A hydrogen atom in an excited state emits a photon of wavelength 486 nm. What are the initial and final states of the hydrogen atom

Answer:

sunlight

Explanation:

Answer:

each chlorine atom will lose one electron

Answer:

Compounds are substances composed of two or more elements chemically combined that can be separated into simpler substances only by chemical means. Water, for example, is a compound because pure water is composed of only H2O molecules.

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To determine the amount of heat released by the complete combustion of acetone, we need to calculate the moles of acetone present in the given volume and then use the molar heat of combustion to find the heat released.

Given:

Volume of acetone (nail polish remover) = 177 ml

Density of acetone = 0.788 g/ml

First, we can calculate the mass of acetone using its density:

Mass of acetone = Volume x Density = 177 ml x 0.788 g/ml

Next, we need to convert the mass of acetone to moles using its molar mass. The molar mass of acetone (C3H6O) is:

(3 x atomic mass of carbon) + (6 x atomic mass of hydrogen) + (1 x atomic mass of oxygen) = 3(12.01 g/mol) + 6(1.01 g/mol) + 1(16.00 g/mol) = 58.08 g/mol

Moles of acetone = Mass / Molar mass = (177 ml x 0.788 g/ml) / 58.08 g/mol

Now, we need to use the molar heat of combustion of acetone to find the heat released. The molar heat of combustion of acetone is typically given as -1790 kJ/mol.

Heat released = Moles of acetone x Molar heat of combustion = (177 ml x 0.788 g/ml) / 58.08 g/mol) x -1790 kJ/mol

Simplifying the expression:

Heat released = (177 ml x 0.788 g/ml x -1790 kJ/mol) / 58.08 g/mol

Finally, we can calculate the value:

Heat released ≈ -415 kJ

Therefore, approximately -415 kJ of heat is released by the complete combustion of the acetone present in the 177 ml of nail polish remover. The negative sign indicates that the process is exothermic, meaning heat is released.

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The pH of the resulting solution from mixing HNO₂ and RbOH is 3.25.

pH of a solution can be defined as the concentration of H⁺ ions in the solution.To determine the pH of the resulting solution from mixing HNO₂ and RbOH,  write the balanced equation for the reaction between the two:

HNO₂ + RbOH → RbNO₂ + H₂O

Step 1: Write the dissociation reaction for HNO₂ and its equilibrium expression:

HNO₂ + H₂O ⇌ H₃O⁺ + NO₂⁻

K = [H₃O⁺][NO₂⁻] / [HNO₂]

Step 2: Calculate the initial concentration of HNO₂:

Molarity = moles / volume (in L)

moles HNO₂ = 1.860 M × 0.162 L = 0.30132 moles

Step 3: Calculate the initial concentration of RbOH:

Molarity = moles / volume (in L)

moles RbOH = 1.090 M × 0.121 L = 0.13169 moles

Step 4: Determine which reactant is limiting:

HNO₂: 0.30132 moles → produces 0.30132 moles of H₃O⁺

RbOH: 0.13169 moles → produces 0.13169 moles of OH⁻

Since HNO₂ produces more moles of H₃O⁺ than RbOH produces of OH⁻, HNO₂ is the limiting reactant.

Step 5: Calculate the concentration of H₃O⁺ ions using the equilibrium expression and the initial concentration of HNO₂:

K = [H₃O⁺][NO₂⁻] / [HNO₂]

[H₃O⁺] = K x [HNO₂] / [NO₂⁻] = (5.62 × 10⁻⁴) x (0.30132) / (0.30132) = 5.62 × 10⁻⁴ M

Step 6: Calculate the pH of the solution:

pH = -log[H₃O⁺] = -log(5.62 × 10⁻⁴) = 3.25

Therefore, the pH of the resulting solution from mixing HNO₂ and RbOH is 3.25.

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The question is incomplete, but most probably the complete question is,

Determine the pH of the solution resulting from mixing a solution of 162 mL of HNO₂ (K-5.62e-04) at a 1.860 M concentration, with 121 mL of a 1.090 M solution of RbOH?

Color of apple and cranberry juice is yellow and red respectively as the two colors of  juices are different each color has it's own λ max according to Beer's law and hence apple juice contributes to  color of cranberry-apple juice .

The Beer's law states that the absorbance is directly proportional to the concentration of a solution that is,A∝C .Most substances follow Beer's law from low to moderate temperature ranges only.It is not followed well in case of saturation effects which are present in highly concentrated samples.

Due to the direct relation between absorbance and concentration , absorbance is preferred over transmittance for recording the spectra.

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Answer:

A. They are malleable, ductile, and conduct electricity.

Explanation:

Answer:

a

Explanation:

Answer:

the correct answer is air.

Answer:

water

Explanation:

the medium an electromagnetic wave travel the fastest is in water

Answer:

Medication

Explanation:

These pharmaceuticals can pollute our water and unintentionally expose us to the chemicals in these medications. Recent studies have found that medicines flushed down the drain can contaminate our lakes and streams, which can hurt fish and other aquatic wildlife, and end up in our drinking water.

Answer:

Atoms are electrically neutral because they contain equal quantities of positively charged protons and negatively charged electrons. Electrons and protons have equal but opposite charges, so the result is no net charge. Ions are atoms that have gained or lost electrons.

It would take approximately 0.144 hours to produce 7.5 moles of copper metal using the given current and cell potential.  

To produce 7.5 moles of copper metal from an electrolytic cell, we can use the following equation:

moles of copper produced = moles of Cu produced

here:

moles of Cu produced is the number of moles of Cu that are produced as the Cu ions dissolve in the solution and move towards the cathode.

We are given that the current passed through the cell is 50.0 A and the cell potential is 2.50 V. Therefore, we can calculate the number of moles of Cu produced using the following equation:

moles of Cu produced = -50.0 A x 2.50  x time

To find the time required to produce 7.5 moles of copper, we can rearrange the equation as follows:

time = -moles of Cu produced / (50.0 A x 2.50 V)

time = -7.5 moles / (50.0 A x 2.50 V)

time = 0.144 hours

Therefore, it would take approximately 0.144 hours to produce 7.5 moles of copper metal using the given current and cell potential.  

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Answer: 3

Explanation:

Running a blank solution is crucial in spectrophotometry experiments to establish the zero %T and account for background absorbance. Without running a blank, the results can be affected by systematic errors.

It is important to run a blank solution to set the zero %T in both Parts 1 and 2 of the experiment because it helps to account for any background absorbance or interference from the solvent or other components in the sample. Running a blank solution allows us to establish a baseline measurement of the solvent or the solution without the analyte, which helps in accurately measuring the absorbance caused by the analyte of interest.

If a blank solution is not run, the results can be affected in several ways:

Systematic Error: The absence of a blank solution can introduce a systematic error, causing a constant offset in the measured absorbance values. This offset can lead to incorrect calculations and interpretations.

Overestimation or Underestimation: Without running a blank, the measured absorbance may include contributions from the solvent or other interfering substances. This can lead to overestimation or underestimation of the analyte concentration, affecting the accuracy of the results.

Distorted Beer's Law Plot: In the absence of a blank, the plot obtained may not accurately represent the linear relationship between concentration and absorbance according to Beer's Law. This can lead to incorrect calculations of the slope (molar absorptivity) and affect the accuracy of future concentration determinations.

In spectrophotometry, the blank solution serves as a reference for setting the zero %T (transmittance) or absorbance value. By measuring the blank, we can account for any absorbance caused by the solvent, impurities, or other components in the sample. The blank solution typically contains all the components except the analyte of interest. It is measured under the same conditions as the sample solutions.

The blank measurement allows us to subtract any background absorbance from the sample measurements, providing a more accurate representation of the absorbance caused solely by the analyte. This helps in obtaining reliable and precise measurements for concentration determination using Beer's Law.

Running a blank solution is crucial in spectrophotometry experiments to establish the zero %T and account for background absorbance. Without running a blank, the results can be affected by systematic errors, inaccurate concentration determinations, and distorted Beer's Law plots. It is important to always include a blank solution to ensure accurate and reliable measurements.

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The answer to your question is Ke = 33.06.

[Cl₂] = 0.21 M

[H₂] = 0.13 M

[HCl] = 0.95 M

Balanced chemical reaction

                     Cl₂(g)  +  H₂(g)  ⇔  2HCl (g)

Formula

              Ke = Substitution

              Ke = [0.95]² / [0.21][0.13]

Simplification

             Ke = 0.9025 / 0.0273

Result

             Ke = 33.06

The equilibrium constant does not have units.

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Answer:

Option (A) the solid X is ground to a fine powder.

Explanation:

X(s) + 2B(aq) → X+(aq) + B2(g)

In the reaction above, the rate of the reaction will be highest, when X being a solid is ground to fine powder.

Grounding X to fine powder simply means increasing the surface area of X.

An increase in surface area of reactants will definitely increase the rate of reaction because the particles of the solid will collide with the right orientation and hence speed up the reaction rate.

Answer:

The Rio Grande drainage basin (watershed) has an area of 182,200 square miles (472,000 km2)

If 28.0 grams of N2 and 5.04 grams of H2 are reacted, producing 17.8 grams of NH3. the percent yield is 52.4%. Therefore, the answer is option 3,

To calculate the percent yield, we first need to calculate the theoretical yield of NH3 based on the amounts of N2 and H2 that were reacted.

The balanced chemical equation for the reaction is:

N2 + 3H2 → 2NH3

From the equation, we can see that 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3. Therefore, the moles of N2 and H2 reacted can be calculated as:

moles of N2 = mass of N2 / molar mass of N2

= 28.0 g / 28.014 g/mol

= 0.999 mol

moles of H2 = mass of H2 / molar mass of H2

= 5.04 g / 2.016 g/mol

= 2.5 mol

Since N2 is the limiting reactant (its mole value is less than H2's mole value), we can calculate the amount of NH3 produced based on the mole ratio of N2 and NH3:

moles of NH3 = 2/1 x moles of N2

= 2/1 x 0.999 mol

= 1.998 mol

The theoretical yield of NH3 can be calculated from its mole value:

mass of NH3 = moles of NH3 x molar mass of NH3

= 1.998 mol x 17.031 g/mol

= 34.06 g

Now, we can calculate the percent yield by dividing the actual yield (17.8 g) by the theoretical yield (34.06 g) and multiplying by 100:

percent yield = actual yield / theoretical yield x 100%

= 17.8 g / 34.06 g x 100%

= 52.24%

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The acetic acid/acetate buffer system consists of a weak acid (acetic acid, CH3COOH) and its conjugate base (acetate ion, CH3COO-). When a base is added to the buffer system, the following process occurs to neutralize it:

1. The base reacts with the weak acid (acetic acid) in the buffer system to form its conjugate base (acetate ion) and water. For example, if a hydroxide ion (OH-) is added, it reacts with acetic acid as follows:

  OH- + CH3COOH → CH3COO- + H2O

2. The conjugate base (acetate ion) that is formed acts as a reservoir for hydrogen ions (H+). It can accept hydrogen ions from the solution if the pH increases. This helps to maintain the pH of the buffer system within a certain range.

3. The buffer system resists large changes in pH because the equilibrium between the weak acid and its conjugate base is shifted to maintain a relatively constant concentration of both species. This allows the system to neutralize the added base and maintain its acidic nature.

The acetic acid/acetate buffer system neutralizes an added base by reacting with it to form the conjugate base and water, and by utilizing the conjugate base to accept hydrogen ions and maintain the pH of the system.

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Nanoscience is a branch of science that focuses on the study of phenomena at the nanoscale, typically between 1 and 100 nanometers. This field encompasses a wide range of scientific disciplines, including physics, chemistry, biology, and engineering. The study of nanoscience involves investigating the unique properties and behaviors that occur at the nanoscale, which can differ significantly from those at larger scales.

Nanoscience is not limited to the study of single atoms or electrons, although these are certainly important areas of investigation within the field. Rather, it is a more broad and interdisciplinary approach to exploring the properties and behavior of matter at very small scales. For example, nanoscience may involve studying how the structure and composition of materials change at the nanoscale, or how the interactions between nanoparticles can lead to new and interesting phenomena.

The study of nanoscience has important implications for a wide range of fields, including medicine, electronics, and energy. By better understanding the unique properties of materials and systems at the nanoscale, researchers can develop new technologies and applications that can revolutionize our world.

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The tonicity of a solution refers to its ability to cause a change in the shape or size of cells by altering the water content.

In this case, since the membrane is impermeable to glucose but permeable to water, the glucose molecules cannot pass through the membrane, while water molecules can. Since the solution is made of 0.3M glucose, it means that the concentration of glucose in the solution is 0.3 moles per liter.

When blood is added, the impermeable membrane prevents glucose molecules from passing through, but water molecules can move freely. The presence of a higher concentration of glucose inside the membrane than in the blood creates a hypertonic environment. This causes water to move from the blood (where the concentration of solutes is lower) into the solution, via osmosis.

As a result, the solution will become more diluted as water enters it, causing it to expand and potentially change the shape or size of the cells.

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Answer:

Chemical energy

Explanation:

The energy stored in the bonds of atoms and molecules, is chemical energy .

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Answer: Chemical energy. :]

Explanation:

Answer:

the atom of the oxidized molecule donates an electron to the reduced molecule that attracts the electrons

During an oxidation-reduction reaction, electrons are transferred between two molecules. The molecule that loses electrons is oxidized, while the molecule that gains electrons is reduced.

Oxidation-reduction reactions involve a transfer of electrons from one molecule to another. The molecule that loses electrons becomes oxidized because it has lost electrons, while the molecule that gains electrons becomes reduced because it has gained electrons. This transfer of electrons is typically facilitated by the presence of a catalyst or an electron acceptor, such as oxygen or a metal ion.

Thus, during an oxidation-reduction reaction, electrons are transferred between two molecules, leading to the oxidation of one molecule and the reduction of the other. This process is essential for many biological and chemical reactions, including cellular respiration and the combustion of fuels.

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Answer:

-The independent variable is a variable often denoted by X, whose variation does not depend on that of another.

-The dependent variable is a variable often denoted by Y, whose value depends on that of another.

After the calculating we have Test statistic: -3.874.

Critical values: -2.086 and 2.086.

To test if the population mean pH of rainwater is equal to 5.4, we can perform a one-sample t-test.

We have the data:

Population mean (μ) = 5.4

Sample mean (x) = 4.7

Sample standard deviation (s) = 0.8

Sample size (n) = 21

Significance level (α) = 0.05

To calculate the test statistic, we can use the formula:

t = (sample mean - population mean) / (sample standard deviation / sqrt(sample size))

Plugging in the values:

t = (4.7 - 5.4) / (0.8 / √(21))

Calculating:

t ≈ (-0.7) / (0.8 / 4.582)

t ≈ -3.874

The test statistic is approximately -3.874.

To find the critical values, we need to refer to the t-distribution table or use statistical software. At a significance level of α = 0.05 with (n-1) degrees of freedom (n = sample size), the critical values for a two-tailed test are approximately -2.086 and 2.086.

Therefore, the correct answer is:

Test statistic: -3.874.

Critical values: -2.086 and 2.086.

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The given statement that "the rate of a second order reaction can depend on the concentrations of more than one reactant" is true because the rate of the reaction is proportional to the concentration of both reactants.

The second-order reaction is a chemical reaction in which two reactants interact and the rate of the reaction is proportional to the concentration of both reactants or to the square of the concentration of a single reactant. The equation is as follows:

k = k[reactant1] [reactant2] or k = k[reactant1]²

The reaction rate constant (k) for a second-order reaction is proportional to the concentration of one or two reactants. The concentration of the reactants has an impact on the reaction rate, as indicated by the order of the reaction.

Therefore, the statement that "the rate of a second order reaction can depend on the concentrations of more than one reactant" is true.

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Answer:

it is a result of hydrogen bonds present within water molecules.

Explanation:

when the water is transformed to ice at zero degrees Celsius, the water molecules are in crystal lattice in a structure that has a lot of empty space around each molecule.

The final temperature of the gas that expands from a volume of 22.4 l at 278k to a volume of 38.3 l will be 475 K.

The volume as well as Kelvin temperature will be directly proportional whenever the pressure on even a sample of such a dry gas remains held constant. PV = k would be the law's equation.

Charle's law give the relation between the temperature and volume is shown as:

\(V_{1} / T_{1} = V_{2} / T_{2}\)

where. V is volume and T is temperature.

Given data :

\(V_{1} =22.4 l\\V_{2} = 38.3 l\\T_{1} = 278 K\\T_{2} = ?\)

Put the value of given data in above equation.

22.4 l /   38.3 l = 278k / \(T_{2}\)

\(T_{2}\) = 475 K.

Therefore, the final temperature will be 475 K.

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The term evapotranspiration combines infiltration and transpiration is False.

False. The term evapotranspiration does not combine infiltration and transpiration. Evapotranspiration refers to the combined process of evaporation and transpiration.

Evaporation is the process by which water changes from a liquid to a gas state and is primarily driven by heat energy from the sun. Transpiration, on the other hand, is the process by which plants release water vapor through their leaves.

Infiltration, however, is a separate process that refers to the downward movement of water from the surface into the soil. It is not directly related to evapotranspiration.

Therefore, the term evapotranspiration does not combine infiltration and transpiration.

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Unlike protons and neutrons, which are housed inside the atom's nucleus at its center, electrons are found outside the atom.

An atom can have a label in addition to a symbol or atomic number. The label is formatted as "(text)" (without the quotation marks), which means "text, closed curved bracket, open curved bracket." If an isotopic mass is present, it should come after the chemical symbol, followed by the label.

The element is represented by the letter(s) in the centre. The atomic number, which indicates the quantity of protons, is the number in the bottom left corner.

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