which of the following mixtures would create a buffer solution? i. 50 ml of 0.5m hf 50 ml of 0.5m naf ii. 100 ml of 0.5m nh 3 50 ml of 0.5m nh 4 cl iii. 100 ml of 1.0m hcl 50 ml of 0.5m nh 3 iv. 100 ml of 1.0m naoh 50 ml of 0.5m hf a. i only b. ii only c. iii and iv d. i and ii only e. i, ii, and iii only

The substance tested is likely marijuana or related cannabis compounds if the Duquenois-Levine test turns purple.

In the event that the Duquenois-Levine arrangement becomes purple when added to an example, it recommends the presence of maryjane or other marijuana related substances.

The Duquenois-Levine test is a colorimetric test used to recognize the presence of weed in an example. It includes blending the example in with a progression of reagents, including Duquenois reagent and chloroform. Assuming the subsequent chloroform layer becomes purple, it proposes the presence of cannabinoids, which are the dynamic mixtures tracked down in cannabis.

It is essential to take note of that the Duquenois-Levine test isn't conclusive and can't be utilized to affirm the presence of maryjane all alone. All things considered, it is in many cases utilized as a fundamental screening test and might be circled back to other corroborative tests to give a more exact distinguishing proof.

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The main causes of the Grevy's zebra population decrease are habitat degradation, competition for resources with domestic livestock, and hunting for their skins and meat.

The main factor contributing to the decrease of Grevy's zebras in Ethiopia is hunting. Although their striking skins are the main reason they are hunted, they are also rarely slain for food and, in some areas, for medicinal purposes.

Zebras from Grevy's are in peril. Grevy's zebras have experienced one of the greatest range reductions of any African animal, and are now restricted to northern Kenya and southern and eastern Ethiopia. They are no longer residing in Somalia, Eritrea, Djibouti, and it's possible that they've left Sudan as well.

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1. The C in the first structure should have four total valence electrons. To complete its octet, it thus requires 4 extra electrons. The molecule should thus have 8 + 2 = 10 valence electrons overall, yet 14 valence electrons are present in this configuration. Thus, this is not the proper Lewis structure.

2. While both elements' octets are full in the second form, the total valence electron is incorrect. Total valence electrons should be =7+6+1=14, with 7 coming from the 7 valence electrons of a Cl atom, 6 from the 6 valence electrons of O, and 1 from the negative charge. Yet, there are a total of 8 + 4 = 12 electrons in the structure, where 8 is for 4 lone pairs of electrons and 4 is from the double bond. Thus, it is likewise an improper Lewis structure.

3. The valence electron count in the N2 molecule, the third structure, is accurate. The N atom, however, has not yet reached octet. There are 6 electrons in each N. The two N atoms do not thus have an octet arrangement. Thus, it is not a valid Lewis structure.

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If 10 ml of 0.05 m NaOH is introduced to a 20 ml solution of 0.1 m NaNO₂ and 0.1 m HNO₂, the pH of the resultant solution is 3.74.

The balanced chemical equation for the reaction between NaOH, NaNO₂, and HNO₂ is:

HNO₂ (aq) + OH⁻ (aq) → NO₂⁻ (aq) + H₂O (l)

Before any NaOH is added, the solution contains 20 mL of 0.1 M NaNO₂ and 0.1 M HNO₂. The HNO₂ is a weak acid, and its dissociation in water can be represented as follows:

HNO₂ (aq) + H₂O (l) ⇌ H₃O+ (aq) + NO₂⁻ (aq)

The acid dissociation constant (Ka) for HNO2 is 4.5 x 10⁻⁴ at 25°C.

Adding 10 mL of 0.05 M NaOH to the solution will result in the formation of 0.005 moles of OH-. The reaction between OH- and HNO₂ will consume some of the HNO₂ and form NO₂⁻ and H₂O. The amount of HNO₂ that reacts can be calculated using the balanced chemical equation:

1 mol HNO₂ reacts with 1 mol OH-

Therefore, the amount of HNO₂ that reacts is:

0.005 moles of OH- x (1 mol HNO₂ / 1 mol OH-) = 0.005 moles of HNO₂

The remaining amount of HNO₂ in the solution is:

Initial moles of HNO₂⁻ moles of HNO₂ that reacted = (0.1 mol/L x 0.020 L) - 0.005 mol = 0.002 mol

The amount of NO₂⁻ that forms is equal to the amount of HNO2 that reacted:

0.005 moles of HNO₂ = 0.005 moles of NO2-

The amount of H³O+ that forms can be calculated using the equilibrium constant expression for HNO₂:

Ka = [H³O+][NO₂⁻] / [HNO₂]

[H₃O⁺] = Ka x [HNO₂] / [NO₂⁻] = (4.5 x 10⁻⁴) x (0.002 mol) / (0.005 mol)

                                                = 0.00018 M

The pH of the solution can be calculated as:

pH = -log[H³O⁺] = ㏒(0.00018) = 3.74

As a result, the pH of the resulting solution is 3.74.

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In this case, since the unmarked beaker contained a strong base, we can expect its pH to be greater than 7.

.
To determine the pH of the unmarked beaker before adding the acid, we need to understand the pH scale. The pH scale ranges from 0 to 14, with a pH of 7 being neutral, below 7 being acidic, and above 7 being basic.
Since we know the solution in the unmarked beaker was a strong base, it is likely to have a high pH value.

Common strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH). The pH of these strong bases in a concentrated solution is typically between 12 and 14.
However, without additional information about the specific strong base and its concentration, it is impossible to give an exact pH value for the unmarked beaker.

In summary, we can conclude that the pH of the unmarked beaker before adding the acid was above 7, indicating a strong basic solution, but we would need more information to determine the exact pH value.

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The coefficient of h in the balanced chemical equation above is 2.

When the skeleton equation above is balanced and all coefficients reduced to their lowest whole-number terms, the coefficient for h is 2.What is a skeleton equation?

A skeleton equation is an equation in which the reactants and products are listed using their chemical formulas but not their stoichiometric coefficients. A balanced chemical equation is one in which the stoichiometric coefficients for reactants and products are included in such a way that the law of conservation of mass is fulfilled,

and the number of atoms of each element present in the reactants equals the number of atoms of that element present in the products.For instance, a typical chemical equation, which shows the chemical reactants and products, can be represented as:

2 NaOH (aq) + H2SO4 (aq) → Na2SO4 (aq) + 2 H2O

(l)Here, the reaction involves two moles of sodium hydroxide, one mole of sulfuric acid, one mole of sodium sulfate, and two moles of water. To balance this equation,

the coefficients should be added as:2 NaOH (aq) + H2SO4 (aq) → Na2SO4 (aq) + 2 H2O (l)The balanced chemical equation represents the actual stoichiometric ratios of reactants and products in the chemical reaction.

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Specific heat capacity is a property of a material that represents the amount of heat required to change the temperature of one kilogram of the substance by one degree Celsius.

It is expressed in units of joules per kilogram per degree Celsius (J/kg°C).To find the specific heat capacity of a sample, you should divide its heat capacity by its mass. This distinction is important because specific heat capacity allows for the comparison of different materials' abilities to store thermal energy.

For example, if you have two different materials with the same mass, the one with the higher specific heat capacity will require more energy to heat it up by the same temperature difference. This will provide you with the amount of energy required to change the temperature of one kilogram of the substance by one degree Celsius.

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the Clausius equation relates the change in entropy of a system to the heat flow and temperature at which the heat is transferred. This physical relationship reflects the fundamental principle that the entropy of a system tends to increase over time, and that heat flows spontaneously from hotter to cooler objects in order to achieve this increase in entropy.

The Clausius equation relates the change in entropy of a system to the heat flow and temperature at which the heat is transferred. It is given by:

ΔS = Qrev/T

where ΔS is the change in entropy of the system, Qrev is the amount of heat transferred reversibly between the system and its surroundings, and T is the temperature at which the heat is transferred.

To understand the physical basis of this equation, we need to consider the concept of entropy. Entropy is a measure of the disorder or randomness in a system. As a system evolves, it tends to move towards a state of maximum entropy, where its energy is spread out uniformly and there is no gradient or potential for further energy transfer. The second law of thermodynamics states that the entropy of an isolated system always increases over time, which implies that heat always flows spontaneously from hotter to cooler objects.

The Clausius equation relates this concept of entropy to the transfer of heat between a system and its surroundings. It tells us that the change in entropy of a system is proportional to the amount of heat transferred reversibly between the system and its surroundings, and inversely proportional to the temperature at which the heat is transferred. The term "reversible" refers to a process that can be reversed with infinitesimal changes to external conditions, so that the system and its surroundings return to their original states.

The physical relationship between the quantities in the Clausius equation can be understood as follows. The change in entropy of a system is related to the amount of heat transferred reversibly between the system and its surroundings, because heat flow is a key factor in determining the degree of disorder or randomness in a system. As heat flows from a hotter object to a cooler object, it tends to spread out and become more evenly distributed, which increases the entropy of the system. The temperature at which the heat is transferred is also important, because the higher the temperature, the greater the potential for heat to flow and increase the entropy of the system.

In summary, the Clausius equation relates the change in entropy of a system to the heat flow and temperature at which the heat is transferred. This physical relationship reflects the fundamental principle that the entropy of a system tends to increase over time, and that heat flows spontaneously from hotter to cooler objects in order to achieve this increase in entropy.
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For boric acid, with a pKa of approximately 9.24, the good buffering capacity occurs over the pH range of 8.24 to 10.24.

Boric acid is a weak acid often used as a buffering agent in contact lens solutions to resist pH changes. Its good buffering capacity is due to its ability to maintain a relatively constant pH level when small amounts of acids or bases are added to the solution. To understand the pH range over which boric acid has a good buffering capacity, we need to look at its acid dissociation constant (Ka) and the Henderson-Hasselbalch equation.

The Ka value for boric acid is approximately 5.8 x 10^-10. The pKa, which is the negative logarithm of the Ka, is calculated as follows:

pKa = -log(Ka) ≈ 9.24

The Henderson-Hasselbalch equation relates the pH, pKa, and the ratio of the concentrations of the conjugate base ([A-]) to the weak acid ([HA]) in a solution:

pH = pKa + log ([A-]/[HA])

A good buffering capacity is achieved when the pH of the solution is within one unit of the pKa value. This is because the ratio of the conjugate base to the weak acid ([A-]/[HA]) is near 1, meaning both the acid and its conjugate base are present in similar amounts, and the buffer can effectively neutralize added acids or bases.

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Answer:

Buffer solutions are essential in regulating blood acidity because they help maintain a stable pH level in the body. The pH of blood needs to be tightly controlled within a narrow range of 7.35 to 7.45 for optimal physiological functioning. Buffers work by absorbing excess hydrogen ions (H+) or hydroxide ions (OH-) that may be introduced into the bloodstream from various metabolic reactions. For example, if the blood becomes too acidic due to an increase in H+ ions, buffer systems such as the bicarbonate-carbonic acid system can neutralize the excess H+ ions and restore the pH balance. Conversely, if the blood becomes too alkaline due to an increase in OH- ions, buffer systems can absorb the excess OH- ions and bring the pH back to normal. In this way, buffer solutions help maintain the delicate acid-base balance crucial to the proper functioning of our bodies.

Answer:

7 km/hr

Explanation:

rate = distance / time

Rate: in km/hr

Distance: 14 km

Time: 2 hr

Rate = 14 km / 2 hr

Rate = 7 km/hr

2.56 x 10²² propane molecules must be burned with 6.82 grams of oxygen.

The following is the balanced equation for propane combustion:

[tex]C3H8 + O2 = 3CO2 + 4H2O[/tex]

Hence, we require 5 oxygen molecules for every molecule of propane.

We must multiply the quantity of propane molecules by the ratio of oxygen molecules to propane molecules in order to determine how many oxygen molecules are needed to burn 2.56 x 1022 propane molecules.

[tex]O2[/tex] to [tex]C3H8[/tex] Ratio: 5:1

The necessary number of O2 molecules is (5/1) times 2.56, which equals 1.28 x 10²³.

So, using the molar mass of oxygen, we can convert the quantity of oxygen molecules to grams.

1 mole of [tex]O2[/tex] = 32 g

1.28 x 10²³ molecules of O2 = (1.28 x 10²³/ 6.022 x 10²³) moles of O2

Mass of [tex]O2[/tex] = (1.28 x 10²³/ 6.022 x 10²³) x 32 g.

Mass of [tex]O2[/tex] = 6.82 grams.

Hence, 6.82 grams of [tex]O2[/tex] are required to burn 2.56 x 10²² propane molecules.

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A higher pH indicates a higher concentration of hydroxide in an aqueous solution containing a weak base. The correct answer is (A).

At much higher concentrations, acid A can be weaker than acid B, which is strong. As a result, A's pH is lower because it can still dissociate to produce more H+ in the solution.

pH is a proportion of how acidic/fundamental water is. The range is 0 to 14, with 7 representing neutrality. pH values below 7 indicate acidity, while pH values above 7 indicate a base. pH is a proportion of the overall measure of free hydrogen and hydroxyl particles in the water.

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Q- when looking at an aqueous solution of a weak acid, a lower ph corresponds to: select the correct answer below:

A. a higher concentration of hydronium

B. a lower concentration of hydronium

C. a higher concentration of hydroxide

D. a more dilute solution

The % by mass of aniline in the distillate is approximately 1.97%.

To find the % by mass of aniline in the distillate from a mixture of aniline and water steam distilled at normal atmospheric pressure with an initial temperature of 97.3°C and partial pressure of water at 745 mmHg, follow these steps:

Step 1: Determine the total pressure: Since normal atmospheric pressure is approximately 760 mmHg, the total pressure is 760 mmHg.

Step 2: Calculate the partial pressure of aniline: Subtract the partial pressure of water (745 mmHg) from the total pressure (760 mmHg) to get the partial pressure of aniline. Partial pressure of aniline = 760 mmHg - 745 mmHg = 15 mmHg.

Step 3: Find the mole fraction of aniline: Divide the partial pressure of aniline (15 mmHg) by the total pressure (760 mmHg) to get the mole fraction. Mole fraction of aniline = 15 mmHg / 760 mmHg = 0.0197368.

Step 4: Calculate the mass % of aniline in the distillate: The mole fraction represents the ratio of aniline to the total mixture. To find the mass %, multiply the mole fraction by 100. Mass % of aniline = 0.0197368 x 100 = 1.97368%.

So, the % by mass of aniline in the distillate is approximately 1.97%.

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If the initial concentration of that potassium fluoride in water is 0.251 m, then The pH of the mixture is roughly 9.61.

Potassium fluoride is an ionic compound that dissociates into potassium cations [tex](K^+)[/tex] and fluoride anions [tex](F^-)[/tex] when it is dissolved in water. The dissociation equation is:

[tex]KF(s)[/tex] → [tex]K^+(aq) + F^-(aq)[/tex]

The equilibrium constant for this dissociation reaction is denoted by [tex]K_{sp}[/tex], and its value depends on the temperature of the solution.

At 298 K, the value of [tex]K_{sp}[/tex] for potassium fluoride is approximately [tex]1.76 * 10^{-10}[/tex]. This means that only a small fraction of the potassium fluoride molecules will dissociate into ions in water, and the majority of the molecules will remain in their undissociated form.

To calculate the pH of the solution, we need to consider the effect of the fluoride ions on the acidity of the water. Fluoride ions are weak bases that can react with water molecules to form hydrofluoric acid (HF) and hydroxide ions (OH-):

[tex]F^-(aq) + H_2O(l)[/tex] ⇌ [tex]HF(aq) + OH^-(aq)[/tex]

The equilibrium constant for this reaction is denoted by [tex]K_b[/tex] and its value is [tex]3.5 * 10^{-11}[/tex] at 298 K.

To determine the pH of the solution, we need to find the concentration of hydroxide ions in the solution. This can be calculated from the concentration of fluoride ions using the [tex]K_b[/tex] value and the equilibrium constant expression:

[tex]K_b = \frac{[HF][OH^-]}{[F^-]}[/tex]

⇒ [tex][{OH}^-] = K_b * \frac{[F^-]}{[HF]}[/tex]

The concentration of hydrofluoric acid can be calculated from the concentration of fluoride ions using the dissociation constant for HF, which is denoted by Ka and has a value of [tex]7.2 * 10^{-4}[/tex] at 298 K.

[tex]K_a = \frac{[H^+][F^-]}{[HF]}[/tex]

⇒ [tex][H^+] = K_a * \frac{[HF]}{[F^-]}[/tex]

Substituting the given values, we get:

[tex][F^-] = 0.251 M[/tex]

[tex]K_b = 3.5 * 10^{-11}[/tex]

[tex]K_a = 7.2 * 10^{-4}[/tex]

[tex][HF] = \frac{[F^-] * K_a}{[H^+]}[/tex]

⇒ [tex][H^+] = \frac{[F^-] * K_a}{[HF]}[/tex]

⇒ [tex][H^+] = \frac{[F^-] * K_a}{(\frac{[F^-] * K_a}{[H^+]})}[/tex]

⇒ [tex][H^+] = \frac{(K_b * [F^-])}{[HF]}[/tex]

⇒ [tex][H^+] = \frac{(3.5 * 10^{-11}) * (0.251)}{(\frac{[F^-] * K_a}{[HF]})}[/tex]

⇒ [tex][H^+] = 2.45 * 10^{-10} M[/tex]

[tex]pH = -log[H^+][/tex]

⇒ [tex]pH = -log(2.45 * 10^{-10})[/tex]

⇒ [tex]pH = 9.61[/tex]

Therefore, the pH of the solution is approximately 9.61.

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The rate constant is the quantity that describes the connection between the molar concentration of the reactants and the rate of the chemical reaction.

If the reaction is occurring throughout the volume of the solution, [A] and [B] are the molar concentrations of substances A and B in moles per unit volume of solution and the reaction rate constant varies on temperature.

The rate constant is denoted by the letter k.

Given data, BOD₆ = 213 mg/l

ultimate BOD = 318.4 MG/l = L

Assume temperature = 20° C

and t = 6 day

k = ?

BOD = L(1- [tex]e^{-kt}[/tex])

213 = 318.4 (1-[tex]e^{-k*6}[/tex])

[tex]e^{-k6}[/tex] = 0.331

Taking logs on both sides

-k*6 = -1.105

k = 0.1842 d⁻¹

≈ 0.184⁻²/day

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When silver nitrate and sodium chloride are combined with water, silver chloride will solidify and precipitate out of solution. In this instance, silver chloride is the precipitate.

Precipitation includes the following: rain, hail, sleet, and snow. Rain forms when water vapour in clouds condenses on dust particles, which eventually grow too big to stay in the cloud and fall to the ground, where they collect more water and enlarge further.

The chemical reaction between potassium chloride and silver nitrate, in which solid silver chloride precipitated out, is among the greatest examples of precipitation reactions. This precipitation reaction resulted in the formation of an insoluble salt.

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The concentration of the conjugate base at the equivalence point after the initial neutralization is 0.152 M. Then the answer is 0.152 M.

When titrating an acid with a base, we can determine the concentration of the conjugate base at the equivalence point using the equation MaVa = MbVb. So in order to reach the equivalence point in their titration, Sonni needed to add 19.42 ml of KOH to 20.00 ml of 0.309 M HF.

What is the concentration of the conjugate base at the equivalence point after the initial neutralization?SolutionWe can start by writing the balanced chemical equation for the reaction between KOH and HF:HF + KOH → KF + H2OSince the equation is balanced,

we can say that 1 mole of HF reacts with 1 mole of KOH to produce 1 mole of KF and 1 mole of H2O. Therefore, the moles of KOH added to the solution is equal to the moles of HF present initially:

moles of KOH = Molarity × Volume in liters

= 0.309 M × (19.42 / 1000) L

= 0.006007 Mmoles of HF

= Molarity × Volume in liters

= 0.309 M × (20.00 / 1000) L

= 0.00618 MSince the moles of KOH added is slightly less than the moles of HF present initially, the solution is still acidic, and there is still some HF remaining after the initial neutralization. At the equivalence point, all of the HF has reacted with KOH,

and the solution contains only KF and water. So, we can use the balanced chemical equation to calculate the number of moles of KF produced when all of the HF has reacted with KOH.

Number of moles of KF = 0.006007 mol

HF + KOH → KF + H2O1 mole HF produces 1 mole KF;

therefore, 0.006007 moles HF will produce 0.006007 moles of KF. The volume of the solution at the equivalence point is 19.42 ml + 20.00 ml = 39.42 ml = 0.03942 L.

Therefore, the concentration of KF at the equivalence point is:Concentration of KF = (0.006007 mol) / (0.03942 L)= 0.152 MFinally, we know that KF is the conjugate base of HF,  

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The boiling point of the 3.6 molal solution of ethylene glycol in benzene is 89.208 ºC.

What is Boiling Point?

Boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure, usually atmospheric pressure. At the boiling point, bubbles of vapor are formed throughout the liquid, and the liquid changes phase to become a gas.

The boiling point elevation of a solution is given by the formula:

ΔTb = Kb x molality

Where ΔTb is the boiling point elevation, Kb is the ebullioscopic constant of the solvent, and molality is the molal concentration of the solute.

For benzene, Kb = 2.53 ºC/m.

Since the molality of the ethylene glycol solution is 3.6 molal, we can calculate the boiling point elevation as:

ΔTb = 2.53 ºC/m x 3.6 molal = 9.108 ºC

This means that the boiling point of the solution is 9.108 ºC higher than the boiling point of pure benzene.

To find the boiling point of the solution, we need to add this value to the boiling point of pure benzene, which is 80.1 ºC. Therefore:

Boiling point of solution = 80.1 ºC + 9.108 ºC = 89.208 ºC

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Being non-polar molecules, acetone and pentane interact by London dispersion forces. Option a is correct.

Both acetone and pentane are non-polar molecules and interact through London dispersion forces, which are the weakest type of intermolecular force and arise from temporary dipoles induced in the molecules.

Neither acetone nor pentane has a hydrogen atom bonded to a highly electronegative atom, which is necessary for hydrogen bonding. Ion-induced dipole interactions arise between an ion and a non-polar molecule, but neither acetone nor pentane is an ion. Dipole-dipole interactions occur between polar molecules, but acetone is a polar molecule and pentane is non-polar, so they cannot interact through this type of force. Hence option a is correct.

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--The complete question is, How acetone and pentane interact.
Choose one or more: a. london dispersion b. hydrogen bonding c. ion-induced dipole d. dipole-dipole--

When a 0.005 mol HCl is added to the buffer solution containing 0.500 mol HF and 0.500 mol KF, it will use up one of the components and destroy the buffer solution.

A buffer solution is a chemical mixture that resists changes in pH by neutralizing small amounts of added acids or bases. It contains a weak acid and its conjugate base or a weak base and its conjugate acid.

Buffer solutions are necessary for many chemical processes since pH changes can dramatically affect the behavior of chemical compounds.

Buffer solutions can be prepared using a wide range of chemical compounds, and the exact composition of the solution is determined by the desired pH range and the concentration of the buffer components.

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The molarity of a solution made by dissolving 51.6 grams of NaCl in enough water to make 650 ml of solution  is approximately 1.36 M

The molarity of a solution can be calculated using the formula:

Molarity (M) = (moles of solute) / (volume of solution in liters)

First, we need to convert the mass of NaCl (51.6 grams) to moles. To do this, we'll use the molar mass of NaCl, which is approximately 58.44 g/mol.

Moles of NaCl = (51.6 grams) / (58.44 g/mol) = 0.883 moles

Next, we'll convert the volume of the solution from milliliters (mL) to liters (L).

Volume of solution = 650 mL * (1 L / 1000 mL) = 0.65 L

Now, we can calculate the molarity of the solution using the formula.

Molarity (M) = (0.883 moles) / (0.65 L) = 1.36 M

Thus, the molarity of the solution made by dissolving 51.6 grams of NaCl in enough water to make 650 mL of solution is approximately 1.36 M (rounded to two decimal places).

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Explanation:

1. Count each type of atom in reactants and products. ...

2. Place coefficients, as needed, in front of the symbols or formulas to increase the number of atoms or molecules of the substances. ...

3. Repeat steps 1 and 2 until the equation is balanced.

The rate constant is 3.0 x [tex]10^{4} M^{-1} S^{-1}[/tex] which is calculated by using the  Arrhenius equation.

We can use the Arrhenius equation to find [tex](E_{a} / R)[/tex][([tex](1/ T_{2} ) - ( 1/ T_{1} )[/tex]] separately,

We have, Activation energy, [tex]E_{a}[/tex] = 30.0 kJ/mole = 30000 J/mole

R = 8.314 J/mole .K

Temperature T2 = 201.0C = 201.0 + 273 = 474 K

T1 = 172 C = 172 + 273 = 445 K

Hence,

{ [tex](E_{a} / R)[/tex][([tex](1/ T_{2} ) - ( 1/ T_{1} )[/tex] } = (30000/8.314) x [(1/474) – (1/445)]

[tex](E_{a} / R)[/tex][([tex](1/ T_{2} ) - ( 1/ T_{1} )[/tex] =  – 0.4961

Let us use this value and Rate constant  [tex]K_{2}[/tex] = 5.0 x 104[tex]M^{-1} S^{-1}[/tex] and have to solve it for [tex]K_{1}[/tex]

[tex]K_{1}[/tex] / (5.0 x 104) = e –0.4961.

[tex]K_{1}[/tex] / (5.0 x 104) = 0.6089

[tex]K_{1}[/tex] =  5.0 x 104 x 0.6089

[tex]K_{1}[/tex] = 3.0 x [tex]10^{4} M^{-1} S^{-1}[/tex]

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The complete question is,

The rate constant of a certain reaction is known to obey the Arrhenius equation, and to have an activation energy is 30.0 kJ/mole. if the rate constant of this reaction is at  5.0 x 104[tex]M^{-1} S^{-1}[/tex], what will the rate constant be at  172 C? round your answer to significant digits.

The distance travelled by the chromatogram substance divided by the solvent front's travel distance yields the Rf (retention factor) value. Hence, the sample's Rf value is close to 0.7.

It is a dimensionless quantity that aids in the identification and description of substances separated by chromatography. A different technique that may be used to determine if a material is pure or impure is paper chromatography. Moreover, it may be used to separate mixtures of soluble chemicals in order to identify the components of the mixture.

They are frequently coloured materials like food colouring, ink, dye, or plant pigments. The Rf value in this situation may be determined using the formula below: Rf is equal to the sum of the distances covered by the substance front and the solvent front.

Rf = 4.2 cm ÷ 6.0 cm

Rf ≈ 0.7

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Explanation:

As heat is added to melt the solid, the motion of the particles increases. This is because the heat energy increases the kinetic energy of the particles, causing them to vibrate more and move faster. Eventually, the increased motion overcomes the forces holding the particles together in a solid lattice structure, and the solid melts into a liquid.

Answer:

Answer and Explanation: Vapor pressure has an inverse relationship with intermolecular forces. This means that the stronger the intermolecular forces are, the lower the vapor pressure is.

Answer:

Explanation:

The intermolecular forces in carbon dioxide are weak, so its vapor pressure is relatively high.

We need 1.08 mL of NaOH solution to reach a pH of 7.10.

To solve this problem, we need to use the balanced chemical equation for the neutralization reaction between phosphoric acid (H₃PO₄) and potassium hydroxide (KOH); H₃PO₄ + 3KOH → K₃PO₄ + 3H₂O

From the equation, we can see that one mole of H₃PO₄ reacts with three moles of KOH. Therefore, the number of moles of KOH required to neutralize 0.149 moles of H₃PO₄ is;

n(KOH) = 3 × n(H₃PO₄) = 3 × 0.149 mol = 0.447 mol

Next, we need to calculate the volume of 1.250 M KOH solution that contains 0.447 mol of KOH;

V(KOH) = n(KOH) / C(KOH) = 0.447 mol / 1.250 mol/L

= 0.358 L = 358 mL

So, 358 mL of 1.250 M KOH solution is required to neutralize the 0.149 moles of H₃PO₄.

Now, to reach a pH of 7.10, we need to add a strong base such as NaOH to the solution until the pH reaches the desired value. Since NaOH is a strong base, it will react completely with the remaining H₃PO₄ to form water and sodium phosphate (Na₃PO₄)

H₃PO₄ + 3NaOH → Na₃PO₄ + 3H₂O

To calculate the volume of NaOH solution required to reach a pH of 7.10, we need to know the initial pH of the solution. Assuming that the solution is initially acidic, we can use the Henderson-Hasselbalch equation to calculate the initial pH;

pH = pKa + log([A]/[HA])

where pKa is the dissociation constant of H₃PO₄, [A] is the concentration of the conjugate base (H₂PO₄⁻), and [HA] is the concentration of the acid (H₃PO₄).

The pKa values for phosphoric acid are;

pKa₁ = 2.148

pKa₂ = 7.198

pKa₃ = 12.319

Since we are assuming that the solution is initially acidic, we can use the first dissociation constant (pKa1 = 2.148) to calculate the concentration of H₂PO₄⁻;

[H₂PO₄⁻] = [A] = K × [HA] / (K + [HA])

where K is the equilibrium constant for the dissociation of H₃PO₄:

K = [H⁺][H₂PO₄⁻] / [H₃PO₄]

At a pH of 7.10, [H⁺] = [tex]10^{-7.10}[/tex] = 7.94 × 10⁻⁸ M. Substituting this value into the equation for K and solving for [H₂PO₄⁻], we get:

K = 7.94 × 10⁻⁸ × [H₂PO₄⁻] / 0.149 M

[H₂PO₄⁻] = (K × 0.149 M) / 7.94 × 10⁻⁸

[H₂PO₄⁻] = 2.81 × 10⁻⁵ M

Now we can use the Henderson-Hasselbalch equation to calculate the initial pH:

pH = pKa₁ + log([A]/[HA])

= 2.148 + log(2.81 × 10⁻⁵ / 0.149)

= 1.08

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

"A solution made with 0.149 moles of phosporic acid (H₃PO₄) dissolved in 159mL of solution was titrated with 1.250 M KOH . How many mL of NaOH solution are necessary to reach a pH of 7.10?"--

The correct answer is 8. To determine the number of hydrogen atoms (H) in (NH4)2CO3, we need to count the number of H atoms in each of the constituent ions and then multiply by the number of ions present in the formula.

The (NH4)2CO3 formula contains two ammonium ions (NH4+) and one carbonate ion (CO32-). Each ammonium ion contains four hydrogen atoms, while the carbonate ion contains no hydrogen atoms.

Therefore, the total number of hydrogen atoms in (NH4)2CO3 is:

2 ammonium ions x 4 hydrogen atoms per ammonium ion = 8 hydrogen atoms

Thus, the correct answer is 8.

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Kinetic molecular theory states that there is no attractive and repulsive force between the gas molecules. So option (3) is false.

According to the kinetic molecular theory the gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant which is in random motion. This theory states that the energy that an object has because of its motion. The Kinetic Molecular Theory can be explained as the forces between molecules and the energy that they possess. This is explained as a theoretical model which describes the molecular composition of the gas in terms of a large number of submicroscopic particles that includes atoms and molecules. This states that the gas pressure arises due to particles colliding with each other and the walls of the container.

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The complete question is,

Which of the following statements about the kinetic-molecular theory of gases is false?

1. the average kinetic energy of a gas molecule is independent of the temperature.

2. collisions between molecules are elastic.

3. Attractive and repulsive forces are present between gas molecule.