Devise a detailed experimental procedure to purify ~ 20 grams of benzoic acid that is contaminated with sodium chloride. Justification of the steps (including solubility calculations) that are included in the procedure. In other words, explain why the steps are being included.

Answer:

0.

Explanation:

All elements existing on their own in their free states has an oxidation number of 0.

The oxidation number of Se in Se8 is 0. The element Se in its elemental state has an oxidation number of 0.

Chemistry uses the idea of oxidation number, also known as oxidation state, to describe the charge that an atom seems to have when it forms a compound or ion. It is a notion that aids in our comprehension of how electrons are distributed within a molecule or ion. Oxidation numbers can be used to balance chemical equations and identify the many kinds of chemical reactions that may take place. For a better understanding of the reactivity and bonding of various elements in compounds, they offer insights into the transfer or sharing of electrons between atoms. Se in Se8 has an oxidation number of 0. Se has an oxidation number of 0 when it is in its purest form.

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Answer:

a lower temperature to liquefy

Explanation:

Answer:

I would put A

Explanation:

A new substance is produced as a result of a chemical reaction in which bonds between the molecules of the reactant and product are broken and new bonds are formed. Here the products are Al₂O₃ and Fe. The correct option is A.

Chemical reactions are interactions between two or more molecules that result in the production of new products. Products, as opposed to reactants, are compounds that result from an interaction between two other substances.

The reactants are on the left, while the products that are created are on the right. A one-headed or two-headed arrow connects the reactants and products.

Thus the correct option is A.

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Answer:

1.5 L  

Explanation:

If the gas is contained in a steel tank, the volume will remain constant when the temperature changes.

The volume will be 1.5 L.

Answer:

See explanation

Explanation:

For the first part of the question, we have to check the chiral carbons in 4-methyl-1,2-cyclohexanediol. In this case carbons, 1 and 2 are chiral, if we have 2 chiral carbons we will have 4 isomers. We have to remember that formula 2^n in which "n" is the number of chiral carbons, so:

2^n = 2^2 = 4 isomers

And the isomers that we can have are:

1) (1R,2S)-4-methylcyclohexane-1,2-diol

2) (1S,2S)-4-methylcyclohexane-1,2-diol

3) (1S,2S)-4-methylcyclohexane-1,2-diol

4) (1S,2R)-4-methylcyclohexane-1,2-diol

See figure 1

For the second part of the question, we have to remember that the oxidation with [tex]OsO_4[/tex] is a syn addition. In other words, the "OHs" are added in the same plane. In this case, we have the methyl group with a wedge bond, so the "OH" groups will have a dashed bond due to the steric hindrance. Due to this we only can have 1 isomer ((1S,2R,4S)-4-methylcyclohexane-1,2-diol). Finally, on this molecule, we dont have any symmetry planes (this characteristic will cancel out the optical activity), so the product of this reaction has optical activity.

See figure 2

I hope it helps!

Answer:

[tex]Pb(CO_{3})_{2} \\Pb(NO_{3})_{4} \\FeCO_{3}\\Fe(NO_{3})_{2}[/tex]

Explanation:

[tex]Pb^{4+}(CO_{3}^{2-})_{2} --->Pb(CO_{3})_{2} \\Pb^{4+} (NO_{3}^{-})_{4} --->Pb(NO_{3})_{4} \\Fe^{2+} CO_{3}^{2-} --->FeCO_{3}\\Fe^{2+} (NO_{3}^{-})_{2}--->Fe(NO_{3})_{2}[/tex]

Answer:

[A] = 1.438M = 1.4M (Two s.f)

Explanation:

Rate constant, k =  0.00317

Initial Concentration, [A]o = 1.44M

Final Concentration, [A] = ?

Time, t = 0.240 s

Since this is a second order reaction, the formula for this is given as;

1 / [A] = 1 / [A]o + kt

1 / [A] = 1 / 1.44 + (0.00317 * 0.240)

1 / [A] = 0.6944 + 0.0007608

1 / [A] = 0.6952

[A] = 1.438M = 1.4M (Two s.f)

Answer:

33.3% of Sn in the sample

Explanation:

The addition of SO₄⁻ ions produce the selective precipitation of Pb²⁺ to produce PbSO₄.

Moles of PbSO₄ (molar mass 303.26g/mol) in 2.93g are:

2.93g ₓ (1mol / 303.26) = 9.66x10⁻³ moles PbSO₄ = Moles Pb²⁺.

As molar mass of Pb is 207.2g/mol, mass in 9.66x10⁻³ moles of Pb²⁺ is:

9.66x10⁻³ moles of Pb²⁺ ₓ (207.2g / mol) = 2.00g of Pb²⁺

As mass of the sample is 3.00g, mass of Sn²⁺ is 3.00g - 2.00g = 1.00g

And the percentage of Sn in the sample is:

1.00g / 3.00g ₓ 100 =

Answer:

The lewis structure of the compounds can be drawn by making the skeleton of the molecule first. Then the different atoms are arranged and the electrons are arranged in their bonding pattern. The lone pair of the atoms, which are not involved in the bonding are represented by the dots.

So the lewis structures of both the compound methyl mercaptan has been in the attached image:

Spelling of methyl metcaptain is wrong, the correct spelling is methyl mercaptan.

Answer:

Methyl mercaptan is also known as Methanethiol with the chemical formula  CH3SH and it is an organosulfur compound.

For lewis structure of methyl mercaptan (CH3SH), there are total 14 valence electrons. Four hydrogen atoms has one valence electron each, carbon has four valence electrons and sulfur has six valence electrons. Carbon form one bond with three hydrogen atoms by sharing one electron with each, carbon form one single bond with sulfur atom by sharing one electron with it and sulfur form one single bond with hydrogen. Sulfur left with four unpair electrons.

Answer:

0.623 M

Explanation:

Step 1: Given data

Step 2: Calculate the percent by volume (%m/v)

We will use the following expression.

[tex]\%m/v = \%m/m \times \rho = 7.00\% \times 1.071g/mL = 7.50g\%mL[/tex]

Step 3: Calculate the molarity

7.50 g of magnesium sulfate are dissolved in 100 mL of the solution. The molarity is:

[tex]M = \frac{7.50g}{120.37g/mol \times 0.100L } = 0.623 M[/tex]

Answer:

Exothermic interractive are the following: NaOH, KOH, CaCl₂

Endothermic interactive are the following: NaCl, NH₄NO₃, NaNO₃

Explanation:

NaOH, KOH, and CaCl2 are exothermic reactants. NaCl, NH4NO3, and NaNO3 are endothermic interacting substances.

Chemical processes that can release or absorb energy are referred to as endothermic. In endothermic reactions, more energy is used when bonds in the reactants are broken than is released when new bonds are formed in the products.

When the temperature of the an isolated system drops while the surroundings of the a non-isolated system warm up, this is known as an endothermic response. The heat of reaction is generally positive in endothermic processes (qrxn>0).

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Answer:

1.25 g.

Explanation:

5% or 25 g

= 0.05 * 25

= 1.25 g (answer).

Answer:

MgO

Explanation:

The following data were obtained from the question:

mass of crucible and cover + magnesium metal = 33.741 g

mass of crucible and cover = 33.5 g

mass of crucible and cover + magnesium oxide = 33.899 g

Next, we shall determine the mass of magnesium metal. This can be obtained as follow:

mass of crucible and cover + magnesium metal = 33.741 g

mass of crucible and cover = 33.5 g

Mass of magnesium metal =..?

Mass of magnesium metal = (mass of crucible and cover + magnesium metal) – (mass of crucible and cover)

Mass of magnesium metal = 33.741 – 33.5

Mass of magnesium metal = 0.241g

Next, we shall determine the mass of magnesium oxide. This can be obtained as follow:

mass of crucible and cover + magnesium oxide = 33.899 g

mass of crucible and cover = 33.5 g

Mass of magnesium oxide =?

Mass of magnesium oxide = (mass of crucible and cover + magnesium oxide) – (mass of crucible and cover)

Mass of magnesium oxide = 33.899 –. 33.5

Mass of magnesium oxide = 0.399g

Next, we shall determine the mass of oxygen. This can be obtained as follow:

Mass of magnesium oxide = 0.399g

Mass of magnesium metal = 0.241g

Mass of oxygen =..?

Mass of oxygen = (Mass of magnesium oxide) – (Mass of magnesium metal)

Mass of oxygen = 0.399 – 0241

Mass of oxygen = 0.158g

Now, we can obtain the empirical formula for the magnesium oxide as follow:

Mg = 0.241g

O = 0.158g

Divide by their molar mass

Mg = 0.241 / 24 = 0.01

O = 0.158 / 16 = 0.0099

Divide by the smallest

Mg = 0.01 / 0.0099 = 1

O = 0.0099 / 0.0099 = 1

Therefore, the empirical formula for the magnesium oxide is MgO

Answer:

22.29%

Explanation:

Percent yield = experimental yield / theoretical yield * 100

= 12.89 / 57.82 * 100 = 22.29%

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Actually Welcome to the Concept of the Rate Constant.

Here, the "K" is the Rate Constant.

so the ANSWER IS C.) 0.5

The rate of constant is 0.5.

The answer is option C.

To determine the fee regulation from a desk, you have to mathematically calculate how differences in molar concentrations of reactants affect the response charge to parent out the order of every reactant. Then, plug in values of the response charge and reactant concentrations to discover the particular rate constant.

The particular rate constant is the proportionality steady touching on the rate of the reaction to the concentrations of reactants. The fee regulation and the unique charge constant for any chemical response need to be decided experimentally. The price of the fee regular is temperature-established.

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Answer:

The incorrect statement from the options is OXIDATION IS A "GAIN" OF ELECTRONS

Explanation:

Oxidation in a redox reaction is the loss of electrons. It is also the increase in the oxidation states of an atom or ion or atoms in a molecule. A redox reaction is a type of chemical reaction in which there is a transfer of electrons from an atom or ion to another resulting in a change in oxidation states of the substances involved. The reducing agent in the reaction is undergoes oxidation by losing electrons while the oxidating agent is reduced that is it gains electrons at the end of the reaction. The atom or ion from which electron is lost is said to be oxidized while the other atom or ion involved in the reaction is reduced.

Oxidation is also the combination with O atoms and it is always accompanied by reduction because oxidation forms a half of the whole redox reaction. A substance cannot be oxidized except it has reduced another substance by losing electrons to it.

Answer:

On the off chance that the wavelength(λ) maximum worth has been changed to 520 nm from 470 nm on the spectrophotometer, less light would be absorbed and in this way %T would be higher than the one found at 470 nm. The wavelength utilized at 520 nm isn't adequate for the excitation and consequently lesser light is absorbed by the arrangement.

Explanation:

A spectrophotometer is an analytical equipment used to quantitatively gauge the transmission(passage) or impression of visible light, UV light or infrared light through a medium.

Transmittance (τ) is the ratio of the brilliant or luminous flux at a given wavelength that is transmitted to that of the incident radiation.

where, Keq is the equilibrium constant.

On the off chance that the wavelength(λ) has been changed to 520 nm from 470 nm on the spectrophotometer, less light would be absorbed and in this way %T would be higher than the one found at 470 nm.

A spectrophotometer is an analytical equipment used to quantitatively gauge the transmission(passage) or impression of visible light, UV light or infrared light through a medium. Transmittance (τ) is the ratio of the brilliant or luminous flux at a given wavelength that is transmitted to that of the incident radiation. The wavelength utilized at 520 nm isn't adequate for the excitation and consequently lesser light is absorbed by the arrangement. As the concentration goes up, more radiation is absorbed and the absorbance goes up. Therefore, the absorbance is directly proportional to the concentration.

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Answer: The pH of the solution is 11.2

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in ml

moles of [tex]Ba(OH)_2[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{0.867g}{171g/mol}=0.00507mol[/tex]         (1g=1000mg)

Now put all the given values in the formula of molality, we get

[tex]Molarity=\frac{0.00507\times 1000}{170}[/tex]

[tex]Molarity=0.0298[/tex]

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

[tex]pOH=-\log [OH^-][/tex]

[tex]Ba(OH)_2\rightarrow Ba^{2+}+2OH^{-}[/tex]

According to stoichiometry,

1 mole of [tex]Ba(OH)_2[/tex] gives 2 mole of [tex]OH^-[/tex]

Thus 0.0298 moles of [tex]Ba(OH)_2[/tex] gives =[tex]\frac{2}{1}\times 0.0298=0.0596[/tex] moles of [tex]OH^-[/tex]

Putting in the values:

[tex]pOH=-\log[0.0596]=2.82[/tex]

[tex]pH+pOH=14[/tex]

[tex]pH=14-2.82[/tex]

[tex]pH=11.2[/tex]

Thus the pH of the solution is 11.2

Answer:

1.30atm

Explanation:

P1/T1 = P2/T2

1.07/393 = P2/478

Answer: the first one is correct

Explanation:

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Answer:

Molecules = 7.5 × 10²³ molecules

Explanation:

Given:

Moles = 1.25 mol

Avogadro's No. = [tex]N_{A}[/tex] = 6.022 * 10²³

Required:

Molecules = ?

Formula:

Molecules = Moles × [tex]N_{A}[/tex]

Solution:

Molecules = 1.25 × 6.022 × 10²³

Molecules = 7.5 × 10²³ molecules

Answer:

Wavelength, λ  = 6.7 x 10^-11 m

Explanation:

Frequency and wavelength are inversely proportional to each other.

In this problem;

f =  4.5 x 10^18 Hz

wavelength, λ = ?

Speed of light, c = 3 x 108 m/s.

These variables are related by the following equation;

c = λ * f

Making λ subject of focus, we have;

λ = c / f

λ = 3 x 10^8 / 4.5 x 10^18

λ  = 0.67 x 10^-10

λ  = 6.7 x 10^-11 m

Answer:

pH = 9.58

Explanation:

First of all, we need to determine the molarity of the solution.

We determine the molar mass of morphine:

12g/m . 17 + 1 g/m . 19 + 14 g/m + 16 g/m . 3 = 285.34 g/m

molar mass g/m, is the same as mg/mm

25 mg . 1 mmol / 285.34 mg = 0.0876 mmoles / 100 mL = 8.76×10⁻⁴ M

In diltuted solution, we must consider water.

Mass balance for morphine = [Morphine] + [Protonated Morphine]

8.76×10⁻⁴ M = [Morphine] + [Protonated Morphine]

As Kb is too small, I can skipped, the [Protonated Morphine]

8.76×10⁻⁴ M = [Morphine]

In the charge balance I will have:

[OH⁻] = [H⁺ morphine] + [H⁺]

Let's go to the Kb expression

Morphine + H₂O  ⇄  MorphineH⁺  +  OH⁻        Kb

Kb = [MorphineH⁺]  [OH⁻] / [Morphine]

Kb = [MorphineH⁺]  [OH⁻] / 8.76×10⁻⁴ M

So now, we need to clear [MorphineH⁺] to replace it in the charge balance

Kb  . 8.76×10⁻⁴ M / [OH⁻] = [MorphineH⁺]

Now, the only unknown value is the [OH⁻]

[OH⁻] = Kb .  8.76×10⁻⁴ M / [OH⁻]  + Kw/[OH⁻]

Remember that Kw = [H⁺] . [OH⁻]

[H⁺] = Kw/[OH⁻]

[OH⁻]² = 1.62×10⁻⁶ . 8.76×10⁻⁴ + 1×10⁻¹⁴

[OH⁻] = √(1.62×10⁻⁶ . 8.76×10⁻⁴ + 1×10⁻¹⁴)

[OH⁻] = 3.76×10⁻⁵  →  - log [OH⁻] = pOH = 4.42

pH = 14 - pOH  →  14 - 4.42 = 9.58

Answer:

Water is used as a solvent.

Explanation:

In order to purify the new molecule, recrystallization occurs in which the new molecule should be added in water and heated the water in order to increase the solubility of the solution. The new molecule dissolve in water while the impurity remains undissolved which can be removed from the solution and then remain the solution to be cold down and the new molecule will again undissolved and the molecule can be extracted without any impurities. We use water instead of ethanol due to lower solubility.

Combining quantum theory with wave motion of atomic particles is: Wave Mechanics

Answer:

(a) [tex]\% H_2O=10.65\%[/tex]

(b) [tex]\% H_2O=32.2[/tex]

Explanation:

Hello.

For this questions we must consider the ratio of the molar mass of water to  hydrated compound molar mass as shown below:

(a) In this case, we can consider that inside the manganese (II) sulfate monohydrate, whose molar mass is 169.02 g/mol, there is one water molecule that has a molar mass of 18 g/mol, for which the theoretical percentage of water is:

[tex]\% H_2O=\frac{18g/mol}{169.0g/mol} *100\%\\\\\% H_2O=10.65\%[/tex]

(b) In this case, we can consider that inside the manganese (II) sulfate tetrahydrate, whose molar mass is 223.1 g/mol, there are four water molecules that have a molar mass of 4*18 g/mol, for which the theoretical percentage of water is:

[tex]\% H_2O=\frac{4*18g/mol}{223.1g/mol} *100\%\\\\\% H_2O=32.27\%[/tex]

Best regards.

Answer:

Mechanical to Heat

explanation:

The wood itself can make mechanical energy but when it's on fire it makes heat energy

Answer: Chemical to heat and light

Explanation: The energy transforms from chemical energy to heat and light energy. Because when the candle burns a chemical reaction occurs and produces heat and light.

Answer:

A, B and C are compounds

Explanation:

First of all, I need to establish that when carbon is burnt in excess oxygen, carbon dioxide is obtained as shown by this equation; C(s) + O2(g) ----> CO2(g).

Looking at the presentation in the question, A was said to be heated strongly and it decomposed to B and C. Only a compound can decompose when heated. Elements can not decompose on heating. Secondly, compounds usually decompose to give the same compounds that combined to form them. Compounds hardly decompose into their constituent elements.

Again from the information provided, the compound A is a white solid. This is likely to be CaCO3. It decomposes to give another white solid. This may be CaO and the gas was identified as CO2.

Hence;

CaCO3(s)--------> CaO(s) + CO2(g)

Answer:

Option (B) 3.

Explanation:

In the model represented above, the two extreme represent carbon atoms since no other group are attached to it. The joint at the middle also represent carbon atom.

Thus, we can write a more simplify illustration for the model above as

C—C—C

From the above illustration, we can see that the model contains 3 carbon atom.

Answer:

The third reaction

(2NaOH + NiCL2 ---> 2NaCl + Ni(OH)2)

Explanation:

By definition, a precipitation reaction refers to the formation of an insoluble salt when two solutions containing soluble salts are combined.

(Source: lumenlearning)

From the 4 options, we can eliminate the first and second one immediately because there is no formation of an insoluble salt.

Then, the last one can also be eliminated because even though there is insoluble solid formed, but it is not a salt, and, the reactants are not solutions too. In fact, the last one is a displacement reaction. A more reactive metal displaces a less reactive metal to form an ion.

Since the third reaction matches the definition of precipitation reaction, this is the answer.

Answer:

The total surface area of these N spherical droplets is 4.4929 m²

Explanation:

From the information given :

assuming that :

30 cm³ of gasoline is atomized into N spherical droplets &

each with a radius of 2.0 × 10−5 m

We are tasked to determine the total surface area of these N spherical droplets

We all known that:

[tex]1 \ cm^3 = 10 ^{-6} m^3[/tex]

Therefore

[tex]30 \ cm^3 = 30 * 10 ^{-6} m^3 = 3 *1 0^{-5} \ m^3[/tex]

For each droplet; there is a required volume which is = [tex]\dfrac{4}{3} \pi r ^3[/tex]  since it assumes a sphere shape .

Thus;

replacing radius(r) with 2.0 × 10−5 m; we have:

[tex]= \dfrac{4}{3} \pi * (2.0 *10^{-5} m) ^3[/tex]

= [tex]3.35 * 10^{-14} \ m^3[/tex]

However; there are [tex]3*10^{-5} \ m^3[/tex] gasoline atomized into N spherical droplets with each with radius 2.0 × 10−5 m

For N ; we have ;

[tex]=\dfrac{3*10^{-5} \ m^3}{3.35 * 10^{-14} \ m^3/ droplet}[/tex]

= [tex]8.95*10^8 \ droplet s[/tex]

So; each droplet have a surface area = [tex]4 \pi r^2[/tex]

= [tex]4 \pi (2.0*10^{-5}m) ^2[/tex]

= [tex]5.02*10^{-9} \ m^2/droplets[/tex]

The surface area per droplet is equivalent to [tex]5.02*10^{-9} \ m^2/droplets[/tex]

Thus;

The total surface area of these N spherical droplets will be :

= [tex]8.95*10^8 \ droplet s * 5.02*10^{-9} \ m^2/ droplets[/tex]

= 4.4929 m²

The total surface area of these N spherical droplets is 4.4929 m²