in which pair do both compounds exhibit predominantly ionic bonding? group of answer choices naf and mgo so2 and hcl rbf and no2 kno3 and ch4 kcl and co2

At the atmospheric pressure on the summit of Mt. Everest (0.333 atm), water boils at a temperature of approximately 2710.39 °C.

In this specific question, we are being asked to calculate the temperature (in °C) at which water boils on the summit of Mt. Everest, given that the atmospheric pressure there is 0.333 atmospheres and ∆Hvap for water is 40.7 kJ/mol.

We can use the Clausius-Clapeyron equation to solve for the boiling point of water at this pressure. The equation is given by:ln(P2/P1) = (∆Hvap/R) * (1/T1 - 1/T2)

where:P1 = 1 atm (standard pressure)

P2 = 0.333 atm (pressure on the summit of Mt. Everest)

∆Hvap = 40.7 kJ/molR = 8.31 J/mol*K (universal gas constant)

T1 = 373 K (boiling point of water at standard pressure)

T2 = ? (boiling point of water at 0.333 atm pressure)

Solving for T2, we get:T2 = T1 * {∆Hvap/R * ln(P2/P1) + 1}T2 = 373 K * {40.7 kJ/mol / (8.31 J/mol*K) *

ln(0.333 atm / 1 atm) + 1}T2 = 373 K * {7.98}T2 = 2983.54 K

We can convert the boiling point of water at 0.333 atm pressure from Kelvin to Celsius by subtracting 273.15 from the result:T2 (in °C) = 2983.54 K - 273.15K = 2710.39 °C

Therefore, at the atmospheric pressure on the summit of Mt. Everest (0.333 atm), water boils at a temperature of approximately 2710.39 °C.

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The pair of aqueous solutions that will result in a precipitation reaction is (i) potassium carbonate and barium hydroxide. When these two solutions are mixed, they will react to form solid barium carbonate and aqueous potassium hydroxide. The balanced chemical equation for this reaction is:

K2CO3(aq) + Ba(OH)2(aq) → BaCO3(s) + 2KOH(aq)

The other two pairs of solutions, (ii) aluminum nitrate and sodium phosphate, and (iii) ammonium bromide and potassium hydroxide, will not result in a precipitation reaction. When these two solutions are mixed, they will form aqueous solutions of the resulting products.

It is important to remember that the solubility rules can be used to predict whether a precipitation reaction will occur when two aqueous solutions are mixed. If one of the products formed in the reaction is insoluble in water, then a solid precipitate will form.

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Answer:

When carbon is heated in air, it reacts with oxygen to form carbon dioxide. As the carbon reacts with oxygen to form carbon dioxide, the mass of the carbon decreases while the mass of the oxygen and carbon dioxide increases.

Answer:

When carbon is heated in air, it undergoes a process known as combustion or burning. During this process, carbon reacts with oxygen present in the air, resulting in the production of carbon dioxide gas. This reaction causes the carbon atoms to be lost in the form of carbon dioxide molecules. Hence, the original mass of carbon decreases due to the formation of lighter carbon dioxide molecules that are released into the atmosphere. Overall, the burning of carbon in air results in a reduction in its mass.

Charles's Law-

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\star\longrightarrow\sf \underline{\dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}}\\[/tex]

Where:-

As per question, we are given that -

We are given the initial temperature in °C.So, we first have to convert the temperature in Celsius to kelvin by adding 273-

[tex]\:\:\:\:\:\:\star\sf T_1[/tex] = 65+ 273 =338 K

Now that we have obtained all the required values, so we can put them into the formula and solve for T₂ :-

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\star\longrightarrow\sf \underline{\dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}}\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf \underline{\dfrac{T_2}{V_2}=\dfrac{T_1}{V_1}}\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf \underline{T_2=\dfrac{T_1}{V_1} \times V_2}\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf T_2=\dfrac{338}{3.75} \times 6.52\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf T_2=90.13333...... \times 6.52\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf T_2=587.669.........\:K\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf T_2=(587.67 -273)°C\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf T_2=314.66933…....\:°C\\[/tex]

[tex]\:\:\:\:\:\: \:\:\:\:\:\:\longrightarrow\sf \underline{T_2=314.67\:°C}\\[/tex]

Therefore, the temperature will change from 65°C to 314.67°C, when the volume of a gas is changed from 3.75 L to 6.52 L.

The correct answer is C, Percent ionization is the ratio of the concentration of the ionized acid at equilibrium to the initial acid concentration times 100%.

Ionization refers to the process by which an atom or molecule gains or loses one or more electrons, resulting in the formation of an ion. When an atom or molecule gains electrons, it becomes negatively charged and is called an anion, while losing electrons leads to a positively charged ion known as a cation.

Ionization can occur due to several reasons such as exposure to high-energy radiation or collision with other particles. It is a fundamental concept in understanding chemical reactions, particularly those involving acids and bases. For example, in an acid-base reaction, an acid donates a proton (H+) to a base, leading to the formation of a cation (H+) and an anion. Ionization also plays a critical role in numerous natural processes such as photosynthesis, atmospheric chemistry, and the behavior of metals in solution. I

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Complete Question:

which of the subsequent defines the percent ionization of a weak acid? pick the proper solution under:

A). percent ionization is the equilibrium regular for the ionization of a weak acid.

B). percent ionization is the ratio of the concentration of the undissociated acid at equilibrium to its initial awareness instances 100%.

C). percentage ionization is the ratio of the attention of the ionized acid at equilibrium to the initial acid attention times 100%.

D). not one of the above

The rate of an aromatic bromination reaction can be increased by adding a Lewis acid catalyst. The correct option is 1. "by adding a lewis acid catalyst."

A Lewis acid catalyst is a substance that can increase the rate of a reaction without being consumed in the reaction. A Lewis acid catalyst can act as an electron acceptor and facilitate the formation of the intermediate species, which leads to the product faster than the uncatalyzed reaction.

Placing the reaction in the dark may not necessarily increase the rate of an aromatic bromination reaction. Adding NaOH can actually decrease the rate of the reaction as it can neutralize the acid that forms during the reaction. Constantly stirring to keep the reaction well-mixed can also help increase the rate of the reaction by bringing the reactants into contact with each other more frequently.

The complete question is:

Besides increasing the temperature, how might the rate of an aromatic bromination reaction be increased?

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The concentration (M) of the hydroxide ion when 25ml of saturated  Ca(OH)₂ is titrated with 0.028 ml of HCl is  0.054 M.

The concentration of the hydroxide ions can be calculated using the following formula:

[OH⁻] = ([tex]V_{B}[/tex] × [tex]M_{B}[/tex])/ ([tex]V_{S}[/tex] × n)

where [tex]V_{B}[/tex] is the volume of HCl used, [tex]M_{B}[/tex] is the molarity of HCl, [tex]V_{S}[/tex] is the volume of Ca(OH)₂ solution used and n is the number of OH⁻ ions per molecule of Ca(OH)₂ which is 2.

Here, [.] denotes the concentration of an entitled ion or molecule.

The concentration of a chemical species, specifically a solute in a solution, is measured by its molarity. It is described as the quantity of solute in one liter of solution, expressed in moles. The letter M stands for molarity.

After substituting the values provided in the question, we get:

[OH⁻] = (38.1 ml × 0.028 M) / (25 ml × 2)

[OH⁻] = 0.054 M

Therefore, the concentration of hydroxide ion in the saturated Ca(OH)2 solution is 0.054 M.

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The mass of acetic acid in the solution is 0.30025 g. The mass percentage of acetic acid in the solution is 3.0025%.

(a) To find the mass of acetic acid in the solution, follow these steps:

Determine the moles of acetic acid:

Since 0.00500 moles of base were required for titration, it means that there are 0.00500 moles of acetic acid in the 10.0 ml sample (assuming a 1:1 reaction).

Calculate the mass of acetic acid:

Acetic acid (CH₃COOH) has a molecular weight of 12.01 (C) + 4.03 (4H) + 16.00 (2O) = 60.05 g/mol.

Multiply the moles of acetic acid by its molecular weight to find the mass is;

0.00500 moles × 60.05 g/mol = 0.30025 g.

So, the mass of acetic acid in the solution is 0.30025 g.

(b) To find the mass percentage of acetic acid in the solution, follow these steps:

Calculate the mass of the 10.0 ml solution:

Since the density is 1.0 g/ml, the mass of the solution is 10.0 ml × 1.0 g/ml = 10.0 g.

Calculate the mass percentage of acetic acid:

Divide the mass of acetic acid by the mass of the solution and multiply by 100:

(0.30025 g / 10.0 g) × 100 = 3.0025%.

So, the mass percentage of acetic acid in the solution is 3.0025%.

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To determine the number of water molecules that can be produced from a given set of reactants, we need to know the chemical equation for the reaction and the amounts of each reactant present.

For example, if we have the reaction:

2H2 + O2 → 2H2O

This indicates that two molecules of the gas hydrogen (H2) and one molecule of the gas oxygen (O2) combine to form two molecules of water.

If we have 4 molecules of hydrogen gas and 2 molecules of oxygen gas present, then we have enough reactants to produce 4 molecules of water. However, if we have only 3 molecules of hydrogen gas and 2 molecules of oxygen gas present, then we have enough oxygen to react with only 2 molecules of hydrogen gas, producing 2 molecules of water and leaving one molecule of hydrogen gas unreacted.

So the number of water molecules that can be produced depends on the stoichiometry of the reaction and the amounts of reactants present.

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The following are the predictions if whether each of the substances will conduct an electric current: a) Conducts b) Does not conduct c) Does not conduct hence the correct option is b.

a) Potassium hydroxide (KOH) is an ionic compound that dissolves in water to form potassium ions (K+) and hydroxide ions (OH-), which allows the solution to conduct an electric current.

b) Glucose (C6H12O6) is a covalent compound and does not dissociate into ions when dissolved in water, so the solution does not conduct an electric current.

c) Ethanol (C2H5OH) is also a covalent compound and does not dissociate into ions when dissolved in water, so the solution does not conduct an electric current.

The correct options are therefore a)conducts, b) does not conduct and c) does not conduct which corresponds to choice b.

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0.056 mol of H₂ gas occupies a volume of 1.26 L at 25°C and 1.11 atm pressure. To solve this problem we make use of the expression of ideal gas law equation.

The ideal gas law is an equation that relates the pressure, volume, temperature, and number of moles of an ideal gas. It is expressed mathematically as:

PV = nRT

where P = pressure,

V = volume,

n = the number of moles,

R = 0.0821 L·atm/mol·K, and

T = the temperature in Kelvin.

First, we need to convert the temperature of 25°C to Kelvin:

T = 25°C + 273.15 = 298.15 K

From ideal gas law:

(1.11 atm) V = (0.056 mol) (0.0821 L·atm/mol·K) (298.15 K)

Simplifying the equation, we get:

V = (0.056 mol) (0.0821 L·atm/mol·K) (298.15 K) / (1.11 atm)

V = 1.26 L

Therefore, 0.056 mol of H₂ gas occupies a volume of 1.26 L at 25°C and 1.11 atm pressure.

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Given: The concentration of lactic acid: [C₃H₆O₃] = 0.1 M

           The pH value of the solution: pH = 2.44

To calculate: Kₐ for lactic acid

The concentration of hydronium ions can be calculated by using the pH value.

[H₃O⁺] = 10⁻[tex]^{pH}[/tex]

           = 10[tex]^{-2.44}[/tex]

           = 0.00363 M

The ICE table for the dissociation of lactic acid is given:

Initial (M):          C₃H₆O₃ + H₂O ⇄ C₃H₅O₃⁻ + H₃O⁺

Change (M):          -x                          +x            +x

Equilibrium (M):    0.1M - x                 x            0.00363 M

From the ICE table at the equilibrium condition

x = [H₃O⁺] = [C₃H₅O₃⁻] = 0.00363 M

[C₃H₅O₃⁻] = 0.1 M - x

                = 0.1 M - 0.00363 M

                0.09637 M

The expression for Kₐ = [H₃O⁺] [C₃H₅O₃⁻] / [C₃H₆O₃]

On substituting the corresponding values in the equation,

Kₐ = 0.00363 M × 0.00363 M / 0.09637 M

     = 1.37 × 10⁻⁴

Hence the Kₐ for lactic acid is 1.37 × 10⁻⁴.

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Then the solution is supersaturated.

As per the question, if NaCl is soluble in water to the extent 36.0 g NaCl/100 g H2O at 20 °C, then a solution at 20°C containing 45 g NaCl/160 g H2O would be:

Supersaturated at 20°C

Explanation:

A solution is considered to be supersaturated if it contains more solute than what can dissolve in it at a particular temperature. It is, therefore, an unstable solution, and if any disturbance is provided, the excess solute starts to form crystals or precipitate. Thus, such a solution is capable of further dissolving the solute.

Suppose a solution of NaCl is considered, which is soluble in water to the extent of 36.0 g NaCl/100 g H2O at 20°C. This information helps in determining the solubility of NaCl at 20°C, which is 36.0 g NaCl/100 g H2O.Now, consider another solution that contains 45 g NaCl/160 g H2O at 20°C.

For determining whether the solution is saturated, unsaturated or supersaturated, compare the solubility of NaCl at 20°C to the given concentration of NaCl in the solution.The solubility of NaCl is 36.0 g NaCl/100 g H2O at 20°C, whereas the given concentration of NaCl in the solution is 45 g NaCl/160 g H2O. This concentration is higher than the solubility of NaCl.

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The concentration of reactants and products in a system is determined by the equilibrium constant.

When the statement "carbon monoxide binds to hemoglobin 140 times more strongly than oxygen does" is taken into account, what does this tell you about the equilibrium constants for the two reactions of hemoglobin with carbon monoxide and oxygen?

The answer is: the equilibrium constant for the binding of CO is greater.Carbon monoxide (CO) is a highly toxic gas that is often found in confined spaces such as garages, buildings, and mines.

The gas is odourless, colourless, and tasteless, making it difficult to detect without special instruments.When carbon monoxide binds to hemoglobin, it binds to the same sites as oxygen, but it does so about 200 times more tightly.

As a result, a small amount of CO binding to hemoglobin can have a significant impact on the oxygen-carrying capacity of the blood. The equilibrium constant for CO is greater than that for oxygen due to the fact that CO has a stronger affinity for hemoglobin than oxygen does.

Hemoglobin binds to oxygen with high affinity, and as a result, oxygen binds to hemoglobin more tightly than carbon monoxide does.

The formation of an equilibrium is a common occurrence when a reaction is reversible. An equilibrium constant, in simple terms, is a measure of the extent to which a reaction favours the formation of products over reactants.

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As an object falls, its potential energy is converted into kinetic energy. This is because the object is being pulled down by gravity, which increases its velocity and therefore its kinetic energy.

At the same time, the object is losing height and therefore potential energy. The amount of potential energy lost will be equal to the amount of kinetic energy gained, so the sum of the two energies will remain constant.

In other words, the potential energy will decrease in an amount equal to the increase in kinetic energy. This is known as the conservation of energy principle, which states that energy cannot be created or destroyed, only converted from one form to another.

As the object falls, the potential energy it had due to its position in the Earth's gravitational field is transformed into kinetic energy due to its motion. This relationship between potential and kinetic energy is important in understanding the behavior of falling objects and other systems where energy is conserved.

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The base dissociation (Kb) of the fluoride anion is 1.32 × 10⁻¹¹. The value indicates the strength of fluoride ions as a base. The lower the value of Kb, the weaker the base. The Kb of fluoride ions is quite small, indicating that it is a weak base.

To find the Kb of the fluoride anion, we need to use the relationship between the acid dissociation constant, Ka, and the base dissociation constant, Kb, for the conjugate acid-base pair.

The equation for this relationship is:

Ka x Kb = Kw

where Kw is the ion product constant for water, which is equal to 1.0 x 10⁻¹⁴ at 25°C.

In this case, the acid is HF and its conjugate base is F⁻ (fluoride). The student has determined that the Ka of HF is 7.6 x 10⁻⁴.

Therefore, we can use the above equation to solve for the Kb of F⁻:

Ka x Kb = Kw

Kb = Kw / Ka

Kb = 1.0 x 10⁻¹⁴ / 7.6 x 10⁻⁴

Kb = 1.32 x 10⁻¹¹

Therefore, the Kb of the fluoride anion is 1.32 x 10⁻¹¹.

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The position of the element in the periodic table influences the cation that it forms.

An ion is a particle that has either a positive or negative charge. Ions are formed by removing or adding electrons from/to an atom or molecule. They could be classified into two categories: cations and anions. Cations are positively charged ions that are formed when an atom loses one or more electrons.

Anions are negatively charged ions that are formed when an atom gains one or more electrons.The position of the element in the periodic table influences the cation that it forms. Because the number of valence electrons changes as we move through the periodic table from left to right or top to bottom, this is the case.

As a result, the chemical properties of the elements change as we move from left to right or top to bottom. This influences the type of cations that are formed because cations are formed by losing electrons. The most prevalent cations are those that result from the loss of one, two, or three electrons by an element. Cations such as H+, Na+, K+, and Ca2+ are formed by metals.

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The chemical potential of a pure liquid or solid equal to its standard state chemical potential at a given temperature simplifies the analysis of chemical equilibrium and allows you to focus on temperature effects, as changes in pressure have minimal impact on the equilibrium position for these substances.

It is reasonable to set the chemical potential of a pure liquid or solid substance equal to its standard state chemical potential at a given temperature, independent of the pressure when considering chemical equilibrium for the following reasons:

1. Minimal volume change: In the case of pure liquids and solids, the volume change during a reaction is typically very small. As a result, changes in pressure have little effect on the equilibrium position.

2. Incompressibility: Both liquids and solids are relatively incompressible compared to gases. This means that their volumes do not change significantly with changes in pressure.

3. Constant chemical potential: When the volume change is negligible, the chemical potential of a pure liquid or solid substance can be considered constant and equal to its standard state chemical potential at that temperature. This simplifies calculations when analyzing chemical equilibrium.

4. Focus on temperature effects: By setting the chemical potential equal to its standard state chemical potential, you can more easily focus on the effect of temperature on the equilibrium position. The temperature often has a more significant impact on the position of equilibrium than pressure, especially for reactions involving liquids and solids.

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To calculate the following for test tube 1 and test tube 2:

1. The number of moles of copper(II) sulfate used:

Test tube 1: 0.2 g of copper(II) sulfate was used, which is equivalent to 0.001255 moles (0.2 g / 159.60 g/mol).
Test tube 2: 0.4 g of copper(II) sulfate was used, which is equivalent to 0.002510 moles (0.4 g / 159.60 g/mol).

2. The heat absorbed by the water, in joules:

Test tube 1: Q = (10.0 g) x (4.186 J/g°C) x (20.0°C) = 837.2 J

Test tube 2: Q = (10.0 g) x (4.186 J/g°C) x (30.0°C) = 1257.9 J

3. The change in internal energy of the copper(II) sulfate:
Since the energy released by the copper(II) sulfate is absorbed by the water, the change in internal energy of the copper(II) sulfate is equal to the negative of the heat absorbed by the water.
Test tube 1: ΔU = -837.2 J
Test tube 2: ΔU = -1257.9 J
4. The reaction enthalpy, in joules/mole:
The reaction enthalpy can be calculated using the formula ΔH = ΔU + PΔV, where PΔV represents the work done by the system. Assuming that the reaction was carried out at constant pressure (i.e., atmospheric pressure), PΔV can be approximated to zero, and thus the reaction enthalpy is equal to the change in internal energy.
Test tube 1: ΔH = -837.2 J / 0.001255 mol = -666,876 J/mol
Test tube 2: ΔH = -1257.9 J / 0.002510 mol = -500,357 J/mol
Therefore, the results can be recorded in the following table:

|           | Moles of CuSO4 used | Heat absorbed by water (J) | Change in internal energy (J) | Reaction enthalpy (J/mol) |
|-----------|---------------------|-----------------------------|---------------------------------|---------------------------|
| Test tube 1 | 0.001255            | 837.2                       | -837.2                          | -666,876                 |
| Test tube 2 | 0.002510            | 1257.9                      | -1257.9                         | -500,357                 |

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[tex]\sf \underline{CuCl_2 +\pink{2NaNO_3} \longrightarrow \pink{ Cu(NO3)_2}+2NaCl}[/tex]

According to the equation, 1 mole of [tex]\sf CuCl_2 [/tex] reacts with 2 moles of [tex]\sf NaNO_3[/tex] to produce 1 mole of [tex]\sf Cu(NO_3)_2[/tex] and 2 moles of [tex]\sf NaCl [/tex]

Molar mass of [tex]\sf Cu(NO_3)_2[/tex] -

[tex] \:\:\:\:\:\:\longrightarrow \sf 63.5 + 2\times 14 + 16 \times 6 \\[/tex]

[tex] \:\:\:\:\:\:\longrightarrow \sf 187.5 \\[/tex]

The given statement {when solving for x in a Ka or Kb expression, the change in concentration (x) can be ignored if the error is less than 5% of the concentration of the acid or base.} is True.

The statement is true. When solving for x in a Ka or Kb expression, the change in concentration (x) can only be ignored if the error is less than 5% of the concentration of acid or base. This is because a change in concentration beyond 5% can lead to significant errors in the calculated pH value, which can lead to inaccurate results. Therefore, any changes in concentration (x) must be carefully considered and evaluated to ensure accurate results are obtained. So the answer is true.

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The mass of scheelite that contains a million oxygen atoms is 0.478 femtograms.

Scheelite is the calcium tungstate mineral, with the chemical formula CaWO₄. To calculate the mass of scheelite that contains a million oxygen atoms, we need to use the Avogadro's number to convert the number of atoms to the number of moles, and then use the molar mass of CaWO₄ to calculate the mass.

The molar mass of CaWO₄ can be calculated as follows;

Molar mass of CaWO₄ = (molar mass of Ca) + (molar mass of W) + 4 x (molar mass of O)

Molar mass of Ca = 40.08 g/mol

Molar mass of W = 183.84 g/mol

Molar mass of O = 16.00 g/mol

Molar mass of CaWO₄ = 40.08 g/mol + 183.84 g/mol + 4 x 16.00 g/mol

Molar mass of CaWO₄ = 287.94 g/mol

Now, we can use Avogadro's number to convert the number of oxygen atoms to moles;

1 mole of oxygen atoms = 6.022 x 10²³ oxygen atoms

1 million oxygen atoms = 1 x 10⁶ / 6.022 x 10²³ moles of oxygen atoms

1 million oxygen atoms = 1.661 x 10⁻¹⁸ moles of oxygen atoms

Since there is 1 oxygen atom in 1 molecule of CaWO₄, the number of moles of CaWO₄ is also 1.661 x 10⁻¹⁸ moles.

Finally, we can calculate the mass of CaWO₄ using its molar mass.

Mass of CaWO₄ = number of moles x molar mass

Mass of CaWO₄ = 1.661 x 10⁻¹⁸ moles x 287.94 g/mol

Mass of CaWO₄ = 4.78 x 10⁻¹⁶ g or 0.478 femtograms (fg)

Therefore, the mass of scheelite contains a million oxygen atoms is 0.478 femtograms.

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When the student repeated the experiment using hydrochloric acid with a higher concentration, the rate of the reaction between magnesium and hydrochloric acid increased.

This is because the higher concentration of hydrochloric acid provided more H+ ions, which increased the frequency of collisions between magnesium and the acid molecules, resulting in more successful collisions and a faster reaction rate.

The correct statement would be "The magnesium reacted more quickly". This is because the increase in acid concentration increases the reaction rate by increasing the number of collisions between the reactants.

Activation energy is a measure of the minimum energy required for a reaction to occur, and it is not affected by changes in the concentration of the reactants. The total volume of gas collected would not be smaller, as the amount of hydrogen gas produced is directly proportional to the amount of magnesium consumed and the reaction rate.

Therefore, the concentration of hydrochloric acid affects the rate of the reaction by increasing the frequency of successful collisions between the reactants.

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Beta-carotene expects to move farther on the TLC plate than Xanthophyll because of their relative polarities. More polar molecules tend to have stronger interactions with the chromatography plate and move less far than less polar molecules.

In a plant pigment chromatography experiment, the movement of a molecule on the chromatography plate depends on several factors, including the polarity of the solvent, the polarity of the molecule, and the affinity of the molecule to the chromatography plate.

Both xanthophyll and beta-carotene are non-polar molecules that are insoluble in water but soluble in organic solvents such as acetone or petroleum ether. However, xanthophyll is generally more polar than beta-carotene due to the presence of polar hydroxyl (-OH) or carbonyl (C=O) functional groups.

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The pH of the solution made by mixing 10.00 mL of 0.10 M acetic acid with 10.00 mL of 0.10 M KOH is 4.74.

To calculate the pH of the solution, we need to first determine the concentration of the remaining species in solution after the neutralization reaction between acetic acid and KOH is complete.

The balanced chemical equation for the neutralization reaction is:

CH3COOH + KOH → CH3COOK + H2O

The concentration of the potassium acetate can be calculated from the stoichiometry of the reaction:

moles of potassium acetate = moles of acetic acid = moles of KOH

moles of acetic acid = 0.10 mol/L × 0.0100 L = 0.0010

mol

moles of KOH = 0.10 mol/L × 0.0100 L = 0.0010 mol

moles of potassium acetate = 0.0010 mol

The volume of the final solution is 20.00 mL, so the concentration of the potassium acetate is:

[CH3COOK] = moles of potassium acetate / volume of solution

= 0.0010 mol / 0.0200 L

= 0.050 mol/L

The dissociation of potassium acetate can be written as:

CH3COOK ⇌ CH3COO- + K+

The equilibrium constant for this reaction is given by the expression:

Ka = [CH3COO-][H+]/[CH3COOH

At equilibrium, the concentration of CH3COOH is zero, so we can simplify this expression to:

Ka = [CH3COO-][H+]/[CH3COOK]

We know the value of Ka for acetic acid, which is 1.8 x

[tex] {10}^{ - 5} [/tex]

We can use this value to solve for the concentration of H+ in the solution:

1.8 x

[tex] {10}^{ - 5} [/tex]

= [H+][CH3COO-] / [CH3COOK]

To convert the concentration of H+ to pH, we use the expression:

pH = -log[H+]

= 4.74

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To make a pH 6.5 buffer, we need to choose a weak acid and its conjugate base with a pKa value close to 6.5. Looking at the given pKa values of H3A, we see that pKa2 is the closest to 6.5. Therefore, we should choose the conjugate acid-base pair Na2HA/NaHA.

To prepare the buffer, we would add a solution of Na2HA and NaOH to water and adjust the pH to 6.5 using a pH meter or pH indicator. The resulting solution will be a buffer with a pH of 6.5.

Now, let's move on to the second part of the question:

We are given 20.0 mL of 0.250 M NH4Cl and 30.0 mL of 0.250 M NH3 to prepare a buffer. The relevant equilibrium involved in this buffer is:

NH4+ + NH3 ⇌ NH3 + H+

From the given information, we can find the initial concentrations of NH4+ and NH3 in the buffer solution as:

[NH4+] = (0.250 mol/L) x (20.0 mL/1000 mL) = 0.0050 M

[NH3] = (0.250 mol/L) x (30.0 mL/1000 mL) = 0.0075 M

The equilibrium concentration of NH3 and H+ can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log([NH3]/[NH4+])

Substituting the given values:

pH = 9.25 + log(0.0075/0.0050) = 9.25 + 0.18 = 9.43

Therefore, the pH of the buffer is approximately 9.43.

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