:
[tex]N=M-Z[/tex]
That said, the N/Z ratio equation becomes:
[tex]N/Z=\frac{M-Z}{Z}=\frac{M}{Z}-1=\frac{230}{94}-1=1.45[/tex]
This is a relatively high number thinking about the belt of stability of isotopes. Ideally, stable isotopes with a low Z value have an N/Z ratio of 1. Heavier isotopes with Z > 50 would have a slightly higher N/Z ratio and would be stable around N/Z = 1.25. This means we wish to decrease the N/Z ratio as much as possible.
Among all the decays, alpha-decay is preferred to decrease the N/Z ratio significantly (1.45 is much higher than 1.25). That said, we'll release an alpha particle with some nucleotide X of mass M and atomic number Z:
[tex]_{94}^{230}Pu\rightarrow _Z^MX+_2^4\alpha[/tex]
According to the mass and charge conservation law:
[tex]230=M+4\therefore M=230 - 4 = 226[/tex]
[tex]94=Z+2\therefore Z = 94-2 = 92[/tex]
Identify an element with Z = 92 in the periodic table. This is uranium, U:
[tex]_{92}^{226}U[/tex]
As the model in the picture shows, I am confused that why the work by gas during the expansion is -P times deltaV (P represents the external pressure). In my view, this should be the work done on the gas by environment. And the work done by gas should be the pressure of the gas (i.e. the internal pressure) which is changed by the volume of gas. (PS. The picture is from a chapter about thermochemistry in my General Chemistry textbook)
Answer:
Here's what I get
Explanation:
Assume that the piston is weightless and frictionless and has an area of 0.01 m², and that the cylinder contains 0.001 m³ of air at 1 bar.
Then the gas is slowly heated, making the gas expand and force the piston up until the volume is 0.002 m³.
The gas is doing work, because it is pushing back against the pressure of the atmosphere in order to expand. The sign is negative, because of the thermodynamic convention that anything going out of the system is negative.
How much work has the gas done?
w = F × d, and
p = F/A, so
F = p × A. Then
w =p × A × d
A × d is the change in volume (ΔV) swept out by the piston as the gas expands. Thus
w = -pΔV (negative sign because of the convention)
= -1 × 10⁵ Pa × 0.001 m³ =-100 Pa·m³ = -100 J
The gas has done 100 J of work by expanding against an external pressure.
Answer:
actually the sign convention in physics and chem varies:
Explanation:
In chem , work done by the system (gas) is taken as negative.
Work done on the system (gas) is taken as positive.
this is because when the gas does work , its internal energy decreases and thus it looses energy upon doing work , so it is taken as negative.
delta V is the change in volume.
P is the ext. pressure.
Now , to make it simple , when external pressure is applied to the gas , it gets compressed and thus it (gas) does work by exerting more pressure on the walls of the cylinder, which is why it is -P.
14. Several days after a snowfall, the roofs of some homes on your street have almost no snow on them, while the roofs on other homes are still snow covered. Assuming they have all received the same amount of sunlight, give one reason for this observation related to thermal energy and insulation.
The variance in snow coverage on roofs can be attributed to differences in insulation quality and roof material albedo, with well-insulated and darker roofs more likely to have less snow. Highly efficient insulation in some Northern European homes ensures warmth even when unoccupied.
Explanation:The observation that some roofs still have snow on them while others do not, despite receiving the same amount of sunlight, can be explained by differences in thermal energy and insulation. Roofs with better insulation retain heat within the home more efficiently, preventing the snow from melting as quickly. On the other hand, roofs with poor insulation allow more heat to escape, which contributes to the snow melting faster. Additionally, the albedo of the roof material could impact snow retention, with darker materials absorbing more heat and potentially melting snow quicker than lighter materials that reflect more sunlight.
In the case of Northern European homes that remain warm without heating systems, the explanation lies in highly efficient insulation that minimizes heat loss. This robust insulation keeps the internal temperature stable, even in the absence of residents to produce body heat. Thus, when the homes are unoccupied, they can still maintain warmth due to the lack of heat exchange with the colder outside environment.
8.
number of trees people cut down.
Compared to developing nations, developed nations have
lower health standards.
greater personal wealth.
faster-growing populations.
higher health standards.
Hardin's "Tragedy of the Commons" essay addresses the conflicts associated with what environmental chal
Final answer:
The Tragedy of the Commons, described by Garrett Hardin, highlights how individual actions based on self-interest can lead to the depletion of shared resources, exemplified by environmental issues like overfishing, deforestation, and air pollution. It underscores the conflict between individual interests and the common good.
Explanation:
The concept of the Tragedy of the Commons was introduced by Garrett Hardin in 1968 to describe a dilemma in which multiple individuals acting independently and rationally according to their own self-interest can ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this to happen. This concept applies to environmental issues such as overfishing, deforestation, and air pollution. Hardin's essay illustrates the conflict between individual interests and the common good, and the need for responsible resource management.
Examples today include the overuse of fisheries, forest areas, and the Earth's atmosphere as a dumping ground for greenhouse gases. The Tragedy of the Commons extends to various aspects of the environment, where the absence of restrictions leads to the over-exploitation of resources and environmental degradation. The predicament lies in the freedom of individuals to use common resources without considering the long-term effects and sustainability, potentially leading to the ruin of the resources for everyone.
3. At which Celsius temperature does lead change
from a solid to a liquid?
Answer:
the Melting point is 621.5 F or it can be 327.5 C
hope it right