9. It says its wrong? someone help!

A solution is prepared by dissolving sodium benzoate and benzoic acid in water to give a 9 m mol / liter concentration of each compound. The mixture has a pH of 4.21 at 25 °C. the acid dissociation constant of benzoic acid, Ka is 6.1 × 10⁻⁵.

the pH of solution is given as :

pH = pka + log ( [sodium benzoate / benzoic acid])

4.21 = pka + log 1

pka = 4.21

pka = - log ka

ka = 10^- pka

ka = 6.2 × 10⁻⁵

Thus, A solution is prepared by dissolving sodium benzoate and benzoic acid in water to give a 9 m mol / liter concentration of each compound. The mixture has a pH of 4.21 at 25 °C. the acid dissociation constant of benzoic acid, Ka is 6.1 × 10⁻⁵.

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Metallic bonds occur amid metal atoms. Whereas ionic bonds combine metals with non-metals, metallic bonding fixes several metal atoms.

An ionic bond is formed by joining a metal and a nonmetal, while a covalent bond is formed by allying two nonmetals. So we check the periodic table to see if our compound is made up of metals or nonmetals, or of two nonmetals.

Covalent compounds are built when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds that carry hydrogen are also usually covalent compounds. Metallic elements produced compounds with non-metallic elements with the help of ionic bonds.

So we can conclude that In metals, the electrons leave the outer shells of metal atoms, devise positive metal ions and a 'sea' of delocalized electrons.

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The number of moles of F₂ is 0.453 mol

The grams of F₂ are present is 17.21 g

given that :

pressure P = 5.2 atm

volume V = 2.55 L

temperature T = ( 273 + 83 ) = 356 K

using the gas equation , we get

PV = nRT

n = PV / RT

n = ( 5.2 × 2.55 ) / (0.0821 × 356)

n = 13.26 / 29.22

n = 0.453 mol

the mass of F₂ = moles × molar mas

                         = 0.453 × 38

                         = 17.21 g

Thus, The number of moles of F₂ is 0.453 mol

The grams of F₂ are present is 17.21 g

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The frequency of the photon is 3.57 * 10^14 Hz. the energy in joules is 2.4 * 10^-19 J while the energy in kJ/mol is 3.9 * 10^-40 kJ/mol.

The energy of the photon can be obtained by the use of an adaptation of the Plank equation. Let us now use;

E = hc/λ

E = energy

h = Plank Constant

c = Speed of light

λ = wavelength

a)

c = λf

f = c/λ

Substituting values;

f = 3 * 10^8/839.6 * 10^-9

f = 3.57 * 10^14 Hz

b)

E = 6.6 * 10^-34 * 3 * 10^8/ 839.6 * 10^-9

E = 2.4 * 10^-19 J

c)

Energy in kJ/mole

Substituting values;

2.4 * 10^-19 J * 10^3/6.02 * 10^23

= 3.9 * 10^-40 kJ/mol

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If we have 37.75 g of S , the number of moles is 1.17 mol.

Given that :

mass of Sulphur , S = 37.75 g

Molar mass of Sulphur , S = 32 g / mol

The number of moles of substances is equals to the ,mass of substance given to the molar mass of that substance.

number of moles = mass / molar mass

number of moles  of sulphur = 37.75 g / 32 g / mol

number of moles of sulphur = 1.17 mol

Thus, If we have 37.75 g of S , the number of moles is 1.17 mol.

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Starch and cellulose have similar chemical structures, but differ in the orientation of bonds between glucose monomers.

Starch is glucose polymer in which repeating unit are connect by alpha bond and all the repeating unit are direct in one direction. starch is present in foods. it is less crystalline.

Cellulose is also a glucose polymer but cellulose units can be rotated around the axis of backbone of glucose polymer. cellulose is natural organic compound. glucose if formed by the combination of carbon, hydrogen , oxygen , .

Thus, Starch and cellulose have similar chemical structures, but differ in the orientation of bonds between glucose monomers

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Polyatomic ions: [tex]CH_3COO^-[/tex], [tex]NO_3^-[/tex], [tex]NH^+[/tex], [tex]CN^-[/tex], [tex]Li^+[/tex], and [tex]OH^-[/tex]

Monatomic ions: [tex]Ca^{2+[/tex], [tex]O^{2-[/tex], and [tex]Fe^{3+[/tex]

In chemistry, monoatomic ions are ions that consist of only a single type of atom. They are usually positive or negatively charged and are otherwise known as simple ions. Examples include  [tex]Ca^{2+[/tex], [tex]O^{2-[/tex], and [tex]Fe^{3+[/tex]

Polyatomic ions, on the other hand, are ions that consist of more than one atom, unlike monoatomic ions. The two or more atoms are covalently bonded and the entire structure behaves like a single chemical entity in reactions. Polyatomic ions are otherwise known as molecular ions.

Examples of polyatomic ions are  [tex]CH_3COO^-[/tex], [tex]NO_3^-[/tex], [tex]NH^+[/tex], [tex]CN^-[/tex], [tex]Li^+[/tex], and [tex]OH^-[/tex]

Thus, from the diagram:

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The pH of the solutions are as follows:

a. pH = 4.4

b. pH = 0.2

The pH of a solution is a measure of the acidity or basicity of a solution.

The pH is defined as the negative logarithm of the hydrogen ion concentration of a substance.

pH = -log [H⁺]

where [H⁺] is the hydrogen ion concentration

The pH of the solutions are as follows:

a.  150.0 ml of a 3.5 x 10⁻⁵ M HNO3.

pH = -log (3.5 x 10⁻⁵)

pH = 4.4

b. 250.0 ml of a 0.63 M solution of HNO2

pH = -log (0.63)

pH = 0.2

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If a gas has a volume of 145 mL at 125 °C, then it will have 108.56 mL at 25 °C.

According to Charles’ law, the volume of a gas is directly proportional to the temperature.

Thus, V1/T1=V2/T2 .......(i)

Here, V1 ⇒ initial volume

T1  ⇒ initial temperature in Kelvin

V2 ⇒ final volume

T2 ⇒ final temperature in Kelvin.

In the given question:

V1 = 145mL

T1 = 125°C= (125+273)K= 398K

T2 = 25°C= (25+273)K= 298K

Putting these values in equation (i),

145mL / 398K = V2 / 298K

Solving for V2, we get

V2 = 145mL * 298K /398 K

V2 = 108.56 mL

Therefore, at 25 °C, the gas will have a volume of 108.56 mL.

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Answer:

In each test, iron(II) sulfate and iron(III) nitrate were combined with the same substance or substances. However, the sulfate and nitrate parts of the compounds didn’t participate in any of the chemical reactions; only the iron ions reacted. Comparing the results for each pair of tests, what can you conclude about the iron(II) and iron(III) ions? i need the answer to it please do this

There are various kind of reaction like combustion reaction, displacement reaction. So to solve this problem we must be knowing the displacement reaction. Displacement reaction is taking place over here

What is displacement reaction?

Displacement reaction is a reaction in which one atom replaces other atom from a molecule on the basis of reactivity strength. The element which on the top of reactivity series displace the element that is lying below to that reactive element

According to our question the balanced equation is

FeSO₄+Zn ZnSO₄+Fe(II)

Fe(NO₃)₂+Zn      Zn(NO₃)₂+Fe(II)

In both reaction Zn is more reactive than Fe(II) and Fe(III) that is why Zn replace or displace iron ion from its compound of sulfate and nitrate. Metal displace metals. anions are displaced by anions. So, here metal is displaced by zinc.

Thus we can conclude that zinc is more reactive than iron Fe(II) and Fe(III). Displacement reaction is taking place over here

Hope this helps!

Answer:

True.

Explanation:

Based on the mass of the sample, the percentage mass of urea in the urea/cholesterol mixture is 65.3%.

The percentage mass of urea in the urea/cholesterol mixture is determined using the formula below:

The mass of urea in the sample is obtained using the formula below:

During the separation procedure of the mixture, urea which is soluble in water goes into the solvent phase whereas cholesterol is obtained as a solid.

Hence, the 0.52 g solid sample collected is cholesterol.

mass of urea = 1.50 - 0.52

mass of urea = 0.98

Percentage urea = 0.98/1.5 * 100%

Percentage mass of urea = 65.3%

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The elements give off specific color because the energy of shells of different elements are specific.

Electrons when excited jump from a lower energy level to higher energy level. in higher energy level the electron are less stable . so, after some time they return from higher to lower energy level an emit some light of different wavelength of specific colors. The difference in the energy of the shells of the atom are specific. the color of different elements are different because of the light emitted and the wavelength is inversely proportional to energy.

E = hc / λ

Thus, The elements give off specific color because the energy of shells of different elements are specific.

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The solution of 12.0 M HCl and to prepare 300 mL of a 0.6 M solution , the initial volume is 0.015 L.

given that :

Molarity M1 = 12.0 M

volume V1 = ?

Molarity M2 = 0.6 M

Volume V2 = 300 mL = 0.3 L

The dilution law is given as :

M1 V1 = M2 V2

12.0 × V1 = 0.6 × 0.3 L

V1 = 0.18 / 12

V1 = 0.015 L

Thus, The solution of 12.0 M HCl and to prepare 300 mL of a 0.6 M solution , the initial volume is 0.015 L.

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The hissing sound from the water bottle occurred due to increase in thermal energy of the car which is the immediate environment of the water bottle.

Thermal energy is defined as the type of energy that expresses the flow of heat through a medium.

When there is increase in heat energy, outside the an enclosed medium such as a car, all the contents within the medium also increases in temperature.

There is also a rise in temperature of water in the water bottle and this causes the water molecules to gain energy, vibrate and collide more often among each other.

The hissing sound occurs due to a rise in pressure of the water occuring due to rise in temperature.

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Answer:

24.984466667

Explanation:

add all mass values and divide by amount (3)

Avogadro's constant is the same as the number of copper II sulfate formula units in 160g of copper II sulfate; option C.

Avogadro's constant is a number that describes the number of particles in 1 mole of a substance.

The value of the Avogadro constant is 6.02 * 10²³.

The carbon-12 isotope is used as the standard to define the mole of a substance.

12 grams of the carbon-12 isotope contains the Avogadro number of particles which is equal to 6.02 * 10²³.

Hence, 1 mole of a substance is defined as the amount of a substance that contains as many elementary particles as there are in 12 grams of carbo-12.

Considering the given substances:

a. 24g of magnesium off magnesium contains two moles of magnesium atoms.

b. 14g of nitrogen gas contains 0.5 moles of nitrogen gas molecules

c. 160g of copper (ii) sulfate contains 1 mole of copper (ii) sulfate formula units. Hence, this is equal to the  Avogadro constant

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The  typical sequence of events in the scientific method is to define question , make prediction, collect data, analyze data, Experiment, test hypothesis, draw conclusion , report result.

the following are the steps in the scientific method :

1) first step to define a question for the investigation.

2) Then make prediction : do some research related to the question and the study related theories.

3)collect the data : collect all the data from the research .

4) analyze the data

5) experiments : perform the experiments

6) test the hypothesis: accept or reject hypothesis.

7) draw the conclusion

8) report your result.

Thus , The  typical sequence of events in the scientific method is to define question , make prediction, collect data, analyze data, experiments , test hypothesis, draw conclusion , report result.

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Answer:

No entendí porfavor puedes explicarme

Answer:

Strontium is a chemical element with symbol Sr and atomic number 38. Classified as an alkaline earth metal, Strontium is a solid at room temperature.

Explanation:

The volume of CO₂ produced at STP when 891.6 grams of C2H6 is burned in excess oxygen gas is 1331.4 liters.

The volume of a gas produced at STP is determined from the mole ratio of the reaction that produces the gas.

The mole ratio of the reaction that produces the gas is obtained from the equation of the reaction.

Considering the given data, the volume of CO₂ produced when  891.6 grams of C2H6 is burned in excess oxygen gas is calculated as follows:

Equation of reaction: 2 C₂H₆ (g) + 7 O₂ (g) → 4 CO₂ (g) + 6 H₂O (g)

2 moles of C₂H₆ when burned in excess oxygen at STP produces 4 moles of CO₂.

The number of moles of C₂H₆ in 891.6 grams is calculated as follows:

Moles = mass / molar mass

The molar mass of C₂H₆ = 30 g/mol

Moles of C₂H₆ in 891.6 g = 891.6 / 30

Moles of C₂H₆ = 29.72 moles

Hence moles of CO₂ produced = 29.72 * 4/2 moles

Volume of 1 mole of CO₂ at STP = 22.4 liters

Volume of CO₂ produced = 29.72 * 4/2 * 22.4

Volume of CO₂produced = 1331.4 liters.

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The ratio of mol of ZnSO₄ : mol H₂O is 1:7.

Empirical formula- The relative ratios of the various atoms in a compound are given by an empirical formula. The ratios are still valid at the molar level. As a result, H₂O is made up of two hydrogen and one oxygen atoms. Similar to how 2.0 moles of hydrogen and 1.0 mole of oxygen make up 1.0 mole .

Steps to determine Empirical formula-

Determine the masses in Step 1. Step 2: Multiply the grams by the atomic mass to get the number of moles. Step 3: Subtract the smallest number of moles from the total number of moles of each element. Step 4: Make entire numbers out of the numbers.

Given,

0.05216 mol of ZnSO₄

0.3609 mol of H₂O

Here, the smallest number of mole is 0.05216.

Dividing each by the smallest number of moles to get the ratio -

⇒ 0.05216/ 0.05216 = 1

⇒ 0.3609/ 0.05216 = 6.91 ≈ 7

Therefore the mol ratio of ZnSO₄ and H₂O are 1 and 7 respectively.

Hence, 1 mol ZnSO₄ : 7 mol H₂O.

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Using the Valence shell electron pair repulsion theory, there are six  electron dense areas in the compound.

According to the valence shell electron pair repulsion theory, the number of electron pairs that surround the valence shell of the central atom of the molecule is the determinant factor of the  shape of the molecule.

Thus, the repulsion between the electron pairs would make  the compound to assume a certain shape as the electrons would be able to maximize the repulsion that does exists between them.

In this case, we have a compound that have a central tom that is surround be six electron pairs that surround the central atom and they are all bond pairs of electron thus we would have six areas of electron density.

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The heat that is released by the 1.39 Kg of pentane is 58518 kJ.

We know that the combustion of pentane is an exothermic reaction because heat is released in the process. We have to look to the  balanced thermochemical reaction equation for the combustion of pentane.

Given that the number of moles of the pentane that is burnt here =  1.39 * 10^3 g/72 g/mol

= 19.3 moles

Now;

If we require 3032 kJ of energy to burn one mole of pentane

If we have 19.3 moles of pentane then we have;

19.3 moles *  3032 kJ/ 1 mole

= 58518 kJ

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The vapor-pressure lowering, AP, of an aqueous solution is 2.44Torr.

Mole = [tex]\frac{weight}{molecular weight}[/tex]

In a 1.80m (molal) solution, 1 kilogram of the solvent contains 1.80 moles of the solute (which is water in this case).

Water's molar mass is equal to 2(atomic mass of H) + [2(1)+16] (atomic mass of O).

=18g/mol

The mole of water in 1 kilogram (equivalent to 1000 grams)::

[tex]n_{H_{2} O}[/tex]= [tex]\frac{1000}{18g/mol}[/tex] = 55.56mol

The solute's mole fraction in the 1.80 m solution is as follows::

[tex]x_{solute}[/tex] = [tex]\frac{n_{solute} }{n_{H_{2}O }}[/tex]

   ⇒[tex]x_{solute} =[/tex] [tex]\frac{1.80}{55.56}[/tex] = 0.032

a. Sucrose is a non-electrolyte, i.e., it does not undergo dissociation in the aqueous solution.

As a result, the Van't Hoff factor for sucrose is = i = 1

The lowering in vapor pressure of the solution, which is 1.80m in sucrose:

=[tex]ix_{solute}p^{0}[/tex]

=(1)(0.032)(17.54)Torr

=(0.56)Torr

b. Aluminum chloride dissociate in water as follows:

[tex]AlCl_{3}[/tex] →[tex]Al^{3+}+ 3Cl^{-}[/tex]

As a result, an aqueous solution containing one aluminum chloride particle yields four more particles.

Thus, i=4

The lowering in vapor pressure is thus:

=[tex]ix_{solute}p^{0}[/tex]

=(4)(0.032)(17.54)Torr

=(2.24)Torr

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-18,037.5  are joules are needed to increase the temperature of 150 g of water from 313K to 338 K.

What is joules?

In the International System of Units (SI), a joule is a unit of work or energy equal to the work done by a force of one newton acting through one metre. It is named after the English physicist James Prescott Joule and equals 107 ergs, or about 0.7377 foot-pounds. The joule is equal to one watt-second in electrical terms, which is the amount of energy released in one second by a current of one ampere through a resistance of one ohm.

The distinction between heat and temperature can be difficult to grasp. Heat is essentially the total amount of kinetic energy that a substance's molecules contain, and it is measured in joules (J). Temperature is measured in degrees and is proportional to the average kinetic energy of the individual molecules. When the same quantity of heat is applied to different materials, the temperature rises at varying rates depending on the substance's specific heat capacity. If you know the amount of the substance and its specific heat capacity, you may determine the final temperature.

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Plants absorbs the atmospheric carbon dioxide and use it up for photosynthesis.  Hence, increasing plant biomass reduces the atmospheric carbon dioxide.

Photosynthesis is a biochemical process by which the plants synthesis glucose and energy in leaves using carbon dioxide and water with the aid of light energy.

The pigment chlorophyll is a photoactive substance which absorbs the light energy. Using carbon dioxide and water plants synthesis glucose and oxygen is released in this reaction.

Therefore, as the plant biomass increases, the intake of carbon dioxide by these plants increases, leading to a reduction in the atmospheric carbon  dioxide which is good to decline the effect of global warming also.

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Answer:

The answer is if a solid gets dissolved in a liquid then sedimentation and decantation cannot be used because these methods are used to separate an insoluble solid substance but if we add a little sugar or salt it will dissolve in the liquids it is soluble solid making it hard to separate.

Explanation:

I hope this helps

The IUPAC names of the organic compounds would be as follows:

1. Methanol or 1-Methanol

2. Propan-2-ol or 2-Propanol

3. 2-MethylButane

4. 1-Hexanol

5. 1-Heptanol

In the naming of organic compounds, some fundamental rules come into practice. Some of these rules include:

Following these rules and more, the name of the organic compounds whose structures are shown in the image would be as follows:

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