Qual número atômico do ferro?

Answer:

C₆H₆

Explanation:

Each border of the figure represents 1 atom of carbon. We have 6 borders = 6 atoms of carbon.

Each atom of carbon form 4 bonds. All the carbons are doing a double bond and a single bond with other carbons. That means are bonded 3 times. The other bond (That is not represented in the figure. See the image) comes from hydrogens. As we have 6 carbons that are bonded each 1 with one hydrogen. There are six hydrogens and the molecular formula is:

This structure is: Benzene

Answer:

The answer is d because the light is energy of wave

The frequency of a light wave can be determined

So, option D is correct one.

What is frequency?

Energy equation,

[tex]E= hv[/tex]

where,

[tex]E[/tex] = Energy of light

[tex]h[/tex]= Planks constant

[tex]v[/tex] = Frequency of wave.

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Answer:

joib

Explanation:

Answer:

Percent yield = 48.3%

Explanation:

The reaction is:

CCl₄  +  2HF → CF₂Cl₂ + 2HCl

1 mol of CCl₄ reacts with 2 moles of hydrofluoric acid in order to produce 1 mol of CF₂Cl₂ and 2 moles of hydrogen chloride.

HF is in excess, so the limiting reagent is the CCl₄.

We convert mass to moles:

32.9 g . 1mol / 153.8g = 0.214 moles

Ratio is 1:1. In conclussion: 0.0813 moles of CCl₄ can produce 0.0813 moles of CF₂Cl₂. We convert moles to mass, to determine the theoretical yield:

0.214 mol . 120.91g /mol = 25.8 g

Percent yield = (Yield produced /Theoretical yield) . 100

Percent yield = (12.5 g/ 25.8g) . 100 = 48.3%

Answer:

1.6 x 10⁻²⁴ moles

Explanation:

We have 0.984 molecules of F₂. We know that 1 mol is equal to 6.022 x 10²³ molecules. Thus, we have a conversion factor: 1 mol/6.022 x 10²³ molecules

So, we multiply the molecules of F₂ by the conversion factor to calculate the moles:

0.984 molecules x  1 mol/6.022 x 10²³ molecules = 1.6 x 10⁻²⁴ moles

Answer:

2

Explanation:

2 alkenes are formed by E2 elimination of HBr from 3-bromo -3, 4 - dimethylhexane using a strong base such as sodium methoxide

Answer:

Write a chemical equation for KOH(aq) showing how it is an acid or a base according to the Arrhenius definition.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Write a chemical equation for NH4+(aq) showing how it is an acid or a base according to the Arrhenius definition.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Explanation:

According to this theory, an acid is a substance that is a proton donor when the substance is dissolved in water.

The base is the one that gives OH- ions when dissolved in water.

KOH(aq) is a base.

Because it releases OH- ions when dissolved in water.

[tex]KOH(aq)->K^+(aq)+OH^-(aq)[/tex]

The ammonium ion is an acid.

It can donate a proton when dissolved in water.

[tex]NH_4^+(aq)->NH_3(aq)+H^+(aq)[/tex]

Answer:

[tex]n=6\ to\ n=3[/tex]

Explanation:

From the question we are told that:

Wavelength [tex]\lambda=274 *10^{-9}m[/tex]

Bohr's constant [tex]R = 1.097 × 10^7 / m (or m−1)[/tex]

Helium atom [tex]z=2[/tex]

Generally the equation for Wavelength is mathematically given by

 [tex]\frac{1}{\lambda}=Rz^2(\frac{1}{nf^2}-\frac{1}{nf^2})[/tex]

 [tex]0.083=(\frac{1}{nf^2}-\frac{1}{nf^2})[/tex]

Therefore

The Range of n fall at

 [tex]n=6\ to\ n=3[/tex]

Answer:

d. the conjugate base of the weak acid

Explanation:

The strong base (BOH) is completely dissociated in water:

BOH → B⁺ + OH⁻

The resulting conjugate acid (OH⁻) is a weak acid, so it remains in solution as OH⁻ ions.

By other hand, the weak acid (HA) is only slightly dissociated in water:

HA ⇄ H⁺ + A⁻

The resulting conjugate base (A⁻) is a weak base. Thus, it reacts with H⁺ ions from water to form HA, increasing the concentration of OH⁻ ions in the solution.

Therefore, the resulting solution will have a pH > 7 (basic).

Answer:

n = 0.0814 mol

Explanation:

Given mass, m = 35.7g

The molar mass of Tin(IV) bromate, M = 438.33 g/mol

We need to find the number of moles of bromine. We know that,

No. of moles = given mass/molar mass

So,

[tex]n=\dfrac{35.7}{438.33}\\\\n=0.0814\ mol[/tex]

So, there are 0.0814 moles of bromine in 35.7g of  Tin(IV) bromate.

Answer:

D

Explanation:

PV =nRT

So V and T are inversely proportional

Answer:

26.9 g

81%

Explanation:

The equation of the reaction is;

4 KO2(s) + 2 CO2(g) → 3 O2(g) + 2 K2CO3(s)

Number of moles of KO2= 27.9g/71.1 g/mol = 0.39 moles

4 moles of KO2 yields 2 moles of K2CO3

0.39 moles of KO2 yields 0.39 × 2/4 = 0.195 moles of K2CO3

Number of moles of CO2 = 57g/ 44.01 g/mol = 1.295 moles

2 moles of CO2 yields 2 moles of K2CO3

1.295 moles of CO2 yields 1.295 × 2/2 = 1.295 moles of K2CO3

Hence the limiting reactant is KO2

Theoretical yield = 0.195 moles of K2CO3 × 138.205 g/mol = 26.9 g

Percent yield = actual yield/theoretical yield × 100

Percent yield = 21.8/26.9 × 100

Percent yield = 81%

Answer:

0.9433g

Explanation:

Theoretical yield is defined as the mass produced assuming all reactant reacts producing the product.

Assuming the reaction is 1:1, we need to find the moles of E-stilbene (Reactant). If all reactant reacts, the moles of E-stilbene = Moles of product.

Using the molar mass of the product we can find the theoretical yield as follows:

Moles E-stilbene:

0.50g * (1mol/180.25g) = 0.00277 moles = Moles Product

Mass Product = Theoretical yield:

0.00277 moles * (340.058g/mol) = 0.9433g

Answer:

a) The mechanism of the reaction is the Elimination Bimolecular or E2.

b) Steps for the mechanism of this reaction is given as follows,

c) Reaction rate = K[Organic compound][[tex]NaoCH_{2} CH_{3}[/tex]].  

Explanation:

a) The mechanism of the reaction is the Elimination Bimolecular or E2.

c) This is an E2 reaction, so it depends on the concentration of both substrate and reactant. If we increase the concentration of [tex]NaoCH_{2} CH_{3}[/tex], the reaction rate will be increased.

Reaction rate = K[Organic compound][[tex]NaoCH_{2} CH_{3}[/tex]].  

b) Steps for the mechanism of this reaction is given as follows,

Answer:

Hope it is helpful to you

Answer:

Certain ketones such as fructose can be oxidized by Benedict's reagent under basic conditions to form what type of compound

Explanation:

Benedict's solution is a mixture of copper sulfate, anhydrous sodium carbonate, and sodium citrate.

In presence of mild reducing agents, Cu(II) ion in Benedict's solution becomes the Cu(I) ion.

Fructose has an alpha-hydroxy ketone group.

It undergoes tautomerism and forms alpha-hydroxy aldehyde which gives a positive test with Benedict's reagent.

During this test, aldehydes will be converted into carboxylic acids.

The reaction of fructose with Benedict's reagent is shown below:

Explanation:

For this question, we apply the equation: Q = mCp AT Where m is the mass of the substance, Cp

is its specific heat capacity and AT is the

temperature change. Q = 896 x 0.45 x (5-94)

Q = -35884.8 Joules

So about -36 kilojoules of heat is released.

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Answer:

Option A (0.043 g) is the correct answer.

Explanation:

Given:

= 43 mg

As we know,

[tex]1 \ mg = \frac{1}{1000} \ g[/tex]

then,

⇒ [tex]43 \ mg = \frac{43}{1000} \ g[/tex]

              [tex]= 0.043 \ g[/tex]

Thus, the above is the correct alternative.

Answer:

A molecule of sucrose (C12H22O11) has 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.

Explanation:

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There are   1.4376  × 10²⁶ carbon atoms in 15 lbs of sugar (C12H22O11).

From the given information,

Using the standard conversion method;

1 lbs = 453.592 gram

∴

15 lbs = (453.592 gram × 15 lbs/1 lbs)

= 6803.88 grams

Now, we will need to determine the molar mass of the sugar compound C12H22O11.

Molar mass of C12H22O11 =  (12 × 12) +(1 × 22) + (16 × 11)

Molar mass of C12H22O11 = 144 + 22 + 176

Molar mass of C12H22O11 = 342 g/mol

Using the relation:

[tex]\mathbf{Number \ of \ moles = \dfrac{mass}{molar \ mass}}[/tex]

Number of moles = [tex]\dfrac{6803.88 }{ 342}[/tex]

Number of moles of C12H22O11   = 19.894 moles

Since we've known the number of moles present in C12H22O11, the next thing to do is determine the number of molecules of sugar by using Avogadro's constant:

i.e.

number of moles of sugar = [tex]19.894 moles \times \dfrac{6.023 \times 10^{23}}{mol}[/tex]

= 1.198 × 10²⁵ molecules of C12H22O11

Now to determine the number of carbon atoms in 15 lbs, we have:

= number of carbon atoms × amount of molecules

= 12 × 1.198 × 10²⁵ carbon atoms

= 1.4376  × 10²⁶ carbon atoms

Therefore, we can conclude that there are  1.4376  × 10²⁶ carbon atoms present in 15 lbs of sugar, C12H22O11

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Answer is 9

pKb=−logK

b=−log10^-5=5

pOH=pKb+log[acid]*[salt]

Substitute values in the above expression.

pOH=5+log0.1*0.1=5

Hence, the pH of the solution is pH=14−pOH=14−5=9

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Answer:

Mass of sodium produced = 2.74 × 10⁵ g of Na

Mass of chlorine produce = 4.24 × 10⁵ g of Cl₂

Explanation:

In the electrolysis of molten NaCl as described above, the quantity of charge used is given by the formula, Q = I × t

Where I isnthe current passed in amperes and t is time in seconds.

Q = 4.0 × 10⁴ A × (8 × 60 × 60) s = 1.152 × 10⁹ C

Equation for the discharge of sodium is; Na+ + e- ---> Na (s)

One mole of electrons is required to discharge one mole of Na

One mole of electron = 1 faraday = 96500 C

One mole of Na has a mass of 23 g

96500 C produces 23 g of Na

1.152 × 10⁹ C will produce 23 g × 1.152 × 10⁹ C / 96500 C = 2.74 × 10⁵ g of Na

Equation for the discharge of chlorine gas is; 2 Cl- ---> Cl₂(g) + 2e-

Two mole of electrons are required to discharge one mole of chlorine gas

Two moles of electron = 2 faraday = 2 × 96500 C = 193000

One mole of Cl₂ has a mass of 71 g

193000 C produces 71 g of Cl₂

1.152 × 10⁹ C will produce 71 g × 1.152 × 10⁹ C / 193000 C = 4.24 × 10⁵ g of Cl₂

The amount of Na produced is 274551 g and the amount of Cl₂ produced is 423763.5 g.

Current passed through the cell = [tex]4.0\times10^4 A[/tex]

Time = 8 Hours

We have to calculate the amount of Na and [tex]Cl_2[/tex] produced in 8 hours in the downs cell.

The Downs process is an electrochemical method for the commercial preparation of metallic sodium, in which molten NaCl is electrolyzed in a special apparatus called the Downs cell.

The total charge passed through the cell is calculated by the given formula as

Charge(Q) = Current(I) × time(t)

Q = [tex]4.0\times10^4 A \times t[/tex]

[tex]t = 8 \times 60\times 60[/tex] sec

t = 28800 sec

Q = [tex]4.0\times10^4 A \times 28800[/tex] sec

Q = [tex]115200\times 10^4 A\ sec[/tex]

We know that, Ampere = Coulombs per sec

Q = [tex]115200\times 10^4\ C[/tex]

1 mol of electrons  96500 C charge

Therefore, the number of mols of electrons carries this [tex]115200\times 10^4\ C[/tex] charge = [tex]\frac{115200\times10^4}{96500}[/tex] = 1.1937 × 10⁴ = 11937 mol electrons

In the Down's cell

Half cell reactions are:

Reduction half-reaction: [tex]2Na^+(aq)+2e^- \to 2Na(s)[/tex]

Oxidation half-reaction: [tex]2Cl^-(aq)\to Cl_2(g) + 2e^-[/tex]

We know that no. of moles = [tex]\frac{given \ mass}{molar \ mass}[/tex]

Molar mass of Na = 23 g/mol

The mass of Na formed = 11937 mol × 23 g/mol = 274551 grams

The molar mass of Cl₂ = 71 g/mol

The mass of Cl₂ = [tex]\frac{11937}{2}\times 71 = 423763.5 \ grams[/tex]

Hence, the amount of Na produced is 274551 g and the amount of Cl₂ produced is 423763.5 g.

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Answer:

It predicts whether or not a reaction will be spontaneous.

Explanation:

The equation;

∆G= ∆H - T∆S enables us to obtain the Gibbs free energy of a chemical process.

The Gibbs free energy value tells us whether a chemical process will be spontaneous or not.

When;

∆G>0 the reaction is not spontaneous

∆G=0 the reaction is at equilibrium

∆G<0 the reaction is spontaneous

Answer:

Hindi ko po ma gets sinasabi nyu pwedeng pakiayus

Answer:

SN1 substitution reaction

Explanation:

cyclohexanol is a secondary alkanol. The mechanism of acid catalysed dehydration of cyclohexanol involves the protonation of the -OH group.

This is followed by loss of water which is a good leaving group. At this stage, a proton could be abstracted to yield cyclohexene by E1 mechanism or an SN1 substitution reaction may occur to yield Cyclohexyl chloride.

The both reactions are equally likely.

Answer:

4.33 L

Explanation:

Assuming ideal behaviour and that all 0.300 moles of gas reacted, we can solve this problem using Avogadro's law, which states that at constant temperature and pressure:

Where in this case:

We input the given data:

And solve for V₂:

Answer:

10.5 × 10^5 M

Explanation:

E°cell = E°cathode - E°anode

E°cell = 0.85 - (-0.74) = 1.59 V

From Nernst's equation;

Ecell = E°cell - 0.0592/n log Q

1.499 = 1.59 - 0.0592/6 log [Cr^3+]/6.35x10^-4

1.499 - 1.59 = - 0.0592/6 log [Cr^3+]/6.35x10^-4

-0.091 = -0.00987 log [Cr^3+]/6.35x10^-4

-0.091/ -0.00987 = log [Cr^3+]/6.35x10^-4

9.22 = log [Cr^3+]/6.35x10^-4

Antilog (9.22) = [Cr^3+]/6.35x10^-4

1.66 × 10^9 = [Cr^3+]/6.35x10^-4

[Cr^3+] = 1.66 × 10^9 × 6.35x10^-4

[Cr^3+] = 10.5 × 10^5 M

Answer:

b. glass and charcoal

Explanation:

Step 1: Given data

Step 2: Determine which material will float in molten lead

Density is an intrinsic property of matter. Less dense materials float in more dense materials. The materials whose density is lower than that of lead and will therefore float on it are glass and charcoal.

Answer:

5.0molO

Explanation:

To find the moles of oxygen in 2.5 moles of caffeine, we will first research caffeine's molecular formula: C8H10N4O2. From the molecular formula, we can see there are 2 oxygen atoms in every 1 molecule of C8H10N4O2.We can therefore multiply by the following mole ratio to get the moles of oxygen.

2.5molC8H10N4O2×2molO/1molC8H10N4O2 = 5.0molO.