Need help with chemistry question

Answer: [tex]CaCl_2(aq)+K_2CO_3(aq)\rightarrow 2KCl(aq)+CaCO_3(s)[/tex]

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.

The balanced reaction between aqueous calcium chloride reacts with aqueous potassium carbonate is shown as:

[tex]CaCl_2(aq)+K_2CO_3(aq)\rightarrow 2KCl(aq)+CaCO_3(s)[/tex]

Answer: Chromatography is a technique which is used for the separation of components present in a mixture into sub-components.

Explanation:

The solvent or liquid used for the separation of the chromatographic mixture should lie below the spot point where the mixture is loaded in an alumina column. This is done to prevent the air bubbles formations, which can lead to poor sanitation. Also this is done to prevent the mixing of the mixture to be separated with the solvent instead of running with the solvent via capillary action.

Answer:

22.29%

Explanation:

Percent yield = experimental yield / theoretical yield * 100

= 12.89 / 57.82 * 100 = 22.29%

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: Manganese(II)bromide

Explanation:

Because it is a chemical compound composed of manganese and bromine

Answer:

[tex]N^{4+}O_2+2OH^-\rightarrow (N^{5+}O_3)^-+1e^-+H_2O[/tex]

Explanation:

Hello,

In this case, for the given reaction, we first start by the writing of the oxidation states of all the involved elements:

[tex]Bi^{3+}(OH)^-+N^{4+}O^{2-}_2\rightarrow Bi^0+(N^{5+}O^{2-}_3)^-[/tex]

In such a way, we are noticing nitrogen is undergoing an increase in its oxidation state, therefore it is being the oxidized species, for which the oxidation half reaction, should be (considering basic conditions):

[tex]N^{4+}O_2+H_2O+2OH^-\rightarrow (N^{5+}O_3)^-+1e^-+2H^++2OH^-\\\\N^{4+}O_2+H_2O+2OH^-\rightarrow (N^{5+}O_3)^-+1e^-+2H_2O\\\\N^{4+}O_2+2OH^-\rightarrow (N^{5+}O_3)^-+1e^-+H_2O[/tex]

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Answer:

a) I, II, and III

Explanation:

For the first statement;

Solvation, is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. if the solvent is water, we call this process hydration.

This means the statement is TRUE.

For the second statement;

The negatively-charged side of the water molecules are attracted to  positively-charged ions. In the case of water, the oxygen end is the negatively charged side of water. This means the statement is TRUE.

For the third statement;

The positively-charged side of the water molecules are attracted to the negatively-charged chloride ions. In the case of water, the hydrogen end is the positively charged side of water. This means the statement is TRUE.

Going through the options, we can tell that the correct option is option A.

Answer:

Dalton's theory had to be modified after mass spectrometry experiments demonstrated that atoms of the same element can have different masses because the number of neutrons can vary for different isotopes of the same element

Answer:

1.25 g.

Explanation:

5% or 25 g

= 0.05 * 25

= 1.25 g (answer).

Answer:

The answer is B

Explanation:

Answer:

B. Learning about the physical world through observation

Explanation:

A p e x 2021 :) Trust me!

Answer:

See explanation

Explanation:

In this case, we have an addition reaction. Additionally, this is a marknovnikov addition, therefore the "Br" atom would be added in the most substituted carbon (in this case carbon a). And we are going to have 2 enantiomers (2S,4S)-2,4-dibromopentane and  (2R,4S)-2,4-dibromopentane. In the case of (2R,4S)-2,4-dibromopentane we will have a symmetry plane (a point in the molecule in which we can divide the molecule into two equal parts). When this happens we will have a mesocompound and we will not have optical activity.

See figure 1

I hope it helps!

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 number of moles of solute present in 4.00 L of an 8.30 M solution​ is 33.2

Explanation:

The Molarity (M) or Molar Concentration is the number of moles of solute per liter of solution; in other words it is the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:

[tex]Molarity=\frac{number of moles of solute}{volume}[/tex]

Molarity is expressed in units ([tex]\frac{moles}{liter}[/tex])  or M.

In this case:

Replacing:

[tex]8.30 M=\frac{number of moles of solute}{4 L}[/tex]

Solving:

number of moles of solute= 8.30 M* 4 L= 8.30 [tex]\frac{moles}{liter}[/tex] * 4 L

number of moles of solute =33.2

The number of moles of solute present in 4.00 L of an 8.30 M solution​ is 33.2

Answer:

33.2 is the answer

Explanation:

did the test already :)

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!

Silver chloride (AgCl) is a crystalline solid substance that is composed of silver and chloride ions. AgCl is an ionic solid. Thus, option D is correct.

Ionic solids are substances that show the properties of solid matter and have ionic, positive, and negative charges in them. They are linked together by the attraction of the opposite charges.

The silver metal in the molecule has a positive charge and the chloride ions are negative in charge making them establish an ionic bond.

The solid molecule is held together by ionic bonds and not the covalent or other metallic bonds. The cations and anions of AgCl are linked together by the electrostatic forces that make their structure appear strong and brittle.

Therefore, AgCl has been known as an ionic solid.

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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.

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]

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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:

ok

Explanation:

Answer:

They are also relatively soft metals: sodium and potassium can be cut with a butter knife.

Answer:A

Explanation:

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:

Homoanular dienes have a greater base value than heteroanular dienes

Explanation:

Woodward in 1945 gave a set of rules relating the wavelength of maximum absorption to the structure of a compound. These rules were modified by Fieser in 1959. These sets of rules describe the absorption of organic molecules in the UV region of the electromagnetic spectrum.

Each system of diene or triene has a given fixed value at which maximum absorption is expected to occur according to Woodward rules. This given fixed value is called the base or parent value. If the two double bonds are trans to each other, the diene is said to be transoid. If the two double bonds belong to different rings, the system is said to be heteroanular and the base value in each case is 215nm. If the double bonds are cis to each other (cisoid), or the two double bonds are in the same ring (homoanular), then the base value is 253nm.

Since λmax = base value + ∑ substituent contributions + ∑ other contributions, if the other contributions are not very significant, homoanular diene will have a greater λmax because of its larger base value compared to heteroanular diene. This correlates well with the fact that conjugated systems absorb at a longer wavelength.

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:

The potential difference between the cathode and anode are set up from the chemical reaction. Inside the battery electrons are pushed by the chemical reaction toward the positive end creating a potential difference. It is this potential difference that drives the electrons through the wire.

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:

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:

See explanation.

Explanation:

Hello,

a. In this case, the change of color is evident for instance when copper reacts with nitric acid to form hydrogen and copper (II) nitrate since copper orange-like and nitric acid is colorless, but copper (II) nitrate is green (dry) or blue (hydrated).

b. In this case, when we make react hydrochloric acid and magnesium, we notice a gas giving off while the magnesium chloride remains aqueous, due to the fact that magnesium displaces hydrogen which is given off as a gas.

c. In this case, we can consider an egg since when it is edible it has a tasty smell but when it decomposes to rotten egg, hydrogen sulfide is given off due to the action of specific bacteria, causing a change in smell to a quite stinky one.

d. In this case, a reaction by which a change of state is exhibited is for instance when aqueous lead (II) nitrate reacts with aqueous potassium iodide to yield potassium nitrate which remains aqueous whereas the lead (II) iodide precipitates out as a solid due to its tiny solubility as a yellow solid.

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Answer:

T2 = 133.333°K

Explanation:

Using Combined Gas Laws:

(600 torr)(10L)/500°K = (200 torr)(8L)/x°K

[tex]\frac{600 torr(10L)}{500K} =\frac{200 torr(8L)}{xK}[/tex]

Cross multiply:

x°K (600 torr)(10L) = 500°K(200 torr)(8L)

Divide:

x°K = (500°K(200 torr)(8L))/(600 torr)(10L)

[tex]xK = \frac{500K(200 torr)(8L)}{600 torr(10L)}[/tex]

x = 400/3°K or 133.333°K

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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:

Product A: cis; no

Product B: cis: no  

Explanation:

Two common methods of forming oxiranes from alkenes are:

1. Reaction with peroxyacids

(a) Stereochemistry

The reaction with a peroxyacid is a syn addition, so the product has the same stereochemistry as the alkene.

The starting alkene is cis, so the product is cis-2,3-diethyloxirane.

(b) Configuration

The product is optically inactive because it has an internal plane of symmetry.

It will not rotate the plane of polarized light.

2. Halohydrin formation

(a) Stereochemistry

The halogenation of the alkene proceeds via a cyclic halonium ion.

The backside displacement of halide ion by alkoxide is also stereospecific, so a cis alkene gives a cis epoxide.

The product is cis-2,3-diethyloxirane.

(b) Configuration

The cyclic halonium ion has an internal plane of symmetry, as does the product (meso).

The oxirane will not rotate the plane of polarized light.