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marta [7]
3 years ago
12

Sub-atomic particles like negatively charged electrons, positively charged

Chemistry
1 answer:
leonid [27]3 years ago
8 0

Answer:

neutral

Explanation:

There are three basic subatomic particles. These are;

  1. Protons (positively charged)
  2. Electrons (negatively charged)
  3. Neutrons (neutral)

A neutron has no charge unlike the proton and the electron. It is present in the nucleus and contributes to the mass of the atom.

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How many atoms of hydrogen combine with one carbon atom to form methane
bonufazy [111]

Answer:four hydrogen atoms

Explanation:

4 0
3 years ago
A sample contains 6.73 g of Na2CO3 in water to make a total of 250.0 mL of solution. What is the molarity of sodium carbonate in
wlad13 [49]

Answer:

Molarity of Na₂CO₃ = 0.25M

% mass = 2.69

Explanation:

Molarity means mole of solute in 1L of solution

Molar mass of solute (Na₂CO₃) = 105,98 g/m

Moles = mass / molar mass → 6.73 g / 105.98 g/m = 0.0635 m

Mol/L = [M]

0.0635 mol/0.250L = 0.25M

Density of solution = Solution mass / Solution volume

1 g/ml = Solution mass / 250 mL → Solution mass is 250g

% mass will be:

In 250 g of solution we have 6.73 g of solute

in 100 g of solution we have (100 . 6.73)/250 = 2.69

6 0
3 years ago
Read 2 more answers
Which of these is the best definition of a fuel cell?
oksian1 [2.3K]

Answer:

A voltaic cell that uses the oxidation of a fuel to produce electricity  

Explanation:

A fuel cell is a voltaic cell that converts the chemical energy of a fuel and an oxidizing agent into electricity.

A. is wrong. This definition is so broad that it could include a candle in a cup.

C is wrong. The batteries in flashlights and cell phones are not fuel cells.

 

3 0
3 years ago
B. For the following questions, use the reaction NO2(g) N2(g) + O2(g), with ΔH = –33.1 kJ/mol and ΔS= 63.02 J/(mol·K).
Troyanec [42]

Answer:

I. Kindly, see the attached image.

II. The reaction is exothermic.

III. - 51.88 kJ/mol.

IV. The reaction is spontaneous.

Explanation:

I. Draw a possible potential energy diagram of the reaction. Label the enthalpy of the reaction.

  • Since the sign of ΔH is negative, the reaction is exothermic reaction.

In an exothermic reaction, the energy of the reactants is higher than that of the products.

<u><em>Kindly see the attached image to show you the potential energy diagram of the reaction.</em></u>

     

<em>II. Is the reaction endothermic or exothermic? Explain your answer.</em>

  • The reaction is exothermic reaction.
  • The sign of ΔH indicates wither the reaction is endothermic or exothermic one:

If the sign is positive, the reaction is endothermic.

If the sign is negative, the reaction is exothermic.

Herein, <em>ΔH = - 33.1 kJ/mol, </em>so the reaction is exothermic.

<em>III. What is the Gibbs free energy of the reaction at 25°C? </em>

∵ ΔG = ΔH - TΔS.

Where, ΔG is the Gibbs free energy change (J/mol).

ΔH is the enthalpy change (ΔH = - 33.1 kJ/mol).

T is the temperature (T = 25°C + 273 = 298 K).

ΔS is the entorpy change (ΔS = 63.02 J/mol.K = 0.06302 J/mol.K).

<em>∴ ΔG = ΔH - TΔS</em> = (- 33.1 kJ/mol) - (298 K)(0.06302 J/mol.K) = <em>- 51.88 kJ/mol.</em>

IV. Is the reaction spontaneous or nonspontaneous at 25°C?

The sign of ΔG indicates the spontaneity of the reaction:

If ΔG < 0, the reaction is spontaneous.

If ΔG = 0, the reaction is at equilibrium.

If ΔG > 0, the reaction is nonspontaneous.

Herein, <em>ΔG = - 51.88 kJ/mol, </em>so the reaction is spontaneous.

7 0
3 years ago
Draw the structure of the compound C9H10O2 that might exhibit the 13C-NMR spectrum below. Impurity peaks are omitted from the pe
zhenek [66]

Complete question

Draw the structure of the compound C_{9}H_{10}O_{2} that exhibits the ^{13}C-NMR spectrum shown on the first uploaded image(on the second and third uploaded image is closer look at the ^{13}C-NMR spectrum ) . Impurity peaks are omitted from the peak list. The triplet at 77 ppm is CDC_{l3}.

Answer:

The structure that might exhibit the ^{13}C-NMR  spectrum is shown on the fifth uploaded image

Explanation:

    In order to get a good understanding of the answer above we need to know that

• Proton NMR spectrum: proton NMR spectroscopy is one of the techniques, which is useful to predict the structure of the compound.

• In ^{\rm{1}}{\rm{H NMR}}  spectroscopy, peaks are observed at the point where the wavelength of proton nuclei matched to substance nuclei wavelength.

• In same manner there are other spectroscopies are present like ^{{\rm{13}}}{\rm{C NMR}}

, IR and mass spectroscopy.

• Infrared spectroscopy is used to determine the functional groups present in a compound.

• Infrared bands observed when there is change in dipole moment occurs between the atoms. Infrared bands describe about the bond stretches, which causes due to the dipole moment present in the molecule.

Fundamentals

Double bond equivalence: number of double bonds or number of rings in the structure can be calculated by using double bond equivalence formula.

DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})

Where,

N_{c} = number of carbon atoms

N_{H}= number of hydrogen atoms

N_{Cl} = number of chlorine atoms

N_{N}=number of nitrogen atoms

The table for the ^{{\rm{13}}}{\rm{C NMR}} is shown on the fourth uploaded image

Molecular formula of the compound is {{\rm{C}}_9}{{\rm{H}}_{{\rm{10}}}}{{\rm{O}}_{\rm{2}}}

Double bond equivalence of the compound is calculated below.

  DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})

Where,

N_{c} = 9

N_{H}= 10

N_{Cl} = 0

N_{N}= 0

                    DBE = N_{c} + 1 - (\frac{(10+0) -0}{2}})

                    DBE =5

Therefore, the compound has five double bonds, which indicating that there is chance of getting aromatic rings too.

Note:

Double bond equivalence is calculated as 5 which indicates that there are 5 double bond (may rings) in the structure of the compound.

Double bond equivalence is calculated by using this formula.

           DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})

13C NMR data of the compound is explained below.

1.A peak at 166.5 ppm, which indicates the presence of ester group

2.Peaks at 132.7, 130.5, 129.5, 128.2 ppm (aromatic carbons) are indicating a mono substituted aromatic ring

3.A peak at 60.9 ppm means methylene group attached to oxygen atom

4.A peak at 14.3 ppm, which indicates the presence of methyl group

According to this data and the using the double bond equivalence, structure of the compound shown on the fifth uploaded image .

Note:

According to given spectral data, structure of the compound has been predicted. It is clear that; -ester functional group is present in the structure because there is a peak at 166.5ppm. According to given proton ^{13}C NMR data, above structure has been drawn. Therefore, the compound is ethyl benzoate.

7 0
4 years ago
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