2. Would the following procedural changes cause the experimentally determined mass percent of NH3 in Ni(NH3)nCl2 to be too high, too low, or unchanged. Briefly explain each answer.
(a). After dissolving a known mass of Ni(NH3)nCl2, a student directly titrated the NH3 with HCl solution, using a mixed bromocresol green – methyl red indicator.
(b). A student added excess standard HCl solution to a known mass of dissolved Ni(NH3)nCl2 and back titrated the excess HCl with standard NaOH solution, using phenolphthalein indicator solution.

Answer:

1.8mL

Explanation:

What is the volume?

Density = Mass / Volume

19.3g/mL = 35g/v

19.3g/mL (v) = 35g/v (v)

19.3g/mL x v = 35g

v = 35g/19.3g/mL

v = 1.8mL

Answer:

82

Explanation:

Lead (207) has 82 protons and 82 electrons, generally. As it is neutral, there will be no change in the number of electrons as the electrons will cancel out with the number of protons, so the number of electrons equals the atomic number of 207Pb, which is 82.

Answer:

Significant Figures in 200.0

Result 200.0

Sig Figs 4 (200.0)

Decimals 1 (200.0)

Scientific Notation 2.000 × 102

E-Notation 2.000e+2

One displacement reaction is the answer. Single displacement reactions occur when an element in one compound is changed in another. Metal magnesium reacts in the reaction described.

This powdery substance is created when magnesium delivers 2 electrons to oxygen atoms. The reaction here is exothermic. Chemical reactions that release energy on a net basis are referred to as exothermic reactions.

When magnesium and water mix, hydrogen is created along with a large amount of heat. Metallic magnesium responds rather slowly, but mag vapour, which is created when magnesium burns, reacts very quickly because of the elevated temp and effective mixing, and it swiftly generates heat. Water is added to burning magnesium, which causes an explosion.

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The number of moles of HCl produced along with the 2.9 moles of H₃PO₄ is 14.5 moles

From the question, we are to determine the number of moles of HCl that are produced along with 2.9 moles of H₃PO₄

The given balanced chemical equation of the reaction is

PCI₅ + 4H₂O ---> H₃PO₄ + 5HCI

From the balanced chemical equation,

1 mole of PCI₅ reacts with 4 moles of H₂O to produce 1 mole of H₃PO₄ and 5 moles of HCI

Now,

If 2.9 moles of H₃PO₄ are produced from the reaction,

Then,

5 × 2.9 moles of HCl will be produced along with the H₃PO₄

5 × 2.9 =  14.5 moles

Hence, the number of moles of HCl produced is 14.5 moles

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Answer:

silver metal and potassium nitrate

Explanation:

silver nitrate

potassium ions

potassium metal

no reaction

silver ions

Methanol has the highest boiling point.

Methanol, with its hydrogen bonding, has a much higher boiling point than ethane, which has only an instantaneous dipole. The higher boiling point indicates a much stronger attraction between molecules.

The boiling point of a liquid varies according to the applied pressure; the normal boiling point is the temperature at which the vapor pressure is equal to the standard sea-level atmospheric pressure (760 mm [29.92 inches] of mercury). At sea level, water boils at 100° C (212° F).

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Answer:10

Explanation:

Multiply the volume by the density to get the mass.

Divide the mass by the molar mass to get the number of moles.

Answer:

atoms have same atomic number but different atomic masses is called isotopes

Explanation:

The total entropy change of the steam during this process is 24.885 kJ/K.

During this process, the system undergoes a phase change from a saturated liquid-vapor mixture to a saturated vapor. The initial state can be determined using a steam table, which shows that at 225 kPa, the saturation temperature of water is 120.23°C. Therefore, the initial state is a mixture of liquid water and steam at 120.23°C with 80% of the mass in the liquid phase.

When the electric resistance heater vaporizes all of the liquid, the system transitions to a state of saturated vapor at the same pressure of 225 kPa and temperature of 120.23°C. The total entropy change of the steam during this process can be calculated using the formula:

ΔS = m * s_final - m * s_initial

where ΔS is the total entropy change, m is the mass of the steam, s_final is the specific entropy of the final state, and s_initial is the specific entropy of the initial state.

At the initial state, using the steam table, the specific entropy of the saturated liquid-vapor mixture can be found to be 1.5875 kJ/kg-K. At the final state, the specific entropy of the saturated vapor can also be found to be 7.2925 kJ/kg-K.

Therefore, the total entropy change of the steam is:

ΔS = 4.2 kg * (7.2925 kJ/kg-K - 1.5875 kJ/kg-K)
ΔS = 24.885 kJ/K

Therefore, the total entropy change of the steam during this process is 24.885 kJ/K.

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Modern continents hold clues to their distant past. Evidence from fossils, glaciers and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed. Some life "rode" on diverging plates, became isolated, and evolved into new species.

Earthquakes, mountain building and volcanic activity occur mostly at the boundaries of the moving plates. Only shallow earthquakes occur where plates diverge at mid-ocean ridges, whereas earthquakes extend to a great depth where plates converge at subduction zones. Magma generation, igneous intrusions, metamorphism, volcanic action, earthquakes, faulting, and folding are usually the result of plate tectonic activity. The earth's crust is divided into six large pieces, and about twenty smaller pieces, by deep fault systems.

The exact net benefit for the farmer (NPB) is: NPB = - (3/2)Q^2 - 6Q = -18

The exact net benefit for the neighbors is: Net Benefit for Neighbors = -TD = - (12Q + 2Q^2) = -80

1. If the mushroom farmer does not take the bad smell imposed on his neighbors into account, he will produce the quantity of mushrooms where his marginal cost equals his marginal revenue. To find this quantity, we equate the marginal cost (MC) to the marginal revenue (MR):

  MC = TPC' = 9 + 3Q

  MR = Qd = 21 - (1/5)P

  Setting MC = MR:

  9 + 3Q = 21 - (1/5)P

  Solving for Q, we get:

  Q = 4

  The Net Private Benefit (NPB) for the farmer is the difference between the total revenue (TR) and the total cost (TC):

  NPB = TR - TC = P * Q - TPC = PQ - (9Q + (3/2)Q^2) = - (3/2)Q^2 - 6Q

  The Net Social Benefit (NSB) for society is the difference between the total benefit (TB) and the total cost (TC):

  NSB = TB - TC = TD - TPC = (12Q + 2Q^2) - (9Q + (3/2)Q^2) = - (1/2)Q^2 + 3Q

2. The optimal number of units of mushrooms for society occurs where the social marginal benefit (SMB) equals the social marginal cost (SMC). To find this quantity, we equate the marginal benefit (MB) to the marginal cost (MC):

  MB = Qd = 21 - (1/5)P

  MC = TPC' = 9 + 3Q

  Setting MB = MC:

  21 - (1/5)P = 9 + 3Q

  Solving for Q, we get:

  Q = 4

  The NPB for the farmer at this optimal number is:

  NPB = - (3/2)Q^2 - 6Q = -18

  The NSB for society at this optimal number is:

  NSB = - (1/2)Q^2 + 3Q = 6

3. In a situation without transaction costs and a ruling that the farmer is not allowed to bother neighbors without their permission, the farmer will produce the quantity of mushrooms that maximizes his net private benefit (NPB). This occurs at the quantity where the marginal cost (MC) equals the marginal private benefit (MPB) for the farmer:

  MC = TPC' = 9 + 3Q

  MPB = Qd = 21 - (1/5)P

  Setting MC = MPB:

  9 + 3Q = 21 - (1/5)P

  Solving for Q, we get:

  Q = 4

  The exact net benefit for the farmer (NPB) is:

  NPB = - (3/2)Q^2 - 6Q = -18

  The exact net benefit for the neighbors is:

  Net Benefit for Neighbors = -TD = - (12Q + 2Q^2) = -80

4. In a situation without transaction costs and a ruling that the farmer is allowed to produce as much bad smell as he wants, the farmer will produce the quantity of mushrooms that maximizes his net private benefit (NPB). This occurs at the quantity where the marginal cost (MC) equals the marginal private benefit (MPB) for the farmer:

  MC = TPC' = 9 + 3Q

  MPB = Qd =

21 - (1/5)P

  Setting MC = MPB:

  9 + 3Q = 21 - (1/5)P

  Solving for Q, we get:

  Q = 4

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The condition with the highest entropy, S, for one mole of Ar is 167 °C and 101 L.

Entropy is a measure of the dispersal of energy and particles in a system. In this case, we are comparing different conditions for one mole of Ar. The two main factors that affect entropy are temperature and volume. For an ideal gas, an increase in either temperature or volume will lead to a higher entropy. The Boltzmann equation, S = k ln(W), where S is entropy, k is the Boltzmann constant, and W is the number of microstates, shows that a higher number of microstates corresponds to higher entropy. With a higher temperature or volume, more microstates are available for the gas particles to occupy, resulting in a greater degree of disorder.

Comparing the given conditions, the one with the highest temperature and volume is 167 °C and 101 L. This condition will provide the greatest number of available microstates for the gas particles and, therefore, result in the highest entropy for one mole of Ar.

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Considering the definition of Avogadro's Number, 7.37×10²² moles of Cu are in a 3.56g sample of Cu?

The molar mass of substance is the amount of mass that a substance contains in one mole.

Avogadro's Number is the number of particles that make up a substance (usually atoms or molecules) in the amount of one mole of the substance. Its value is 6.023×10²³ particles per mole.

Avogadro's number applies to any substance.

The molar mass of Cu is 63.54 g/mole. The amount of moles of Cu can be calculated as:

amount of moles= 3.56 g÷ 63.54 g/mole

amount of moles= 0.056 moles

Now you can apply the following rule of three: 1 mole of the compound has 6.023×10²³ atoms, 0.056 mole contains how many atoms?

amount of atoms of Cu= (0.056 moles ×6.023×10²³ atoms)÷ 1

amount of atoms of Cu= 7.37×10²²

Finally, 7.37×10²² moles of Cu are present.

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Answer:

True

Explanation:

Size-exclusion chromatography (SEC) is a suitable chromatographic method for isolating pure a and b chains.

SEC is a technique that separates molecules based on their size. In this case, the a and b chains can be separated from other components based on their molecular weight. SEC columns have porous beads that allow smaller molecules to enter and travel through the beads, while larger molecules are excluded and elute first. By choosing an appropriate SEC column, the a and b chains, which typically have different molecular weights than other components, can be isolated and collected separately. This method ensures the purity of the isolated a and b chains.

Size-exclusion chromatography (SEC) is a useful chromatographic method for isolating pure a and b chains. The technique separates molecules based on their size, and by utilizing a suitable SEC column, the a and b chains can be separated from other components due to their distinct molecular weights. This approach guarantees the purity of the isolated a and b chains, making it an effective method for their isolation.

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The activation energy was lowered by 9.0 kJ/mol when the catalyst was used. The correct answer is (a) -9.0 kJ/mol.

To solve this problem, we can use the Arrhenius equation, which relates the rate constant (k) of a chemical reaction to the activation energy (Ea) and the temperature (T). The equation is as follows:

k = A * exp(-Ea / (R * T))

Where:

k = rate constant

A = pre-exponential factor

Ea = activation energy

R = gas constant (8.314 J/(mol·K))

T = temperature in Kelvin

We are given the activation energy (Ea) at a certain temperature and the rate increase factor when a catalyst is used. We need to find how much the activation energy is lowered when the catalyst is used.

Let's begin by converting the given temperature from Celsius to Kelvin:

T = 42°C + 273.15 = 315.15 K

Now, let's consider the rate increase factor when the catalyst is used:

Rate increase factor = k_catalyst / k_no_catalyst

= exp(-Ea_catalyst / (R * T)) / exp(-Ea_no_catalyst / (R * T))

= exp((Ea_no_catalyst - Ea_catalyst) / (R * T))

We know the rate increase factor is 31. Therefore:

31 = exp((Ea_no_catalyst - Ea_catalyst) / (R * T))

To find the activation energy difference (ΔEa = Ea_no_catalyst - Ea_catalyst), we can take the natural logarithm (ln) of both sides:

ln(31) = (Ea_no_catalyst - Ea_catalyst) / (R * T)

Rearranging the equation to solve for ΔEa:

ΔEa = ln(31) * R * T

Now, let's plug in the known values:

ΔEa = ln(31) * (8.314 J/(mol·K)) * 315.15 K

Calculating this:

ΔEa ≈ 9.0 kJ/mol

Therefore, the activation energy was lowered by approximately 9.0 kJ/mol when the catalyst was used. The correct answer is (a) -9.0 kJ/mol.

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Answer:

its letter B.

Explanation:

If an avalanche occurs, the snow on the mountain accelerates down slope, converting more gravitational potential energy to kinetic energy.

Answer:

General equation = acid +metal---->salt+ hydrogen

word equation =hydrochlooric acid + magnesium ---> magnesium chloride + hydrogen gas.

Explanation:

I hope this is what you want.

Answer:

The magnesium reacts with the acid, producing visible bubbles of hydrogen gas. ... Magnesium ribbon is a flammable solid. Hydrochloric acid is a corrosive liquid. Hydrogen gas is explosive.

Summary: Magnesium, mossy zinc and copper foil are reacted with hydrochloric acid to produce hydrogen gas and a salt. The reaction rates are compared. Hazards: Hydrochloric acid is corrosive and toxic.

Answer:

E. The substitution allows each carbon atom to accept more than four valence electrons.

Explanation:

Halogens (except for fluorine) have seven valence electrons, which gives them the flexibility to participate in more than four covalent bonds. Hydrogen only has one valence electron, so it tends to form only four covalent bonds. In a substitution reaction, each halogen provides the carbon atom with additional electrons, allowing it to accept more than the usual four.

Answer:

C. The bonds between the carbon atoms in the molecule become weaker.

Explanation:

There is one atom of Fe present in each body-centered cubic (BCC) unit cell of iron.

In a body-centered cubic (BCC) unit cell, there is one atom at each corner of the cube, and one atom in the center of the cube.

The atom at the center is shared between eight adjacent unit cells. Therefore, the total number of atoms per unit cell is 1+1/8 = 1.125.

However, we cannot have a fractional number of atoms, so we round down to 1 atom per unit cell. In the case of iron, which has a BCC crystal structure, there is one atom of Fe present in each unit cell.

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Answer:

The answer is Hydrogen and Oxygen Elements

Answer:

B. hydrogen and oxygen elements

The statement that is not true about proteins is "Proteins are naturally acidic." Option C is correct.

Proteins are biological macromolecules made up of long chains of amino acids. They are also referred to as polypeptides because they are composed of multiple peptide bonds between the amino acids. The specific sequence and arrangement of amino acids in the polypeptide chain determine the unique 3D structure and function of the protein.

Proteins can have a structure characterized by loops, bends, and twists, and this structure is held together by a variety of intermolecular interactions, including hydrogen bonds, disulfide bonds, electrostatic interactions, and van der Waals forces.

While some amino acids have acidic or basic side chains, proteins as a whole are not necessarily naturally acidic. The overall charge of a protein is dependent on the charge of its constituent amino acids and the pH of the surrounding environment.

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--The given question is incomplete, the complete question is

"All of the following statements are true about proteins except. -Proteins can have a structure characterized by loops, bend, and twists. A) Proteins are composed of amino acids. B) Proteins are polypeptides C) Proteins are naturally acidic. D) Hydrogen bonds keep the protein together"--

Chymotrypsin has an α-helix that contains 2.5 turns. Approximately 9 amino acids are involved in this helix.

What is chymotrypsin?

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Thale balanced half-reaction of aqueous Vanadium to solid Vanadium is  

V⁵⁺ + 3e- → V(s)

The reduction of vanadium(V) cations to solid vanadium involve the transfer of three electrons to vanadium cations, leading to a net reduction of the cations. Vanadium is a transition metal and is located in the fifth period of the periodic table.

Due to its electron configuration, vanadium has five valence electrons and can form five covalent bonds with other atoms. In the aqueous form, vanadium(V) cations have a charge of +5, which is due to the five electrons that it has lost.

In order for the reduction of vanadium(V) cations to solid vanadium to take place, three electrons must be transferred to the vanadium cations. This results in a balanced half-reaction, which can be written as

V⁵⁺ + 3e- → V(s)

The three electrons that are donated to the vanadium cations reduce the cations from a +5 charge to a neutral charge, resulting in the formation of solid vanadium.

The reduction of vanadium(V) cations to solid vanadium is an important process in many industrial and chemical applications.

Vanadium is often used to produce alloys and is used in the production of steel. It is also used as a catalyst in the production of sulfuric acid and is used in the production of dyes and inks.

The reduction of vanadium(V) cations to solid vanadium are also important in biological systems, as vanadium is an essential trace element for some organisms.

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Answer:

D.  18,800 J/mol

Explanation:

We need to use the Arrhenius equation to solve for this problem:

\(k=Ae^{\frac{-E_a}{RT}\), where k is the rate constant, A is the frequency factor, \(E_a\) is the activation energy, R is the gas constant, and T is the temperature in Kelvins.

We want to find the value of \(E_a\), so let's plug some of the information we have into the equation. The gas constant we can use here is 8.31 J/mol-K.

At 0°C, which is 0 + 273 = 273 Kelvins, the rate constant k is \(4.6*10^{-2}\). So:

\(k=Ae^{\frac{-E_a}{RT}\)

\(4.6*10^{-2}=Ae^{\frac{-E_a}{8.31*273}\)

At 20°C, which is 20 + 273 = 293 Kelvins, the rate constant k is \(8.1*10^{-2}\). So:

\(k=Ae^{\frac{-E_a}{RT}\)

\(8.1*10^{-2}=Ae^{\frac{-E_a}{8.31*293}\)

We now have two equations and two variables to solve for. We just want to find Ea, so let's write the first equation for A in terms of Ea:

\(4.6*10^{-2}=Ae^{\frac{-E_a}{8.31*273}\)

\(A=\frac{4.6*10^{-2}}{e^{\frac{-E_a}{8.31*273}} }\)

Plug this in for A in the second equation:

\(8.1*10^{-2}=Ae^{\frac{-E_a}{8.31*293}\)

\(8.1*10^{-2}=\frac{4.6*10^{-2}}{e^{\frac{-E_a}{8.31*273}} }e^{\frac{-E_a}{8.31*293}\)

After some troublesome manipulation, the answer should come down to be approximately:

Ea = 18,800 J/mol

The answer is thus D.

Answer:

d

Explanation:

check if one element replaces another element in a compound

The single replacement reaction can be identified when there has been the replacement of one element with another element in the compound. Thus, option C is correct.

The replacement reaction can be defined as the reaction in which the highly reactive element replaced the low reactive element in the reaction and forms a compound.

The reaction has been given as:

X + AY \(\rightarrow\) AX + Y

The X has been highly reactive than Y replaces Y in the compound and forms the compound AX.

The single replacement reaction can be identified when there has been the replacement of one element with another element in the compound. Thus, option C is correct.

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Answer:

a) [H₃O⁺] = 1.8x10⁻⁵ M

b) pH = 4.75

c) % rxn = 3.5x10⁻³ %

Explanation:

a) The dissociation reaction of HCN is:

HCN(aq) + H₂O(l) ⇄ H₃O⁺(aq) + CN⁻(aq)

0.5 M - x                       x               x

The dissociation constant from the above reactions is given by:

\(Ka = \frac{[H_{3}O^{+}][CN^{-}]}{[HCN]} = 6.17 \cdot 10^{-10}\)

\( 6.17 \cdot 10^{-10} = \frac{x*x}{(0.5 - x)} \)

\( 6.17 \cdot 10^{-10}*(0.5 - x) - x^{2} = 0 \)

By solving the above quadratic equation we have:

x = 1.75x10⁻⁵ M = 1.8x10⁻⁵ M = [H₃O⁺] = [CN⁻]

Hence, the [H₃O⁺] is 1.8x10⁻⁵ M.

b) The pH is equal to:

\(pH = -log[H_{3}O^{+}] = -log(1.75 \cdot 10^{-5} M) = 4.75\)    

Then, the pH of the HCN solution is 4.75.

c) The % reaction is the % ionization:

\( \% = \frac{x}{[HCN]} \times 100 \)

\( \% = \frac{1.75 \cdot 10^{-5} M}{0.5 M} \times 100 \)

\( \% = 3.5 \cdot 10^{-3} \% \)          

Therefore, the % reaction or % ionization is 3.5x10⁻³ %.

I hope it helps you!