90 POINTSSSS!!!
Step 3: Determine the amount of energy change in the reaction. a) Use the table of enthalpy values (Table A) provided in the Student Worksheet to locate the enthalpy of formation (∆Hf) for each reactant and each product. Record these values along with the reactants and products in Table B of the Student Worksheet. b) Determine the total enthalpy of the reactants and the total enthalpy of the products. Record these values in Table C of the Student Worksheet. c) Use the following formula to find the net change in enthalpy for the reaction and to determine whether the reaction is endothermic or exothermic.

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Answer:

The answer is Electronegativity increases up and to the right

Explanation:

When you move from left to right it increases ( in the periodic table )

But when you move down the table electronegativity decreases.

So “ Electronegativity increases up and to the right” describes the trends the best.

Hope this helps! :)

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Answer:

D. Use x-ray radiation to see if there are any fractured bones.

Explanation:

The football player may have fractured a bone while he was practicing or playing, so it is best for the doctor to check if the player broke his bone or fractured it.

Answer:

62.12kJ/mol

Explanation:

The neutralization reaction of HCl and NaOH is:

HCl + NaOH → NaCl + H₂O + HEAT

You can find the released heat of the reaction and heat of neutralization (Released heat per mole of reaction) using the formula:

Q = C×m×ΔT

Where Q is heat, C specific heat of the solution (4.06J/gºC), m its mass and ΔT change in temperature (27.5ºC-20.0ºC = 7.5ºC).

The mass of the solution can be finded with the volume of the solution (50.0mL of HCl solution + 50.0mL of NaOH solution = 100.0mL) and its density (1.02g/mL), thus:

100.0mL × (1.02g / mL) = 102g of solution.

Replacing, heat produced in the reaction was:

Q = C×m×ΔT

Q = 4.06J/gºC×102g×7.5ºC

Q = 3106J = 3.106kJ of heat are released.

There are 50.0mL ×1M = 50.0mmoles = 0.0500 moles of HCl and NaOH that are reacting releasing 3.106kJ of heat. That means heat of neutralization is:

3.106kJ / 0.0500mol of reaction =

Answer:

Explanation:

water then

The heat lose by aluminum = The heat gain by the water.

Q₁=Q₂

Where,

Q = m ×s× ΔT

m= mass of an object

s= specific heat of the

Answer: The answer is Strontium(Sr) i.e there are 38 electrons in this electronic configuration.

How To Find: You should count the number of electrons in each orbitals.

For example:

Answer:

Explanation:

⁵⁹₂₆Fe --------- ⁰₋₁e + ⁵⁹₂₇Co

Co- 59 is known as Cobalt

its symbol is ⁵⁹₂₇Co

The name of the product is Cobalt-59 and the symbol of the nuclide is [tex]^{59}Co_{27}[/tex].

It is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide.

When the nuclide iron-59 undergoes beta decay it will lead to the formation of cobalt-59. The reaction can be represented as:

[tex]^{59}Fe_{26} --> ^0e_{-1} + ^{59}Co_{27}\\[/tex]

Thus, The name of the product is Cobalt-59 and the symbol of the nuclide is [tex]^{59}Co_{27}[/tex].

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Answer:

.5 L

Explanation:

- Start with the Ideal Gas Law. This equation will be P1V1T2=P2V2T1

- Next, take out temperature because that is not given and therefore constant.

- Rearrange the equation. You should get V2=V1P1/P2

- Fill in with variables. You should get V2=((5.)(50))/500

- Solve and you will get .5L

- Lastly, you can check this by knowing that P and V at constant T have an inverse relationship. Hence, volume went down, while pressure went up.

Answer:

a. NH₃ : base

CH₃COOH (acetic acid) : acid

NH₄⁺ : conjugate acid

CH₃COO⁻ : conjugate base

b. HClO₄ (perchloric acid) : acid

NH₃ : base

ClO₄⁻ : conjugate base

NH₄⁺ : conjugate acid

Hope this helps.

Answer: [tex]2AgNO_3(aq)+BaCl_2(aq)\rightarrow 2AgCl(s)+Ba(NO_3)_2(aq)[/tex]

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.

The reaction for aqueous silver nitrate solution with barium chloride solution produces barium nitrate solution and a white precipitate of silver chloride.

Thus the balanced chemical reaction will be:

[tex]2AgNO_3(aq)+BaCl_2(aq)\rightarrow 2AgCl(s)+Ba(NO_3)_2(aq)[/tex]

Answer:

A. 70.7%

Explanation:

In the first step lets compute the molar mass of CH₃OH and CO

Molar Mass of CH₃OH =  1(12.01 g/mol) + 4(1.008 g/mol) +1(16.00 g/mol)

                                     = 32.042 g/mol

Molar Mass of CO₂      = 1(12.01 g/mol) + 2(16.00 g/mol)  

                                     = 44.01 g/mol

Mass of only one reactant i.e. CH₃OH is given so  it must be the limiting reactant. Next, the theoretical yield is calculated directly as follows:

Given mass of CH₃OH is 10.4 g. So we have:

                                     10.4g CH₃OH

Convert grams of CH₃OH to moles of CH₃OH utilizing molar mass of CH₃OH as:

                          1 mol CH₃OH / 32.042 g CH₃OH

Convert CH₃OH to moles of CO₂ using mole ratio as:

                             2 mol CO₂ / 2 mol CH₃OH

Convert moles of  CO₂ to grams of  CO₂ utilizing molar mass of  CO₂ as:

                           44.01 g/mol CO₂ / 1 mol CO₂

Now calculating theoretical yield using above steps:

[ 10.4 g CH₃OH ]  [1 mol CH₃OH / 32.042 g CH₃OH ]  [2 mol CO₂ / 2 mol CH₃OH]  [44.01 g/mol CO₂ / 1 mol CO₂]

Multiplication is performed here. We are left with 10.4 and 44.01 g CO₂ from numerator terms in the above equation and 32.042 from denominator terms after cancellation process of above terms. So this equation becomes:

= ( 10.4 ) ( 44.01 ) g CO₂ / 32.042

= 457.704/32/042

=  14.28 g CO₂

Theoretical yield =  14.28 g CO₂  

Finally compute the percent yield for a process in which 10.4g of CH₃OH reacts and 10.1 g of CO₂ is formed:

percent yield = (actual yield / theoretical yield) x 100

As we have calculated theoretical yield which is 14.28 g CO₂ and actual yield is 10.1 g CO₂ So,

percent yield = (10.1 g CO₂ / 14.28 g CO₂) x 100%

                       = 0.707 x 100%

                       = 70.7 %

Hence option A 70.7% yield is the correct answer.

The percent yield for a process is:

A. 70.7%

In the first step, lets compute the molar mass of CH₃OH and CO

Molar Mass of CH₃OH =  1(12.01 g/mol) + 4(1.008 g/mol) +1(16.00 g/mol)

= 32.042 g/mol

Molar Mass of CO₂ = 1(12.01 g/mol) + 2(16.00 g/mol)  

= 44.01 g/mol

Mass of only one reactant i.e. CH₃OH is given so it must be the limiting reactant.

Given mass of CH₃OH= 10.4 g.

Converting into number of moles:

1 mol CH₃OH / 32.042 g CH₃OH

Convert CH₃OH to moles of CO₂ using mole ratio as:

2 mol CO₂ / 2 mol CH₃OH

Convert moles of CO₂ to grams of  CO₂ utilizing molar mass of  CO₂ as:

44.01 g/mol CO₂ / 1 mol CO₂

Calculation for theoretical yield:

[ 10.4 g CH₃OH ]  [1 mol CH₃OH / 32.042 g CH₃OH ]  [2 mol CO₂ / 2 mol CH₃OH]  [44.01 g/mol CO₂ / 1 mol CO₂]

= ( 10.4 ) ( 44.01 ) g CO₂ / 32.042

= 457.704/32/042

=  14.28 g CO₂

Theoretical yield =  14.28 g CO₂  

Adding values in percent yield formula:

Percent yield = (actual yield / theoretical yield) / 100

Percent yield = (10.1 g CO₂ / 14.28 g CO₂) x 100%

= 0.707 x 100%

= 70.7 %

Hence, option A is the correct answer.

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Answer:

First the aqueous solution of iodine is heated mildly and then collection of the iodine crystals is done from its vapors.

Explanation:

Iodine is one of the elements that can get recovered easily from a given solution by going through the process of mild heating. For doing this, first, the aqueous solution is heated mildly over a low flame with a dish placed over the flame. As the process of mild heating continues, the fumes of the iodine start to originate that slowly get condense around the dish's cooler parts.  

With condensation, the formation of pure iodine crystals takes place. These iodine crystals can now be extracted easily by a physical method.  

Answer:

volume = 972.23ml

Explanation:

using general gas law

P1V1/T1 = P2V2/T2

765 x 585/293 = 443 x V2/282

1527.39 =443 x V2/282

1527.38 x 282 = 443 x V2

430695.78 = 443 x V2

V2 = 430695.68/443

V2 = 972.23mL

Answer:

ΔH°r = -1009.8 kJ

Explanation:

Let's consider the following balanced reaction.

2 NH₃(g) + 3 N₂O(g) ⇒ 4 N₂(g) + 3 H₂O(l)

We can calculate the standard enthalpy of the reaction (ΔH°r) using the following expression.

ΔH°r = [4 mol × ΔH°f(N₂(g)) + 3 mol × ΔH°f(H₂O(l))] - [2 mol × ΔH°f(NH₃(g)) + 3 mol × ΔH°f(N₂O(g))]

ΔH°r = [4 mol × 0 kJ/mol + 3 mol × (-285.8 kJ/mol)] - [2 mol × (-46.2 kJ/mol) + 3 mol × 81.6 kJ/mol]

ΔH°r = -1009.8 kJ

Answer:

THE FREEZING POINT OF THE AQUEOUS SOLUTION IS - 7.3 °C

Explanation:

To solve this problem, we must know the following variables:

Normal boiling point of water (solvent) = 100 °C

The molar boiling point elevation constant of water  = 1.51 °C /m

Normla freezing point of water ( solvent) = 0 °C

The molar freezing point depression constant = 1.86 °C /m

The boiling point of the aqueous solution = 105.9 °C

Molarity = xM

Change in boiling point = boiling point of solution - boiling point of water

Change in boiling point = 105.9 - 100 °C

= 5.9 °C

From the formula:

Change in boiling point = i * Kb * M

Re- arranging the formula by making M the subject of the equation, we have:

M = change in boiling point / Kb

i = 1

M = 5.9 °C / 1.51 °C/m

M = 3.907 M

Then, we calculate the freezing point:

Change in freezing point = i * Kb * M

= 1 * 1.86 °C/m * 3.907 M

= 7.267 °C

Hence, the freezing point = freezing point of water - change in freezing point

Freezing point = 0 °C - 7.267 °C

Freezing point = - 7.267 °C

Freezing point = -7.3 °C

Answer:

The volume of the solution must be increased to 71.429 millimeters by adding 66.359 millimeters of solute to reduce molarity from 6.82 M to 0.49 M.

Explanation:

The molarity is a unit used for solution that is equivalent to the amount of moles of solute per unit volume of solution. That is:

[tex]M = \frac{n_{st}}{V_{sol}}[/tex]

Where:

[tex]n_{st}[/tex] - Amount of moles of solute, measured in moles.

[tex]V_{sol}[/tex] - Volume of the solution, measured in liters.

To reduce the molarity of the solution, more millimeters of solvent should be added. Firstly, the amount of moles of acetic acid inside the 6.82 M solution needs to be determined ([tex]M_{o} = 6.82\,M[/tex] and [tex]V_{sol} = 5.07\times 10^{-3}\,L[/tex]):

[tex]n_{st} = M_{o}\cdot V_{sol}[/tex]

[tex]n_{st} = (6.82\,M)\cdot (5.07\times 10^{-3}\,L)[/tex]

[tex]n_{st} = 0.035\,mol[/tex]

Now, the resulting volume of solution after diluting the acetic acid solution is: ([tex]M_{f} = 0.49\,M[/tex] and [tex]n_{st} = 0.035\,mol[/tex]):

[tex]V_{sol} = \frac{n_{st}}{M_{f}}[/tex]

[tex]V_{sol} = \frac{0.035\,mol}{0.49\,M}[/tex]

[tex]V_{sol} = 71.429\times 10^{-3}\,L[/tex]

[tex]V_{sol} = 71.429\,mL[/tex] (1 L = 1000 mL)

The amount of solvent needed to dilute the solution is:

[tex]\Delta V_{sol} = 71.429\times 10^{-3}\,L - 5.07\times 10^{-3}\,L[/tex]

[tex]\Delta V_{sol} = 66.359 \times 10^{-3}\,L[/tex]

[tex]\Delta V_{sol} = 66.359\,mL[/tex] (1 L = 1000 mL)

The volume of the solution must be increased to 71.429 millimeters by adding 66.359 millimeters of solute to reduce molarity from 6.82 M to 0.49 M.

Answer:

the energy of the third excited rotational state [tex]\mathbf{E_3 = 16.041 \ meV}[/tex]

Explanation:

Given that :

hydrogen chloride (HCl) molecule has an intermolecular separation of 127 pm

Assume the atomic isotopes that make up the molecule are hydrogen-1 (protium) and chlorine-35.

Thus; the reduced mass μ = [tex]\dfrac{m_1 \times m_2}{m_1 + m_2}[/tex]

μ = [tex]\dfrac{1 \times 35}{1 + 35}[/tex]

μ = [tex]\dfrac{35}{36}[/tex]

∵ 1 μ = 1.66 × 10⁻²⁷ kg

μ  = [tex]\\ \\ \dfrac{35}{36} \times 1.66 \times 10^{-27} \ \ kg[/tex]

μ  = 1.6139 × 10⁻²⁷ kg

[tex]r_o = 127 \ pm = 127*10^{-12} \ m[/tex]

The rotational level Energy can be expressed by the equation:

[tex]E_J = \dfrac{h^2}{8 \pi^2 I } \times J ( J +1)[/tex]

where ;

J = 3 ( i.e third excited state)  &

[tex]I = \mu r^2_o[/tex]

[tex]E_J= \dfrac{h^2}{8 \pi \mu r^ 2 \mur_o } \times J ( J +1)[/tex]

[tex]E_3 = \dfrac{(6.63 \times 10^{-34})^2}{8 \times \pi ^2 \times 1.6139 \times 10^{-27} \times( 127 \times 10^{-12}) ^ 2 } \times 3 ( 3 +1)[/tex]

[tex]E_3= 2.5665 \times 10^{-21} \ J[/tex]

We know that :

1 J = [tex]\dfrac{1}{1.6 \times 10^{-19}}eV[/tex]

[tex]E_3= \dfrac{2.5665 \times 10^{-21} }{1.6 \times 10^{-19}}eV[/tex]

[tex]E_3 = 16.041 \times 10 ^{-3} \ eV[/tex]

[tex]\mathbf{E_3 = 16.041 \ meV}[/tex]

Answer:

Vitamin K

Explanation:

this is the answer

Answer:

1.1 × 10⁻³ g

Explanation:

Step 1: Given data

Henry's Law constant for methane (k): 1.4 × 10⁻³ M/atm

Volume of water (=volume of solution): 75 mL

Partial pressure of methane (P): 0.68 atm

Step 2: Calculate the concentration of methane in water (C)

We will use Henry's law.

[tex]C = k \times P = 1.4 \times 10^{-3}M/atm \times 0.68atm = 9.5 \times 10^{-4}M[/tex]

Step 3: Calculate the moles of methane in 75 mL of water

[tex]\frac{9.5 \times 10^{-4}mol}{L} \times 0.075 L = 7.1 \times 10^{-5}mol[/tex]

Step 4: Calculate the mass corresponding to 7.1 × 10⁻⁵ mol of methane

The molar mass of methane is 16.04 g/mol.

[tex]7.1 \times 10^{-5}mol \times \frac{16.04g}{mol} = 1.1 \times 10^{-3} g[/tex]

Answer:

Molar mass = 52.96g/mol

density = 1.91g/L

Explanation:

using ideal gas equation

PV=nRT

Ideal gas law is valid only for ideal gas not for vanderwaal gas. Density and mass of unknown gas is 1.91g/L and 52.96g/mol respectively. The equation used to solve this is PM=dRT.

Ideal gas equation is the mathematical expression that relates pressure volume and temperature.

Mathematically the relation between Pressure, Molar mass and temperature can be given as

PV=nRT

This equation is arranged as

PM=dRT

Where,

P=pressure of gas = 1.05 atm

M= molar mass=?

d= density=?

R = Gas constant = 0.0821 L.atm/K.mol

T=temperature=354K

density=mass÷ volume

density=3.35 g÷1.75 L

density = 1.91g/L

PM=dRT

P×M=d×R×T

1.05 atm ×M= 1.91g/L× 0.0821 ×354K

M=52.96g/mol

Therefore, density and mass of unknown gas is 1.91g/L and 52.96g/mol respectively.

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Answer:

Alkanes

Explanation:

Alkanes are hydrocarbons containing only C-H and C-C single bonds. They're saturated compounds and they form a homologous series with the general formula CₙH₂ₙ₊₂, where n is the number of carbon atoms. Example of members in this group are

Methane = CH₄

Ethane = C₂H₆

Propane = C₃H₈

All alakane compounds ends with with the suffix "-ane" and this differentiate them during naming from other compounds.

Answer: The mass of [tex]H_3PO_4[/tex] produced is, 13.82 grams.

Explanation : Given,

Mass of [tex]P_4O_{10}[/tex] = 10.00 g

Mass of [tex]H_2O[/tex] = 12.00 g

Molar mass of [tex]P_4O_{10}[/tex] = 283.89 g/mol

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

First we have to calculate the moles of [tex]P_4O_{10}[/tex] and [tex]H_2O[/tex].

[tex]\text{Moles of }P_4O_{10}=\frac{\text{Given mass }P_4O_{10}}{\text{Molar mass }P_4O_{10}}[/tex]

[tex]\text{Moles of }P_4O_{10}=\frac{10.0g}{283.89g/mol}=0.0352mol[/tex]

and,

[tex]\text{Moles of }H_2O=\frac{\text{Given mass }H_2O}{\text{Molar mass }H_2O}[/tex]

[tex]\text{Moles of }H_2O=\frac{12.0g}{18g/mol}=0.666mol[/tex]

Now we have to calculate the limiting and excess reagent.

The balanced chemical equation is:

[tex]P_4O_{10}+6H_2O\rightarrow 4H_3PO_4[/tex]

From the balanced reaction we conclude that

As, 1 mole of [tex]P_4O_{10}[/tex] react with 6 mole of [tex]H_2O[/tex]

So, 0.0352 moles of [tex]P_4O_{10}[/tex] react with [tex]0.0352\times 6=0.211[/tex] 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]P_4O_{10}[/tex] is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of [tex]H_3PO_4[/tex]

From the reaction, we conclude that

As, 1 mole of [tex]P_4O_{10}[/tex] react to give 4 mole of [tex]H_3PO_4[/tex]

So, 0.0352 mole of [tex]P_4O_{10}[/tex] react to give [tex]0.0352\times 4=0.141[/tex] mole of [tex]H_3PO_4[/tex]

Now we have to calculate the mass of [tex]H_3PO_4[/tex]

[tex]\text{ Mass of }H_3PO_4=\text{ Moles of }H_3PO_4\times \text{ Molar mass of }H_3PO_4[/tex]

Molar mass of [tex]H_3PO_4[/tex] = 98.00 g/mole

[tex]\text{ Mass of }H_3PO_4=(0.141moles)\times (98.00g/mole)=13.82g[/tex]

Therefore, the mass of [tex]H_3PO_4[/tex] produced is, 13.82 grams.

Answer

Naphthalene is a non electrolyte

If the unknown compound is an electrolyte it gives 2 or more ions in solution

( NaCl >> Na+ + Cl- => 2 ions

Ca(NO3)2 >> Ca2+ + 2 NO3- => 3 ions)

the f.p. lowering is directly proportional to the molal concentration of dissolved ions in the solution )

For naphthalene

delta T = 1.86 x m

for a salt that gives 2 ions

delta T = 1.86 x m x 2

hence the lowering in freezion point of unkown is greater then napthalene

Answer:

[tex]x_B=0.0769[/tex]

[tex]m=0.990m[/tex]

Explanation:

Hello,

In this case, we can compute the mole fraction of benzene by using the following formula:

[tex]x_B=\frac{n_B}{n_B+n_C}[/tex]

Whereas n accounts for the moles of each substance, thus, we compute them by using molar mass of benzene and cyclohexane:

[tex]n_B=6.24g*\frac{1mol}{78.11g}=0.0799mol\\ \\n_C=80.74g*\frac{1mol}{84.16g} =0.959mol[/tex]

Thus, we compute the mole fraction:

[tex]x_B=\frac{0.0799mol}{0.0799mol+0.959mol}\\ \\x_B=0.0769[/tex]

Next, for the molality, we define it as:

[tex]m=\frac{n_B}{m_C}[/tex]

Whereas we also use the moles of benzene but rather than the moles of cyclohexane, its mass in kilograms (0.08074 kg), thus, we obtain:

[tex]m=\frac{0.0799mol}{0.08074kg}=0.990mol/kg[/tex]

Or just 0.990 m in molal units (mol/kg).

Best regards.

Considering the definition of mole fraction and molality:

You know that:

The molar fraction is a way of measuring the concentration that expresses the proportion in which a substance is found with respect to the total moles of the solution.

Being the molar mass and the mass in the solution of each compound, the number of moles of each compound can be calculated as:

So, the total moles of the solution can be calculated as:

Total moles = 0.08 moles + 0.96 moles = 1.04 moles

Finally, the mole fraction of benzene can be calculated as follow:

[tex]\frac{number moles of benzene}{total moles} =\frac{0.08 moles}{1.04 moles} = 0.077[/tex]

Finally, the mole fraction of benzene is 0.077.

Molality is the ratio of the number of moles of any dissolved solute to kilograms of solvent.

The Molality of a solution is determined by the expression:

[tex]Molality=\frac{number of moles of solute}{kilograms of solvent}[/tex]

In this case, you know:

Replacing:

[tex]Molality benzene=\frac{0.08 moles}{0.08074 kg}[/tex]

Molality benzene= 0.9908 [tex]\frac{moles}{kg}[/tex]

Finally, the molality of benzene is 0.9908 [tex]\frac{moles}{kg}[/tex].

Learn more about:

The question is incomplete; the complete question is: Classify each molecule by whether its real bond angles are the same as or different than its model (ideal) bond angles. In other words, do the bond angles change when you switch between Real and Model mode at the top of the page? Same (angles do not change) Different (angles change) Answer Bank | H2O | CO2, SO2, XeF2, BF3 CIF3, NH3, CH4, SF4, XeF4, BrF5, PCI5,SF6

Answer:

Compounds whose real bond angle are the same as ideal bond angle;

SF6, BF3, CH4, PCI5

Compounds whose real bond angles differ from ideal bond angles;

H2O, CO2, SO2, XeF2, CIF3, NH3, SF4, XeF4, BrF5

Explanation:

According to the valence shell electron pair repulsion theory (VSEPR), molecules adopt various shapes based on the number of electron pairs on the valence shell of the central atom of the molecule. The electron pairs usually orient themselves as far apart in space as possible leading to various observed bond angles.

The extent of repulsion of lone pairs is greater than that of bond pairs. Hence, the presence of lone pairs on the valence shell of the central atom in the molecule distorts the bond angles of molecules away from the ideal bond angles predicted on the basis of valence shell electron pair repulsion theory.

For instance, methane is a perfect tetrahedron having an ideal bond angle of 109°28'. Both methane and ammonia are based on a tetrahedron, however, the presence of a lone pair of electrons on nitrogen distorts the bond angle of ammonia to about 107°. The distortion of lone pairs in water is even more as the bond angles of water is about 104°.

Answer:

Its washed with 2M Naoh to remove acidic impurities like sulphuric acid and HBr

Its washed in water to remove water soluble impurities

Its washed with Nacl to remove large quantity of water that may be in the organic layer

Explanation:

Answer:

[tex]12.16[/tex]

Explanation:

We have to start with the reaction between nitric acid and potassium hydroxide:

[tex]HNO_3~+~KOH~->~H_2O~+~KNO_3[/tex]

With this in mind, we can calculate the number of moles of each compound if we use the molarity equation: [tex]M=\frac{mol}{L}[/tex] (this means that we have to find the Litters dividing by 1000)

[tex]95~mL~=~0.095~L[/tex]

[tex]320~mL~=~0.32~L[/tex]

Now, we can calculate the moles:

[tex]moles~=~0.2*0.095~=~0.019~mol~HNO3[/tex]

[tex]moles~=~0.078*0.32~=~0.025~mol~KOH[/tex]

If we have a molar ratio 1:1 (1 mol of [tex]KOH[/tex] reacts with 1 mol of [tex]HNO_3[/tex]). So, if we have [tex]0.019~mol~HNO3[/tex] we will need [tex]0.019~mol~KOH[/tex]. So, we have to calculate the amount of KOH that remains in the solution, so:

[tex]0.025-0.019~=~0.006~mol~KOH[/tex]

If we have an excess of KOH, this compound will be the cause of the pH value. Therefore we have to calculate the concentration. We already know the moles we have to calculate the volume. The total volume:

[tex]Vt~=~95mL~+~320mL~=~415~mL~=~0.415~L[/tex]

With this value, we can calculate the concentration of KOH:

[tex]M=\frac{0.006~mol~KOH}{0.415~L}=0.0145~M[/tex]

We have to keep in mind that this compound is a base, so we have to calculate the pOH value first and then the pH:

[tex]pOH~=~-Log(0.0145~M)~=~1.84[/tex]

If we remember that: 14 = pH + pOH we can find the pH value:

[tex]pH~=~14-1.84~=~12.16[/tex]

I hope it helps!

Answer:

In the attached image the Lewis equation is shown where it is shown how two oxygens react with two hydrogens to meet the octet of the electrons.

Explanation:

Hydrogen peroxide is one of the most named chemicals since it is not only sold as "hydrogen peroxide" in pharmacies but it is also one of the great weapons of immune defense cells to defend ourselves against anaerobic bacteria.

The disadvantage of this compound is that when dividing it forms free oxygen radicals that are considered toxic or aging for our body.

In the attached image below, you will see the Lewis equation is shown there. There, you will see how two oxygens react with two hydrogens to come about the octet of the electrons.

When two or more atoms bond with each other, they often form a molecule. When two hydrogens and an oxygen share electrons through covalent bonds, a water molecule is formed.

The octet rule is known as when most atoms want to gain stability in their outer most energy level by filling themselves that is the S and P orbitals of the highest energy level with eight electron.

HOOH is the compound  that is form. It is called Hydrogen peroxide. This because it is has reactive oxygen species and the simplest peroxide.

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Answer:

mass of the gram after 28 days = 1.29 grams

Explanation:

From the diagram attached below; we would see the plot of the mass vs the time (days).

However ; to predict what would be the mass of the crystal after 28 days  if the growth is linear; we have the following analysis;

Let the mass be Y ( since it falls on the y-axis) and the time (days) be X (since it falls on the x-axis)

So; we can have a table as shown below:

              X                 Y                   XY                   XX

              0                  0.500          0                       0

              7                   0.648          4.536               49

              14                 0.899           12.586            196

              21                  1.081            22.701            441

Total  [tex]\sum[/tex] :42                3.128            39.823         686

If the growth is linear ; the linear regression equation can be represented as :

y = a+ bx

where ;

[tex]a = \dfrac{\sum Y * \sum XX - \sum X * \sum XY }{n* \sum X X- ( \sum X)^2}[/tex]

and

[tex]b= \dfrac{n * \sum XY - \sum X* \sum Y }{n* \sum X X- ( \sum X)^2}[/tex]

n = samples given =  4

x = number of days = 28

so;

from the table ; replacing the corresponding values; we have:

 [tex]a = \dfrac{3.128* 686 - 42 * 39.823 }{4* 686- (42)^2}[/tex]

[tex]a = \dfrac{2145.808 -1672.566}{2744- 1764}[/tex]

[tex]a = \dfrac{473.242}{980}[/tex]

a = 0.4829

[tex]b= \dfrac{4 * 39.823 - 42* 3.128 }{4* 686- ( 42)^2}[/tex]

[tex]b= \dfrac{159.292 -131.376 }{2744- 1764}[/tex]

[tex]b= \dfrac{27.916 }{980}[/tex]

b = 0.0289

Recall:

y = a+ bx

y = 0.4829 + 0.0289 (28)

y = 0.4829 + 0.8092

y = 1.2921 grams

y ≅ 1.29 grams

mass of the gram after 28 days = 1.29 grams

Answer:

A. None of these.  

Explanation:

A crystal structure is an arrangement of atoms or ions in a repeating three-dimensional array.

B. is wrong. Metal atoms, such as gold, arrange themselves into a crystal structure.

C. is wrong. Ionic solids, such as sodium chloride, arrange themselves into a crystal structure.

D. is wrong. Macromolecules (network solids), such as diamond, arrange themselves into a crystal structure.

The correct answer is None of these.  

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