what was the purpose of rinsing with hexanes in the cyalume synthesis procedure?

Answer:

I. Concrete sidewalks

Explanation:

One of the factor that affects the infiltration of water into the surface of the soil is the use of concrete sidewalks.

Concrete is impermeable and non - porous media

When concrete pavements are used, water will not be able to move into the ground. They run on the surface and collects into nearby streams and water bodies.

Answer:

Approximately \(7.25\).

Explanation:

If the concentration of \({\rm H^{+}}\) ions in a solution is \(x\; {\rm M}\), the \({\rm pH}\) of that solution would be \((-\log_{10}(x))\).

Note that the base of the logarithm in this calculation should \(10\). One way to be sure is to state the base explicitly. Using the change of base rule of logarithms:

\(\begin{aligned}-\log_{10}(x) = -\frac{\ln(x)}{\ln(10)}\end{aligned}\).

In this question, it is implied that the concentration of \({\rm H^{+}}\) in the given solution is \(5.6 \times 10^{-8}\; {\rm M}\), such that \(x = 5.6 \times 10^{-8}\). Using the equations above:

\(\begin{aligned}& \text{pH of this solution} \\ =\; & -\log_{10}(x) \\ =\; & -\frac{\ln(x)}{\ln(10)} \\ =\; & -\frac{\ln(5.6 \times 10^{-8})}{\ln(10)} \\ \approx\; & 7.25\end{aligned}\).

Answer:

it's volume also decrease

The enantiomeric excess (e.e.) of the mixture containing 5.70 g of (-)-glyceraldehyde and 2.0 g of (+)-glyceraldehyde is 48%.

To calculate the enantiomeric excess (e.e.) of a mixture, we need to determine the difference in the amounts of the two enantiomers and express it as a percentage of the total amount.

Given;

Mass of (-)-glyceraldehyde = 5.70 g

Mass of (+)-glyceraldehyde = 2.0 g

Calculate the total amount of glyceraldehyde in the mixture.

Total mass of glyceraldehyde = Mass of (-)-glyceraldehyde + Mass of (+)-glyceraldehyde

= 5.70 g + 2.0 g

= 7.70 g

Calculate the individual amounts of each enantiomer as a fraction of the total amount.

Fraction of (-)-glyceraldehyde = Mass of (-)-glyceraldehyde / Total mass of glyceraldehyde

= 5.70 g / 7.70 g

= 0.740

Fraction of (+)-glyceraldehyde = Mass of (+)-glyceraldehyde / Total mass of glyceraldehyde

= 2.0 g / 7.70 g

= 0.260

Calculate the enantiomeric excess (e.e.).

e.e. = (Fraction of (-)-glyceraldehyde - Fraction of (+)-glyceraldehyde) × 100%

= (0.740 - 0.260) × 100%

= 0.480 × 100%

= 48%

Therefore, the enantiomeric excess (e.e.) of the mixture containing 5.70 g of (-)-glyceraldehyde and 2.0 g of (+)-glyceraldehyde is 48%.

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Answer:

0

Explanation:

Answer:

a. The chemical symbols represent the chemical element and are 1 to 2 letters long.

Example: Er- Erbium

b. The chemical formulas identify each element by it's chemical symbol and indicates the proportionate number of atoms in each element.

Example: Salt- NaCI

c. A chemical equation is the symbolic equation of a chemical reaction in the form of symbols and formulas.

Example: H2+O=H2O (One water molecule)

Answer:-8

Explanation:

edmentum

The solution for the given linear equation can be solved by simplifying the equation. The value of x is obtained as - 8.

Linear equations are the equations which shows a linearity with a second expression which is similar to the first but having different mathematical operations and signs.

By solving linear equations we can solve for the unknown value of x. The value of x can be obtained by taking the whole expression to one side and which is having a constant value.

Given, - 3x + 7x - 8 = 34 + 9x -2.

          = 4x - 8 = 32 + 9x

          = 4x - 8 - 9x = 32

             -5x = 40

              x = - 40/5 = - 8.

Hence, solution of the given equation is  -8.

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A reaction is said to have reached equilibrium when the reaction rate is equal in both directions (c).

Like, take the example of copper in copper sulphate solution. When you add Cu to CuSO4 soln., there won't be any change occurring as the reaction rate is equal (Cu is added to CuSO4 soln., there won't be any change as displacement reaction won't take place due to Cu being the same metal as in CuS04 soln...their reaction is the same).

_____

RainbowSalt2222 ☔

The compound is C₈H₁₀O. The peak shown at 3000 cm⁻¹ is for C-H and for and -CN group, the peak will be shown as 2250 cm⁻¹.

The IR spectrum is a plot of % transmittance (or absorbance) of the radiation through the molecule as opposed to wave quantity of the radiation. Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the size of the interplay of infrared radiation with count number with the aid of using absorption, emission, or reflection. It is used to have a look at and discover chemical materials or useful corporations in solid, liquid, or gaseous forms. It may be used to signify new substances or discover and confirm acknowledged and unknown samples.

The peak shown at 3000 cm⁻¹ is for C-H and for and -CN group, the peak will be shown as 2250 cm⁻¹.

For cyclic compound, the peak of C-H at sp³ carbon is 2980 cm⁻¹ and for c=o or saturated cyclic six membered ring is 1720 cm⁻¹.

The compound is C₈H₁₀O.

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The expression for α0, α1, and α2 implicated in the speciation of H2CO3 into HCO3- and CO32- are:

(2)These reactions can be defined using the acid dissociation constant (Ka) of H2CO3 as follows:

From these definitions, the acid dissociation constants for H2CO3's first (Ka1) and second (Ka2) dissociation reactions can be expressed as shown below:

An acid is a molecule or ion that can donate a proton, or, alternatively, can form a covalent bond with an electron pair. The first category of acids is the proton donor or Brønsted acid. In the special case of an aqueous solution, the proton donor forms the hydronium ion H₃O⁺ and is known as an Arrhenius acid. PH is the degree of acidity or alkalinity of a solution, expressing the negative logarithm of the concentration of H ions with a base number of 10. Neutral solutions have a PH of 7, acids less than 7, bases greater than 7. In waters that are not polluted, PH is controlled by CO2 ions, Carbonates and Bicarbonates.

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The substance in the image above would be classified as a mixture of elements (option E).

A compound is a substance formed by chemical bonding of two or more elements in definite proportions by weight.

On the other hand, a mixture is made when two or more substances are combined, but they are not combined chemically.

According to this question, an image is shown with two different substances or elements as distinguished by coloration (white and purple). These elements are combined but not chemically bonded, hence, is a mixture.

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The molar mass of the gas, given that 3.25 g of the gas occupied 2.56 L is 30.66g/mol

To obtain the molar mass of the gas, we shall first obtain the number of mole of the gas. This can be obtained as follow:

PV = nRT

0.95 × 2.56 = n × 0.0821 × 280

Divide both sides by (0.0821 × 280)

n = (0.95 × 2.56) / (0.0821 × 280)

n = 0.106 mole

Haven obtain the mole of the gas, we shall determine the molar mass of the gas as follow:

Molar mass = mass / mole

Molar mass of gas = 3.25 / 0.106

Molar mass of gas = 30.66g/mol

Thus, the molar mass of the gas is 30.66g/mol

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Answer:

397,570 g/m^3

Explanation:

The volume of the cylinder can be calculated using its height and diameter.

Mass of the soil sample (m) = 30 g

Height of the cylinder (h) = 6 cm

Diameter of the cylinder (d) = 4 cm

First, we need to calculate the radius (r) of the cylinder

Radius (r) = diameter / 2 = 4 cm / 2 = 2 cm = 0.02 m

Now, we can calculate the volume (V) of the cylinder

V = π * r^2 * h

V = 3.14159 * (0.02 m)^2 * 0.06 m

V = 7.5398 E-5 m^3

Calculate the bulk density (ρ) using this formula

ρ = m / V

ρ = 30 g / 7.5398 E-5 m^3

ρ = 397,887 g/m^3

The wavelength of the football thrown by an NFL quarterback traveling at 50 mph is approximately 6.99 x 10^-35 m.

To calculate the wavelength of the football, we need to first calculate its velocity in meters per second.

We can convert 50 mph to meters per second as follows:

1 mph = 0.44704 m/s (conversion factor)

50 mph = 50 x 0.44704 m/s

50 mph = 22.352 m/s (velocity of the football)

Next, we need to calculate the momentum of the football using the equation:

p = mv , where p is momentum, m is mass, and v is velocity.

We can convert the mass of the football from grams to kilograms as follows:

425 g = 0.425 kg (conversion factor)

So, the momentum of the football is:

p = mv

p = 0.425 kg x 22.352 m/s

p = 9.498 kg*m/s

Finally, we can calculate the wavelength of the football using the equation:

wavelength = h/p

where h is Planck's constant (6.626 x 10^-34 J*s).

So, the wavelength of the football is:

wavelength = h/p

wavelength = (6.626 x 10^-34 Js)/(9.498 kgm/s)

wavelength = 6.99 x 10^-35 m

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The wavelength of the football is λ = 7.17 * 10^-{26} nm .

The wavelength of the football can be calculated using the de Broglie wavelength equation: λ = h/mv, where h is Planck's constant, m is the mass of the object, v is the velocity of the object.
First, we need to convert the mass of the football from grams to kilograms: 425 g = 0.425 kg.
Next, we need to convert the velocity from mph to m/s: 50 mph = 22.35 m/s.
Now we can plug in the values into the equation:
λ = \frac{(6.626 * 10^{-34} J*s) }{ (0.425 kg * 22.35 m/s) }
λ = 7.17 * 10^{-26} nm
Therefore, the correct answer is C) 7.17 * 10^-{26} nm.
It's important to note that this calculation assumes that the football is behaving as a wave, which is not necessarily the case in reality. However, this calculation can still provide a useful estimate of the football's wavelength.

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Air Mass Definition

Air mass can be defined as a large air volume with uniform temperature and moisture. These masses can stretch thousands of miles horizontally over the Earth’s surface, and vertically from ground level to the stratosphere (10 miles) into the atmosphere.

Categorization of Air Masses

Meteorologists classify air masses based on where they are formed. Here is the classification.

Typically, there are 4 types of air masses

Arctic: These air masses form in the Arctic region and are very cold.

Tropical: These air masses form in low lying latitudes and are warm up to a moderate level.

Polar: These air masses form in the high-latitude region and are cold.

Equatorial: They start forming over the Equator and are warm.

Besides this classification, there is another way to categorise air masses. Meteorologists classify them based on whether they form over water or land. These distinctions are:

Maritime: Maritime ones form over the water bodies and are filled with moisture.

Continental: Whereas, the Continental ones form over the land and are arid.

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Answer:

H2O

Explanation:

Answer:

Explanation:

The new volume can be found by using the formula for Boyle's law which is

\(P_1V_1 = P_2V_2\)

Since we are finding the new volume

\(V_2 = \frac{P_1V_1}{P_2} \\\)

From the question we have

\(V_2 = \frac{145.7 \times 1.08}{1.35} = \frac{157.356}{1.35} \\ \)

We have the final answer as

Hope this helps you

In second energy level, maximum 8 electrons can be filled.

For the first four energy levels, the maximum number of electrons are as follows:

I Energy level: 2 electrons max.

II Energy level: 8 electrons max.

III Energy level: 18 electrons max.

IV Energy level: 32 electrons max.

The greatest number depends on how many orbitals are present at a certain energy level. A volume of space within an atom known as an orbital is where an electron is most likely to be found.

As a result, we may conclude that Energy level II has four orbitals and hence, requires eight electrons to completely occupy it.

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Answer:

C. It received genes that are exactly the same as the parent's genes

In asexual reproduction in hydra,offspring has no genetic variation from the parent because it received genes that are exactly the same as the parent's genes.

Asexual reproduction is a type of reproduction where the offsprings are  not produced by the combination of genetic material of two individuals which are of different sexes rather they are produced by a single parent.

It is the  not the dominant form of reproduction in living beings.Here, the offsprings are identical to their parents as there is no recombination of genetic material.It is observed in both unicellular or multicellular organisms.

There is no fertilization or gamete formation taking place.Types of asexual reproduction include budding, binary fission,fragmentation,etc.

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After considering all the given options we conclude that the satisfactory option for the given question is the pH has not yet changed, which is option E.

The pH of the solution progressively goes under an alteration when the titrant is added when titrating a weak acid with a strong base. The pH of the solution from the start is acidic because the weak acid dominates it before the equivalence point.

The weak acid is neutralized as the strong base is placed and interacts with it. The weak acid and strong base, however, have identical numbers of moles at the halfway point to the equivalence point, making a buffer system.

The weak acid's (pKa) dissociation constant is used to evaluate the solution's pH at the halfway point. The pH does not vary considerably and stays generally steady due to a buffer forms. Hence, the pH at the halfway point of the titration is the same as the pKa of the weak acid.

Finally, halfway to the equivalence point in a titration curve of a weak acid with a strong base, the pH has not yet changed.

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These orbital configurations represent the arrangement of electrons within the different energy levels and subshells of the respective elements.

The orbital configurations of the given elements are as follows:

Helium: 1s² - Helium has two electrons that occupy the 1s orbital.

Nitrogen: 1s² 2s² 2p³ - Nitrogen has two electrons in the 1s orbital, two electrons in the 2s orbital, and three electrons in the 2p orbital (specifically, 2p³ indicates three electrons in the 2p subshell).

Silicon: 1s² 2s² 2p⁶ 3s² 3p² - Silicon has two electrons in the 1s orbital, two electrons in the 2s orbital, six electrons in the 2p orbital, two electrons in the 3s orbital, and two electrons in the 3p orbital (specifically, 3p² indicates two electrons in the 3p subshell).

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After equilibrium is established, then type of ion in solution in largest concentration, other than the k ion, is : (b) HPO₄²⁻.

In chemistry, equilibrium is a state of balance or stability achieved in chemical reaction when the rates of forward reaction and reverse reaction are equal.

The balanced chemical equation for the reaction between H₃PO₄ and KOH is:

H₃PO₄ + 3KOH → K₃PO₄ + 3H₂O

In this reaction, one mole of H₃PO₄ reacts with three moles of KOH to produce one mole of K₃PO₄ and three moles of water.

When equal volumes of 0.10 M H₃PO₄ and 0.20 M KOH are mixed, the concentration of OH⁻ ions will be in excess because KOH is strong base and H₃PO₄ is a weak acid. The OH⁻ ions will react with H⁺ ions of H₃PO₄ to form water, according to following reactions:

H₃PO₄ + OH⁻ → H₂PO₄⁻ + H₂O

H₂PO₄⁻ + OH⁻ →  HPO₄²⁻ +H₂O

The net effect of these reactions is that H₃PO₄ reacts with OH⁻ to produce HPO₄²⁻. Therefore, the type of ion in solution in largest concentration, other than the K+ ion, is  HPO₄²⁻.

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Answer:

6.14x10^24

Explanation:

convert the given 47.0g to mols then to molecules.

\(\frac{47.0g}{} x\frac{1mol}{46.07g}x\frac{6.022x10^{23} }{1 mol}\)

46.07 is the molar mass of ethanol

6.022x10^23 is avogadros number

Answer:Atomic radius gets bigger

Explanation:

Atomic radius bigger because not only do the atoms have more and more protons and neutrons, and thus more mass in general, there is also stronger shielding affect. Shielding affect is when electrons closer to the nucleus block the positive charge from reaching electrons farther from the nucleus, and thus those far electrons are not drawn towards the nucleus as strongly, and spread out more, increasing atomic radius.

One way of which element has the lowest or highest ionization energy is by looking at the periodic table. The periodic table has many properties possible to be understood, one of which is ionization energy, which is the ability of an element to make ions, becoming more reduced (gain electrons) and making another atom become more oxidized (lose electrons), the trend of ionization energy in the periodic table follow the directions up and right, so if the atom if in the far right of the periodic table, this means that this atom has a high ionization energy, and from the given options the one with the higher ionization energy will be Fluorine, answer letter B

Answer:

3.6x10^21  Ca ions

Explanation:

The definition of molar (M) is moles/liter.  A 1.50M Calcium chloride (CaCl2) solution has 1.5 moles of CaCl2 in every liter.  The number of moles in 4 ml can be calculated by including a conversion factor to account for the fact that concentration is expressed in liters, but the sample size is in ml.  If we converted the 1.5 moles/liter into moles/ml, we could just multiply the two to find the number of moles in the 4 ml aliquot.

Bt definition, 1000ml = 1 liter

We can arrange this into either of two conversion factors:

  1)  (1000ml/1 liter), or

  2)  (1 liter)/(1000 ml)

I'll use the second option, because the terms will cancle using multiplication.  (1000ml/iliter) can be used, but it would require a division, which I dislike, given a chance to multiply.

(1.5 moles CaCl2/1 liter)*(4 ml)*(1 liter/1000 ml) = 0.006 moles CaCl2 in 4 ml of 1.5M CaCl2 solution.

1 mole is 6.02x10^23 molecules of CaCl2.  Multiply this conversion facor times the moles CaCl2 to find molecules of CaCl2:

(0.006 moles CaCl2)(6.02x10^23 molecules/mole CaCl2) = 3.6x10^21 molecules CaCl2.

Since there is 1 Ca per molecule, we'll have 3.6x10^21 Ca ions.

Answer:

If this is for the "functional groups" question:

1. aldehyde

2. ketone

3. ester

4. carboxylic acid

Explanation:

Got them all right on edge.

The drop-down menus to identify the names of the structures in the table to the right

1. Aldehyde

2. Ketone

3. Ester

4. Carboxylic acid

A functional group in organic chemistry is a pool of atoms within molecules which bind jointly to react in predicted ways.

Examples of functional groups contain the group hydroxyl, ketone, amine, and ether.

Thus, these are the drop down menus.

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32.3699% Tin (Sn)

15.2774% Nitrogen (N)

52.3527% Oxygen (O)

Answer:Which of the following can be formed by physically combining pure substances?a. an element c. a compound b. a mixture d. all of the above Weegy: It is true.The formula for Density is Mass divided Volume.

Explanation:

Answer:

It is B. a mixture

Explanation:

A is wrong because an element is part of a compound and can't be physically mixed, C is wrong because atm don't jin by just physically mixing then there must be a change in smething at the physical level

also correct on edg.

This formula is wrong because a substituent can't attach with 1st carbon in chain or the here the no. of carbon in carbon chain is 8