Which of the following required Bohr's model of the atom to need modification ? A. Energies of electrons are quantized. B. Quantized electron energies are responsible for emission spectra lines. C. An electron's energy increases the farther it moves from the nucleus. D. Electrons do not follow circular orbits around the nucleus..

Answer: B. 430 K

Explanation:

According to Gibb's equation:

[tex]\Delta G=\Delta H-T\Delta S[/tex]

[tex]\Delta G[/tex] = Gibbs free energy  

[tex]\Delta H[/tex] = enthalpy change  = +62.4 kJ/mol

[tex]\Delta S[/tex] = entropy change  = +0.145 kJ/molK

T = temperature in Kelvin

[tex]\Delta G[/tex]  = +ve, reaction is non spontaneous

[tex]\Delta G[/tex]  = -ve, reaction is spontaneous

[tex]\Delta G[/tex]  = 0, reaction is in equilibrium

[tex]\Delta H-T\Delta S=0[/tex] for reaction to be spontaneous

[tex]T=\frac{\Delta H}{\Delta S}[/tex]

[tex]T=\frac{62.4kJ/mol}{0.145kJ/molK}=430K[/tex]

Thus the Reaction is spontaneous when temperature is 430 K.

Answer:

430 K

Explanation:

i just took the test on a pex :)

Answer:

1. C- Three.

2. A- Methionine

3. D- Translocation.

4. C- OH.

5. A - 5'

6. A - 3' carbon

7. A. adenine and guanine

Explanation:

1. A codon is a group of three nucleotide sequence that encodes or specifies an amino acid. This means that, during translation (second stage of gene expression), when a CODON is read, an amino acid is added to the growing peptide chain.

2. The codon that initiates the translation process is called a start codon. It has a sequence: AUG and it specifies Methionine amino acid. Hence, during translation where a tRNA binds to the mRNA codon to read it and add its corresponding amino acid, a tRNA with a complementary sequence of AUG (start codon) binds to it and carries Methionine amino acid.

3. Translocation is a process during translation whereby the mRNA-tRNA moeity moves forward in the ribosome to allow another codon to move into the vacant site for translation process to continue.

4. The sugar component of a nucelotide that makes up the nucleic acid (DNA or RNA) i.e. ribose or deoxyribose, contains an hydroxyll functional group (-OH).

5. A nucleotide consists of a pentose (five carbon) sugar, phosphate group and a nitrogenous base. The phosphate group (PO43-) is attached to the 5' carbon of the sugar molecule.

6. The free hydroxyll group (-OH) of the five carbon sugar molecule in DNA is attached to its 3' carbon.

7. Nitrogenous bases are the third component of a nucleotide, the other two being pentose sugar and phosphate group. The nitrogenous bases are four viz: Adenine, Guanine, Cytosine, and Thymine. These bases are classified into Purines and Pyrimidines based on the similarity in their structure. Adenine (A) and Guanine (G) are Purines because they possess have two carbon-nitrogen rings, as opposed to one possessed by Pyrimidines (Thymine and Cytosine).

Answer:

[tex]\Large \boxed{\mathrm{C_3 H_8 \ (g)+5O_2 \ (g) \Rightarrow 3CO_2 \ (g)+4 H_2 O \ (l)}}[/tex]

[tex]\rule[225]{225}{2}[/tex]

Explanation:

[tex]\sf C_3 H_8 +O_2 \Rightarrow CO_2 + H_2 O[/tex]

Balancing Carbon atoms on the right side,

[tex]\sf C_3 H_8 +O_2 \Rightarrow 3CO_2 + H_2 O[/tex]

Balancing Hydrogen atoms on the right side,

[tex]\sf C_3 H_8 +O_2 \Rightarrow 3CO_2 +4 H_2 O[/tex]

Balancing Oxygen atoms on the left side,

[tex]\sf C_3 H_8 +5O_2 \Rightarrow 3CO_2 +4 H_2 O[/tex]

[tex]\rule[225]{225}{2}[/tex]

The combustion reaction of propane is :C₃H₈ [tex]_(g)[/tex]+5 O₂ [tex]_(g)[/tex][tex]\rightarrow[/tex]3 CO₂[tex]_(g)[/tex] + 4 H₂O[tex]_(l)[/tex].

Combustion is defined as a high temperature exothermic reaction  between a fuel which acts as a reductant  and an oxidant which is usually atmospheric oxygen.It does not result in fire as the flame is visible only when substance which undergoes combustion vaporizes.

Activation energy must be overcome so that combustion is initiated.Solid fuels such as wood and coal initially undergo endothermal pyrolysis  which results in gaseous fuels. It is widely used in industry  and the application is based on concepts of chemistry, physics and mechanics.

It is a complex chemical process involving many steps which depend on properties of combustible material. It is a type of redox reaction.

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Answer: 18.8 g

Explanation:

To find the mass of a 23.8 mL sample, all we have to do is set up a proportion.

[tex]\frac{0.791g}{mL} =\frac{x}{23.8mL}[/tex]

[tex]18.8358=x[/tex]

x=18.8 g

We round to 18.8 because of significant figures.

Taking into account the definition of density, the mass of a 23.8 mL sample of methanol is 18.83 g.

But first you must know that density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space.

Then, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance. That is, it is the relationship between the weight (mass) of a substance and the volume it occupies.

Then, the expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:

[tex]density= \frac{mass}{volume}[/tex]

In this case:

Replacing in the definition of density:

[tex]0.791 \frac{g}{mL} = \frac{mass}{23.8 mL}[/tex]

Solving:

mass= 0.791 [tex]\frac{g}{mL}[/tex]× 23.8 mL

mass= 18.83 g

In conclusion, the mass of a 23.8 mL sample of methanol is 18.83 g.

Learn more about density:

Answer:

[tex]\mathbf{ \Delta H_{rxn} = -1936 \ kJ/mol}}[/tex]

Explanation:

The equation for the reaction is given as:

[tex]\mathbf{ CH_{4(g)} + 4 F_{2(g)} \to CF_{4(g)} + 4 HF_{(g) }}[/tex]

At standard conditions; the bond energies are as follows;

Bond       Bond Energies (kJ/mol)

C-H           413

F-F            155

C-F            485

H-F            567

[tex]\mathbf{\Delta \ H_{rxn} = \sum \Delta H ( reactant) - \sum \Delta H (product)}[/tex]

[tex]\mathbf{\Delta \ H_{rxn} = \sum [\Delta H \ 4( C-H) + \Delta H \ 4(F-F) ]- \sum[ \Delta H \ 4( C-F)+\Delta H \ 4( H-F)] (product)}[/tex]

[tex]\mathbf{\Delta \ H_{rxn} = \sum{ \Delta \ H (4*413) + \Delta \ H (4*155) - \Delta \ H (4(485)) + \Delta H (4(567) }}[/tex]

[tex]\mathbf{ \Delta H_{rxn} = \sum ({ (1652 + 620) - (1940 + 2268)})}[/tex]

[tex]\mathbf{ \Delta H_{rxn} = \sum ({2272- 4208})}[/tex]

[tex]\mathbf{ \Delta H_{rxn} = -1936 \ kJ/mol}}[/tex]

Answer:

3-bromobenzoic acid

Explanation:

In this case, we have to remember that the [tex]Br_2/FeBr_3[/tex]  is a reaction in which we add Br into the molecule an electrophilic aromatic substitution. Additionally, we have a carboxylic acid in the benzene. This carboxylic acid is an ortho director because is a deactivating group (it removes electrons from the benzene ring). With this in mind, a "Br" atom would be added in an ortho position respect to the COOH group and we will obtain 3-bromobenzoic acid.

See figure 1.

I hope it helps!

To create 3-bromobenzoic acid, a "Br" atom would be placed at an orthogonal position to the COOH group according to electrophilic aromatic substitution.

Electrophilic aromatic substitution is a type of organic reaction in which an atom or group in an aromatic ring is substituted with an electrophile. It is a fundamental reaction in aromatic chemistry that happens due to the aromatic system's high electron density.

It is an electrophilic aromatic substitution process in which Br is incorporated into the molecule. In addition, the benzene contains a carboxylic acid. Because it removes electrons from the benzene ring, this carboxylic acid functions as an ortho director. To create 3-bromobenzoic acid, a "Br" atom would be placed at an orthogonal position to the COOH group. The product is seen in the photographs below.

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Answer:

Option B is correct.

Only this option has the first underlined element with a lower oxidation number than the second amongst the options.

Explanation:

Complete Question

In which pair of substances does the first underlined atom have a lower oxidation number than the second?

A. NH₃OH⁺, NH₄⁻ (N is underlined)

B. H₂O, H₂O₂ (O is underlined)

C. SO₃, SO₄²⁻ (S is underlined)

D. HCHO, C (C is underlined)

Solution

In determination of the oxidation number of an atom in a compound, we first name the unknown oxidation number x.

Then, the total oxidation number of the atoms in the compound is equal to the charge of on the compound (or radical).

So, elements in their neutral state have no charge and no oxidation number.

A. NH₃OH⁺, NH₄⁻ (N is underlined)

N in NH₃OH⁺

Oxidation number of N = x

Oxidation number of H = +1

Oxidation number of O = -2

x + (3×+1) + (-2) + (+1) = +1

x - 3 - 2 + 1 = 1

x = +5

N in NH₄⁻

Oxidation number of N = x

Oxidation number of H = +1

x + (4×1) = -1

x + 4 = -1

x = -1 - 4 = -5

First underlined element has a greater oxidation number than the second. So, this doesn't qualify.

B. H₂O, H₂O₂ (O is underlined)

O in H₂O

Oxidation number of H = +1

Oxidation number of O = x

(2×1) + x = 0

2 + x = 0

x = -2

H₂O₂

Oxidation number of H = +1

Oxidation number of O = x

(2×1) + (2×x) = 0

2 + 2x = 0

2x = -2

x = (-2/2) = -1.

First underlined element has a lower oxidation number than the second. So, this qualifies.

C. SO₃, SO₄²⁻ (S is underlined)

S in SO₃

Oxidation number of S = x

Oxidation number of O = -2

x + (3×-2) = 0

x - 6 = 0

x = +6

SO₄²⁻

Oxidation number of S = x

Oxidation number of O = -2

x + (4×-2) = -2

x - 8 = -2

x = 8 - 2 = +6

First underlined element has the same oxidation number as the second. So, this doesn't qualify.

D. HCHO, C (C is underlined)

C in HCHO

Oxidation number of H = +1

Oxidation number of C = x

Oxidation number of O = -2

+1 + x + 1 - 2 = 0

x = 0

C in C

Oxidation number of C = x

x = 0

First underlined element has the same oxidation number as the second. So, this doesn't qualify.

Hope this Helps!!!

Answer:

d) El agua pesada contiene mas elementos

Explanation:

La diferencia fundamental entre el agua pesada y el agua ligera es que la primera tiene una proporción mayor de deuterio que la segunda. El deuterio es un ión del hidrógeno que tiene un peso atómico mayor que el hidrógeno común y corriente. Por ende, la opción D ofrece la mejor aproximación.

Answer:

....................

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Explanation:ki

Answer: An ion of a single pure element always has an oxidation number of

zero.

Explanation:

Answer:

the products of the equations is D₃O⁺ + DSO₄⁻

Explanation:

attached is the diagram which explain the reaction

reaction of the equation

D₂O +  D₂SO₄ ----------- D₃O⁺ + DSO₄⁻

Note: in phenol, OH is in an ortho and para direction

ortho and para direction indicates direction of non-hydrogen substitute on hydrocarbon ring(benzene family)

Answer:

Molarity

Explanation:

The conversion of g/mol to g/L molarity can be used. Thus, option C is correct.

The g/mol has been the amount of solute present in a mole. The g/mol has been the molecular weight of the compound.

The g/L has been the mass of solute present in a L of solution. The g/L has  the unit for density.

Molarity has been the moles of solute present in the liter of solution. It has been given as mol/L.

The product of g/mol and g/L gives the value of mol/L. Thus, to convert g/mol to g/L molarity can be used. Thus, option C is correct.

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Answer:

Sn and Ge

Explanation:

To obtain the more metallic element, we compare the group in which both elements are. Generally the element with the lower ionzation energy is he more metallic one.

Ionization energy increases fro left to right across a period. Ionization energy decreases down the group.

1. When comparing the two elements A s and S n , the more metallic element is ______based on periodic trends alone.

Sn has a lower ionization energy so it is the more metallic one.

2. When comparing the two elements G e and S b , the more metallic element is ________ based on periodic trends alone.

Ge has a lower ionizaiton energy compared to Sb. So it is more metallic element than Sb.

Answer:

* [tex]\Delta G=-101.6kJ[/tex]

* Spontaneous reaction.

Explanation:

Hello,

In this case, for the given reaction, we can compute the Gibbs free energy by using the shown below equation:

[tex]\Delta G=\Delta H-T\Delta S[/tex]

In such a way, we proceed as follows with the proper units:

[tex]\Delta G=-137.5kJ-(25+273.15)K*(-120.5\frac{J}{K}*\frac{1kJ}{1000J} )\\\\\Delta G=-101.6kJ[/tex]

Therefore, since the Gibbs free energy of reaction is less than 0, the reaction is said to be spontaneous.

Best regards.

The value of  ΔG  should be -101.6KJ.

The reaction should be Spontaneous.

Here the Gibbs free energy by using the  below equation:

So,

=-137.5K - (25 + 273.15)K * (-120.5J/K * 1KH/1000J)

= -101.6KJ

As we can see that the Gibbs free energy of reaction is less than 0, the reaction is said to be spontaneous.

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Answer:

677.7 mmHg

Explanation:

The first empirical study on the behaviour of a mixture of gases was carried out by John Dalton. He established the effects of mixing gases at different pressures in the same vessel.

Dalton's law states that,the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases present in the mixture of gases. When a gas is collected over water, the gas also contains some water vapour. The partial pressure of the gas will now be given as; total pressure of gas mixture - saturated vapour pressure of water (SVP) at that temperature.

Given that;

Total pressure of gas mixture = 692.2 mmHg

SVP of water at 17°C = 14.5 mmHg

Therefore, partial pressure of oxygen = 692.2-14.5

Partial pressure of oxygen = 677.7 mmHg

Answer:

4.96 mol/dm³

Explanation:

From the question,

Mass of NaCl that dissolved in 0.5L of water = 500-346.8 = 153.2 g.

Therefore, 145.2(1/0.5)g of NaCl will dissolve in 1 L of water

mass of NaCl that will dissolve in 1 L of water = 290.4 g/dm³

Molar mass of NaCl = 58.5 g/mol.

Solubility is the amount of substance in mol that will dissolve in 1 L or 1 dm³ Solution.

 solubility in (mol/dm³) = solubility in (g/dm³)/molar mass.

solubility in (mol/dm³) = 290.4/58.5

solubility in (mol/dm³) = 4.96 mol/dm³

Answer:

The correct answer is - Al(OH)3

Explanation:

At the point when a substance is blended in with a soluble, there are a few potential outcomes. The deciding variable for the outcome is the solubility of the substance, which is characterized as the maximum concentration of the solute. These rules help figure out which substances are solvent, and how much.

According to the 11 rules of solubility rules, the insoluble compound in water is - Al(OH)3

Answer:

Na2So4

Explanation:

If you consult a table of solubility rules, like the one below, you will see that sodium sulfate (Na2SO4) is soluble in water.

Answer:

The composition of the allow, in weigh percent, is 89.971 % Titanium, 6.026 % Aluminium and 4.003 % Vanadium.

Explanation:

The weight percentage of a element in an allow is equal to the mass of the element divided by the total mass of the allow and multiplied by 100. Then:

Titanium (Ti)

[tex]\% m_{Ti} = \frac{m_{Ti}}{m_{Ti}+m_{Al}+m_{V}}\times 100\,\%[/tex]

[tex]\%m_{Ti} = \frac{218\,kg}{218\,kg+14.6\,kg+9.7\,kg}\times 100\,\%[/tex]

[tex]\%m_{Ti} = 89.971\,\%[/tex]

Aluminium (Al)

[tex]\% m_{Al} = \frac{m_{Al}}{m_{Ti}+m_{Al}+m_{V}}\times 100\,\%[/tex]

[tex]\%m_{Al} = \frac{14.6\,kg}{218\,kg+14.6\,kg+9.7\,kg}\times 100\,\%[/tex]

[tex]\%m_{Al} = 6.026\,\%[/tex]

Vanadium (V)

[tex]\% m_{V} = \frac{m_{V}}{m_{Ti}+m_{Al}+m_{V}}\times 100\,\%[/tex]

[tex]\%m_{V} = \frac{9.7\,kg}{218\,kg+14.6\,kg+9.7\,kg}\times 100\,\%[/tex]

[tex]\%m_{Al} = 4.003\,\%[/tex]

The composition of the allow, in weigh percent, is 89.971 % Titanium, 6.026 % Aluminium and 4.003 % Vanadium.

Answer:

146 mL

Explanation:

Step 1: Write the balanced equation

H₃PO₄ + 3 NaOH ⇒ Na₃PO₄ + 3 H₂O

Step 2: Calculate the reacting moles of sodium hydroxide

119 mL of 0.315 M NaOH react.

[tex]0.119L \times \frac{0.315mol}{L} = 0.0375mol[/tex]

Step 3: Calculate the reacting moles of phosphoric acid

The molar ratio of H₃PO₄ to NaOH is 1:3. The reacting moles of H₃PO₄ are 1/3 × 0.0375 mol = 0.0125 mol.

Step 4: Calculate the reacting volume of phosphoric acid

0.0125 moles of H₃PO₄ are in a 0.0855 M solution.

[tex]0.0125 mol \times \frac{1L}{0.0855mol} \times \frac{1,000mL}{1L} =146 mL[/tex]

Answer:

Less.

Explanation:

Since there was an increase of concentration of NaOH, there would be more molecules of NaOH present. There would be no need to use the same amount of NaOH because there was already more in the solution.

The titration will require a less amount of the NaOH solution.

I will like to state here that the amount we are talking about is the volume of the NaOH solution.

Concentration is defined as mole per unit volume i.e

We can see from the formula above that the concentration is inversely proportional to the volume.

This means that a higher concentration requires a lower volume and a lesser concentration requires a higher volume.

Therefore, we can conclude that the titration will require a less amount (i.e volume) of the 0.5 M NaOH solution.

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Answer: What is required on a chemical label includes pictograms, a signal word, hazard and precautionary statements, the product identifier, and supplier identification.

Explanation:

According to Occupational Safety and Health Administration (OSHA), the following are required on the label of a chemical;

All these requirements on a chemical label helps to minimize the risk associated with such chemical substance especially if it has been marked as hazardous.

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Answer:

[tex]\mathbf{C_{10}H_8}[/tex]   ( Naphthalene )

Explanation:

Given that:

4.50 g of a Compound X is made up of Carbon , Hydron and Oxygen

It's molecular molar mass = 128 g/mol

Compound X undergoes combustion reaction and the product yield :

CO_2 with mass 15.47g and :

H_2O with mass 2.53 g

The objective is to use this information to determine the molecular formula of X.

We all know that ; number of moles = mass/molar mass

where the molar mass of H_2O is 18 g/mol

number of moles of H_2O product = 2.53 g/18 g/mol

number of moles of H_2O product = 0.1406 moles

Also; the molar mass of CO_2 product = 44 g/mol

number of moles of CO_2 product = 15.47g/ 44 g/mol

number of moles of CO_2 product =  0.3516 moles

number of moles of Compound X in the reactant side= 4.50 g /128 g/mol

number of moles of Compound X n the reactant side= 0.03516 moles

Now; number number of moles of CO_2 in reactant = 0.3516 moles/0.03516 moles

Now; number number of moles of CO_2 in reactant = 10

number of moles of H_2O reactant = 0.1406 moles × 2/0.03516

number of moles of H_2O reactant = 7.997 ≅ 8

Since we said the Compound X is known to be made of Carbon C , Hydrogen H and Oxygen O

Then the molecular formula can be written as :

[tex]\mathbf{C_{10}H_8O_{x}}[/tex]

In order to find the x; we have

128  = (12 × 10 + 1 × 8 + 16 × x)

128 = 120 + 8 + 16x)

128  =  128 + 16 x

128 - 128 = 16 x

0 = 16 x

x = 0/16

x = 0

As x = 0 ; hence there are no oxygen present in the reaction

Thus; the molecular formula of Compound X = [tex]\mathbf{C_{10}H_8}[/tex] which is also known as Naphthalene

As a skier goes down the hill:

A. Gravitational potential energy to kinetic energy

Answer:

Thrust.

Explanation:

hope this helps you :)

Answer:

thrust

Explanation:

Answer:

what is the question is it

Answer: [H2SO4] = 0.5M;

              [KOH] = 1M

Explanation: Molarity is the solution concentration defined by:

molarity = [tex]\frac{mol}{L}[/tex] or M

To determine the concentration of the mixture, find how many mols of each compound there are in the mixture:

50 mL = 0.05L

H2SO4

1 mol/L * 0.05L = 0.05mol

KOH

2mol/L * 0.05L = 0.1 mol

The mixture has a total volume of:

V = 50 + 50 = 100 mL = 0.1 L

The concentration of the resullting solutes:

[H2SO4] = [tex]\frac{0.05}{0.1}[/tex] = 0.5 M

[KOH] = [tex]\frac{0.1}{0.1}[/tex] = 1 M

Concentration of H2SO4 is 0.5M while for KOH is 1M.

Answer:

Explanation:

1 molecule contains 1 carbon atom.

9.837 * 10^24 molecules contains 9.837 * 10^24  atom of carbon.

It's a 1 to 1 ratio.

Answer:

B) hydraulics

Explanation:

Answer:

hydraulics

Explanation:

i got it right the test on apex

:DDDDDDDD

Answer:

0.583M NaCl

Explanation:

Molarity is an unit of concentration defined as the ratio between moles of solute and liters of solution.

In the puddle, the solute is sodium chloride that is dissolved in water and you have 0.449 moles of NaCl per liter of water

When the solution begins to evaporate, amount of water decreases whereas moles of NaCl remain constant.

As 23% of the water evaporates, amount of water that remains is 100-23 = 77%, that means now you have 0.449 moles of NaCl per 77% of a liter, 0.770L. The new concentration is:

0.449 moles NaCl / 0.770L =

Answer:

[tex]V_{HI}=236LHI[/tex]

Explanation:

Hello,

In this case, for the given balanced chemical reaction:

[tex]H_2(g)+I_2(g)\rightarrow 2HI(g)[/tex]

Thus, since hydrogen and hydrogen iodide are in a 1:2 mole ratio, we can easily compute the yielded volume as shown below:

[tex]V_{HI}=118LH_2*\frac{2molHI}{1molH_2} \\\\V_{HI}=236LHI[/tex]

Thus, is possible, due to the Avogadro's law which allows to relate moles and volume by a directly proportional relationship.

Regards.

Answer:

[tex]x_{acetone}=7.970x10^{-3}[/tex]

Explanation:

Hello,

In this case, for the given molarity, we can assume a volume of 1 L of solution, to obtain the following moles of acetone:

[tex]n=0.422mol/L*1L=0.422mol[/tex]

Then, with the density of solution, we can compute the mass of the solution for the selected 1-L volume basis:

[tex]m_{solution}=1L*\frac{1000mL}{1L}*\frac{0.970g}{1mL}=970g[/tex]

After that, we compute the mass of water in the solution, considering the mass of acetone (molar mass = 58.08 g/mol):

[tex]m_{H_2O}=970g-0.422molAcetone*\frac{58.08g\ Acetone}{1mol\ Acetone} =945.49gH_2O[/tex]

Next, the moles of water:

[tex]n_{H_2O}=945.49g*\frac{1molH_2O}{18gH_2O} =52.53molH_2O[/tex]

Finally, the mole fraction:

[tex]x_{acetone}=\frac{n_{acetone}}{n_{acetone}+n_{H_2O}}=\frac{0.422mol}{0.422mol+52.53mol}\\ \\x_{acetone}=7.970x10^{-3}[/tex]

Regards.