Worth +90 points College Chemistry Question

A scientist measures the standard enthalpy change for the following reaction to be -572. 6 kJ:

H2CO(g) + O2(g)CO2(g) + H2O(l)


Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of H2O(l) is?

Answer:

  18.87 g

Explanation:

  80.1% of 23.56 g = 18.87 g is the mass of the silver

The process of turning pennies into brass simply has to do with dissolving the copper in the penny by a chemical process and this is then replaced with a brass alloy and this process could theoretically be applied to other coins.

A coin is a tiny, flat, round piece of metal or plastic which is used as legal tender or a medium of exchange. It should be noted that they are mass-produced at a mint so as to facilitate trade, and their weight is standardized.

In order achieve various mechanical, electrical, and chemical properties, it should be noted that copper and zinc can be combined in different ratios in order to create the alloy known as brass.

The composition of other coins, such as quarters, nickels, and dimes, is different from pennies and would require different chemical processes to alter. Additionally, it is illegal to deface or alter U.S. coin currency, so it would not be legal to do this process on any other coin. In this case, it can be applied to other coins.

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Explanation:

No of mass = no of moles × molar mass

=2.55 × 18 g

= 45.9 g

Building block molecules for biosynthetic pathways are indeed obtained from both the cell's catabolic pathways and the environment, providing the necessary raw materials for the synthesis of complex biomolecules.

Building block molecules for biosynthetic pathways are derived from two sources: the cell's catabolic pathways and the environment.

Catabolic pathways involve the breakdown of complex molecules, such as carbohydrates, proteins, and lipids, into smaller components through processes like glycolysis, the citric acid cycle, and fatty acid oxidation. These breakdown reactions release energy and generate precursor molecules that can be used for biosynthesis.

Simultaneously, cells acquire building block molecules from the environment through nutrient uptake. Organisms obtain essential nutrients, such as amino acids, nucleotides, vitamins, and minerals, from their surroundings. These molecules serve as raw materials for the synthesis of complex biomolecules within the cell.

The combination of catabolic pathways and environmental nutrient uptake provides the necessary building blocks for the cell to perform biosynthetic processes, creating complex macromolecules like proteins, nucleic acids, carbohydrates, and lipids. These macromolecules play vital roles in cell structure, function, and regulation.

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The atoms inside the reactants reorganise their chemical bonds during a chemical reaction to create products. There will therefore always be a shift in energy when chemical reactions take place.

The atoms inside the reactants rearrange and link differently throughout a chemical reaction to create one or more innovative brands with properties distinct from the reactants. A chemical change occurs when a new material is created.

Exothermic refers to chemical reactions which release energy. When bonds are created in the products of exothermic processes, more energy is produced than is required to rupture the connections between the reactants. Endothermic refers to chemical reactions that either use or absorb energy.

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Answer:

It should be B: 0.01 kJ

Answer:

Hey...The answer is B) 0.01 kJ

The moles is  10 moles of diphosphorus hexaoxide

0.75 moles of PbO is produced

The mass of oxygen is  3.7 g

If 3 moles of oxygen produces 2 moles of diphosphorus hexaoxide

15 moles of oxygen produces 15 * 2/3

= 10 moles of diphosphorus hexaoxide

2) If 1 mole of oxygen produces 1 mole of PbO

0.75 moles of oxygen will produce 0.75 moles of PbO

3) Number of moles of potassium trioxochlorate V = 9.5 g/122.5 g/mol

= 0.078 moles

If 2 moles of  potassium trioxochlorate V produces 3 moles of oxygen

0.078 moles of  potassium trioxochlorate V produces 0.078 * 3/2

= 0.117 moles

Mass of oxygen = 0.117 moles * 32 g/mol

= 3.7 g

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Answer:

a

Explanation:

i hope i am right

The insolubility of calcium sulfide (CaS) in water is due to weak ion-dipole interactions, strong ion-ion interactions, the presence of covalent bonds, and a decrease in entropy upon dissolution.

These factors prevent CaS from dissolving in water and result in its insoluble nature. Calcium sulfide (CaS) is insoluble in water due to several reasons:
1. Ion-dipole interactions: When a salt dissolves in water, the positive ions are attracted to the negative end of water molecules (oxygen atom), and the negative ions are attracted to the positive end of water molecules (hydrogen atoms). However, in the case of calcium sulfide (CaS), the ion-dipole interactions between the calcium ions (Ca2+) and water molecules are very weak. This means that the attraction between the Ca2+ ions and water molecules is not strong enough to overcome the strong attraction between the Ca2+ ions and the sulfide ions (S2-), resulting in the insolubility of CaS in water.

2. Ion-ion interactions: In the case of salts containing Ca2+ ions, they are generally insoluble in water. This is because the ion-ion interactions between the Ca2+ and sulfide ions (S2-) are very strong. The attractive forces between these ions are much stronger than the attractive forces between the ions and water molecules. As a result, the Ca2+ and sulfide ions remain together as a solid rather than dissolving in water.

3. Covalent bonds: Another reason for the insolubility of CaS in water is the presence of covalent bonds in the compound. In CaS, the calcium and sulfur atoms are bonded together by covalent bonds. Covalent bonds are formed by the sharing of electrons between atoms. Breaking these covalent bonds requires a significant amount of energy. Therefore, for CaS to dissolve in water, the energy required to break the covalent bonds would be too high, making it unlikely for the compound to dissolve.

4. ΔS (change in entropy): When a substance dissolves in water, there is often an increase in the disorder or randomness of the system, which is indicated by a positive change in entropy (ΔS). However, in the case of CaS, the possible arrangements for water molecules would decrease upon dissolution, resulting in a negative change in entropy (ΔS). This decrease in entropy further contributes to the insolubility of CaS in water.

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A low Km value means: A) The enzyme has a very high affinity for the substrate.

The Michaelis constant, Km, is a measure of the substrate concentration at which the enzyme achieves half of its maximum reaction rate (Vmax). It provides information about the affinity of the enzyme for the substrate.

A low Km value indicates that the enzyme-substrate interaction is strong, meaning the enzyme has a high affinity for the substrate. In other words, the enzyme binds tightly to the substrate. A low Km value implies that even at low substrate concentrations, a significant proportion of the enzyme's active sites are occupied by the substrate.

This high affinity enables the enzyme to effectively catalyze the reaction, even at low substrate concentrations. The enzyme-substrate complex is formed rapidly, facilitating efficient enzymatic activity. As a result, a low Km value indicates that the enzyme can bind tightly to the substrate and react quickly.

In summary, a low Km value signifies that the enzyme has a very high affinity for the substrate, allowing for tight binding and rapid reaction rates.

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Answer: Salt- at room temperature is a solid

sugar- at room temperature is a solid

cooking oil- at room temperature is a liquid .

Explanation: hope this helps !

A state of matter is "one of the distinct forms that different phases of matter take on". :The four states of matter are solid, liquid, gas, and plasma.

Solid are the state of matter in which the atoms or molecules are tightly packed or arranged either by chemical bonds or intermolecular forces.

Liquid is "the form of matter in which molecules move around freely but still experience attractive forces".

Gas is "a state of matter that has no fixed shape and no fixed volume".

Plasma is "an ionized gas, a gas into which sufficient energy is provided to free electrons from atoms or molecules and to allow both species, ions and electrons to coexist".

Hence, the state of

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The new pressure of the gas is \(45.906 torr.\)

To calculate the new pressure:

\(P2 = P1 * (T2 / T1)\)

where:

P1 is the initial pressure\((32.6 torr)\)

T1 is the initial temperature \((735 K)\)

P2 is the final pressure (unknown)

T2 is the final temperature \((1035 K)\)

Substituting the values into the formula, we get:

\(P2 = 32.6 torr * (1035 K / 735 K)\)

\(P2 = 45.906 torr\)

Therefore, the new pressure of the gas is \(45.906 torr.\)

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Answer:

See explanation

Explanation:

When a beaker of ethanoic acid is placed in the refrigerator, its temperature drops and the vessel feels cool.

Now, when we mix ethanoic acid and sodium carbonate, an endothermic reaction occurs, fizzing is observed as carbon dioxide is given off and heat is lost to the surroundings causing the reaction vessel to feel cool to touch.

The difference between putting ethanoic acid in the refrigerator and adding  sodium carbonate to the solution is that, in the former, no new substance is formed. The substance remains ethanoic acid when retrieved from the refrigerator. In the later case, new substances are formed. The substance is no more ethanoic acid because a chemical reaction has taken place.

First, we must know Avogadro's number:

1 mol of any substance = 6.02x10^23 formula units (ions, atoms, molecules, etc)

Also, we can say this:

1 mol of Li2O = its mass expressed in grams

(from Li2O molar mass = 30 g/mol approx.)

Now,

1 mol Li2O = 30 g = 6.02x10^23 molecules Li2O

30 g Li2O ----------- 6.02x10^23 molecules Li2O

x ----------- 2.8x10^24 molecules Li2O

x = 140 g approximately

Answer: 140 g

Sodium (Na) and chlorine (Cl) are the largest dissolved components in ocean water due to the abundance of sodium and chloride ions in the Earth's crust and the continuous input of these elements into the oceans through various processes. Sodium is one of the most common elements in the Earth's crust, and chlorine is widely distributed in rocks, minerals, and salts.

Over millions of years, weathering of rocks, volcanic activity, and erosion release these elements into rivers and ultimately into the oceans. The combination of sodium and chlorine ions results in the formation of sodium chloride, which is commonly known as table salt and contributes to the salinity of seawater.

The most abundant dissolved gas in ocean water is carbon dioxide (CO2). Carbon dioxide dissolves in the surface waters of the ocean through gas exchange with the atmosphere. It plays a crucial role in regulating the pH of seawater and is an essential component of the carbon cycle. Carbon dioxide is involved in various biological and chemical processes in the ocean, including photosynthesis by marine plants and the formation of calcium carbonate shells by marine organisms. Additionally, the increase in atmospheric carbon dioxide due to human activities has led to ocean acidification, which is a significant concern for marine ecosystems.

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Due to the fact that they combine to form the ionic compound sodium chloride (NaCl), also known as salt, sodium (Na) and chlorine (Cl) are the two most abundant dissolved elements in ocean water.

Thus, Salts are among the many dissolved compounds that water from rivers and streams transports into the ocean.

In particular, sodium and chloride ions have accumulated in the ocean throughout time, leading to the high concentration of these elements in seawater. Magnesium, calcium, potassium, and sulphate ions are among the other dissolved substances in ocean water.

Oxygen  is the dissolved gas that is most prevalent in ocean water.

Thus, Due to the fact that they combine to form the ionic compound sodium chloride (NaCl), also known as salt, sodium (Na) and chlorine (Cl) are the two most abundant dissolved elements in ocean water.

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The ground-state electron configuration of O⁻² is 1s² 2s² 2p⁶. This configuration represents the most stable arrangement of the 10 electrons in the O⁻² ion, which includes the 8 electrons from the neutral oxygen atom and the 2 extra electrons from the negative charge.

Let's break it down step-by-step:

1. Identify the element: O is the symbol for oxygen, which has an atomic number of 8. In its neutral state, an oxygen atom has 8 electrons.

2. Add the extra electrons due to the negative charge: Since O⁻² has a charge of -2, it means that there are 2 additional electrons, giving a total of 10 electrons.

3. Determine the electron configuration: The electron configuration is based on the arrangement of electrons in different energy levels and subshells. You can use the periodic table to follow the Aufbau principle, which states that electrons fill the lowest energy orbitals first.

4. Fill the orbitals in order:
  - 1s subshell can hold up to 2 electrons: 1s²
  - 2s subshell can also hold up to 2 electrons: 2s²
  - 2p subshell can hold up to 6 electrons: For O⁻², there are 6 remaining electrons, so the 2p subshell is filled completely: 2p⁶

5. Combine the configurations: The electron configuration for O⁻² is 1s² 2s² 2p⁶.

In conclusion, the ground-state electron configuration of O⁻² is 1s² 2s² 2p⁶. This configuration represents the most stable arrangement of the 10 electrons in the O⁻² ion, which includes the 8 electrons from the neutral oxygen atom and the 2 extra electrons from the negative charge.

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The reason why the elements above and below each other may be similar is that they have the same number of valence electrons.

Since the beginning of chemistry, there have always been a need for the systematization of the elements. There are currently about a hundred and twenty elements in the periodic table. The elements that can be found in the periodic able are arranged in groups and periods.

The groups are the vertical columns that we find in the periodic table while the periods are the horizontal rows that we find in the periodic table. All the elements in the same group have the same number of valence electrons while the elements in the same period have the same number of shells.

Thus, the elements that are above and below each other in the periodic

table have similar physical and chemical properties because they have the same number of valence electrons.

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to activate metabolic processes that wouldn't happen on their own; to move chemicals across membranes that are necessary; and to do mechanical activity, like moving muscles.

Acetylation. A relatively frequent metabolic process that involves amino, hydroxyl, or sulfhydryl groups is acetylation. Acetyltransferases catalyze the process by transferring the acetyl group from acetyl-coenzyme A.

Anabolic and catabolic responses are the two different categories of metabolic processes. Protein synthesis in living things and the synthesis of carbohydrates in plants are examples of anabolic responses. Cellular respiration and glycolysis are examples of catabolic processes that occur in several species.

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Answer:

A

Explanation:

The measure of how densely a material is packed together is called density. As the mass per unit volume, it has that definition. The density of aluminum in g/cm³ is 2.70 g/cm³.

A substance's density is a measurement of how heavy it is in relation to its size. If an object is placed in water, it will float if it is less dense than the water, and it will sink if it is more dense. The density of a material is a distinguishing quality that is independent of the substance's volume.

The volume of the metal =315 cm³

Then density is:

Density = mass /volume

Density of metal = 851 g / 315cm³

D = 2.70 g / cm³

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Compound 1 incorporated the amino acid serine as a future site of covalent attachment to ha prior to mineralization.

Serine contains a hydroxyl group (-OH) on its side chain, which can form a covalent bond with other molecules. In this case, the hydroxyl group of serine can attach to ha (hyaluronic acid) through a covalent bond.

The other options, alanine (ala), tyrosine (tyr), and threonine (thr), do not have a hydroxyl group on their side chains and therefore cannot form the same type of covalent bond with ha.

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Answer: 2,090J

The equation to find the specific heat is determined by the equation q = mcΔT, where q = total heat, m=mass, c = specific heat, and ∆T change in temperature.

Recall that the specific heat capacity for water is 4.18J/gºC

So, plug this along with your specific values into the equation.

q = 100g * (4.18J/gºC) * (20.0ºC-15.0ºC)
q = 2090J

Answer:

Water molecules forming hydration shells around Na+ and Cl- ions. The partially positive ends of the water molecules are attracted to the negative Cl- ion, while the partially negative ends of the water molecules are attracted to the positive Na+ ion.

Explanation:

I got this from another source, I hope this helps tho!

Answer:

260

Explanation:

Answer:

e

Explanation:

The half-life of radioactive elements is 46 days.

We need to know about the half-life of the radioactive elements to solve this problem. The radioactive element will decay over time depends on the half-life and follow the equation

N = No(1/2)^(t/t'')

where N is the final quantity, No is the initial quantity, λ is the decaying constant, t is time and t'' is the half-life of a radioactive element.

From the question above, we know that

No = 8 mg

N = 0.5 mg

t = 184 days

By substituting the given parameters, we can calculate the half-life

N = No . (1/2)^(t / t'')

0.5 = 8(1/2)^(184 / t'')

1/16 = (1/2)^(184 / t'')

(1/2)^4 = (1/2)^(184 / t'')

4 = 184/t''

t'' = 184/4

t'' = 46 days

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Answer:

Iron metal is more reactive than copper.

Explanation:

Iron metal is more reactive than copper. ... Cu is less reactive than iron, therefore, cannot replace iron from iron sulphate (FeSO4). we have already seen that iron is more reactive than copper. So that means that in this reaction, copper is less reactive than iron. That means copper cannot displace iron. It cannot kick out iron from a sulfate.

The solution to the equation and value of variable 21(3d - 4) + 100 = 58 is d = 2/3.

Solve the equation 21(3d - 4) + 100 = 58, we can begin by simplifying and isolating the variable:

21(3d - 4) + 100 = 58

Distribute 21 to the terms inside the parentheses:

63d - 84 + 100 = 58

Combine like terms:

63d + 16 = 58

Subtract 16 from both sides:

63d = 42

Divide both sides by 63:

d = 42/63

Simplifying the fraction gives:

d = 2/3

The solution to the equation is d = 2/3.

The solution to the equation 21(3d - 4) + 100 = 58 is d = 2/3. By simplifying the equation, we find that dividing both sides by 63 results in the solution of d = 2/3, which satisfies the original equation.

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