How many grams of NaF should be added to 500 mL of a 0.100 M solution of HF to make a buffer with a pH of 3.2

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Answer: The silver metal was OXIDIZED.

Explanation:

OXIDATION is defined as loss of electrons and increase in oxidation number of an atom.

Oxidation number is the charge on an ion in an ionic compound or the charge that an atom in a covalent compound would have it it were ionic. There are basic rules governing oxidation number, they include:

--> the oxidation number of elements in their free states is ZERO. Example O2, Cl2,Na, Al, Ag.

-->The oxidation number for an ion is the same as the size and sign of the charge on the ion. For example the oxidation number of Zn2+ is +2.

--> the sum of all the oxidation numbers of the elements in a compound is zero.

--> oxidation numbers are always written with either a positive or a negative sign.

On the other hand, reduction is the opposite of oxidation. As oxidation is taking place, reduction is also taking place. Reduction involves:

--> Gain of electron and

--> decrease in oxidation number

From the question, the silver metal had ZERO as it's oxidation number because it's in free state. After being exposed to oxygen to form silver oxide, the oxidation number became +1.

Since there is an increase in the oxidation number, the silver metal was OXIDIZED

Answer:

See explanation and image attached

Explanation:

The product of the Grignard reaction between methyl benzoate and excess phenylmagnesium bromide is triphenyl methanol.

The reaction proceeds by nucleophillic reaction as the carbonyl moiety is attacked. A tetrahedral intermediate is formed. Loss of the -OMe group is accompanied by the attack of the first molecule of PhMgBr.

Attack by a second PhMgBr molecule yields trimethyl phenoxide. Protonation of this specie yields the final product which is obtained by aqueous workup.

Explanation:

P1V1/T1 = P2V2/T2

=((390.89×313.9)/76.6)×((718.3×V2)/154.2)

= (122700.371/76.7) × ((718.3×V2)/154.2)

make V2 the subject of the formula...

V2 =(122700.371×154.2)/(76.6×718.3)

V2 =18920397.21/55021.78

V2 = 343.87

Answer:

0.3323

Explanation:

GIven that:

Density of the metal = 10.6 g/cm^3

atomic weight = 176.8 g/mol

atmic radius = 0.130 nm

values of a and c = 0.570 nm and 0.341 nm respectively

For us to determine the atomic packing factor, we need to first determine the volume of all spheres (Vs) and the volume of unit cell (Vc).

However, the number of atoms  in the unit cell (n) can be computed as:

[tex]n = \dfrac{\rho * V_c *N_A}{A} \\ \\ n = \dfrac{(10.6) * (5.7)^2 (3.41)*(10^{-24}) *(6.022*10^{23})}{176.8}[/tex]

n = 4.0

Thus, the number of atoms in the unit cell is 4

∴

The atomic paking factor (APF) is calculated by using the formula:

[tex]\dfrac{Vs}{Vc} = \dfrac{4 * \dfrac{4}{3}\pi *R^3 }{a^2 *c} \\ \\ \\ \dfrac{Vs}{Vc} = \dfrac{4 * \dfrac{4}{3}\pi *(1.30*10^{-8})^3 }{(5.70*10^{-8})^2 *(3.41*10^{-8})}[/tex]

= 0.3323

Answer:

K+ClKCl

Explanation:

because the reaction is between metal Potassium and Non-metal Chlorine

Answer:

Explanation:

a) It is a redox reaction because KCl is an ionic compounds with K having a + charge and Cl having a - charge. Originally, both have an oxidation state of 0 and not K has 1+ and Cl has 1-. Therefore, one species was oxidized and one was reduced which is indicative of a redox reactions.

b)

2K + Cl2 => 2KCl

Answer:

B. Complex B.

Explanation:

Complex B will have binding site with high affinity for reduced plastocyanin due to greater redox potential. The high number of redox potential will will transport electron chain in cyanobacteria.

Redox potential is the measure of the electron gain or loss to the electrode. For reduced plastocyanin complex B will have the highest affinity.

Electron affinity is the energy released when the atom gets attached to the atom or other molecule. The high number of redox potential increases the electron transport in the cell.

The greater the redox potential more will be its tendency to show electron affinity. To bond with reduced species, the oxidized species must have greater redox potential.

Therefore, option B. complex b will have the highest affinity.

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Answer:

CuSO4(s) + 5H2O(l) ----> CuSO4.5H2O(s)

Explanation:

Hydration is the process by which anhydrous CuSO4 acquires molecules of water of crystalization to form the pentahydrate.

The water of crystalization becomes attached go the crystals of the CuSO4 to form the hydrated salt.

Beginning with solid anhydrous CuSO4 we have;

CuSO4(s) + 5H2O(l) ----> CuSO4.5H2O(s)

Answer:

A) Val-Gly-Arg-Ala-Val-Lys-Ala-Gly-Phe

B) Ala-Val-Lys-Val-Gly-Arg-Ala-Gly-Phe

Explanation:

The possible sequences that could be obtained from the available dat provided are :

A) Val-Gly-Arg-Ala-Val-Lys-Ala-Gly-Phe

B) Ala-Val-Lys-Val-Gly-Arg-Ala-Gly-Phe

Trypsin is generally a catalyst  for the breakdown of proteins into smaller peptides ( during the hydrolysis of peptide bonds )  

Taking into account its definition, the correct answer is option D) Chromatography.

Chromatography is a method that allows the separation, identification and determination of chemical components in complex mixtures. By means of a chromatography it is possible to separate analytes that are very similar to each other in terms of their physico-chemical properties.

For the separation to occur, the principle of selective retention is used, which consists of the different behavior of the components of a mixture on a specific support (such as paper, a gas, a liquid) and a flowing liquid or gaseous phase. through the bracket.

In other words, there is a stationary phase immobilized on a support and a mobile phase that will drag the sample through the stationary phase. During this process, each component of the sample will move according to its own physicochemical characteristics. The general concept will be that those components that prefer the stationary phase are more retained, while those that prefer the mobile phase will move faster.

In summary, the components of the sample are distributed between two phases of different nature, as a consequence of the speed variation that is established when being dragged by a mobile, liquid or gaseous phase, through a stationary, solid or liquid phase.

Finally, the correct answer is option D) Chromatography.

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We measured the Fe(II) reduction of one of the Co(III) complexes by water at a rate of about 0.545 kJ/mol (to three significant figures).

Calculating a Reaction's Activation Energy A reaction's rate is influenced by the temperature at which it is carried out. The molecules travel more quickly and clash more frequently as the temperature rises. Moreover, the molecules contain greater kinetic energy.

We can use the Arrhenius equation to calculate the reaction's activation energy:

k = A × exp(-Ea/RT)

When the activation energy Ea, the rate constant k, the gas constant R, and the temperature T in Kelvin are all present.

Finding the natural logarithm of the equation's two sides results in:

ln(k) = ln(A) - (Ea/RT)

This equation can be rearranged to take a linear form:

ln(k) = (-Ea/R) × (1/T) + ln(A)

y = mx + b, where (1/T) is x, (-Ea/R) is the slope, and ln(A) is the y-intercept, has the form of a linear equation.

We can get the slope of the line using the given data:

slope = (-Ea/R) = (ln(k2/k1)) / (1/T2 - 1/T1)

where the rate constants for temperatures T1 and T2, respectively, are k1 and k2.

substituting the specified values:

k1 = 0.054s⁻¹ at 293 K

k2 = 0.100s⁻¹ at 298 K

T1 = 293 K

T2 = 298 K

slope = (-Ea/R)

= (ln(0.100/0.054)) / (1/298 - 1/293)

= 65.5 kJ/mol

Therefore, the activation energy of the reaction is:

Ea = slope * R = 65.5 kJ/mol × 8.314 J/mol-K = 545 J/mol

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Answer:

1.28 M

Explanation:

Step 1: Given data

Mass of luminol (solute): 17.0 g

Volume of water: 75.0 mL (this is also the volume of solution)

Step 2: Calculate the moles corresponding to 17.0 g of luminol

The molar mass of luminol is 177.16 g/mol.

17.0 g × 1 mol/177.16 g = 0.0960 mol

Step 3: Calculate the molarity of the solution

We will use the definition of molarity

M = moles of solute / liters of solution

M = 0.0960 mol / 0.0750 L = 1.28 M

Answer:

a) Freezing and condensation

Explanation:

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We are given:

Volume of Solution: 5.7 Liters

Concentration: 1.64 Molar

Number of moles required:

We know that the formula for concentration (in molar) is:

M = N / V              

where M is the concentration, N is the number of moles, and V is the volume of solution (in L)

plugging the given values in the equation:

1.64 = N / 5.7

N = 1.64 * 5.7            

N = 9.35 moles

Answer:

the answer is C

Explanation:

a molecule can be made up of two atoms of the same kind, as when two oxygen atoms bind together to make an oxygen molecule

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Answer:

Because a Lone pair of electrons on nitrogen is involved in delocalization.

Hope this helps you ( ◕ᴗ◕✿)

If it doesn't i'm sorry(◞ ‸ ◟)

Explanation:

In ethylamine ethyl is electron donating group. So more electrons are available aroudn nitrogen for donation. But in aniline phenyl group is electron attracting group.

2.96 × 10²³ molecules is required if Alex drips hydrochloric acid onto a 5.9 g piece of magnesium in a single displacement reaction

According to this question, hydrochloric acid (HCl) reacts with magnesium metal (Mg) to produce magnesium chloride and hydrogen has as follows:

2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)

Where; Mg = 24g/mol

mole = 5.9/24

mole = 0.246mol of Mg

To convert mole to number of molecules, we multiply number of moles by 6.02 × 10²³ (Avogadro's no.)

Hence, number of molecules of HCl required is 0.492mol × 6.02 × 10²³

= 2.96 × 10²³ molecules of HClHCl

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Answer

Accordingly the order of electronegativity of the given elements would be: Fluorine > Chlorine > Bromine > Iodine. ( Fluorine has the highest electronegativity.)

Answer:

1.0188 J/g*C

Explanation:

Using the formula; Q = m × c × ∆T

Q(water) = -Q(metal)

m × c × ∆T (water) = -{m × c × ∆T (metal)}

According to this question,

mass of metal = 25g

initial temp of metal = 99°C

mass of water = 50g

initial temp of water = 10.55°C

final temperature of the system = 20.15°C

c of water = 4.184 J/g*C

50 × 4.184 × (20.15 - 10.55) = 25 × c × (20.15 - 99)

209.2 × 9.6 = 25c × -78.85

2008.32 = -1971.25c

c = 2008.32 ÷ 1971.25

c of metal = 1.0188 J/g*C

The third quantum number (m) describes the specific orbital within a sublevel. The correct answer is option D.

Quantum numbers are a set of four numbers that describe the properties of an electron in an atom. They specify the energy, position, and orientation of an electron in an atom.

The third quantum number (m) is also called the magnetic quantum number. It describes the orientation of the orbital in space. Each orbital within a sublevel has a different orientation in space, and the magnetic quantum number tells us which orbital we are talking about.

The value of m can range from -l to +l, where l is the second quantum number (the angular momentum quantum number). The value of l determines the number of orbitals in a sublevel, and the value of m determines the specific orbital within that sublevel.

In conclusion, the third quantum number (m) describes the specific orbital within a sublevel. It tells us how the orbital is oriented in space, and it can have values ranging from[tex]\rm -l \ to +l[/tex], where l is the second quantum number.

Option D is the correct answer.

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Calories, we know that fat burn is calories.

Answer:

There are many reagents.

1. Use acidified potassium permanganate solution

2. Use acidified potassium dichromate solution

3. Fehling solution.

4. Silver/ oxygen at 500°C

5. Copper/ oxygen at 300°C

6. Lucas reagent ( anhydrous zinc and conc. hydrochloric acid)

Explanation:

Observations:

[with acidified potassium permanganate solution]

» Ethanol : The purple solution turns colourless.

» 2-methyl-2-propanol : no observable change.

[with acidified potassium dichromate solution]

» Ethanol : orange solution turns green

» 2-methyl-2-propanol : no observable change.

[Fehling solution]

» Ethanol : a white precipitate is formed

» 2-methyl-2-propanol : no observable change

The relative atomic mass of dihydrogen monoxide is 18g/mol

According to the periodic table:

Where; H = 1g/mol and O = 16g/mol

H2O = 1(2) + 16

= 2 + 16

= 18g/mol

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Answer:

48.67 seconds

Explanation:

From;

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

[A] = concentration at time t

t= time taken

k= rate constant

[A]o = initial concentration

Since [A] =[A]o - 0.75[A]o

[A] = 0.056 M - 0.042 M

[A] = 0.014 M

1/0.014 = (1.1t) + 1/0.056

71.4 - 17.86 = 1.1t

53.54 = 1.1t

t= 53.54/1.1

t= 48.67 seconds

Hence,it takes 48.67 seconds to decompose.

The question is incomplete, the complete question is shown in the image attached to this answer

Answer:

2,3,3-trimethylhexane

Explanation:

IUPAC nomenclature provides a universally acceptable method of naming organic compounds from its structure.

According to this system of nomenclature;

A comma is used to separate two numbers.

A hyphen is used to separate a number from a letter.

Applying these rules, the name of the compound shown in the question should be written as 2,3,3-trimethylhexane.

Answer:

yea all the answers are true

Redox reaction is the transfer of the electron from one species to another. All of the three statements are true about the redox reaction.

A redox reaction is a type of chemical reaction in which the electrons are gained and lost by a species. The positive EMF of the cell results in spontaneous and will move the reaction in the forward direction.  

In a redox reaction, the cathode reaction is comparatively more negative than the reduction potential present at the anode.

Therefore, option E. All I, II, and III are true.

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We want to find the value of t such that the velocity vector makes an angle of 45° with both axes.

We found that:

t = (2/3)*(b/c)

The velocity vector makes an angle of 45° with the x and y axes.

We know that the position vector is:

r = r=b*t²i + c*t³j

Remember that the versor "i" corresponds to the x-component, and the versor "j" corresponds to the y-component, then:

r = r=b*t²i + c*t³j  = (b*t², c*t³)

The velocity vector is the vector that we get when we differentiate the position one, remember that if:

f(x) = a*x^n

then

f'(x) = n*a*x^(n - 1)

Using this, we can find that the velocity vector is:

v = (2*b*t,  3*c*t²)

Now we want to know, when does the velocity vector make an angle of 45° with the x and y axes.

Let's think of the vector as the hypotenuse of a triangle rectangle, where the x-component is the adjacent cathetus, and the y-component is the opposite cathetus. (so the angle is measured counterclockwise from the x-axis)

We have the trigonometric equation:

tan(a) = (opposite cathetus)/(adjacent cathetus)

So now we can replace these things with the known ones:

a = 45°

opposite cathetus = y-component = 3*c*t²

adjacent cathetus = x-component = 2*b*t

So we will get:

tan(45°)  =  (3*c*t²)/( 2*b*t)

1 = (3/2)*(c/b)*t

Now we can solve this for the variable, t.

1*(2/3)*(b/c) = t

t = (2/3)*(b/c)

We can conclude that at the time:

t = (2/3)*(b/c)

The velocity vector makes an angle of 45° with the x and y axes.

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Given concentration of NaCl=15%

Means ,

In every 100g of Solution 15g of NaCl is present .

Now

So ,

[tex]\\ \Large\sf\longmapsto 250\times 15\%[/tex]

[tex]\\ \Large\sf\longmapsto 250\times \dfrac{15}{100}[/tex]

[tex]\\ \Large\sf\longmapsto 37.5g[/tex]

37.5g of NaCl present in 250g of solution.

Answer:

Given concentration of NaCl=15%

Means ,

In every 100g of Solution 15g of NaCl is present .

Now

Given mass=250g

So ,

➡250 × 15%

➡250×15/100

➡37.5g

37.5g of NaCl present in 250g of solution.