Using standard heats of formation, calculate the standard enthalpy change for the following reaction. Fe(s) + 2HCl(aq)FeCl2(s) + H2(g) ANSWER: ___ kJ
The standard enthalpy change for the given reaction is approximately -156.87 kJ.
To calculate the standard enthalpy change (ΔH°) for the given reaction using standard heats of formation, the balanced equation for the reaction is:
Fe(s) + 2HCl(aq) → [tex]FeCl_2[/tex](s) + [tex]H_2[/tex](g)
The standard heats of formation (ΔH°f) for the compounds involved are as follows:
Fe(s): 0 kJ/mol
HCl(aq): -92.31 kJ/mol (source: NIST Chemistry WebBook)
[tex]FeCl_2[/tex](s): -341.49 kJ/mol (source: NIST Chemistry WebBook)
[tex]H_2[/tex](g): 0 kJ/mol
Now, let's calculate the standard enthalpy change (ΔH°):
ΔH° = Σ(ΔH°f products) - Σ(ΔH°f reactants)
ΔH° = [ΔH°f([tex]FeCl_2[/tex]) + ΔH°f([tex]H_2[/tex])] - [ΔH°f(Fe) + 2ΔH°f(HCl)]
ΔH° = [-341.49 kJ/mol + 0 kJ/mol] - [0 kJ/mol + 2(-92.31 kJ/mol)]
ΔH° = -341.49 kJ/mol + 2(92.31 kJ/mol)
ΔH° = -341.49 kJ/mol + 184.62 kJ/mol
ΔH° = -156.87 kJ/mol
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What is the herbivore in the following food chain: algae → fish → herons?
Answer:
algae
Explanation:
fish and herons arent herbivores
Herbivores are typically tagged as animals that feeds directly on the plants in a food chain.
In the given food chain, Fish is the herbivore
As stated, Fish in the food chain is the herbivore as it feeds directly on the plants. The algae in this case is the producer. While the herons are the carnivore that feeds directly on the flesh of the fish but indirectly on the algae.
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Which statement correctly describes extreme weather?
O A. Extreme weather events follow normal climate patterns.
o O B. Extreme weather events are random occurrences.
O C. Extreme weather events started with global warming.
O D. Extreme weather events are unpredictable until they strike.
Answer: A
Explanation:
Extreme weather events follow normal climate patterns.
how much water, in grams, can be made from 3.58 × 1024 hydrogen molecules? answer in units of g.
To determine the amount of water that can be made from a given number of hydrogen molecules, the molar ratio between hydrogen and water needs to be considered. Based on the balanced chemical equation for the formation of water, 2 moles of hydrogen molecules (H2) react to form 2 moles of water (H2O). Using the Avogadro's number and molar mass of water, the calculation can be performed to find the mass of water in grams.
The balanced chemical equation for the formation of water is:
2H2(g) + O2(g) → 2H2O(l)
From the equation, it can be observed that 2 moles of hydrogen molecules (H2) react to produce 2 moles of water (H2O).
Using Avogadro's number (6.022 × 10^23 molecules per mole), we can determine the number of moles of hydrogen molecules present in 3.58 × 10^24 hydrogen molecules:
Number of moles of hydrogen = (3.58 × 10^24) / (6.022 × 10^23) = 5.95 moles
Since the molar ratio between hydrogen and water is 2:2, we can conclude that 5.95 moles of hydrogen will produce 5.95 moles of water.
To find the mass of water, we need to multiply the number of moles of water by the molar mass of water. The molar mass of water (H2O) is approximately 18.015 g/mol.
Mass of water = 5.95 moles × 18.015 g/mol = 107.17 g
Therefore, approximately 107.17 grams of water can be made from 3.58 × 10^24 hydrogen molecules.
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What variable represents thermal energy in the equation Q = mcΔT?
A.
The variable c
B.
The variable Q
C.
The variable T
D.
The variable m
Answer:
The variable Q
Explanation:
i just took the test and got it right.... i hope this helps :)
The variable Q represents thermal energy in the equation Q = mcΔT. Hence, option B is correct.
What is specific heat capacity?The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases by 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).
Q = mcΔT
Q = heat energy
m = mass
c = specific heat capacity
ΔT = change in temperature
Hence, option B is correct.
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How many mL of water to be added to 10 mL of 0.5M solution to make 0.2 M solution?
Answer:
0.7 is the right
Explanation:
An amphoteric species is neither an acid nor a base. True or False
Answer: False
Explanation: just took on edge
2. Below is a chemical reaction in which two solutions are combined:
CdSO. (aq)+KS(aq) → CdS(s)+ K₂SO4(aq)
a) What does the (s) mean?
b) For the reactants, cadmium sulfate and potassium sulfide, write a chemical equation showing that each of these dissolve in water.
c) On the products side, potassium sulfate is aqueous and cadmium sulfide is solid. What is the difference? How can you observe this difference in the lab?
d) What is the name for this type of reaction?
The reaction between CdSO₄ and K₂S is a precipitation reaction where cadmium sulfide precipitates as a solid, while potassium sulfate remains in the aqueous form.
a) The "(s)" in the chemical equation CdS(s) represents that cadmium sulfide is a solid precipitate. It indicates that the product formed in the reaction is solid.
b) The chemical equation for the dissolution of cadmium sulfate (CdSO₄) in water is:
CdSO₄(s) → Cd²⁺(aq) + SO₄²⁻(aq)
The chemical equation for the dissolution of potassium sulfide (K₂S) in water is:
K₂S(s) → 2K⁺(aq) + S²⁻(aq)
c) The difference between potassium sulfate being aqueous (K₂SO₄(aq)) and cadmium sulfide being a solid (CdS(s)) lies in their solubility in water. Potassium sulfate is soluble in water, meaning it dissolves and dissociates into its respective ions (K⁺ and SO₄²⁻) in the solution. On the other hand, cadmium sulfide is insoluble in water and forms a solid precipitate, indicating that it does not dissolve but instead forms solid particles.
In the lab, the difference can be observed by visual inspection. When the reaction between CdSO₄ and K₂S takes place, a yellow precipitate of cadmium sulfide will form, indicating the presence of the solid. The potassium sulfate, being in an aqueous form, will remain dissolved and not form any visible solid.
d) The name for this type of reaction is a precipitation reaction or double displacement reaction. In this reaction, the ions from two compounds exchange to form an insoluble solid (precipitate) and a soluble compound.
In the given reaction between CdSO₄ and K₂S, cadmium sulfide (CdS) is the insoluble solid (precipitate), and potassium sulfate (K₂SO₄) is the soluble compound formed in solution.
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Compound X has molecular formula C5H10. In the presence of a metal catalyst, compound X reacts with one equivalent of molecular hydrogen to yield 2-methylbutane.
a. Suggest three possible structures for compound X.
b. Hydroboration-oxidation of compound X yields a product with no chirality centers. Identify the structure of compound X.
The structure of compound X is likely 2-Methyl-1-butene (CH3CH=C(CH3)CH2CH3) to yield a product without chirality centers during hydroboration-oxidation.
a. Suggesting three possible structures for compound X (C5H10) can involve considering different isomers of pentane and pentene. Here are three possibilities:
Pentane: CH3CH2CH2CH2CH3
2-Methylbutane: CH3CH(CH3)CH2CH3
2-Methyl-1-butene: CH3CH=C(CH3)CH2CH3
These structures satisfy the molecular formula C5H10 and represent different isomeric possibilities for compound X.
b. Hydroboration-oxidation of compound X yields a product with no chirality centers. This suggests that compound X must be an alkene with a symmetric or non-chiral structure. Among the three possible structures suggested above, the alkene 2-Methyl-1-butene (CH3CH=C(CH3)CH2CH3) would result in a product with no chirality centers when subjected to hydroboration-oxidation.
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calculate the percent by mass of a solution made from 17 g nacl (the solute) and 59 g water.
The percent by mass of the solution made from 17 g sodium chloride, NaCl (the solute) and 59 g water is 22.4%
How do i determine the percent by mass of the solution?First, we shall obtain the mass of the solution. Details below:
Mass of NaCl = 17 gramsMass of water = 59 gramsMass of solution = ?Mass of solution = Mass of NaCl + mass of water
Mass of solution = 17 + 59
Mass of solution = 76 grams
Finally, we shall determine the percent by mass of the solution. Details below:
Mass of NaCl = 17 gramsMass of solution = 76 gramsPercent by mass =?Percent by mass = (mass of NaCl / mass of solution) × 100
= (17 / 76) × 100
= 22.4%
Thus, the percent by mass of the solution is 22.4%
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which statement best describes the reflection of a wave?
The best statement that describes the reflection of a wave is: When a wave reflects off a surface, it retains its characteristics and changes direction.
A wave is defined as a disturbance that moves through space and matter with the transfer of energy from one place to another. When the wave moves from one medium to another, it reflects off the surface. Reflection of a wave is described as the change in the direction of the wave when it bounces back from the surface on which it strikes.
When a wave reflects off a surface, the angle of incidence is equal to the angle of reflection, which is known as the law of reflection. The normal line, which is perpendicular to the surface, splits the incident and reflected waves at the point of incidence. The angle between the normal line and the incident wave is the angle of incidence, and the angle between the normal line and the reflected wave is the angle of reflection.
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What happens in a redox reaction?
50 POINTS PLEASE ANSWER CORRECTLY
What happens to the momentum of two cars when they collide?
A. The total momentum after the collision increases.
B. The total momentum after the collision decreases.
C. The total momentum after the collision is equal to the total momentum before the collision.
D. The total momentum before and after the collision is not conserved.
Answer: I honestly think it might be C
Explanation: Collisions between objects are governed by laws of momentum and energy. When a collision occurs in an isolated system, the total momentum of the system of objects is conserved. ... In the collision between the two cars, total system momentum is conserved.
Answer: C. The total momentum after the collision is equal to the total momentum before the collision.
Hope this helps
Explanation: Collisions between objects are governed by laws of momentum and energy. When a collision occurs in an isolated system, the total momentum of the system of objects is conserved. ... In the collision between the two cars, total system momentum is conserved.
What is the absolute magnitude of the rate of change for [NH₃] if the rate of change for [H₂] is 8.70 m/s in the reaction 2 NH₃(g) → N₂(g) + 3 H₂(g)?
a. 4.35 m/s
b. 8.70 m/s
c. 17.40 m/s
d. 26.10 m/s
Given, the balanced chemical equation is:
2 NH₃(g) → N₂(g) + 3 H₂(g)
The absolute magnitude of the rate of change for [NH₃] is 4.35 m/s.
Therefore, option A is the correct answer.
Given, the balanced chemical equation is:
2 NH₃(g) → N₂(g) + 3 H₂(g)
The rate of change for H2 is 8.70 m/s.
To find the absolute magnitude of the rate of change for [NH₃], we have to use the stoichiometric coefficient in the balanced chemical equation. From the balanced chemical equation, 2 mol NH₃ reacts with 3 mol H₂
We can write,
Rate of change of NH₃ (in m/s) = -1/2 * rate of change of H₂ (in m/s)
So,Rate of change of NH₃ = -1/2 * 8.70 m/s= -4.35 m/s
The absolute magnitude of the rate of change for [NH₃] is 4.35 m/s.
Therefore, option A is the correct answer.
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If a radioactive isotope has a half-life of 400 million years, how long will it take for 50% of the material to change to the daughter product?
If a radioactive isotope has a half-life of 400 million years, it will take 400 million years for 50% of the material to change to the daughter product.
How long it takes for half of the radioactive atoms to decay is known as the half-life of the isotope. A radioactive isotope's half-life is the amount of time it takes for half of the parent material to decay to the daughter product. It's worth noting that a half-life isn't a fixed amount of time for each radioactive isotope.
The following formula can be used to calculate the amount of radioactive isotope remaining after a given period of time:
t=ln(N₀/N) / λ
Where:
t= time elapsedN₀= initial quantity of isotopeN= quantity of isotope after a given timeλ= decay constantFor this problem, we need to solve for the time (t) at which 50% of the radioactive isotope has decayed:
0.5N₀ = N₀ e^(-λt)
0.5 = e^(-λt)
t = ln(0.5) / (-λ)
We know that the half-life of this isotope is 400 million years, which means that λ is equal to:
ln(2) / (400,000,000 years)
λ = 0.00000000017 / year
Substituting that value into the formula:
t = ln(0.5) / (-0.00000000017 / year)
t ≈ 400,000,000 years
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Which of the following cannot be metabolized to make molecules that can enter the citric acid cycle? a. carbohydrates b. lipids c. proteins
d. metal ions
The one that cannot be metabolised to make molecules that can enter the citric acid cycle is d. metal ions.
Carbohydrates, lipids, and proteins can all be metabolized to produce molecules that can enter the citric acid cycle (also known as the Krebs cycle or TCA cycle). These molecules can be converted into acetyl-CoA, a key intermediate in the citric acid cycle, through various metabolic pathways.
Carbohydrates can be broken down into glucose, which can then undergo glycolysis to produce pyruvate. Pyruvate can be further converted into acetyl-CoA, which enters the citric acid cycle.
Lipids (fats) can be hydrolyzed to release fatty acids and glycerol. Fatty acids are broken down through beta-oxidation, resulting in the production of acetyl-CoA. Glycerol can also be converted into glyceraldehyde-3-phosphate, an intermediate in glycolysis that can generate pyruvate and subsequently acetyl-CoA.
Proteins can be broken down into amino acids through protein digestion and cellular processes such as proteolysis. Amino acids can enter various metabolic pathways, some of which lead to the production of intermediates that can feed into the citric acid cycle.
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What is the oxidation number of bromine in the HBrO molecule? a. -1
b. +1 c. +2
d. -2
The oxidation number of bromine in the HBrO molecule is +1. Bromine usually has multiple oxidation states, and in HBrO, it has an oxidation state of +1, the correct answer is b.
This can be determined by assigning oxidation numbers to the other atoms in the molecule and applying the rules for assigning oxidation numbers. In HBrO, hydrogen (H) has an oxidation state of +1, and oxygen (O) typically has an oxidation state of -2. Since the sum of oxidation numbers in a neutral molecule is zero, the oxidation number of bromine (Br) is determined to be +1.
To further explain, oxidation numbers represent the hypothetical charge an atom would have if all the bonds were purely ionic. In HBrO, hydrogen (H) is typically assigned an oxidation state of +1, as it usually donates its one valence electron to form a single bond. Oxygen (O) is generally assigned an oxidation state of -2, as it commonly accepts two electrons to complete its valence shell. The sum of the oxidation numbers in HBrO is then +1 for hydrogen and -2 for oxygen, resulting in a net oxidation number of -1. Since the molecule is neutral, the oxidation number of bromine (Br) must be +1 to balance the charges and achieve a total oxidation number of zero. Therefore, the correct answer is b. +1.
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The particles of a substance lose energy and change from
a disordered structure with large distances between the particles to
a loosely ordered state.
Which change of state is described?
Answer:
A Liquid
Explanation:
structure with large distance (gas) than goes to a loosely ordered state (liquid)
I hope this helps
For the Experiment, 10 mL of a DIVA Sciences’ White Vinegar sample will be dispensed and diluted to 100 mL in a 100-mL Volumetric Flask. Determine the range of initial concentrations.
Diluted DIVA Sciences’ White Vinegar (5%) Solution = ____________________ M
Diluted DIVA Sciences’ White Vinegar (8%) Solution = ____________________ M
To determine the range of initial concentrations, we need to consider the dilution process and the given information.
The initial volume of the vinegar sample is 10 mL, and it is diluted to a final volume of 100 mL. Therefore, the dilution factor is calculated by dividing the final volume by the initial volume:
Dilution factor = Final volume / Initial volume = 100 mL / 10 mL = 10
The diluted solutions are prepared by adding 10 mL of the vinegar sample to a 100 mL volumetric flask and filling it up to the mark with water. So, the final volume of each diluted solution is 100 mL.
Given that the diluted solutions are prepared from the original vinegar sample, we can infer that the percentage concentration refers to the mass/volume percentage. In this case, the percentages (5% and 8%) represent the mass of acetic acid (the main component of vinegar) present in 100 mL of the original sample.
To calculate the molarity of the diluted solutions, we need to know the molar mass of acetic acid, which is approximately 60.05 g/mol.
For the 5% solution:
Mass of acetic acid in 100 mL = (5 g / 100 mL) × 100 mL = 5 g
Using the molar mass, we can convert the mass of acetic acid to moles:
Moles of acetic acid = Mass of acetic acid / Molar mass = 5 g / 60.05 g/mol
Now, we can calculate the molarity:
Molarity (5% solution) = Moles of acetic acid / Final volume (in liters) = (5 g / 60.05 g/mol) / 0.1 L
For the 8% solution, we follow the same steps:
Mass of acetic acid in 100 mL = (8 g / 100 mL) × 100 mL = 8 g
Moles of acetic acid = Mass of acetic acid / Molar mass = 8 g / 60.05 g/mol
Molarity (5% solution) ≈ 0.833 M (rounded to three decimal places)
Molarity (8% solution) ≈ 1.333 M (rounded to three decimal places)
Therefore, the range of initial concentrations is approximately 0.833 M to 1.333 M for the diluted DIVA Sciences' White Vinegar solutions.
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what is the mass of 2.31 x 10^23 formula units of SrF2?
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 40.51 g is the mass of 2.31x10²³ formula units of SrF[tex]_2[/tex].
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance. It measure the number of elementary entities of a given substance that are present in a given sample.
Given number of atoms= 2.31x10²³atoms
we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number
mole =given number of atoms ÷ 6.022×10²³(Avogadro number)
Substituting the values
mole= 2.31x10²³÷ 6.022×10²³
mole = 0.38 moles of SrF[tex]_2[/tex]
mass of SrF[tex]_2[/tex]= moles of SrF[tex]_2[/tex] × Molar mass of SrF[tex]_2[/tex]
mass of SrF[tex]_2[/tex]= 0.38 × 106.6184
mass of SrF[tex]_2[/tex] = 40.51 g
Therefore, 40.51 g is the mass of 2.31x10²³ formula units of SrF[tex]_2[/tex].
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Numbers 15-21
HELP PLEASE!!
Calcular la masa de Mg que se necesita hacer reaccionar con CuSO4 para formar 1.89 g de Cu2O según la siguiente ecuación: Mg + CuSO4 + H2O MgSO4 + Cu2O + H2
Answer:
0.642 g
Explanation:
La ecuación balanceada es:
2Mg + 2CuSO₄ + H₂O → 2MgSO₄ + Cu₂O + H₂Primero convertimos 1.89 g de Cu₂O en moles, usando su masa molar:
1.89 g ÷ 143.09 g/mol = 0.0132 mol Cu₂ODespués convertimos moles de Cu₂O en moles de Mg, usando los coeficientes estequiométricos:
0.0132 mol Cu₂O * [tex]\frac{2molMg}{1molCu_2O}[/tex] = 0.0264 mol MgFinalmente convertimos moles de Mg en gramos, usando la masa molar de Mg:
0.0264 mol Mg * 24.305 g/mol = 0.642 gIf the Earth did not have internal energy, explain what would happen to the carbon cycle and why?
Answer: Carbon cycle wouldn't be able to create rock formation. Respiration, consumption, combustion (such as fossil burning) are all part of the carbon cycle. They would all be possible without internal energy. Except rock formation.
Explanation:
Think about a wooden chair and a balloon. What do these two objects always have in common?
Both are made of atoms.
Both have the same physical properties.
Both are made of the same kind of atom.
Both are made of the same number of atoms.
Answer:
both are made of atoms. .
Answer:
Both are made of atoms.
Explanation:
Consider atoms of the following elements. Assume that the atoms are in the ground state.
(A) S (B) Ca (C) Ga (D) Sb (E) Br
1. The atom that contains exactly two unpaired elec¬trons
2. The atom that contains only one electron in the highest occupied energy sublevel
(A) Sulfur (S) is the atom that contains exactly two unpaired electrons, and (E) Bromine (Br) is the atom that contains only one electron in the highest occupied energy sublevel.
(A) Sulfur (S) has an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁴. The highest energy level, or valence shell, for sulfur is the third energy level (n = 3). The 3p sublevel has four electrons (3p⁴), and among them, two are unpaired. These two unpaired electrons in the 3p sublevel make sulfur the atom that contains exactly two unpaired electrons.
(E) Bromine (Br) has an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵. The highest occupied energy level for bromine is the fourth energy level (n = 4). The highest energy sublevel within the fourth energy level is the 4p sublevel. In the 4p sublevel, there are five electrons (4p⁵), and only one electron is needed to complete the sublevel. Thus, bromine contains only one electron in the highest occupied energy sublevel.
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A compound is found to be made up of 3.21 g Carbon and 1.02 g Oxygen. Determine the percent composition from this data?
Given :
A compound is found to be made up of 3.21 g Carbon and 1.02 g Oxygen.
To Find :
The percent composition from this data.
Solution :
We know, percentage composition is given by :
[tex]\%mass = \dfrac{mass}{mass of compound}\times 100[/tex]
So, percentage composition of Carbon is :
[tex]\%Carbon = \dfrac{3.21}{3.21+1.02}\times 100\\\\\%Carbon = \dfrac{3.21}{4.23}\times 100\\\\\%Carbon = 75.89 \%[/tex]
Since, compound is made up of Carbon and Oxygen.
So, %Oxygen is ( 100 - 75.89 )% = 24.11%
Hence, this is the required solution.
Which two elements on the periodic table share the same period and are both gases?
A. Hydrogen and Helium
B. Fluorine and Bromine
C. Lithium and Potassium
D. Xenon and Argon
Which of Graphs 1 correctly represents the relationship between the pressure and volume of a gas?
Answer:
D
Explanation:
pressure is inversely proportional to gas volume
In a heat engine, 500 J of heat enters the system, and the piston does 300 J of work. What is the final internal (thermal) energy of the system if the initial energy is 1500 J?
200 J
800 J
1300 J
1700 J
Answer:
200J
Explanation:
This is because 500J - 300J = 200J
I hope this helps!!!
Answer:
1700 Joules. I Took the test.
Explanation:
A reaction yields 6.26 grams of a CuCl2. What is the percent yield of CuCl2 if the theoretical yield is 18.81g?
% Yield = (Actual Yield/Theoretical Yield) x 100
Answer:
33% yield
Explanation:
6.26/18.81 =0.33280170122 = 33%