how do you find the change in enthalpy of a reaction. if it is positive, what does this mean? negative?

Riboflavin molecules are polar overall.

Alkyl halides, alcohols, ethers, amines, and thiols. Because of the higher difference in electronegativities between the bonding atoms, these functional groups are noticeably more polar.

These functional groups have stronger intermolecular pressures because of the interactions between the dipoles. Depending on their atomic structure and composition, functional groups can occasionally be categorized as having polar or nonpolar characteristics. The term "polar" refers to a quality that is not symmetrical,

It can have many poles (more or less of something at various locations). Due to resonance, the carboxyl group is polar. Due to the carbonyl group's ability to form a carbocation with the oxygen atom, the hydroxyl group acts as an electron acceptor and the carbonyl group as an electron donor.

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The question is incomplete complete question is given below

circle and identify the functional groups in the following molecules. which have polar bonds? which molecules are polar overall?

5-hydroxy-2-pentanone
Morphine
Riboflavin

The wooden artifact from the ancient tomb contains the 55% of the carbon-14 that is present in the living trees. The time was the artifact made is 4942.2 years.

The half life of the carbon - 12 = 5730 years

The decay model for the isotope is as :

N / No = e^-λt

The time constant for the carbon-14 is as :

λ = 5730 / ln 2

λ = 8266.6 years

The time of the artifact made is as :

The time for the artifact => ln (N / No) = -t / λ

The time for the artifact, t  =  - 8266.6 × ln 0.55

The time for the artifact, t  = 4942.2 years.

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The percentage of O₂ that will react to form NO at 1700 °C is approximately 98.3%.

This can be calculated by using the equilibrium constant and the initial molar ratios of the reactants. By using the equilibrium equation, we can set the initial molar ratio of N₂ and O₂ to Kc.

In this case, Kc = 4.10 × 10⁻⁴ and the initial molar ratio of N₂ and O₂ is 1:1 (as both have 0.459 mole). The equation can then be rearranged to solve for the percentage of O₂ that will react to form NO. This yields a value of approximately 98.3%.

This value can be used to determine the equilibrium concentration of NO in the container. As the initial molar ratio of N₂ and O₂ is 1:1, the equilibrium molar ratio of NO would also be 1:1. Therefore, the equilibrium concentration of NO in the 0.665-L container would be 0.459 mol/L.

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Answer:

Phenol

Explanation:

A phenol is a compound that has an alcohol functional group (-OH) attached to a benzene ring.

The compound formed when an alcohol is attached to an aromatic ring is called a phenol. Phenols are a type of organic compound that contain a hydroxyl group (-OH) attached to an aromatic hydrocarbon group. The hydroxyl group in phenols is directly attached to the carbon atom of the aromatic ring, and this makes phenols distinct from alcohols, which have a hydroxyl group attached to an alkyl group.

Phenols can be prepared by a variety of methods, including the reaction of an aryl halide with a metal hydroxide, such as sodium hydroxide (NaOH), or the reaction of an arene oxide with a proton source, such as an acid. One common method for preparing phenols is called the Dowd-Beckwith reaction, which involves the oxidation of an aromatic hydrocarbon using a peroxyacid, such as m-chloroperoxybenzoic acid (MCPBA).

Phenols have a wide range of applications in industry and in organic chemistry. They are used as disinfectants and antiseptics, as well as in the production of plastics, resins, and other chemicals. Phenols are also used in the synthesis of pharmaceuticals, dyes, and flavors.

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The hydronium ion concentration in an aqueous solution with a pH of 4.33 at 25°C is approximately 4.7 × 10^-5 M (Option C).

To calculate the hydronium ion concentration in an aqueous solution with a pH of 4.33 at 25°C, you can use the following formula:

Hydronium ion concentration (H₃O⁺) = 10^(-pH)

where pH is the negative logarithm of the hydrogen ion concentration (pH = -log[H+]).

Step 1: Plug the given pH value into the formula.
H₃O⁺ = 10^(-4.33)

Step 2: Calculate the hydronium ion concentration.
H₃O⁺ ≈ 4.7 × 10^-5 M

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The reagent that is in excess in this experiment is potassium dichromate (K2CrO4).

To determine which reagent is in excess, we need to calculate the moles of each reagent and compare them.

Moles of AgNO3 = 0.0040 M x 0.0050 L = 2.0 x 10^-5 moles
Moles of K2CrO4 = 0.0024 M x 0.0050 L = 1.2 x 10^-5 moles

Since the moles of AgNO3 is greater than the moles of K2CrO4, we might initially think that AgNO3 is in excess. However, we need to consider the balanced chemical equation for the reaction:

AgNO3 + K2CrO4 → Ag2CrO4 + 2KNO3

From the balanced equation, we can see that 1 mole of AgNO3 reacts with 1 mole of K2CrO4. Therefore, we only need 1.2 x 10^-5 moles of AgNO3 to react completely with the 1.2 x 10^-5 moles of K2CrO4. Since we added 2.0 x 10^-5 moles of AgNO3, we have an excess of AgNO3.

Therefore, the reagent that is in excess is the potassium dichromate (K2CrO4).

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The one which is not necessary for the filtration is thermometer. The correct option is A.

The filtration, the process in which the solid particles present in the liquid or the gaseous fluid will be removed by the use of the filter medium which will the permits and the fluid to pass the through it but it will be retains the solid particles.

The most common example of the filtration is the making tea. When we are preparing the tea, the filter or the sieve which is used when we separate the tea leaves from the water and through the sieve pores, the water will be pass. The correct option is A.

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Polyglycolic acid is a synthetic polymer that is commonly used in absorbable sutures due to its biodegradable and bioresorbable properties, high tensile strength, and low tissue reactivity is (a) True.

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The highest potential is obtained when the anode is zinc (Zn) in ZnSO₄ solution and the cathode is iron (Fe) in FeSO₄ solution. The half-reaction occurring at the anode is Zn(s) → Zn²⁺(aq) + 2e⁻ and the half-reaction at the cathode is Fe²⁺(aq) + 2e⁻ → Fe(s).

The standard reduction potentials of the half-reactions involved in the voltaic cell can be found in reference tables. In this case, the standard reduction potential for the half-reaction Zn²⁺(aq) + 2e⁻ → Zn(s) is more negative than the potential for the half-reaction Fe2+(aq) + 2e- → Fe(s). This means that zinc will be oxidized at the anode and iron will be reduced at the cathode.

The overall cell potential is the difference between the reduction and oxidation potentials, and in this case, it will be positive, resulting in a spontaneous reaction. Zinc has the highest reducing power, which means it can donate electrons more readily than magnesium or iron, making it the best anode. Similarly, iron has a higher reducing power than magnesium, making it the best cathode.

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To draw ortho, meta, and para positions for substituents on benzene rings, you first need to understand the numbering system used for the ring carbons. The carbons on the ring are numbered 1-6 in a clockwise or counterclockwise direction, with the first carbon being the one that is directly connected to the substituent.

Once you know the numbering system, you can draw the substituent in the appropriate position. Ortho positions are located on the carbons adjacent to the substituent, so for example, if the substituent is on carbon 2, the ortho positions would be on carbons 1 and 3. Meta positions are located on the carbon that is two positions away from the substituent, so for example, if the substituent is on carbon 2, the meta position would be on carbon 4. Para positions are located on the carbon that is directly across from the substituent, so for example, if the substituent is on carbon 2, the para position would be on carbon 6.

To draw the positions, you can simply label the appropriate carbons with the corresponding position (o, m, or p) next to the substituent. For example, if the substituent is on carbon 2, the ortho positions would be labeled as o-1 and o-3, the meta position would be labeled as m-4, and the para position would be labeled as p-6.

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To determine the molar solubility of BaF2 in a solution containing 0.0750 M LiF, we need to use the common ion effect.

First, we need to write the balanced equation for the dissolution of BaF2:

BaF2(s) ⇌ Ba2+(aq) + 2F-(aq)

The Ksp expression for BaF2 is:

Ksp = [Ba2+][F-]2

We are given that Ksp = 1.7 × 10^-6.

Next, we need to consider the effect of the added LiF on the solubility of BaF2. Since LiF also contains F- ions, it will shift the equilibrium to the left, decreasing the solubility of BaF2.

Let's assume that x moles of BaF2 dissolve in the presence of 0.0750 M LiF. Then, the equilibrium concentrations of Ba2+ and F- will be:

[Ba2+] = x
[F-] = 2x + 0.0750

We can substitute these into the Ksp expression and solve for x:

1.7 × 10^-6 = x(2x + 0.0750)2

Solving this quadratic equation gives us:

x = 8.5 × 10^-7 M

Therefore, the molar solubility of BaF2 in a solution containing 0.0750 M LiF is option B) 8.5 × 10^-7 M.

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The concentration of dye is monitored during the reaction in this experiment using UV-Vis absorption.

This technique involves measuring the absorption of light by the dye at a particular wavelength. As the dye concentration changes during the reaction, the amount of light absorbed also changes, which can be detected and used to determine the concentration of the dye.
This method involves passing light through the solution and measuring the absorbance of the specific wavelength corresponding to the dye. As the concentration of the dye changes during the reaction, the absorbance will change accordingly, allowing you to monitor the concentration throughout the experiment.

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Answer: The volume of nitrogen evolved at STP when 63 g of ammonium dichromate is heated is approximately 5.6 L.

Explanation:

To find the volume of nitrogen evolved, we'll first need to determine the moles of ammonium dichromate used, and then use the stoichiometry of the balanced equation to find the moles of nitrogen produced. Finally, we'll convert the moles of nitrogen to volume at STP.

The balanced equation is:

(NH4)2Cr2O7 -> Cr2O3 + 4H2O + N2

Calculate the molar mass of ammonium dichromate, (NH4)2Cr2O7:

2 * (14.01 [N] + 4 * 1.01 [H]) + 2 * 51.99 [Cr] + 7 * 16.00 [O] =

2 * (14.01 + 4.04) + 103.98 + 112.00 = 252.06 g/mol

Calculate the moles of ammonium dichromate:

63 g / 252.06 g/mol ≈ 0.25 mol

Use stoichiometry to find moles of nitrogen produced:

1 mol (NH4)2Cr2O7 produces 1 mol N2, so 0.25 mol (NH4)2Cr2O7 produces 0.25 mol N2.

Convert moles of nitrogen to volume at STP (standard temperature and pressure):

At STP (0°C and 1 atm), 1 mole of any gas occupies 22.4 L. Therefore, 0.25 mol N2 occupies:

0.25 mol × 22.4 L/mol ≈ 5.6 L

So, the volume of nitrogen evolved at STP when 63 g of ammonium dichromate is heated is approximately 5.6 L.

To draw the Lewis electron-dot symbol for a main-group element, first determine the number of valence electrons by noting the group number of the element. Place one dot for each electron on each of the four sides of the element symbol, pairing them up once each site has an electron.

Valence electrons are the electrons in the outermost shell of an atom that can participate in chemical bonding. The group number corresponds to the number of valence electrons for main-group elements. In a Lewis electron-dot symbol, the element symbol represents the nucleus and the inner electrons of the atom, while the dots represent the valence electrons. These dots are placed around the element symbol in a specific order to indicate the electron configuration of the atom.

The electron-dot symbol helps visualize how atoms can form bonds with other atoms and illustrates the concept of electron sharing in covalent bonds or electron transfer in ionic bonds. It is a useful tool for understanding and predicting the bonding behavior of main-group elements in chemical reactions. To draw the Lewis electron-dot symbol for a main-group element, first determine the number of valence electrons by noting the group number of the element. Place one dot for each electron on each of the four sides of the element symbol, pairing them up once each site has an electron.

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The best explanation for the pattern in no concentration is that no does not play a significant role in smog formation. Although it is a secondary pollutant, it has a long residence time in the atmosphere and is not quickly oxidized. Furthermore, it is not formed by rush-hour traffic or the rising sun in the morning. Instead, it is likely that no is being absorbed by plants and converted to sugars, which is why it is not found in high concentrations in the atmosphere. This process helps to remove no from the atmosphere and may explain why it does not contribute significantly to smog formation. Overall, the lack of significant no concentration in the atmosphere may be due to the fact that it is being absorbed and processed by plants, rather than being produced by human activity or other natural processes.
NO concentration is that "NO is produced by rush-hour traffic and is quickly oxidized in the atmosphere." Nitrogen oxide (NO) is a secondary pollutant that is generated mainly from human activities, such as vehicle emissions during rush-hour traffic. Once released into the atmosphere, NO reacts with other compounds and is quickly oxidized, playing a significant role in smog formation. This oxidation process helps to maintain the balance of NO concentrations in the lower atmosphere. In contrast, the other statements do not accurately describe the pattern of NO concentration in the atmosphere.

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We need to mix 0.7 liters of ethanol with 0.3 liters of water to make a total of 1 liter of solution.

We need to dilute the stock solution by adding a certain amount of water.

Using formula:

Volume of ethanol = (desired concentration/stock concentration) x total volume of solution

Desired concentration is 70%, the stock concentration is 100%, and the total volume of solution can be any desired amount.

For example, to make 1 liter of 70% ethanol solution:

Volume of ethanol = (70 / 100) x 1 liter = 0.7 liters of ethanol

The remaining volume of the solution will be filled with water, which is:

Volume of water = 1 liter - 0.7 liters = 0.3 liters of water

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a. For the first  response A B--> 2C, the value of ∆ H2 will be equal in magnitude but  contrary in sign to ∆ H1, because the rear  response.

2C--> A B, is just the original  response reversed. So, ∆ H2 = - ∆ H1.  

b. For the first  response A1/2 B--> C, the value of ∆ H2 will also be equal in magnitude but  contrary in sign to ∆ H1, because the rear  response, C--> A1/2 B, is just the original  response reversed. So, ∆ H2 = - ∆ H1.  

c. For the first  response A--> B 2C, the value of ∆ H2 will be equal in magnitude but  contrary in sign to ∆ H1/ 2, because the rear  response, 1/ 2B C-->1/2 A, is just the original  response reversed and halved. So, ∆ H2 = - ∆ H1/ 2.

For the first  general  response, A B--> 2C and 2C--> A B, the value of ∆ H2 will be equal in magnitude but  contrary in sign to ∆ H1, because the rear  response, 2C--> A B, is just the original  response reversed. So, ∆ H2 = - ∆ H1.   This means that the enthalpy change for the rear  response is equal in magnitude but  contrary in sign to the enthalpy change for the forward  response.  

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Acids are more like electrophiles than nucleophiles. The acronym to remember this is "AE": Acids are Electrophiles.

Step-by-step explanation:
1. Acids are substances that can donate a proton (H+).
2. Electrophiles are electron-pair acceptors, meaning they are attracted to regions of high electron density.
3. Since acids can donate a proton, they are seeking electrons to form a bond.
4. Therefore, acids behave as electrophiles.

Remember the acronym "AE" (Acids are Electrophiles) to easily recall this relationship.

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The balanced equation of Sodium hydroxide and sulphric acid​ is 2 NaOH + H2SO4 -> Na2SO4 + 2 H2O.

In this reaction, a base (sodium hydroxide) mixes with an acid (sulphric acid), resulting in the production of a salt (sodium sulfate) and water. The equation is structured to show that the reagents combine in such a way that there are equal numbers of atoms of each element on both sides.

The balanced chemical equation for the combination of sodium hydroxide (NaOH) and sulfuric acid (H2SO4) looks like this:

2 NaOH + H2SO4 -> Na2SO4 + 2 H2O

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The partial pressure of the carbon dioxide is  A 0.5 atm.

To find the partial pressure of carbon dioxide, we can use Dalton's Law of Partial Pressures, which states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each individual gas.

Total moles of gas = moles of O₂ + moles of CO₂ + moles of N₂

                               = 0.5 + 0.1 + 0.4

                               = 1 mole

Now, we can calculate the mole fraction of each gas:

Mole fraction of CO₂ = moles of CO₂ / total moles of gas = 0.1 / 1 = 0.1

Next, we can calculate the partial pressure of CO₂ using the mole fraction:

Partial pressure of CO₂ = mole fraction of CO₂ × total pressure

                                      = 0.1 × 5 atm

                                      = 0.5 atm

So, the partial pressure of carbon dioxide (CO₂) is 0.5 atm, which corresponds to option A.

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Sex cells, also known as gametes, transmit genetic information for determining traits to their offspring through a process called meiosis.

During meiosis, the diploid parent cell undergoes two rounds of cell division, resulting in four haploid daughter cells, each containing half the genetic information of the parent cell.

In humans, the male sex cell, or sperm cell, and the female sex cell, or egg cell, each contains 23 chromosomes, which combine during fertilization to form a diploid zygote with 46 chromosomes. The genetic information carried by these chromosomes determines various traits such as eye color, height, and susceptibility to certain diseases.

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The two variables that determine the total change in entropy in a system are the heat transfer  (Q)  and the temperature (T) of the system. Here's a step-by-step explanation:

Step 1: Understand that entropy is a measure of the disorder or randomness in a system.
Step 2: Recognize that the total change in entropy (ΔS) can be calculated using the formula ΔS = Q/T, where Q represents the heat transfer (in joules) and T is the temperature (in kelvin) of the system.
Step 3: Identify the two variables in the formula: Q (heat transfer) and T (temperature).
Step 4: To determine the total change in entropy, consider how the heat transfer and temperature of the system affect the entropy.
Step 5: Calculate the total change in entropy using the ΔS = Q/T formula, keeping in mind the values of the two variables, heat transfer and temperature.

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The high-mass stars can only fuse up to iron before collapsing and exploding in a supernova.

It actually takes progressively more time to fuse heavier elements inside a high-mass star. This is because heavier elements require higher temperatures and pressures to overcome their increasing electrostatic repulsion and fuse together. As the star runs out of fuel and moves from fusing lighter elements to heavier ones, the fusion process slows down, and eventually stops when iron is produced.

The fusion of elements up to iron releases energy, but the fusion of heavier elements requires more energy than it produces, which is why high-mass stars can only fuse up to iron before collapsing and exploding in a supernova.

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Normality is a measure of the concentration of a solution, which takes into account the number of active particles (ions or molecules) in the solution. It is defined as the number of equivalents of solute per liter of solution.

The equation used to find normality when given molarity depends on the nature of the solute and the reaction in question. In general, the relationship between molarity (M) and normality (N) is given by the formula:
N = M x n

where n is the number of equivalents of solute per mole. For example, if you have a solution of hydrochloric acid (HCl) with a molarity of 1 M, and you want to find its normality, you need to know that HCl is a strong acid that dissociates completely in water, producing one hydrogen ion (H+) and one chloride ion (Cl-) per molecule of HCl. Therefore, the number of equivalents of HCl is 1, and n = 1.

Using the formula above, we get:
N = M x n = 1 M x 1 equiv/mole = 1 N
So the normality of the 1 M HCl solution is 1 N.

In summary, normality is a concentration unit that takes into account the number of active particles in a solution, and the equation to find it from molarity depends on the nature of the solute and the reaction involved.

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A swimmer is moving at a speed of 2.0 meters/second, it will take the swimmer 50 seconds to go 100 meters. So, correct answer is: 50 seconds.

Speed is a measure of how fast an object is moving and can be defined as the distance traveled per unit of time. Standard unit of speed is meters per second (m/s) in International System of Units (SI).

To solve this, we can use the formula time = distance/speed.
In this case, the distance is 100 meters and the speed is 2.0 meters/second.

Step 1: Plug in the values into the formula: time = 100 meters / 2.0 meters/second
Step 2: Calculate the time: time = 50 seconds

So, it will take the swimmer 50 seconds to go 100 meters.

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In the stern-gerlach type of the experiment on the atom with a the single 2p electron, The number of components would the beam will be split is 2.

The Stern–Gerlach experiment explained that the spatial orientation of the angular momentum will be quantized in to the two components that is up and the down. The Stern–Gerlach experiment is to test the Bohr–Sommerfeld hypothesis in which the direction of the angular momentum of the silver atom will quantized.

The Stern-Gerlach experiment was firstly regarded that the crucial test in between the classical theory for the atom and the theory of the Bohr-Sommerfeld theory.

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7.21 × 10^23 particles of C2H6 will be created if  7.21 × 10^23 particles of H2 react.

According to the balanced chemical equation:

C2H4 + H2 → C2H6

H2 and C2H6 have a 1:1 stoichiometric ratio, which means that for every mole of H2 that reacts, 1 mole of C2H6 is generated.

We can use the Avogadro's number (6.022 × 10^23 particles/mol) to convert the given number of particles of H2 to moles:

moles of H2 = 7.2 × 10^23 particles / 6.022 × 10^23 particles/mol

moles of H2 = 1.198 mol

Given that the stoichiometric ratio of H2 to C2H6 is 1:1, 1.198 mol of C2H6 are also created.

Now we can convert the number of moles of C2H6 to particles of C2H6 using the Avogadro's number:

particles of C2H6 = 1.198 mol × 6.022 × 10^23 particles/mol

particles of C2H6 = 7.21 × 10^23 particles

Therefore, 7.21 × 10^23 particles of C2H6 will be created if  7.21 × 10^23 particles of H2 react.

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The number of moles of the unknown quantity of gas is 3.74 mol.

The Ideal gas law states that "the pressure multiplied by volume is equal to moles multiply by the universal gas constant multiply by temperature.

It is expressed as;

PV = nRT

Where P is pressure, V is volume, n is the amount of substance, T is temperature and R is the ideal gas constant ( 0.08206 Latm/molK )

Given that:

Plug the values into the above formula and solve for n.

PV = nRT

n = PV / RT

n = ( 2.3 × 50L ) / ( 0.08206 Latm/molK × 375K )

n = 115 Latm / 30.7725 Latm/mol

n = 3.74 moles.

Therefore, the amount of gas is approximately 3.74 mol.

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