Answer:
Positive values of Enthalpy
Explanation:
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Barbara is conducting an experiment to observe heat flow. She places one piece of metal in a freezer at -18 degrees Celsius (°C) and a second piece of metal in an oven at 200 °C. After 2 hours, she takes the metal pieces out of the freezer and oven and places them both in the same beaker of boiling water for two minutes. Which of the following best describes how some of the heat will initially move in this system?
Heat will flow from the frozen metal into the hot metal.
Heat will flow from the boiling water into the hot metal.
Heat will flow from the boiling water into the frozen metal.
Heat will flow from the frozen metal into the boiling water.
Answer: The correct answer is heat will flow from the boiling water into the frozen metal.
Explanation:
According to the law of conservation of energy, energy cannot be destroyed nor created but it can be transformed from 1 form to another form.
There are 3 processes of heat transfer:
Conduction: This type of heat transfer occurs when there is direct contact between the two objects.Convection: This type of heat transfer occurs when there is a movement of fluid (liquid or gas) due to the movement of hot layers to the top and cold layers to the bottom which leads to convection currents. Radiation: This type of heat transfer occurs when there is a direct transfer of energy through space.The heat moves from a hot surface to a cold surface to maintain equilibrium.
We are given:
A metal is placed in a freezer (cold object) and another metal is placed in an oven (hot object) and then both the metals are placed in boiling water.
Initially, the heat will flow from the boiling water (hot object) into the frozen metal (cold object) to maintain equilibrium
Hence, the correct answer is heat will flow from the boiling water into the frozen metal.
which two terms best describe the level of organization of life shown in this photo?
Answer:
there's no photo, I'm sorry
This mathematical model describes the changes that occur in a sample of water as its temperature increases. Based on this model, how do you expect the motion of the molecules in ice to compare with the motion of molecules in water vapor?
A. I expect the molecules in ice to move more quickly than the molecules in water vapor.
B. This model does not provide enough data to answer the question.
C. I expect the motion to be very similar.
D. I expect the molecules n water vapor to move more quickly than the molecules in ice.
Answer:
D
Explanation:
the motion of particles can move more quickly due to weak force of attraction. water vapour is a gas hence the answer
1) list at least four uses of metals from your day to day life.
Answer:
alloy,copper,gold, silver,cobalt
Explanation:
Which of these statements are true? Select all that apply. The Delta.Hf for Br2(I) is 0 kJ/mol. The Delta.Hf for He(I) is 0 kJ/mol. The Delta.Hf for Hg(I) is 0 kJ/mol. The Delta.Hf for Cl2(g) is 0 kJ/mol. The Delta.Hf for N2(I) is 0 kJ/mol. CORRECT ANSWER IS A, C, AND D.
Answer: The correct options are A, C and D.
Explanation:
Enthalpy of formation is defined as the change in the enthalpy when 1 mole of a chemical substance is formed from its pure element at standard conditions. It is represented by the symbol [tex]\Delta H_{f}[/tex]
Enthalpy of formation for elemental atoms is always equal to 0.
We know:
Bromine (Br) exists in a liquid state.
Helium (He) exists in a gaseous state.
Mercury (Hg) exists in a liquid state.
Chlorine (Cl) exists in a gaseous state.
Nitrogen (N) exists in a gaseous state.
For the given options:
The [tex]\Delta H_{f}[/tex] for [tex]Br_2(l), Hg(l)\text{ and }Cl_2(g)[/tex] will be equal to 0 because they are formed by the natural states of their elemental atoms.
Hence, the correct options are A, C and D.
A substance in its standard state has an enthalpy of formation of 0 kJ/mol.
The enthalpy of formation of a substance in its standard state is 0 kJ/mol.
The standard state of a substance refers to its state at 1 atm and at a temperature of 298 K. Bearing this in mind, we can now identify the true and false statements.
So,
ΔHf for Br2(I) is 0 kJ/mol - True
ΔHf for He(I) is 0 kJ/mol - False
ΔHf for Hg(I) is 0 kJ/mol - True
ΔHf for Cl2(g) is 0 kJ/mol - True
ΔHf for N2(I) is 0 kJ/mol - False
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What is the equilibrium expression for the reaction below?
C(s) + O2(9)
2009)
[0][c]
O A.
[CO]
O B.
1
C с
OC.
[co]
[0][c]
CO2]
D.
Answer:
C
Explanation:
because it is product over reactants. hope this helps :)
The equilibrium expression for the reaction C(s) +[tex]O_{2}[/tex](g) ⇄ [tex]CO_{2}[/tex] (g) will be
[[tex]CO_{2}[/tex] ] / [ [tex]O_{2}[/tex] ].
What is equilibrium?Chemical equilibrium is a state where no net change in the quantities of reactants as well as products takes place during a reversible chemical reaction.
The given reaction is C(s) +[tex]O_{2}[/tex](g) ⇄ [tex]CO_{2}[/tex] (g) .
It is known that solid phase is not considered in equilibrium.
Hence, equilibrium expression = [[tex]CO_{2}[/tex] ] / [ [tex]O_{2}[/tex] ].
Therefore, the correct answer will be option (D).
To know more about equilibrium.
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Which equation represents the correct net ionic equation for the reaction between Ca(OH)2 and H2SO4?
Upper H superscript plus, plus upper O upper H superscript minus right arrow upper H subscript 2 upper O.
2 upper H superscript plus, plus 2 upper O upper H superscript minus right arrow upper H subscript 2 upper O.
Upper C a superscript 2 plus, plus 2 upper O upper H superscript minus, plus upper S upper O subscript 4 superscript 2 minus right arrow upper C a superscript 2 plus, plus upper S upper O subscript 4 superscript 2 minus, plus 2 upper H subscript 2 upper O.
Upper C a (upper O upper H) subscript 2 plus upper H subscript 2 upper S upper O subscript 4 right arrow upper C a upper S upper O subscript 4 plus 2 upper H subscript 2 upper O.
Answer: The correct net ionic equation for the reaction is [tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Explanation:
Net ionic equation is defined as the equations in which spectator ions are not included.
Spectator ions are the ones that are present equally on the reactant and product sides. They do not participate in the reaction.
The balanced molecular equation is:
[tex]Ca(OH)_2(aq)+H_2SO_4(aq)\rightarrow CaSO_4(aq)+2H_2O(l)[/tex]
The complete ionic equation follows:
[tex]Ca^{2+}(aq)+2OH^-(aq)+2H^+(aq)+SO_4^{2-}(aq)\rightarrow 2Ca^{2+}(aq)+SO_4^{2-}(aq)+H_2O(l)[/tex]
As calcium and sulfate ions are present on both sides of the reaction. Thus, they are considered spectator ions.
The net ionic equation follows:
[tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Hence, the correct net ionic equation for the reaction is [tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Answer:
B. no reaction
Explanation:
What makes radioisotopes useful for dating objects?
O A. They have unique emission spectra.
O B. They decay at a predictable rate.
C. Their decay products are easy to detect.
O D. They all have extremely long half-lives.
Answer:A
Explanation:
Option D. They all have extremely long half-lives makes radioisotopes useful for dating objects.
What are radioisotopes?Radioisotopes exist as radioactive isotopes of an element. They can also be described as atoms that include an unstable combination of neutrons and protons, or surplus energy in their nucleus.
A radionuclide exists as a nuclide that contains excess nuclear energy, causing it unstable. This excess energy can be utilized in one of three methods: emitted from the nucleus as gamma radiation; assigned to one of its electrons to terminate it as a conversion electron; or utilized to create and emit a unique particle from the nucleus.
Radioactive isotopes of radium, thorium, and uranium, for example, exist found naturally in rocks and soil. Uranium and thorium also happen in trace amounts in water. Radon, induced by the radioactive decay of radium, stands present in the air.
Hence, Option D. They all have extremely long half-lives makes radioisotopes useful for dating objects.
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What does it mean for something to be radioactive?
A. It has an emission spectrum.
B. It is in a stable condition.
C. It generates radio waves.
D. Its nuclei can split apart.
Answer:
D
Explanation:
Radioactivity means
the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei
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State three pieces of evidence from the diagram which indicate that the plant is pollinated by wind. ( 3 marks)
Your image is saying "Can't load image on this device."
1. Which of the following combinations correctly represents the process of
photosynthesis?
a) Carbon Dioxide + Water + solar energy - Glucose + Oxygen
b) Carbon Dioxide + Water - Glucose + Oxygen + solar energy
c) Glucose + Oxygen Carbon Dioxide + Water + energy
d) Glucose + Oxygen + energy +
Carbon Dioxide + Water
Answer:
A
Explanation:
Answer:
I think It should be option A. It would have been B but, solar energy is not giving out, it's taken in
Evolution can best be described as
A)
the change in size of body structures through use and disuse
B)
the formation of fossils
C)
a process of growth in an organism
D)
a process of change through time
what are alpha particles??
Answer:
a helium nucleus emitted by some radioactive substances, originally regarded as a ray.
Explanation:
Answer:
They're charged particles Identical to the Helium Nucleus
Having 2 protons and 2neutrons and having a Mass of 4.
They're Heavy and slow(speed)In comparison to Beta particles and gamma rays
Usually Emitted from nucleus of radioactive nuclides during decay
Given 7 moles of nitrogen gas, how many moles of ammonia can you make?
Explanation:
just use the molar ratios to figure it out. Notice, you have to balance the chemical equation.
Help me with this this is something i dont know and its not on here please help meeeeeee
Answer:
it would be option A
Explanation:
This is becuase if you look at the chart you can see tyhat the group of rats that got feed to vitamans did gain more wati then the ones on the normal diet.
water is to ____as liquid is to soild
water is to gas as liquid is to solid
Which describes the forces in an unstable nucleus?
A. The electrostatic force is greater than the strong nuclear force.
B. The electrostatic force is greater than the weak nuclear force.
C. The weak nuclear force is greater than the strong nuclear force.
D. The strong nuclear force is greater than the electrostatic force.
Answer:
C. The weak nuclear force is greater than the strong nuclear force
Use the information from the diagram to calculate the enthalpy of combustion for methane. (HELP ASAPPP!!)
A)
+752 kJ
B)
–921 kJ
C)
–604 kJ
D)
+604 kJ
Answer:
where is the diagram sisters
The radiostope radon 222 has a half life of 3.8 days. How much of a 73.9-g sample or radon 222 wouppd be left after 23 days ?? pls show an equation
Answer:
Is there a picture for it
Explanation:
because it would be a hard
If a shell can hold a maximum of 32 electrons, what is the value of n?
Answer:
The value of N would be 4.
Explanation:
The equation would be 2n^x = 32 and therefore, 4.
copper +sulfur + oxygen =
How many moles are equal to 3.0x10^23 atoms of germanium? PLS ANSWER WITH WORK!
EJEMPLOS DE SOLUCIONES QUÍMICAS EN LA NATURALEZA
ahí esta la respuesta espero que te sirva
What important points do you need to remember about combustion?
Explanation:
A substance burning in the presence of oxygen and leads to the formation of heat and light is called combustion.
Some important points about combustion are as follows:
Fuel should be present for burning.Air should be present for the supply of oxygen.There should be heat (or ignition temperature) to initiate the chemical reaction.can someone explain the answer.
Answer:
A
Explanation:
Alkanes undergo substitution reaction with halogen molecules in the presence of light. This reaction occurs by free radical mechanism and the initiation step is the formation of the halogen radical.
The propagation steps involves the abstraction of a hydrogen from the alkane by the halogen radicals.
The termination steps involves the coupling of alky radicals.
Thus for the reaction of ethane and chlorine;
C2H6 + Cl2 -------> C2H5Cl + HCl
What factor makes it possible for animals with endoskeletons to grow larger than animals with exoskeletons?
A. Endoskeletons can be removed and replaced.
B. Endoskeletons are lighter than exoskeletons.
C. Endoskeletons are made of fluid-filled tubes.
D. Endoskeletons lack joints that can break down.
i need help
How is an endothermic reaction identified?
A. It has a large heat capacity.
B. It gives off heat as a product.
C. It requires heat as a reactant.
O D. It results in a phase change.
Answer:
Endothermic is identified if the process requires heat as a reactant, since endothermic means "intake of heat", so it has to take in some type of heat.
How many neutrons does this atom have?
4
6
10
14
Answer:
6
Explanation:
Electrons are floating around, and protons are outside of the nucleus center. The ones in the center are neutrons. I hope this helps.
A hydrocarbon contains 92.24 % carbon by mass and has a molar
mass of 78.12 g mol-1.
Determine the empirical formula and molecular
formula of the hydrocarbon
Explanation:
so for this one you know 92.24 is the mass of C so to work out the mass of hydrogen u so 100-92.24=7.76
so
C : H
92.24/12 : 7.76 /1
7.68 : 7.76
so 7.76÷7.68=1.01
so CH
12+1=13
78.12÷13=6.009
so CH×6= C6H6
hope this helps:)
Which list BEST identifies how the arrows should be arranged around the paper leaf in the model to represent the movement of matter and flow of energy during photosynthesis? A. Point into Leaf: sugars, oxygen (02), Point away from leaf: carbon dioxide(CO2), water(H2O) B. Point into Leaf: sugars, sunlight, Point away from leaf: carbon dioxide(CO2), oxygen (02), water(H2O) C. Point into Leaf: water(H2O), sunlight, Point away from leaf: carbon dioxide(CO2), sugars, oxygen (02) D. Point into Leaf: water(H2O), carbon dioxide(CO2) sunlight, Point away from leaf: sugars, oxygen (02
Answer:
D. Point into Leaf: water(H₂O), carbon dioxide (CO₂) sunlight, Point away from leaf: Sugars, oxygen (O₂)
Explanation:
Photosynthesis is the process used in the production of chemical energy in the form of energy containing organic compounds and oxygen from atmospheric carbon dioxide and liquid water enabled with the energy captured from light (mainly Sunlight) by the chlorophyll in green plants and other organisms
The basic chemical reaction involved in a photosynthesis reaction is presented as follows;
[tex]{}[/tex] Sunlight
[tex]{}[/tex] ↓
[tex]{}[/tex] CO₂ + H₂O (l) → C₆H₁₂O₆ + O₂
Carbon dioxide [tex]{}[/tex] Water Glucose Oxygen
