3. many electrophilic aromatic halogenations require the presence of an aluminum halide (aluminum chloride or aluminum bromide) as a catalyst. why is it unnecessary to include an aluminum halide in the electrophilic aromatic bromination reaction of acetanilide with molecular bromine.

Answers

Answer 1

The aluminum halide is used to increase the electrophilicity of the halogen, in electrophilic aromatic substitutions which is unnecessary because acetanilide is a very good nucleophile.

In electrophilic aromatic substitutions, the aromatic ring acts as the nucleophile, while the other component (halogen, alkyl halide, acyl halide, etc.) acts as the electrophile. The halogen molecules are not great electrophiles, so aluminum halide is added to facilitate the reaction.

However, the nucleophilicity of the aromatic ring can be increased through resonance and inductive effects of the substituents, and in acetanilide the electron-donating amide group is effective enough to make the aromatic ring a good enough nucleophile to, in turn, make the use of aluminum halide unnecessary.

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Related Questions

what mass of sodium chloride would need to be added to the blood to bring the sodium ion concentration up to 0.135 m m , assuming no change in blood volume?

Answers

7.89 g of NaCl is required to bring sodium ion concentration to 0.135 m.

Given:

The molality of NaCl in the given volume of blood=0.135 mol/ kg

1 mol of NaCl contains 1 mol of sodium ion.

Thus, 0.135 mol of sodium chloride is needed to give out 0.135 moles of sodium ion.

Therefore, the mass of sodium chloride needed=moles x molar mass=0.135 mol x 58.44 g/mo

l=7.89 g

What is molality?
The molality (m) is defined as the amount of solute (in moles) present in 1 kg solvent. It is calculated by dividing the moles of solute by the mass of the solvent (in kg). For example, a solution with a molality of 1 mol/kg is often described as 1 molal or 1 m.

Hence, 7.89g of NaCl would be needed.

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Calculate the theoretical yield of acetylsalicylic acid if excess acetic anhdride and 3.50 grams of salicylic are used in the reaction:

Answers

When multiplied by salicylic acid's molecular weight of 1 80.158, it will be equal or smooth. If we compute it now, we will see that the mask, or theoretical yield, is equal to $4.57 million.

Acetylsalicylic AcidAspirin, also known as acetylsalicylic acid (ASA), works by permanently blocking the platelet cyclooxygenase (COX) enzyme, which in turn prevents the production of the platelet thromboxane A2 (TXA-2). A medication called aspirin (acetylsalicylic acid) is used to treat pain or inflammation1. 3 As a non-steroidal anti-inflammatory medicine, it is categorized (NSAID). Pain that is mild to moderate can be treated with aspirin. However, safety concerns regarding the danger of bleeding as well as the possibility of developing a rare but serious liver and brain condition, most commonly in youngsters (Reye's syndrome), should be taken into account.

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A student is studying how far room temperature water could squirt i meant would squirt out of a plastic milk carton when 4mm holes or punch at different heights from the bottom of the container

Answers

Independent variable: Hole height

Water squirting distance is a dependent variable.

The size of the perforations in the milk carton is constant.

During experiments, the value of the independent variable is frequently changed, and the impact of the change on the dependent variable is then measured.

The variable that is actually being measured during an experiment is known as the dependent variable. Changes in the independent variable's values have an impact on the dependent variable's value.

Variables that don't vary over the course of an experiment are known as constants.

Hence, in the illustration:

Independent variable: the height of holes on the milk carton

Dependent variable: distance of squirting water

Constant: the size of holes punched into the milk carton

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COMPLETE QUESTION:

Directions: Read the given scenarios below. Identify each required component for each scenario.

Scenario 1:

A student is studying how far room-temperature water would squirt out of a plastic milk carton when 4 mm holes are punched at different heights from the bottom of the container. Describe which are the independent and dependent variables as well as indicate the constants involved within the experiment and why those are the constants.

Independent Variable:

Dependent Variable:

Constants:​

need help please answer

Answers

Answer:

True

Explanation:

The answer is True if it's wrong forgive me if its right heart it.

let's consider that ethyl acetate is the ideal solvent for this tlc experiment. what might have happened to the spots if you had used t-butyl methyl ether as the eluent instead of ethyl acetate.

Answers

The spots will remain towards the bottom of the TLC plate in the TLC experiment if the eluent is changed from ethyl acetate to t-butyl methyl ether.

The spots will remain at the bottom of the TLC plate because t-butyl methyl ether is less polar and cannot overcome attractions of sample to adsorbent.

TLC experiment concept is simple. In TLC, adsorbent is silica which is highly polar. Then the eluent we can use as in different percentage of ethyl acetate & ether solution depending upon the polarity of given products.

As we know that polar molecules strongly bind with other polar molecules, ethyl acetate and silica gel are highly polar, the solvent ethyl acetate overcomes the strong bonding between the spotted product and adsorbent and takes the spot with the solvent upto the top.

If in this TLC experiment, instead of ethyl acetate, t-Butyl methyl ether is used, which is a highly non-polar or less polar solvent, it does not overcome the bonding since polar spots don't have greater binding affinity towards this non-polar ether solvent, therefore, the spots will remain tightly bonded with silica on TLC plate and spots will remain at the bottom of the TLC plate.

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What is a planet's orbit?

Answers

Answer:

An orbit is a regular, repeating path that one object in space takes around another one.

A certain red light has a wavelength of 680 nm.
a. What is the frequency of the light?

Answers

A certain red light has a wavelength of 680 nm. then, The frequency of the light is 4.4×10^14 s^-1 .

Given,

A certain red light had a wavelength = 680nm

frequency is given by,

f =c/λ

where, f = frequency

c = speed of light = 3×10^8 m/s

λ = wavelength = 680nm

f = (3×10^8 ) /(680× 10^-9 )

f = 0.0044×10^17 = 4.4×10^14 s^-1

Hence, the frequency of the light is 4.4×10^14 s^-1 .

What is wavelength?

The distance between the two crests or troughs of the light wave is known as the wavelength of light. Using the Greek letter lambda (), it is identified. As a result, wavelength refers to the separation between one wave's crest or dip and the following wave.

The formula for wavelength is given by,

wavelength= speed of light /frequency

What is frequency?

According to the definition of frequency, it is the quantity of full wave cycles that pass a spot in a unit of time.

Hertz is the SI unit for frequency (Hz).

The number of full oscillations that any wave element makes in one unit of time is the frequency of a sinusoidal wave.

Frequency is in periodic motion; after going through a number of different situations or postures and then returning to its initial place, it has completed one cycle.

The reciprocal of a wave's period is equal to the wave's frequency.

The frequency mathematical expression is:

frequency = speed of light / wavelength

The length of time it takes for any string element to complete an oscillation is known as a wave's oscillation period.

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if a mixture consisting of 10 % cyclohexane and 90 % toluene were distilled in a fractional distillation apparatus having 2 theoretical plates, what would the composition of cyclohexane be in the first drop of distillate? %

Answers

The first drop of distillate would contain 33 mol% of toluene and 67 mol% of cyclohexane. We can reach this conclusion by consulting the boiling point composition curve attached.

When analyzing the composition of the vapor phase and the liquid phase during the distillation of two liquids with different boiling points, it is necessary to use the boiling point composition curve.

We begin on the right by finding the point on the curve that corresponds to our initial mixture composition (90 mol% toluene, 10 mol% cyclohexane). We then move to the left, to find the composition of the vapor phase. This will be the composition of the distillate after one theoretical plate (approximately 67 mol% toluene, 33 mol% cyclohexane). Because we have two theoretical plates, we repeat the process, but now the composition of the liquid phase is the same as the vapor phase because we are now basically distilling our first distillate for the second time.

So we again move to the left to find the composition of the vapor phase, which will be the composition of our distillate after two theoretical plates: 33 mol% toluene and 67 mol% cyclohexane.

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In which pair of elements are the chemical properties of the elements most similar? Explain your reasoning.

a. sodium and chlorine
b. nitrogen and phosphorus
c. boron and oxygen

Answers

Answer:

b. nitrogen and phosphorus

Explanation:

Elements in the same column of the Periodic Table have similar chemical properties. Both N and P are in the same column.

balance the following equation and express the rate in terms of the change in concentration with time for each substance: no(g) o2(g) n2o3 (g) when n2o3 is forming at 0.527 m/s, at what rate is no decreasing? enter a positive number to 3 decimal places.

Answers

The balanced reaction equation for this redox reaction is:

4NO(g) + O₂(g) → 2N₂O₃(g)

The rate of [NO] decreasing is 1.054 M/s.

This is a redox reaction, so to balance it, we need to identify which elements change their oxidation state. Obviously, nitrogen is oxidized from +2 (N²⁺O²⁻) to +3 (N⁺³₂O²⁻₃), and oxygen is reduced from 0 (O⁰₂) to -2.

N²⁺ → N⁺³ + e⁻

O⁰₂ + 4e⁻ → 2O²⁻

In order for the number of electrons released and taken to be the same, we  need to multiply the number of nitrogens by 4:

4N²⁺ → 4N⁺³ + 4e⁻

O⁰₂ + 4e⁻ → 2O²⁻

We can now apply these numbers to the reaction equation:

4NO(g) + O₂(g) → 2N₂O₃(g)

With the balanced reaction equation, we can see that 4 moles of NO produce 2 moles of N₂O₃. So if 0.527 M were produced in a single second, the rate of NO decreasing would be 2 * 0.527 M = 1.054 M/s.

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ammonia, nh3, is used as a refrigerant. at its boiling point of –33 c, the standard enthalpy of vaporization of ammonia is 23.3 kj/mol. how much heat is released when 50.0 g of ammonia is condensed at –33 c?

Answers

- 68.385 kJ amount of heat will be released when 50.0 g of ammonia is condensed at –33 °C.

The standard enthalpy of vaporization of ammonia = 23.3 kJ/mol

This means the energy required to vaporize one mole of ammonia at its boiling point = -33 °C

Let's calculate the heat released when 50.0 g of ammonia is condensed at -33 °C.

The heat released is the opposite of the enthalpy of vaporization i.e Q = -23.3 kJ/mol (-ve sign indicates the reaction is exothermic)

We are given

Mass of ammonia m(NH₃) = 50.0 g

Number of moles of ammonia n(NH₃) = 50.0 g ÷ 17.031 g/mol.

n(NH₃) = 2.935 mol

The amount of heat released when 2.935 mol moles condensed at -33 °C

Q = Hv x n(NH₃).

Q = 23.3 kJ/mol x 2.935 mol

Q = - 68.385 kJ

Thus, -68.4 kJ amount of heat is released when 50 g of ammonia is  condensed at -33 °C,  where negative sign signifies release of heat.

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A molecule that organisms get from the air or water around them is

Answers

Oxygen i think cause oxygen is a molecule you get from breathing

Compare the arrangements of the molecules of a solid, liquid,
and gas by illustrating them in the boxes below.


(I’VE BEEN STUCK FOR 3 DAYS)

Answers

The arrangements of the molecules of a solid, liquid and gas  as follows

1. Solid: In this state of matter, the particles are closely bonded to each other. This means that they are closely packed in a system and the arrangement is regular. The intermolecular space between the particles is minimum.

2. Liquid: In this state of matter, the particles are not so closely packed. The arrangement between the particles is not regular. The intermolecular spacing between the particles is more than solid but less than gaseous state.

3. Gases: In this state of matter, the particles are very far away from each other and the arrangement is not regular. The intermolecular spacing between the particles is very much in case of gases.

What are the Three States of Matter?

The solid, liquid, and gaseous phases of matter are the three basic states of matter.

Every item we encounter every day—from ice cream to chairs to water is composed of matter. Based on intermolecular forces and the arrangement of the particles, matter can be divided into distinct states such as solid, liquid, and gas. By altering specific environmental variables, these three types of matter can change their state of matter (increasing or decreasing pressure and temperature, for instance). For instance, raising the temperature will cause ice to melt from a solid state.

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What is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180. 0?.

Answers

The atomic mass of hafnium is 178.55 amu based on the mass of the given isotopes.

To determine the average atomic mass of hafnium, we first determine the mass fractions of the isotopes as follows;

m(1) = 5 ÷ 100 = 0.05

m(2) = 19 ÷ 100 = 0.19

m(3) = 27 ÷ 100 = 0.27

m(4) = 14 ÷ 100 = 0.14

m(5) = 35 ÷ 100 = 0.35

Now the average atomic mass of hafnium can be calculated by the addition of the products of the mass fractions of the isotopes and their respective atomic masses.

Average atomic mass = [m(1) × 176] + [m(2) × 177] + [m(3) × 178] + [m(4) × 179] + [m(5) × 180]

Average atomic mass = (0.05 × 176) + (0.19 × 177) + (0.27 × 178) + (0.14 × 179) + (0.35 + 180)

Average atomic mass = 8.8 + 33.63 + 48.06 + 25.06 + 63

Average atomic mass = 178.55

Hence the average atomic mass of Hafnium is calculated to be 178.55 amu.

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In what ways does the element hydrogen behave like elements from group 1 and sometimes like elements from group 17? Make an argument for which group you think hydrogen should be placed in.

Answers

It mimics alkali metals in several of its characteristics, such as its ease in forming cations.

What category does hydrogen fall under?

Chemical element hydrogen has the atomic number 1 and the letter H after it. It is a diatomic gas with the chemical formula H2 that is colorless, odorless, nonmetallic, tasteless, and extremely combustible.

Because it shares some characteristics with alkali metals, such as the ability to form cations easily, hydrogen can be placed in both groups 1 and 17 of the periodic table. However, because it also shares characteristics with halogens, such as the ability to form H2, hydrogen can also be placed in group 17. While hydrogen can take electrons, it also has a propensity to reject them in order to maintain stability. It is the family's tiniest member.

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3. Why is it important for other variables in an experiment to be controlled?

Answers

To derive precise results, it is important for other variables in an experiment to be controlled. Accuracy and precision are the key factors of every practical experiment carried out.

During the course of experiments, special emphasis is laid on the objective of the experiment. Procedures and precautions are highly objective-oriented. There are possibilities of errors as the surrounding becomes an integral part of the system in practicals.

Certain physical and chemical quantities are ignored in theoretical assessment, but they affect the practical work. Impurities and uncontrolled reactions can be barriers. Optimum conditions are sought before conducting experiments.

what is the percent ionization of a 0.427 m solution of ethylamine (ch3ch2nh2) in 0.113 m calcium hydroxide?

Answers

Percentage ionization of ethylamine is 4%.

What is the percent ionization?

The portion of the original chemical that has undergone ionization is the percent ionized. So, we contrast the ion's concentration in solution with the neutral species' initial concentration.

Given,

Concentration of ethylamine =0.427 m,

Concentration of calcium hydroxide = 0.113 m,

As ethylamine(CH₃CH₂NH₂) is a weak base, it will not in equilibrium,

CH₃CH₂NH₂  ⇆ CH₃CH₂NH₃⁺ + OH⁻

also from CaOH₂ ; OH⁻ ions are coming which will show common ion effect

CaOH₂ → Ca⁺ + 2OH⁻

0.113         -           -

-                0.113     0.113×2

                             =0.226

Now,  CH₃CH₂NH₂  ⇆ CH₃CH₂NH₃⁺ + OH⁻

c - cα                                 cα  + 0.226 ≈ 0.226

Kₐ = [ OH⁻] [CH₃CH₂NH₃⁺]/[CH₃CH₂NH₃⁺]

    =[tex]\frac{c\alpha \times 0.226}{c-c\alpha}\\[/tex]

     = [tex]\frac{\alpha\times 0.226 }{c- c\alpha} \\[/tex]

0.01= α ×0.226

α= [tex]\frac{0.01}{0.226}[/tex]

α=0.44

now percentage ionization = 4%.

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Which phase is a good description of kinetic energy?(1 point)


conserved energy


energy from the sun


energy of motion


stored energy

Answers

Answer: Energy of motion :)

Answer: the answer to your question is the energy of motion

Explanation:

What is an ionic compound?

Answers

Answer:

Ionic compounds are neutral compounds made up of positively charged ions called cations and negatively charged ions called anions. For binary ionic compounds (ionic compounds that contain only two types of elements), the compounds are named by writing the name of the cation first followed by the name of the anion

Explanation:

hope this helps!!

Question 11
A material whose particle composition allows heat and electricity to pass through it easily are described as having a high
OA) conductivity
O B) density
OC) hardness
OD) weight

Answers

Answer:

Coductivity

Explanation:

Because heat conducts to them!

You heat 3.970 g of a mixture of Fe3O4 and FeO to form 4.195 g Fe2O3. The mass percent of FeO originally in the mixture was:

Answers

FeO + Fe3O3 + 1/2O2 → 2Fe203

→ Molar mass of Fe2o3 = 159.69g/mol

→ Molar mass of FeO = 71.84g/mol

→Molar mass Fe3o4 = 231.53g/mol

1. first of all , let consider the amount of Fe in Fe2O3

Atomic Mass of Fe = 58.845 g/mol

Percentage of Fe in Fe2)3 = ( 2 x mass of Fe / Molar Mass Fe203) = 2x(55.845) /159.69g/mol

= 0.6994 * 100 = 69.94 %

2. Mass of Fe in 4.195g of Fe2O3 will then be :

0.06994 * 4.195g = 2.934 g

3.(i) percentage of Fe in FeO = (55.845 / 71.84g/mol ) = 0.77735* 100 =77.735

(ii)percentage of Fe in Fe3O4 = (3x 55.845)/231.53g/mol= 0.72359*100 =72.359

(remember , we only have molar mass of FeO as well as molar mass for Fe3O4 , we do not have their mass)

4. so we will say; let x be the mass for Fe3O4

and ; let y be the mass of FeO

However , the mass of FeO and FeO3O4 must equal 3.970 as given in the question.

meaning x +y = 3.970; therefore x = (3.970-y)

But, we also know from the above percentage calculations; that :

• Mass of Fe in FeO = 0.77735 = 0.77735 ,y

,

• Mass of Fe in Fe3O4 = 0.72359 = 0.72359,x

5. now lets solve for x and y by equating the above:

0.77735 y + 0.72359x =2.934 g

0.77735 y + 0.72359(3.970-y) =2.934 g

solving for y; you will get :

0.07735y + 2.8726 -0.72359y = 2.934

0.05385y = 0.061347

therefore y = 1.142 g = mass of FeO

Finally :

Mass percentage= (Mass FeO /given mass of the mixture ) * 100

= 1.142g/3.970 *100

= 28. 7 %

How much heat is needed to raise the temperature of 10 grams of liquid water from 25°C to 50°C?

Answers

It would take 200J of energy.

Raquel would like to describe the observable properties of water. What properties can she use?

A Colorless and rough
B Colorless and smooth
C Smooth and rough
D Soft and smooth


HELP ASAP

Answers

Answer:

b

Explanation:

water is generally transparent and smooth to the touch unless it is frozen, then it is rough

The table gives the numbers of protons, neutrons and electrons in some atoms and ions of elements. The letters used in the table are not the chemical symbols of the elements.

Answers

Explanation:

a. i. R and Z (same number of protons but different number of neutrons therefore are isotopes of the same element).

ii. Q (has more portons than electrons).

iii. X (has more electrons than protons).

iv. L (mass number = protons + neutrons).

v. M (belongs to group 1 alkali metals which are of very reactive metals).

b. 12 (atomic number= number of protons).

c. 7 (X has 9 electrons before ionisation, therefore 7 electrons in the outer most shell).

Q (is also from ionisation reaction).

hope it helps :)

A. (i). Two identical atoms with the letters Q and Z each contain 17 protons.

ii. Protons outnumber electrons in a positive ion. R, which has 17 protons and 17 electrons, is the only atom or ion that has more protons than electrons. It removes an electron to form a positive ion with a charge of +1: R+.

iii. In a negative ion, the number of protons is more than the number of electrons. J has 16 electrons and 16 protons, making it the only atom or ion with more electrons than protons. It becomes a negative ion with a charge of -1, or J-, by the addition of one electron.

iv. Such an atom or ion has the letter M and has 11 protons and 12 neutrons. It adds a proton to form an atom with a mass number of 20: N with 12 protons and 8 neutrons.

v. Group 1 of the periodic table consists of metals that are extremely reactive. L, an atom in group 1 with 10 protons, is the only one in the table to have this characteristic.

What is an Atom?

The fundamental building block of matter, an atom, nevertheless has the characteristics of an element. It consists of a small, compact nucleus with positively charged protons and electrically neutral neutrons surrounded by orbitals of negatively charged electrons.

For the above example,

(b) An atom with an atomic number of 12 has 12 electrons because an atom has exactly the same number of protons in the neutral state as electrons.

(C)

(i) X has exactly 11 protons, the same number of protons as the atom or ion M has. Group 1 of the periodic table, commonly known as the alkali metals, consists of elements with 11 protons.

(ii) An alkali metal is another atom that interacts in the same way as the substance from which ion X is made. According to the table, the only atom in group 1 is L, which has 10 protons. However it lacks the 11 protons of the alkali metals mentioned above

Therefore, two identical atoms with the letters Q and Z each contain 17 protons.

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In the titration of acetic acid and naoh, the use of the color indicator requires that excess base be added in order to detect the endpoint. Will this cause the calculated and reported mass percent of acetic acid in vinegar to be too high or too low? explain.

Answers

When excess base is added in order to detect the end point, then it will cause the calculated and reported mass percent of acetic acid in vinegar to be too high.

A titration is a method of quantitative chemical analysis, in which the concentration of an unknown solution called the analyte, by using a solution of known concentration, called the titrant.

The titrant solution from the burette is added slowly to the analyte solution, in the conical flask, in order to determine the end point of the titration. The end point is indicated by a change in color of the solution in the presence of an indicator.

An acid-base titration involves a neutralization reaction between an acid and a base.

As given in the question, the concentration of acetic acid solution is being determined by sodium hydroxide (NaOH) solution of known concentration.

Therefore, Sodium hydroxide is the titrant and is taken in the burette. Whereas, acetic acid is the analyte which is taken in the conical flask and two- three drops of the indicator is added to it.

Example of the indicator that can be used in an acid-base titration is phenolphthalein. Phenolphthalein is colorless in acidic medium and pink in basic medium.

Initially, the analyte acetic acid solution will be colorless. Since, phenolphthalein is colorless in acidic medium.

Then, NaOH solution will be slowly added from the burette to the acetic acid solution. On reaching the end point, a slight excess amount of the NaOH base is added from the burette.

The excess amount of NaOH makes the solution in the conical flask basic. Therefore, changing the color of the solution, from colorless to pink. Since, phenolphthalein is pink in basic medium.

This excess amount of the titrant i.e. NaOH solution added, increases the volume of the NaOH solution being used in the titration.

Since, acetic acid is directly proportional to volume of NaOH or any base used, then even a slight increase in the volume of the NaOH solution, increases the concentration or molarity of acetic acid

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PLEASE HELP ASAP!!!!! (Show work and explanation please)

Suppose 200.0 g of ice absorb 1255.0 J of heat. What is the corresponding temperature change? Specific heat capacity of ice is 2.1 J/gC.

Answers

the answer is 6.0°C that is the solution

what happens to matter and energy when a substance combusts​

Answers

Nothing is destroyed by burning or other modifications to matter. Before and after changes always occur, the mass of the substance remains constant. According to the principle of conservation of mass, matter cannot be created or destroyed.

Where does matter go when burned?Exothermic reactions characterize all combustion processes. A substance burns when it reacts with oxygen in a combustion reaction. Burning materials often release energy in the form of heat and light.In the chemical process of combustion, an object quickly combines with oxygen to produce heat. The original substance is referred to as the fuel, and the oxygen's source as the oxidizer.Nothing is destroyed by burning or other modifications to matter. Before and after changes always occur, the mass of the substance remains constant. According to the principle of conservation of mass, matter cannot be created or destroyed.combustion is a chemical reaction that often involves the presence of oxygen and produces heat and light in the form of flames.

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The relationship between the energy of a photon and the frequency of light was determined by Ernst Planck (1858 - 1947). Here is the equation he discovered E = hf. Because photons of light have wave-like properties this equation may also be represented using the speed of light and wavelength, E = hc/λ.
Where h is Planck’s constant = 6.63 x 10-34 J*s)
c is the speed of light = 3.00x108 m/s
f is the frequency of the photon (in cycles/sec or s-1)
λ is the wavelength of light (in meters)

1. Show how you calculate the energy of light that has a frequency of f = 4.0 x 10^14 s^-1.

2. Use the information above to determine the wavelength of a photon of light that has the same energy

Answers

The energy of a light that has a frequency of 4.0 × 10¹⁴ Hz is 2.65 × 10-¹⁹J.The wavelength of the photon of light that has the same energy is 7.5 × 10-⁷m.

How to calculate energy?

The energy of a photon can be calculated by multiplying Planck's constant by the frequency of the light.

According to this question, the relationship between the energy of a photon and the frequency of light was determined by Ernst Planck. He proposed a equation as follows:

E = hf

Where;

E = energy in joulesh = Planck's constant (6.626 × 10-³⁴J/s)f = frequency (Hz)

The energy of a frequency 4.0 × 10¹⁴ Hz can be calculated as follows:

E = 6.626 × 10-³⁴ × 4 × 10¹⁴

E = 2.65 × 10-¹⁹J

λ = hc/E

λ = 6.626 × 10-³⁴ × 3 × 10⁸/2.65 × 10-¹⁹

λ = 1.988 × 10-²⁵/2.65 × 10-¹⁹

λ = 7.5 × 10-⁷m

Therefore, 7.5 × 10-⁷m is the wavelength of the photon.

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caco3 is added to a 250 ml volumetric flask with 50 ml of water. hcl is added drop-wise until effervescence is not longer observed, and then diluted to the mark. what is the molarity of caco3 in the flask?

Answers

The concentration of the calcium ions in the solution is obtained as 0.013 M

What is the molarity of the solution?

Now we have to find the concentration of the calcium ions, we have to look at the question. We can see from the question that;

Mass of calcium carbonate =  0.3205g

Number of moles of calcium carbonate =  0.3205g /100 g/mol = 0.003205 moles

Number of moles calcium ions = 0.003205 moles

The question here is that we ought to find the concentration of the EDTA solution and that is what we need to find in the spaces that follow in this answer as we have here.

Concentration of the calcium ions in the solution = 0.003205 moles/250 * 10^-3

= 0.013 M

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Missing parts;

A 0.3205g sample of CaCO3 was dissolved in HCl and the resulting solution diluted to 250.ml in a volumetric flask. A 25 mL sample of the solution required 18.75mL of EDTA solution for titration to the Eriochrome Black T end point. What is the concentration of Ca2+ (mol/L) in the 250.0ml of CaCl2 solution?

at 25 oc the solubility of magnesium fluoride is 1.17 x 10-3 mol/l. calculate the value of ksp at this temperature. give your answer in scientific notation to 2 significant figures (even though this is strictly incorrect).

Answers

The solubility constant is[tex]$6.4 \times 10^{-9}$[/tex].

The equilibrium for the solubility of the salt, [tex]$\mathrm{MgF}_2$[/tex] is,

[tex]$$\mathrm{MgF}_2(s) \stackrel{\mathrm{H} \cdot \mathrm{O}}{\rightleftharpoons} \mathrm{Mg}^{2+}(a q)+2 \mathrm{~F}^{-}(a q)$$[/tex]

The solubility product constant for [tex]$\mathrm{MgF}_2$[/tex] is,

[tex]$$K_{\text {吶 }}=\left[\mathrm{Mg}^{2+}\right]\left[\mathrm{F}^{-}\right]^2$$[/tex]

The molar solubility of [tex]$\mathrm{MgF}_2$[/tex] is taken as x, the x moles of [tex]$\mathrm{MgF}_2$[/tex]is dissolved in one litre water to produce x moles of [tex]$\mathrm{Mg}^{2+}$[/tex]and 2x moles of [tex]$\mathrm{F}^{-}$[/tex].

[tex]$\begin{array}{lccc} & \mathrm{MgF}_2(s) & \stackrel{\mathrm{H}_2 \mathrm{O}}{\rightleftharpoons} \mathrm{Mg}^{2+}(a q)+2 \mathrm{~F}^{-}(a q) \\ \text { Initial } & x & 0 & 0 \\ \text { Change } & & +x & +2 x \\ \text { Equilibrium } & x & 2 x\end{array}$[/tex]

The solubility product constant for[tex]$\mathrm{MgF}_2$[/tex] is,

[tex]$$\begin{aligned}K_{u p} &=\left[\mathrm{Mg}^{2+}\right]\left[\mathrm{F}^{-}\right]^2 \\&=(x)(2 x)^2 \\&=4 x^3\end{aligned}$$[/tex]

Substitute the solubility of [tex]$\mathrm{MgF}_2$[/tex] as [tex]$1.17 \times 10^{-3} \mathrm{~mol} / \mathrm{L}$[/tex]in the above equation as shown below:

[tex]$$\begin{aligned}K_{i p} &=4 x^3 \\&=4\left(1.17 \times 10^{-3}\right)^3 \\&=6.41 \times 10^{-9}\end{aligned}$$[/tex]

The solubility constant is [tex]$6.4 \times 10^{-9}$[/tex].(using 2 significant figures).

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