When a compound is dissolved in hot ethanol during a recrystallization, what is changing on a molecular level? The intermolecular forces between the solute and solvent The covalent bonds of the solute The compound slowly melts into the hot solvent The covalent bonds between the solute and solvent

Answers

Answer 1

Answer:

The intermolecular forces between the solute and solvent.

Explanation:

When you are heating a solvent, the intermolecular forces are reduced because the distances between molecules are large. Thus, in a solution where solvent is hot the intermolecular forces between solute and solvent are lower than those solutions where solvent is in room temperature.

The covalent bonds do not change because this mean a chemical reaction that doesn't occur in a solution.

Usually solid solutes melts in a higher temperature than boiling point in solvents. Thus, a compound normally doesn't melt in a hot solvent.

I hope it helps!

Answer 2
Final answer:

When a compound is dissolved in hot ethanol during recrystallization, the intermolecular forces between the solute and solvent are changing on a molecular level. The process of solution formation involves the formation of new intermolecular forces between the solute and solvent molecules, allowing the compound to dissolve in the solvent.

Explanation:

Intermolecular forces are attractive or repulsive forces between molecules. They include London dispersion forces, dipole-dipole interactions, and hydrogen bonding. These forces influence physical properties like boiling points and solubility in molecular substances. The intermolecular forces between the solute and solvent are changing on a molecular level when a compound is dissolved in hot ethanol during recrystallization.

When the compound is dissolved in the hot solvent, the solute-solvent interactions which is also known as solvatio then naturally takes place. In addition to this, these interactions involve the formation of new intermolecular forces between the solute and solvent molecules, which are nearly as strong as the intermolecular forces within the solute and solvent alone. This favorable solution formation process allows the compound to dissolve in the solvent.


Related Questions


A student dissolved 1.805g of a monoacidic weak base in 55mL of water. Calculate the equilibrium pH for the weak monoacidic base (B) solution. Show all your work.

pKb for the weak base = 4.82.

Molar mass of the weak base = 82.0343g/mole.

Note: pKa = -logKa

pKb = -logKb

pH + pOH = 14

[H+ ] [OH- ] = 10^-14

Answers

Answer:

11.39

Explanation:

Given that:

[tex]pK_{b}=4.82[/tex]

[tex]K_{b}=10^{-4.82}=1.5136\times 10^{-5}[/tex]

Given that:

Mass = 1.805 g

Molar mass = 82.0343 g/mol

The formula for the calculation of moles is shown below:

[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]

Thus,

[tex]Moles= \frac{1.805\ g}{82.0343\ g/mol}[/tex]

[tex]Moles= 0.022\ moles[/tex]

Given Volume = 55 mL = 0.055 L ( 1 mL = 0.001 L)

[tex]Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}[/tex]

[tex]Molarity=\frac{0.022}{0.055}[/tex]

Concentration = 0.4 M

Consider the ICE take for the dissociation of the base as:

                                  B +   H₂O    ⇄     BH⁺ +        OH⁻

At t=0                        0.4                          -              -

At t =equilibrium     (0.4-x)                        x           x            

The expression for dissociation constant is:

[tex]K_{b}=\frac {\left [ BH^{+} \right ]\left [ {OH}^- \right ]}{[B]}[/tex]

[tex]1.5136\times 10^{-5}=\frac {x^2}{0.4-x}[/tex]

x is very small, so (0.4 - x) ≅ 0.4

Solving for x, we get:

x = 2.4606×10⁻³  M

pOH = -log[OH⁻] = -log(2.4606×10⁻³) = 2.61

pH = 14 - pOH = 14 - 2.61 = 11.39

According to the following thermochemical equation, if 951.1 g of NO 2 is produced, how much heat is released at constant pressure? 2NO(g) + O2(g) 2NO 2(g); DH -114.4 kJ

Answers

Answer:

The amount of released is 1,182 kJ.

Explanation:

When heat is released at constant pressure, this change in energy is known as enthalpy (ΔH°) of the reaction. Enthalpy is an extensive property, so it depends on the amount of reacting material. Let's take a look at the provided equation:

2 NO(g) + O₂ ⇄ 2 NO₂(g)   ΔH° = -114.4 kJ

Since this equation is balanced with 2 moles of NO₂(g), we can say that 114.4 kJ are released every 2 moles of NO₂(g) produced. By convention, when enthalpies are negative, it means that energy is released and the reaction is exothermic. Conversely, positive enthalpies mean energy is absorbed and the reaction is endothermic.

We can calculate the amount of energy released taking into account the previous relationship (-114.4 kJ/2 moles of NO₂(g)), the mass of NO₂(g) produced (951.1g) and its molar mass (46.00g/mol). The calculations would be:

[tex]951.1g.\frac{1molNO_{2} }{46.00g} .\frac{-114.4kJ}{2molesNO_{2} } =-1,182kJ[/tex]

The amount of heat released at constant pressure when 951.1 g of [tex]NO_2[/tex] is produced is approximately -544.5 kJ.

The molar mass of [tex]NO_2[/tex] can be calculated from its molecular weight:

Nitrogen (N) has an atomic mass of approximately 14.01 g/mol,

Oxygen (O) has an atomic mass of approximately 16.00 g/mol.

Thus, the molar mass of [tex]NO_2[/tex] is:

[tex]\[ \text{Molar mass of NO}_2 = 14.01 \text{ g/mol} + 2 \times 16.00 \text{ g/mol} = 46.01 \text{ g/mol} \][/tex]

Now, we can calculate the number of moles of [tex]NO_2[/tex] produced:

[tex]\[ \text{moles of NO}_2 = \frac{\text{mass of NO}_2}{\text{molar mass of NO}_2} = \frac{951.1 \text{ g}}{46.01 \text{ g/mol}} \approx 20.67 \text{ mol} \][/tex]

The thermochemical equation given is:

[tex]\[ 2\text{NO}(g) + \text{O}_2(g) \rightarrow 2\text{NO}_2(g); \quad \Delta H = -114.4 \text{ kJ} \][/tex]

This equation tells us that 2 moles of NO2 are produced for every -114.4 kJ of heat released at constant pressure. Therefore, the heat released for the production of 20.67 moles of NO2 is:

[tex]\[ \text{Heat released} = \text{moles of NO}_2 \times \frac{-114.4 \text{ kJ}}{2 \text{ mol}} \][/tex]

[tex]\[ \text{Heat released} = 20.67 \text{ mol} \times \frac{-114.4 \text{ kJ}}{2 \text{ mol}} \approx -544.5 \text{ kJ} \][/tex]

a For each of the salts on the left, match the salts on the right that can be compared directly, using Ksp values, to estimate solubilities. (If more than one salt on the right can be directly compared, include all the relevant salts by writing your answer as a string of characters without punctuation, e.g, ABC.)

1. silver iodide ___ [need answer here]

2. manganese(II) hydroxide ___ [need answer here]

A. Fe(OH)2

B. CaSO3

C. NiCO3

D. Ba3(PO4)2

Write the expression for K in terms of the solubility, s, for each salt, when dissolved in water.

silver iodide Ksp = ___ [need answer here]

manganese(II) hydroxide Ksp = ___ [need answer here]

Note: Multiply out any number and put it first in the Ksp expression. Combine all exponents for s.

Answers

Answer:

a.

silver iodide BC

manganese(II) hydroxide A

b.

silver iodide Ksp = S²

manganese(II) hydroxide Ksp = 4S³

Explanation:

Ksp (Solubility products) are the equilibrium constants for poorly soluble compounds. As every equilibrium constant, it is formed by the product of the products raised to their stoichiometric coefficients divided by the product of reactants raised to their stoichiometric coefficients. We only include in the constant gases and aqueous species. So, to solve this task, we need to write each reaction and its Ksp.

1. Silver Iodide

AgI(s) ⇄ Ag⁺(aq) + I⁻(aq)

When AgI is put in water, the concentration of Ag⁺ and I⁻ that actually dissolve is known as solubility (S). So the concentration of both Ag⁺ and I⁻ would be S.

AgI(s) ⇄ Ag⁺(aq) + I⁻(aq)

                 S             S

We can replace this in the Ksp expression:

Ksp = [Ag⁺].[I⁻] = S.S = S²

We can follow the same steps to find out the relationship between Ksp and S for each compound.

2. Mn(OH)₂(s) ⇄ Mn²⁺(aq) + 2OH⁻(aq)

                                S             2S

In this case, the concentration of OH⁻ is 2S because 2 moles are produced along with 1 mole of Mn²⁺.

Ksp = [Mn²⁺].[OH⁻]² = S.(2S)² = 4S³

A. Fe(OH)₂(s) ⇄ Fe²⁺(aq) + 2OH⁻(aq)

                              S              2S

Ksp = [Fe²⁺].[OH⁻]² = S.(2S)² = 4S³

B. CaSO₃(s) ⇄ Ca²⁺(aq) + SO₃²⁻(aq)

                             S              S

Ksp = [Ca²⁺].[SO₃²⁻] = S.S = S²

C. NiCO₃(s) ⇄  Ni²⁺(aq) + CO₃²⁻(aq)

                            S              S

Ksp = [Ni²⁺].[CO₃²⁻] = S.S = S²              

D. Ba₃(PO₄)₂(s) ⇄ 3 Ba²⁺(aq) + 2 PO₄³⁻(aq)

                                   3S              2S

Ksp = [Ba²⁺]³.[PO₄³⁻]²= (3S)³.(2S)²= 108S⁵

a. The salts that can be compared using the same Ksp expressions are:

silver iodide BC

manganese(II) hydroxide A

b.

silver iodide Ksp = S²

manganese(II) hydroxide Ksp = 4S³

Final answer:

None of the listed salts can be compared to silver iodide using Ksp values. Manganese(II) hydroxide can be compared to Fe(OH)2. The Ksp expressions in terms of solubility, s, are s^2 for silver iodide and 4s^3 for manganese(II) hydroxide.

Explanation:

We can directly compare salts by considering their solubility product constants, or Ksp values

. 1. Silver iodide: No salts on the right share the same ions with silver iodide, so none can be directly compared.
2. Manganese(II) hydroxide: It contains Mn2+ and OH- ions. Thus, it can be compared to the Fe(OH)2 salt which contains Fe2+ and OH- ions, making the matching answer A.

For the solubility expressions for each salt, when Multiplied we put the number first and then combine all exponents:

For silver iodide (AgI), the equilibrium is AgI ↔ Ag+ + I-, so the Ksp expression is Ksp = s x s = s^2.

For manganese(II) hydroxide (Mn(OH)2), the equilibrium is Mn(OH)2 ↔ Mn2+ + 2OH-, so the Ksp expression is Ksp = 4s^3.

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Liquid water boiling in an open pan on a stove is our system. Is the system open or closed? What boundary transfers are happening? Is the system at steady state?

Answers

Answer:

It's an open system, tranfering heat through a rigid, diathermal wall and matter through an imaginary and permeable wall, and it is not at steady state.

Explanation:

An open system is that that interacts with its surroundings exchanging energy and matter. In an open pan with boiling water you have an open system because steam (matter) is leaving the system, as well as heat (energy) through the pan/stove. A boundary is what separates the system from its surroundings, there are many types of boundaries, based on how they transfer energy they can be diathermal (conducting heat) or adiabatic (insulating), on their rigidity they can be rigid, flexible, imaginary or movable and based on their permeability. For the system described we have an imaginary boundary on top that is also permeable allowing matter to go out or in the system, and another wall (the stove/pan itself that is rigid and impermeable avoiding the loss of matter and diathermal, allowing the conduction of heat. It is said that a system is at a steady state when the variables that define that system remain constant over time. In an open pan, you can't fully control those variables, you'll have matter and energy scaping from it with no way to regulate it.

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The diffusion flux is defined as: a) Mass, per unit surface area, per unit time b) Surface area, per unit time c) Time, per unit surface area. d) The product of time and surface area, per unit mass

Answers

Answer:

The correct answer is option a.

Explanation:

Diffusion flux is defined as movement of mas of atoms diffusing through the unit area in per unit time.It measured in ([tex]kg/m^2 s[/tex]).

[tex]J=\frac{1}{A}\frac{dM}{dt}[/tex]

J = diffusion flux

A = Unit area A through which atoms moves.

M = mass of atoms passes in t interval of time.

Final answer:

Diffusion flux is the mass of gas passing through a unit surface area per unit time, influenced by the concentration gradient, surface area, and particle travel distance.

Explanation:

The diffusion flux can be defined as the amount of gas passing through a given area over a unit of time. Therefore, the correct answer is a) Mass, per unit surface area, per unit time. The rate of diffusion is dictated by several factors such as the concentration gradient, the surface area available for diffusion, and the distance the gas particles must travel. In addition, it's important to note that the time required for diffusion is inversely proportional to the diffusion rate.

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out of 2.00 50 mL of water is added to 30 mL of a 0.50 M salt solution. What is the new concentration? (To write your answer using scientific notation use 1.0E-1 instead of 1.0 x 10-1)

Answers

Answer:

The concentration of the new solution will be 0.31 M

Explanation:

The number of moles per liter of the solution is 0.50 mol. Then, in 50 ml there will be:

50 ml · (0.50 mol / 1000 ml) = 0.025 mol.

If we add 30 ml and assuming that the solution is an ideal solution, the final volume will be 80 ml.

Then, 0.025 mol will be present in 80 ml solution. In 1 l there will be:

1000 ml · (0.025 mol / 80 ml) = 0.31 mol.

The concentration of the new solution will be 0.31 M.

An aluminum atom has a mass of 4.48 * 10-23 g and a small airplane has a mass of 5000 kg. Use this information to answer the questions below. Be sure your answers have the correct number of significant digits.

(a) What is the mass of 1 mole of aluminum atoms?
(b) How many moles of aluminum atoms have a mass equal to the mass of a small airplane?

Answers

Explanation:

(a)   According to the mole concept, 1 mole of an atom contains [tex]6.022 \times 10^{23}[/tex] atoms.

Hence, number of atoms present in [tex]4.48 \times 10^{-23}[/tex] g will be as follows.

                 [tex]4.48 \times 10^{-23} \times 6.022 \times 10^{23}[/tex]

                 = 26.97 g

or,              = 27 g

This means that 1 mole of aluminium atoms contain 27 g.

(b)     Mass of air plane is 5000 kg of [tex]5000 \times 1000 g[/tex] (as 1 kg = 1000 g).

As mass of 1 mole aluminium is calculated as 27 g and mass of air plane is given as 5000000 g.

Therefore, calculate the number of moles of aluminium atoms as follws.

               No. of moles of Al atoms = [tex]\frac{\text{mass of small air plane}}{\text{mass of 1 mol Aluminium}}[/tex]

                                             = [tex]\frac{5000000g}{27 g}[/tex]

                                              = 185185.18

So, the answer in three significant digits will be 185000 moles of aluminum atoms have a mass equal to the mass of a small airplane.

The study of chemicals and bonds is called chemistry. There are two types of elements and these are metals and nonmetals.

The correct answer is described below

What are moles?The mole is the base unit of the amount of substance in the International System of Units. It is defined as exactly 6.02214076×10²³ elementary entities, which may be atoms, molecules, ions, or electrons

According to the question, the answer of the first question is:-

The number of atoms will be:-

[tex]4.48*10^{-23}*6.022*10^{23}\\\\=26.97[/tex]

The correct answer is 27

The answer to the second question is as follows:-

The mass of the air is [tex]5000*1000g[/tex]. hence, As the mass of 1-mole aluminum is calculated as 27 g and mass of airplane is given as 5000000 g.

No moles will be

:- [tex]\frac{500000}{27} \\\\=185185.18[/tex]

Hence, the correct answer is mentioned above.

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What is the molar concentration of chloride ions in a
solutionprepared by mixing 100mL of 2.0 M KCL with 50 L of a 1.5
MCaCl2 solution?

Answers

Answer:

The concentration of chloride ions in the final solution is 3 M.

Explanation:

The number of moles present in a solution can be calculated as follows:

number of moles = concentration in molarity * volume

In 100 ml of a 2 M KCl solution, there will be (0.1 l * 2mol/l) 0.2 mol Cl⁻

For every mol of CaCl₂, there are 2 moles of Cl⁻, then, the number of moles of Cl⁻ in 50 l of a 1.5 M solution will be:

number of moles of Cl⁻ = 2 * number of moles of  CaCl₂

number of moles of Cl⁻ = 2 ( 50 l * 1.5 mol / l ) = 150 mol Cl⁻

The total number of moles of Cl⁻ present in the solution will be (150 mol + 0.2 mol ) 150.2 mol.

Assuming ideal behavior, the volume of the final solution will be ( 50 l + 0.1 l) 50.1 l. The molar concentration of chloride ions will be:

Concentration = number of moles of Cl⁻ / volume

Concentration = 150.2 mol / 50.1 l = 3.0 M

Final answer:

To find the molar concentration of chloride ions in the solution, calculate the moles of chloride ions in each solution and add them together, then divide by the total volume of the final solution.

Explanation:

To determine the molar concentration of chloride ions in the solution, we need to calculate the number of moles of chloride ions and divide it by the total volume of the solution.

First, calculate the moles of chloride ions in KCl solution:

Moles of chloride ions = molarity of KCl solution * volume of KCl solution

Next, calculate the moles of chloride ions in CaCl2 solution:

Moles of chloride ions = (molarity of CaCl2 solution * volume of CaCl2 solution) * 2 (since CaCl2 has 2 chloride ions per formula unit)

After finding the moles of chloride ions in each solution, add them together and divide by the total volume of the final solution to get the molar concentration of chloride ions.

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Glucose is a carbohydrate that contains carbon, hydrogen, and oxygen. The empirical formula of glucose is CH2O and its molar mass is 180.12 g/mol. Find the molecular formula of glucose.

Answers

Answer: The molecular formula of glucose is [tex]C_6H_{12}O_6[/tex]

Explanation:

We are given:

Empirical formula of the compound = [tex]CH_2O[/tex]

Empirical mass of the compound = [tex][(1\times 12)+(2\times 1)+(1\times 16)]=30g/mol[/tex]

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

[tex]n=\frac{\text{Molecular mass}}{\text{Empirical mass}}[/tex]

We are given:

Mass of molecular formula = 180.12 g/mol

Mass of empirical formula = 30 g/mol

Putting values in above equation, we get:

[tex]n=\frac{180.12g/mol}{30g/mol}=6[/tex]

Multiplying this valency by the subscript of every element of empirical formula, we get:

[tex]C_{(1\times 6)}H_{(2\times 6)}O_{(1\times 6)}=C_6H_{12}O_6[/tex]

Hence, the molecular formula of glucose is [tex]C_6H_{12}O_6[/tex]

How many cubic centimeters are there in 200 milliliters?

Answers

Answer:

200 mL = 200 cm³

Explanation:

The relationship between cm³ and mL is 1:1.

1 cm³ = 1 mL

Thus, 200 mL is converted to cm³ as follows:

(200 mL)(1 cm³/1 mL) = 200 cm³

An unstable isotope that naturally decays CAN emit which of the following? Choose all correct responses, there are at least two. {Hint: probably are more than two}

Question options:

A) Alpha particle

B) Beta particle

c) Radiation

D) Positron

E) Gamma rays

F) Visible light

Answers

Answer: Isotopes are the species which have same number of protons but differs in the number of neutrons. Or in other words isotopes have same atomic number but different mass number. Isotopes are generally unstable and decays to an stable isotope. When the isotope is unstable it releases energy in the form of radiations. It emits alpha particle, gamma rays, and beta particles.

Therefore, the correct option is (A),(B) and (C)

If atom X has an atomic mass of 12, and atom Y has an atomic mass of 1, what would be the mass of 4.18 moles of the compound X7Y11, in grams? Please report your answer to the nearest whole gram.

Answers

Answer:

397 g

Explanation:

From the information given in the question ,

the atomic mass of X = 12 ,

and , the atomic mass of Y = 1 .

For the molecular formula , X₇Y₁₁ , the molecular mass is given as -

X₇Y₁₁ = 7 * atomic mass of X  +  11 *  atomic mass of Y

         = 7 * 12 + 11 * 1

         = 84 + 11  = 95 g / mol

Hence , molecular mass of X₇Y₁₁ = 95 g / mol .

Moles is denoted by given mass divided by the molecular mass ,

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

From question ,

moles n = 4.18 mol

and ,

m = molecular mass of X₇Y₁₁ = 95 g / mol .

To find the mass of the compound X₇Y₁₁   , the above formula can be used , and putting the respective values ,

n = w / m  

4.18 = w / 95

w = 4.18 * 95 = 397 g

Compute 4.62 x 4.48697. Round the answer appropriately. Express your answer numerically using the proper number of sian

Answers

Answer:

20.7

Explanation:

20.7298014 rounded off to 3 sig fig =20.7

what is the osmotic pressure of a .25 M solution of NaCl at 25 degrees Celsius?

Answers

Answer:

6.113 atm

Explanation:

Data provided in the question:

Molarity of the solution = 0.25 M

Temperature, T = 25° C = 25 + 273 = 298 K

Now,

Osmotic pressure (π) is given as:

π = MRT

where,

M is the molarity of the solution

R is the ideal gas constant = 0.082057 L atm mol⁻¹K⁻¹

on substituting the respective values, we get

π = 0.25 × 0.082057 × 298

or

π = 6.113 atm

For the following reaction, 101 grams of magnesium nitride are allowed to react with 144 grams of water. Mg3N2 (5) + 6 H20 (1) — 3 Mg(OH)2 (aq) + 2 NH2 (aq) What is the FORMULA for the limiting reagent? What is the maximum amount of magnesium hydroxide that can be formed? grams What amount of the excess reagent remains after the reaction is complete? grams Submit Answer Retry Entire Group 8 more group attempts remaining

Answers

Answer : The formula of limiting reagent is, [tex]Mg_3N_2[/tex].

The mass of [tex]Mg(OH)_2[/tex] is, 174 grams.

The mass of excess reactant is, 36 grams.

Solution : Given,

Mass of [tex]Mg_3N_2[/tex] = 101 g

Mass of [tex]H_2O[/tex] = 144 g

Molar mass of [tex]Mg_3N_2[/tex] = 101 g/mole

Molar mass of [tex]H_2O[/tex] = 18 g/mole

Molar mass of [tex]Mg(OH)_2[/tex] = 58 g/mole

First we have to calculate the moles of [tex]Mg_3N_2[/tex] and [tex]H_2O[/tex].

[tex]\text{ Moles of }Mg_3N_2=\frac{\text{ Mass of }Mg_3N_2}{\text{ Molar mass of }Mg_3N_2}=\frac{101g}{101g/mole}=1moles[/tex]

[tex]\text{ Moles of }H_2O=\frac{\text{ Mass of }H_2O}{\text{ Molar mass of }H_2O}=\frac{144g}{18g/mole}=8moles[/tex]

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

[tex]Mg_3N_2+6H_2O\rightarrow 3Mg(OH)_2+2NH_3[/tex]

From the balanced reaction we conclude that

As, 1 mole of [tex]Mg_3N_2[/tex] react with 6 mole of [tex]H_2O[/tex]

So, given 1 moles of [tex]Mg_3N_2[/tex] react with 6 moles of [tex]H_2O[/tex]

From this we conclude that, [tex]H_2O[/tex] is an excess reagent because the given moles are greater than the required moles and [tex]Mg_3N_2[/tex] is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of [tex]Mg(OH)_2[/tex]

From the reaction, we conclude that

As, 1 mole of [tex]Mg_3N_2[/tex] react to give 3 mole of [tex]Mg(OH)_2[/tex]

So, given 1 mole of [tex]Mg_3N_2[/tex] react to give 3 moles of [tex]Mg(OH)_2[/tex]

Now we have to calculate the mass of [tex]Mg(OH)_2[/tex]

[tex]\text{ Mass of }Mg(OH)_2=\text{ Moles of }Mg(OH)_2\times \text{ Molar mass of }Mg(OH)_2[/tex]

[tex]\text{ Mass of }Mg(OH)_2=(3moles)\times (58g/mole)=174g[/tex]

The mass of [tex]Mg(OH)_2[/tex] is, 174 grams.

Now we have to calculate the moles of excess reactant [tex](H_2O)[/tex].

Moles of excess reactant = 8 - 6 = 2 moles

Now we have to calculate the mass of excess reactant.

[tex]\text{ Mass of }H_2O=\text{ Moles of }H_2O\times \text{ Molar mass of }H_2O[/tex]

[tex]\text{ Mass of }H_2O=(2moles)\times (18g/mole)=36g[/tex]

The mass of excess reactant is, 36 grams.

Which form of bond between two carbons is capable of rotation without breaking the bond? * single bond double bond triple bond

Answers

Answer:

single bond

Explanation:

Single bond is the chemical bond in which 2 valence electrons are involved. These are the sigma bond which are formed formed by the head-on overlapping between the orbitals of the two atoms involving in the bond. The bond lies on the inter nuclear axis and thus , the bond can be rotated without the breaking of bond.

On the other hand, double and triple bonds contains one sigma bond and also bonds which are formed by the sideways overlapping of the orbitals and thus, these do not lie on inter nuclear axis and breaks on rotation.

If the molality of a NaBr(aq) solution is 2.50 m, what is the weight percent of NaBr? The molar mass of NaBr is 1029 g/mol 20.5% 25.0% 25.7% 34.6% 65.4% ent Navigator J K L

Answers

Answer:

The weight percent of NaBr is 25,7%

Explanation:

Molality is a way to express the concentration of a chemical in terms of moles of substances per kg of solution. Weight percent is other way to express concentration in terms of mass of substance per mass of solution per 100

Thus, to obtain weight percent you must convert moles of NaBr to grams with molar mass and these grams to kilograms, thus:

2,50 mol / kg solution × (102,9 g / 1mol) × (1 kg / 1000 g) =

[tex]\frac{0,257 kg NaBr}{kg solution }[/tex] × 100 = 25,7 % (w/w)

I hope it helps!

Oil with density of 0.8505 and velocity of 4m/s in a pipe that has a downward slope of 1:50 (sine). At a certain point in the pipe, a pressure gauge shows a pressure of 80kPa.
Determine the pressure at a point 200m downstream of the gauge if:
(a) The flow losses are ignored (ideal case);
(b) There is a flow loss equal to 10% of the total initial head.

Answers

Answer:

(a) Pressure at point 200 m downstream: 113.4 kPa

(b) Pressure at point 200 m downstream: 105.4 kPa

Explanation:

The point of reference, that will be named Point A, is the pressure gage.

The point 200 m downstream will be named Point B.

With a slope of 1:50, the height difference between A and B is (1/50)*200=4m.

(a) In the case there is no friction losses, we can write

[tex]p_a+\frac{\rho V^2}{2} +\rho*g*h_a=p_b+\frac{\rho V^2}{2} +\rho*g*h_b[/tex]

Because ther is no change in the diameter of the pipe, V=constant.

Rearranging

[tex]p_a+\rho*g*h_a=p_b+\rho*g*h_b\\\\\Delta p = \rho * g * \Delta h\\\\\Delta p = 0.8505 * 1000\frac{kg}{m^3} *9.81\frac{m}{s^2}*4 m\\\\ \Delta p = 33.373.62 kg/(m*s^2)=33.373.62 Pa=33.4 kPa[/tex]

Then we have an increase in of 33.4 kPa, and pressure in Point B (downstream) is:

[tex]p_b=p_a+\Delta p = 80 kPa + 33.4 kPa = 113.4 kPa[/tex]

(b) If we consider 10% of the total initial head as friction loss, we have

[tex]p_a+\rho*g*h_a=p_b+hf +\rho*g*h_b\\\\hf=0.1*p_a\\\\\Delta P = \rho*g*\Delta h-0.1*p_a\\\\\Delta P = 0.8505*1000 kg/m^3*9.81m/s2*4m-0.1*80kPa\\\\\Delta P = 33.4kPa-8kPa=25.4kPa[/tex]

In this case the rise in pressure is 25.4 kPa, due to the friction losses.

The pressure at point B is

[tex]p_b=p_a+\Delta p = 80 kPa + 25.4 kPa = 105.4 kPa[/tex]

Solve for t In(A/B) -kt where B-1.65 x 102 M A 1.00 x 10 M. k-4.80 x 104s* and t=

Answers

Answer:

[tex]t=5.84\times 10^{-5}s[/tex]

Explanation:

First rearrange the whole equation by keeping t in one side and rest parameters in another side of equationThen plug-in all the given values for each parameters and get the solution

[tex]ln(\frac{A}{B})=-kt[/tex]

or, [tex]t=\frac{1}{-k}\times ln(\frac{A}{B})[/tex]

Now plug-in all given values:

[tex]t=\frac{1}{-4.80\times 10^{4}s^{-1}}\times ln(\frac{1.00\times 10M}{1.65\times 10^{2}M})[/tex]

So, [tex]t=5.84\times 10^{-5}s[/tex]

Mass transfer rate in convection is ..... mass transfer in conduction
a) more than
b) less than
c) equal to
d) no relation to

Answers

Answer:

(a) more than

Explanation:

Conduction:

Transfer of heat due to direct contact between two mediums at different temperatures, without having any of the bodies traveling. Therefore, conduction heat transfer occurs by the transfer of momentum (molecular) from always the same group of molecules in one medium to another group of molecules in another medium.

Example: Heat transfer INSIDE a solid.

Convention:

Transfer of heat or mass due to at least one traveling medium, where the transfer of momentum is not bounded anymore to the same groups of molecules. Molecules moving to transfer their momentum and keep flowing to the next group, also allowing other molecules behind to do the same. Example: heat transfer by the wind.

Hence, the Mass transfer rate in convection is more than mass transfer in conduction

Final answer:

The mass transfer rate in convection is generally more than (option a) that in conduction due to the macroscopic movement of mass that facilitates faster heat transfer.

Explanation:

The question asks to compare the mass transfer rate in convection to the mass transfer rate in conduction. The correct comparison is that the mass transfer rate in convection is generally more than the mass transfer rate in conduction. This is because conduction is the process by which heat is directly transmitted through a substance when there is a difference of temperature, without movement of the material. In contrast, convection involves the movement of mass (typically a fluid such as air or water) which contributes to a faster transfer of heat. An empirical equation for the rate of heat transfer by forced convection can be represented by Q/t = hA(T₂ – T₁), showing that this rate is dependent on the temperature difference (T₂ – T₁), contact surface area (A), and the convective heat transfer coefficient (h).

Write dissociation equations for the following soluble salts dissolving in water. Then draw a particle - level representation for each (omit water molecules). (a) NaBr (b) ZnCl2

Answers

Answer:

The dissociation equations for NaBr gives Na+ and Br-

The dissociation equations for ZnCl2 gives Zn2+ and 2 Cl-  

Explanation:

The following pictures shows that the dissociation of one particle of NaBr produces one particle of Na+ (sodium cation) and one particle of Br- (bromine anion).

The dissociation of one particle of ZnCl2 produces one particle of Zn+2 (Zinc cation) and two particles of Cl- (chlorine anion).

Which of the following is a definition of an acid? O a. releases heat when dissolved in water. O b. turns cloudy when dissolved in water. O c. donates OH-ions when dissolved in water O d. donates H ions when dissolved in water.

Answers

Answer: Option (d) is the correct answer.

Explanation:

According to Bronsted-Lowry an acid is defined as the specie which is able to donate hydrogen ions when dissolved in water.

For example, [tex]HCl \rightarrow H^{+} + Cl^{-}[/tex]

On the other hand, bases are the species which are able to donate hydroxide ions when dissolved in water.

For example, [tex]NaOH \rightarrow Na^{+} + OH^{-}[/tex]

Thus, we can conclude that a definition of an acid is that it donates H ions when dissolved in water.

Steve holds the world record for the 100-meter dash. At his fastest, Bolt ran 100 meters in 9.58 seconds. Convert his speed into miles per hour. Report your answer using 3 significant figures.

Conversion factors: 1 mile = 1609 meters 60 seconds = 1 minute 60 minutes = 1 hour

Use appropriate Sig Figs in answer!

Answers

Answer:

23.4 mph

Explanation:

The conversion factors are multiplied so that the units cancel out:

(100 meters / 9.58 sec) x (1 mile / 1609 meters) x (60 sec / min) x (60 min /1 hr) = 23.4 mph

How much CrCl3 • 6H20 is needed to prepare 1 L of solution containing 20.0g Cr3+ per L?

Answers

Answer:

salt mass=102.5gCrCl3.6H2O

Explanation:

Hello !

To know how much CrCl3.6H2O we need, we follow the steps below

First we have to know what the mass of the compound is

Cr = 52g / mol

Cl = 35.5g / mol

H = 1g / mol

O = 16g / mol

We calculate the mass

52+ (35.5 * 3) + 6 * (2 * 1 + 16) = 266.5g

We have 20g Cr, so we calculate the amount of salt:

20gCr * (266.5g salt / 52gCr) = 102.5gCrCl3.6H2O

salt mass=102.5gCrCl3.6H2O

Calculate the pressure, in atmospheres, required to compress a sample of helium gas from 27.3 L (at 1.00 atm) to 3.36 L at constant temperature. Enter your answer in the box provided. atm

Answers

Answer:

8.125 atm

Explanation:

Hello,

Boyle's law states that at constant temperature:

[tex]P_1V_1=P_2V_2[/tex]

In this case:

[tex]P_1=1 atm, V_1=27.3L, V_2=3.36L[/tex]

Solving for [tex]P_2[/tex]:

[tex]P_2=\frac{P_1V_1}{V_2}=\frac{1atm*27.3L}{3.36L}\\P_2=8.125atm[/tex]

Best regards!

The quantity of energy released or absorbed as heat during a chemical reaction is called the 28. a. temperature. c. entropy d. free energy enthalpy of reaction.

Answers

Answer: enthalpy of reaction.

Explanation:

Temperature of the gas is defined as the degree of hotness or coldness of a body. It is expressed in units like [tex]^0C[/tex] and [tex]K[/tex]

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

Free energy is the amount of energy that can be converted into useful work.

Enthalpy of the reaction is the difference between the energy of products and the energy of reactants. it is either the heat released or absorbed during the reaction. It is either positive or negative.

Why is it important to have an energy balance on a chemical process facility

Answers

Final answer:

The importance of an energy balance in a chemical process facility lies in ensuring efficient energy use, maintaining safety, optimizing chemical processes for increased yield, and reducing environmental impact.

Explanation:

An energy balance is crucial in a chemical process facility because it ensures the efficient use of energy, minimizes waste, and helps maintain the safety of the operation. Since energy is neither created nor destroyed (law of conservation of energy), it's important to know where energy is being consumed and produced within chemical processes. This understanding allows engineers to optimize the process, increase the yield of the desired product, and reduce environmental impact by minimizing wasted energy and reducing unwanted by-products.

An energy balance aids in maintaining the operation within the desired range of conditions, preventing unsafe levels of energy which could lead to accidents. Moreover, certain reactions require specific amounts of energy to produce raw materials or to synthesize products, and tracking energy use is essential for economic and environmental reasons.

Calculate the heat of reaction for the combustion of one mole of benzene molecules (CH) at 25 (Given the AHE: (CO()] = -393.5 kJ/mol, (H.0(0)] = -285.8 kJ/mol, (CH(B)] = 82.6 kl/mol)

Answers

Answer:

ΔHf = 3301 kJ/mol

Explanation:

The standard enthalpy of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states.

In a reaction ΔHf = ∑ n ΔHproducts - ∑ n ΔHreagents

Where n are moles

For the reaction:

1 C₆H₆ + 7.5 O₂ → 6 CO₂ + 3 H₂O

The ΔHf = -285,8 kJ/mol × 3 - 393,5 kJ/mol×6 - [82,6 kJ/mol×1 -0kJ/mol×7,5]

ΔHf = 3301 kJ/mol

I hope it helps!

Determine the molarity of a 6.0 mole% sulfuric acid solution with SG-a 1.07 Note: Atomic Weight: S (32), O 16); H (O)

Answers

Answer:

The molarity of a 6.0 mole% sulfuric acid solution is 2.8157 Molar.

Explanation:

Suppose there are 100 moles in solution:

Moles of sulfuric acid = 6% of 100 moles = 6 moles

Mass of 6 moles of sulfuric acid = 6 mol × 98 g/mol=588 g

Moles of water = 100%- 6% = 94%= 94 moles

Mass of water = 94 mol × 18 g/mol = 1692 g

Specific gravity of the solution ,S.G= 1.07

Density of solution = D

[tex]S.G=\frac{D}{d_w}[/tex]

[tex]d_w[/tex] = density of water = 1 g/mL

[tex]D=S.G\times d_w=1.07\times 1 g/mL=1.07 g/mL[/tex]

Mass of the solution = 588 g + 1692 g = 2280 g

Volume of the solution = V

Volume = [tex]\frac{Mass}{Density}[/tex]

[tex]=\frac{2280 g}{1.07 g/mL}=2130.84 mL=2.13084 L[/tex]

1 mL = 0.001 L

[tex]Molarity = \frac{n}{V(L)}[/tex]

n = number of moles of compound

V = volume of the solution in L

here we have ,n = 6 moles of sulfuric acid

V = 2.13084 L

So, the molarity of the solution is :

[tex]Molarity=\frac{6 mol}{2.13084 L}=2.8157 mol/L[/tex]

The airspeed velocity of an unladen swallow is 10.00 meters per second. What is it in miles per hour? You must use appropriate significant figures to receive full credit (3 pts) 1 in = 2.54 cm, 100 cm = 1m, 12 in =1ft, 5280 ft = 1 mile, 60 s = 1 min, 60 min = 1 hour

Answers

Answer : The  speed in miles per hour is 22 mile/hr.

Explanation :

The conversion used from meters to miles is:

[tex]1m=100cm\times \frac{1in}{2.54cm}\times \frac{1ft}{12in}\times \frac{1mile}{5280ft}[/tex]

The conversion used from second to hour is:

[tex]1s=\frac{1}{60}min\times \frac{1hr}{60min}[/tex]

The conversion used from meter per second to mile per hour is:

[tex]1\frac{m}{s}=\frac{100cm\times \frac{1in}{2.54cm}\times \frac{1ft}{12in}\times \frac{1mile}{5280ft}}{\frac{1}{60}min\times \frac{1hr}{60min}}[/tex]

[tex]1m/s=2.2mile/hr[/tex]

As we are given the speed 10.00 meter per second. Now we have to determine the speed in miles per hour.

As, [tex]1m/s=2.2mile/hr[/tex]

So, [tex]10.00m/s=\frac{10.00m/s}{1m/s}\times 2.2mile/hr=22mile/hr[/tex]

Therefore, the speed in miles per hour is 22 mile/hr.

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