The following set of reactions show
burning hydrogen and the reverse
process, electrolysis of water. What is
the missing change in enthalpy? Only
put in the numerical value. (The bond
energy of H-H is 432 kJ/mol was used
in the first equation. Other bond
energies are on this form, IF you need
it.)
_2_H₂ + _1_0₂_2_H₂O
_2_H₂O →_2_H₂ +_1_O₂
ΔΗrxn=-498 kJ/mol
ΔΗrxn= ??? kJ/mol

When evaluating a college or university, one important factor to which the cost should be directly compared is the average starting salary of graduates.

Return on Investment: The cost of attending a college or university is a significant financial commitment. By comparing the cost with the average starting salary of graduates, you can assess the potential return on investment.

Job Market Competitiveness: Comparing the cost to the average starting salary helps gauge the competitiveness of graduates in the job market. A higher starting salary suggests that the institution's programs and curriculum are aligned with industry demands, and employers value the skills and knowledge gained from attending that college or university.

Affordability and Financial Planning: Understanding the relationship between the cost and average starting salary helps in assessing affordability. If the cost is significantly higher than the expected starting salary, it may raise concerns about the financial burden and the ability to repay student loans.

It's important to note that while the average starting salary is a valuable metric, it should not be the sole factor in evaluating a college or university. Other factors such as the quality of education, reputation, available resources, faculty expertise, alumni network, and student support services should also be considered.

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The layers that make up the Earth's atmosphere has unique properties that influence the kinds of wavelengths that are reflected, absorbed, or permitted to pass through to the planet's surface. Three layers are troposphere, stratosphere, and mesosphere.

The troposphere, the first layer closest to the surface of the planet, is where the majority of the planet's weather is found. The temperature in this layer drops with altitude, and it is made up of greenhouse gases like carbon dioxide and water vapor.

The stratosphere, which contains the ozone layer, is the next layer. The sun's dangerous UV light is absorbed by ozone, keeping it from reaching the surface of the Earth.

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Answer:

C:.375

Explanation:

Answer:

As the temperature of water increases, the speed of sound waves traveling through it also increases. Therefore, if the water temperature increases from 0°C to 20°C, the speed of the sound wave traveling through it will increase.

The speed of a sound wave in water will increase if the water's temperature increases from 0°C to 20°C due to increased particle collisions resulting from higher kinetic energy.

The best statement that describes how the speed of a wave will change if the water temperature increases from 0°C to 20°C is - The wave speed will increase because the particles will collide more frequently.

This is because an increase in temperature of a fluid (like water) results in an increase in the speed of sound through it. When the temperature increases, the kinetic energy of the particles also increases. As a result, these molecules move around faster, thereby leading to increased collisions which essentially helps the sound wave to propagate faster. So, the speed of the sound wave increases with an increase in temperature.

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The balance equations would be;

1) 2H₂ + O₂ → 2H₂O      2) H₃PO₄ + 3KOH → K₃PO₄ + 3H₂O

3) 6K + B₂O₃ = 3K₂O + 2B    4) HCl + NaOH → NaCl + H₂O

5) 2Na + 2NaNO₃ → 2Na₃O + N₂    6) 4C + 2S₈ → 4CS₂

7) 2Na + O₂ → Na₂O₂     8)   N₂ + 3O₂ → 2N₂O₃

9) H₃PO₄ + 2Mg(OH)₂ → Mg₃(PO₄)₂ + 6H₂O

10)  NaOH + H₂CO₃ → Na₂CO₃ + H₂O   11) KOH + HBr → KBr + H₂O

12) 2H₂ + 2O₂ = 2H₂O₂   13) 4Na + O₂ → 2Na₂O  

14) 2Al(OH)₃ + 3H₂CO₃ → Al₂(CO₃)₃ + 6H₂O   15) 4Al + 3S₈ → 2Al₂S₃

16) 6Cs + N₂ → 2Cs₃N    17) Mg + Cl₂ → MgCl₂  

18) 8Rb + 2RbNO₃ → 5Rb₂O + N₂  19) C₄H₄ + 5O₂ → 4CO₂ + 2H₂O

20) N₂ + 3H₂ → 2NH₃

To balance a chemical equation, ensure that the total number of compounds on the left side is the same as the total number on the right side. Let balance equation 11

11. ......KOH + ..... HBr → .....KBr + ....H₂O

There are 2 H on the left which reflects on the right side. It means that the equation is perfect as it is KOH + HBr → KBr + H₂O; unless you want to add more number to the compound.

if we add 2KOH + 2HBr ⇒ 2KBr + 2H₂O

there are 2K, 2O, 4H , 2Br  on the right we have 2k 2Br 4H and 2O

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A unit of measurement called a mole is used to determine how much of a material there is. We must utilise Avogadro's number, which equals 6.022 x 1023 particles per mole, to convert moles to particles. The Avogadro constant is another name for this quantity.

We must multiply 80 moles of CH4 by Avogadro's number in order to transform it to particles. The computation looks like this: 80 moles x a particle density of 6.022 x 1023 per mole = 4.8176 x 1025 particles. 80 moles of CH4 are therefore equivalent to 4.8176 x 1025 particles.

Particles refer to the individual units, such as atoms or molecules, inside a material, whereas moles are the basic unit used to estimate the amount of a substance. Approximately 6.022 x 1023 particles per mole, or Avogadro's number, serves as a conversion factor between moles and particles.

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When the magnetic field is in the x-direction, the force on the particle is only in the y-direction (Fy = 1.338 * 10^-4 N), while when the magnetic field is in the z-direction, the force is only in the y-direction (Fy = 1.457 * 10^-4 N).

To calculate the force exerted on the particle by a magnetic field, we can use the equation:

F = q * (V x B)

where F is the force vector, q is the charge of the particle, V is the velocity vector, and B is the magnetic field vector.

Given:

q = -1.24 * 10^-8 C (charge of the particle)

V = (4.19 * 10^4 m/s)i + (-3.85 * 10^4 m/s)j (velocity of the particle)

B = (2.80 T)i (magnetic field)

Let's calculate the force:

F = (-1.24 * 10^-8 C) * ((4.19 * 10^4 m/s)i + (-3.85 * 10^4 m/s)j) x (2.80 T)i

The x, y, and z components of the force are:

Fx = 0 N

Fy = 1.338 * 10^-4 N

Fz = -1.44 * 10^-4 N

To calculate the cross product, we use the following rules:

i x i = j x j = k x k = 0

i x j = k

j x k = i

k x i = j

j x i = -k

k x j = -i

Expanding the equation, we get:

F = (-1.24 * 10^-8 C) * [(4.19 * 10^4 m/s)(2.80 T)k - (-3.85 * 10^4 m/s)(2.80 T)j]

F = (-1.24 * 10^-8 C) * (11.692 * 10^4 T)m/s k + (10.78 * 10^4 T)m/s j

F = -1.44 * 10^-4 N k + 1.338 * 10^-4 N j

Now, let's calculate the force exerted on the particle by a magnetic field B = (2.80 T)k:

F = q * (V x B)

Given:

q = -1.24 * 10^-8 C (charge of the particle)

V = (4.19 * 10^4 m/s)i + (-3.85 * 10^4 m/s)j (velocity of the particle)

B = (2.80 T)k (magnetic field)

Using the same formula as before, we have:

F = (-1.24 * 10^-8 C) * [(4.19 * 10^4 m/s)i + (-3.85 * 10^4 m/s)j] x (2.80 T)k

Expanding the cross product:

F = (-1.24 * 10^-8 C) * (-2.80 T)(4.19 * 10^4 m/s)j

F = 1.457 * 10^-4 N j

Therefore, the x, y, and z components of the force are:

Fx = 0 N

Fy = 1.457 * 10^-4 N

Fz = 0 N

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Answer:DNA, along with RNA and proteins, is one of the three major macromolecules that are essential for life. Most of the DNA is located in the nucleus, although a small amount can be found in mitochondria (mitochondrial DNA). Within the nucleus of eukaryotic cells, DNA is organized into structures called chromosomes.

Explanation: science

A chemist determines that a substance is composed of 30.4% nitrogen by mass and 69.6% oxygen by mass. The molar mass of the compound is 230.5 g/mol, the molecular formula is NO₂.

We must compute the empirical formula in order to ascertain the compound's chemical composition.

If we have 100 grams of the compound.

This suggests we have:

30.4 g of nitrogen

69.6 g of oxygen

Now, we have to convert the mass of each element to moles.

The molar mass of nitrogen (N) = 14.01 g/mol

the molar mass of oxygen (O)  =  16.00 g/mol.

Number of moles of nitrogen (N):

2.17 mol

Number of moles of oxygen (O):

4.35 mol

The simplest whole-number ratio between the moles of nitrogen and oxygen must now be determined. To calculate the ratio, we divide both numbers by the smaller value.

Moles N / moles O = 2.17 mol / 2.17 mol = 1.00

Moles O / moles O = 4.35 mol / 2.17 mol = 2.00

The ratio is approximately N₁O₂.

We divide the subscripts by their greatest common divisor to obtain the simplest ratio, since we are looking for the empirical formula. The empirical formula is NO₂ since the greatest common divisor in this situation is 1.

The molecular formula of the compound is NO₂.

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Explanation:

The balanced equation is

2  H2        +    02 ======> 2 H2 O

so it takes twice as many H2 moles as O2 to complete the reaction

  the chemist does not have enough  H2 (needs 8 moles)   , so H2 is the limiting reactant .

Both Ca(OH)₂ (calcium hydroxide) and NaOH (sodium hydroxide) are examples of strong bases.

A base is a substance that can accept protons (H) or donate hydroxide ions (OH) in a chemical reaction. strong bases completely dissociate in water, releasing hydroxide ions.

In the case of Ca(OH)₂, when it is dissolved in water, it dissociates into calcium ions and hydroxide ions  The hydroxide ions make it a strong base.

Similarly, NaOH, when dissolved in water, completely dissociates into sodium ions (Na+) and hydroxide ions (OH-), making it a strong base as well.

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To calculate the root-squared error for ΔH, we need to consider the uncertainties associated with both the heat capacity (c) and the temperature change (T) in the equation.

Temperature change (T) = 3.30 ± 0.60 °C

Heat capacity (c) = 0.862 ± 0.012 kJ °C^(-1)

To calculate the root-squared error, we need to propagate the uncertainties using the formula:

(root-squared error)^2 = (partial derivative of ΔH with respect to c * error in c)^2 + (partial derivative of ΔH with respect to T * error in T)^2

The partial derivative of ΔH with respect to c = T

Error in c = 0.012 kJ °C^(-1)

The partial derivative of ΔH with respect to T = c

Error in T = 0.60 °C

Substituting the values into the formula:

(root-squared error)^2 = (T * error in c)^2 + (c * error in T)^2

= (3.30 °C * 0.012 kJ °C^(-1))^2 + (0.862 kJ °C^(-1) * 0.60 °C)^2

Calculating this expression:

(root-squared error)^2 ≈ (0.0396 kJ)^2 + (0.5172 kJ)^2

≈ 0.00157 kJ^2 + 0.2672 kJ^2

≈ 0.2688 kJ^2

Finally, taking the square root of the result:

root-squared error ≈ √(0.2688 kJ^2)

≈ 0.518 kJ

Therefore, the root-squared error for ΔH is approximately 0.518 kJ.

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In an acetic acid solution:

1. To make a buffer with pH = 5.00, have a ratio of

[tex]\frac{[A-]}{[HA]} = 10^{-5.50}[/tex] = 0.316.

The volume of sodium hydroxide needed:

V(NaOH) = (0.316 M - 0.200 M) / 4.50 M = 0.0316 L = 31.6 mL

Therefore, 31.6 mL of 4.50 M sodium hydroxide must be added to 250.0 mL of 0.200 M acetic acid solution to make a buffer with pH = 5.00.

2. The pH of the buffer is calculated as follows:

pH = pKa + log([tex]\frac{[A-]}{[HA]}[/tex])

= 4.76 + log(0.2/0.1)

= 4.86

Therefore, the pH of the buffer is 4.86.

3. The mass of salt that must be dissolved in 0.25 dm³ of 1 mol dm³ propanoic acid to give a buffer of pH 4.87:

[tex]\frac{[A-]}{[HA]} = 10^{-4.87}[/tex] = 0.0114

Therefore, the mass of acetate that must be dissolved:

Mass of acetate = (0.0114 mol dm³)(0.25 dm³) = 0.00285 g

Therefore, 0.00285 g of sodium propanoate must be dissolved in 0.25 dm³ of 1 mol dm³ propanoic acid to give a buffer of pH 4.87.

4. The pH of the buffer is calculated as follows:

pH = pKa + log([tex]\frac{[A-]}{[HA]}[/tex])

= 4.74 + log(0.1/0.1)

= 4.74

Therefore, the pH of the buffer is 4.74.

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386°C

The ideal gas law allows us to solve for different values of a gas.

Ideal Gas Law

In order to do ideal gas calculations, we make the assumption that gas behaves ideally. This means that gases move in completely straight lines, have perfectly elastic collisions, experience no IMFs (intermolecular forces), and have no volume. When we assume these characteristics, we get the equation:

In this equation, P is pressure, V is volume, n is moles, R is the gas constant, and T is temperature. It is important to note that temperature is always given in Kelvin for the ideal gas law.

Solving For T

To solve for T, all we need to do is plug in the values we were given. The question states:

Now we just need to solve for T. For clarity, I will leave units out of this calculation.

This means the temperature is about 658.82 Kelvin. Rounded for sig figs, this is 659K. However, the question asks for Celsius. So, we need to convert. To convert from Kelvin to Celsius, subtract 273.

The gas is at 386°C.

The balanced chemical equation for the combustion of [tex]CH_{3}[/tex] (methane) is:

[tex]CH_{4} + 2O_{2} = > CO_{2} + 2H_{2} O[/tex]

From the balanced equation, we can see that for every mole of [tex]CH_{4}[/tex] combusted, one mole of [tex]CO_{2}[/tex] is formed.

Given that 25 moles of [tex]CH_{3}[/tex] (methane) combust, we can assume that it refers to 25 moles of [tex]CH_{4}[/tex] since they have the same chemical formula.

Therefore, the number of moles of [tex]CO_{2}[/tex] formed will also be 25 moles, as the reaction produces an equal number of moles of [tex]CO_{2}[/tex].

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Answer:

chlorine gas is reduced in the reaction.

The  AIR MASSES that would affect the climates of Florida : are maritime tropical air mass and the maritime polar air mass,

Maine : maritime polar air mass and maritime tropical air mass,

Montana :  continental polar and maritime polar air masses.

Texas :  maritime tropical air masses  and continental tropical air masses

An air mass is  described as a large body of air with generally uniform temperature and humidity.

An air mass's properties are determined by the region from which it originates. The likelihood that the air mass will take on characteristics of the surface below increases with the amount of time it spends over its source region.

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Considering the Hess's Law,  the enthalpy change for the reaction is -136.8 kJ.

Hess's Law indicates that the enthalpy change in a chemical reaction will be the same whether it occurs in a single stage or in several stages. That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when it occurs in a single stage.

In this case you want to calculate the enthalpy change of:

C₂H₄ + H₂ → C₂H₆

which occurs in three stages, with their corresponding enthalpies:

Equation 1: C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O    ΔH = –1411 kJ

Equation 2:  C₂H₆ + 3 1/2 O₂ → 2 CO₂ + 3 H₂O     ΔH = –1560 kJ  

Equation 3: H₂ + 1/2 O₂ → H₂O     ΔH = - 285.8 kJ

Because of the way formation reactions are defined, any chemical reaction can be written as a combination of formation reactions, some going forward and some going back.

In this case, to obtain the enthalpy of the desired chemical reaction you need one C₂H₆ on product side and it is present in second equation on product side.  So, it is necessary to locate the C₂H₆ invert it. When an equation is inverted, the sign of delta H also changes.

Then, you know that three equations with their corresponding enthalpies are:

Equation 1: C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O    ΔH = –1411 kJ

Equation 2:  2 CO₂ + 3 H₂O → C₂H₆ + 3 1/2 O₂     ΔH = 1560 kJ  

Equation 3: H₂ + 1/2 O₂ → H₂O     ΔH = - 285.8 kJ

Adding or canceling the reactants and products as appropriate, and adding the enthalpies algebraically, you obtain:

C₂H₄ + H₂ → C₂H₆     ΔH= -136.8 kJ

Finally, the enthalpy change for the reaction is -136.8 kJ.

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Answer: 3.4008

Explanation:

Answer: 3.4008

To determine the freezing point of the solution, we need to use the freezing point depression equation:

ΔT = Kf * m

Given:

Kf (benzene) = 5.12 °C/m

m = 0.41 m

Substituting the values into the equation:

ΔT = 5.12 °C/m * 0.41 m

ΔT = 2.0992 °C

To find the freezing point, we subtract the freezing point depression from the freezing point of the pure solvent (benzene). The freezing point of benzene is 5.5 °C.

Freezing point = FP (benzene) - ΔT

Freezing point = 5.5 °C - 2.0992 °C

Freezing point = 3.4008 °C

Therefore, the freezing point of the 0.41 m solution of C5H4 in benzene is approximately 3.4008 °C.

The ranking of the acids from weakest to strongest is Acid X < acid Z < acid Y.

Option A is correct

An acid is described as  a molecule or ion capable of either donating a proton, known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.

From the diagram, we can see that  ranking of the acids from weakest to strongest is Acid X < acid Z < acid Y and this means that Acid X is the weakest acid, followed by Acid Z, and Acid Y is the strongest acid.

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If you're attempting to synthesize 2 benzyl pentanoic acid from acetoacetic ester, keep in mind that you can do so fairly quickly by following these simplified instructions:

From its pungent free scent to its solid state at temperatures ranging from 118 120°C, acetoacetic ester (better known as ethyl acetoacetate) offers significant value for those working within organic synthesis.

As one of many potent ketones utilized by researchers around the globe its unique properties make it ideal for building complex molecules essential for modern medicine and more.

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Answer:

the temperature increased

The molar mass of the gas is 3.58 g/mol.

We can use the ideal gas law equation:

[tex]PV = nRT[/tex]

Where

We can rearrange the equation to solve for n:

[tex]n = PV/RT[/tex]

We know the following values:

P = 918 torr

V = 222 mL

R = 62.36 L torr/mol K

T = 57°C + 273 = 330 K

To solve for n, we can enter these numbers into the equation:

n = (918 torr)(222 mL)/(62.36 L torr/mol K)(330 K) = 0.0108 mol

Now, we can use the definition of molar mass to find the molar mass of the gas:

molar mass = mass/number of moles

We know the following values:

mass = 38.6 mg = 0.0386 g

n = 0.0108 mol

We can plug these values into the equation to solve for the molar mass

molar mass = 0.0386 g/0.0108 mol = 3.58 g/mol

Therefore, the molar mass of the gas is 3.58 g/mol.

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Answer:

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Explanation:

Potassium has 4 energy levels and 1 valence electron.

The periodic table can tell you the number of valence electrons and the number of energy levels an atom has. The group number tells the number of valence electrons, while the period number tells the number of energy levels.

Approximately 0.157 liters or 157 milliliters of the 4.50 M HCl solution can be made by mixing the given solutions.

To determine the volume of 4.50 M HCl that can be made by mixing the given solutions, we can use the concept of the concentration-volume relationship:

C1V1 = C2V2

Where:

C1 = concentration of the first solution

V1 = volume of the first solution

C2 = concentration of the second solution

V2 = volume of the second solution

Let's assign the variables as follows:

C1 = 5.65 M

V1 = unknown volume (we'll solve for this)

C2 = 3.55 M

V2 = 250.0 mL = 0.250 L (since the volume is given in milliliters)

Now we can plug in the values into the equation and solve for V1:

(5.65 M)(V1) = (3.55 M)(0.250 L)

Dividing both sides of the equation by 5.65 M:

V1 = (3.55 M)(0.250 L) / 5.65 M

V1 ≈ 0.157 L

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In 1.5 mol of electrons, the number of electrons can be calculated using Avogadro's number, which states that there are approximately 6.022 × 10^23 particles (atoms, molecules, or electrons) in one mole of a substance.

So, in 1 mole of electrons, there are 6.022 × 10^23 electrons.

To find the number of electrons in 1.5 mol of electrons, we can multiply the number of electrons in 1 mole by 1.5:

Number of electrons = 1.5 mol × (6.022 × 10^23 electrons/mol)

Calculating this expression gives:

Number of electrons = 9.033 × 10^23 electrons

Therefore, there are approximately 9.033 × 10^23 electrons in 1.5 mol of electrons.

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If the molar mass for the compound is 197.31 g/mol the molecular formula of the compound will be BaCO₃. Molar mass of empirical formula (BaCO₃).

Molar mass = (1 × molar mass Ba) + (1 × molar mass of C) + (3 × molar mass of O)

Molar mass = (1 × 137.33 g/mol) + (1 × 12.01 g/mol) + (3 × 16.00 g/mol)

Molar mass = 137.33 g/mol + 12.01 g/mol + 48.00 g/mol

Molar mass = 197.34 g/mol

The molar mass of the empirical formula (BaCO₃) is approximately 197.34 g/mol.

To find the molecular formula, we need to divide the given molar mass (197.31 g/mol) by the molar mass of the empirical formula (197.34 g/mol) and round to the nearest whole number:

Molar mass ratio = molar mass of molecular / molar mass of empirical

Molar mass ratio = 197.31 g/mol / 197.34 g/mol = 0.9999

Rounding it to 1.

The molecular formula is the same as the empirical formula, which is BaCO₃.

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150 grams of NaOH is approximately equal to 2.256 x 10^24 particles of NaOH.

To convert grams of NaOH to particles of NaOH, we need to use the concept of molar mass and Avogadro's number. The molar mass of NaOH is calculated by adding the atomic masses of sodium (Na), oxygen (O), and hydrogen (H) together. It can be determined as follows:

Na: 22.99 g/mol

O: 16.00 g/mol

H: 1.01 g/mol

Molar mass of NaOH = (22.99 g/mol) + (16.00 g/mol) + (1.01 g/mol) = 40.00 g/mol

Now, we can use the molar mass to convert grams of NaOH to moles. Since 1 mole contains Avogadro's number (approximately 6.022 x 10^23) particles, we can determine the number of particles as follows:

150 g NaOH * (1 mol NaOH / 40.00 g NaOH) * (6.022 x 10^23 particles / 1 mol NaOH) ≈ 2.256 x 10^24 particles

It's important to note that this calculation assumes the substance is pure NaOH and that the molar mass and Avogadro's number are accurate.

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