11
SKILL LEVEL
Proficient
Which substance conducts electricity in the liquid state but is a
poor conductor in the solid state?

a: Li₂O
b: SeCl2
C: P205
d: Hg

Answer:

[H₃O⁺] = 2.5 × 10⁻¹⁰ M

pH = 9.6

Explanation:

Step 1: Given data

Concentration of OH⁻ in the solution ([OH⁻]): 4.0 × 10⁻⁵ M

Step 2: Calculate the concentration of H₃O⁺ in the solution

Let's consider the self-ionization of water.

2 H₂O(l) ⇄ H₃O⁺(aq) + OH⁻(aq)

The ion-product of water (Kw) is:

Kw = 1.0 × 10⁻¹⁴ = [H₃O⁺] × [OH⁻]

[H₃O⁺] = 1.0 × 10⁻¹⁴/[OH⁻]

[H₃O⁺] = 1.0 × 10⁻¹⁴/4.0 × 10⁻⁵

[H₃O⁺] = 2.5 × 10⁻¹⁰ M

Step 3: Calculate the pH of the solution

We will use the following expression.

pH = -log [H₃O⁺]

pH = -log 2.5 × 10⁻¹⁰

pH = 9.6

Taking into account the definition of pH and pOH, the pH and [H₃O⁺] of the solution is 9.602 and 2.5×10⁻¹⁰ M respectively.

First of all, pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH is defined as the negative base 10 logarithm of the activity of hydrogen ions, that is, the concentration of hydrogen ions or H₃O⁺:

pH= - log [H⁺]= - log [H₃O⁺]

Similarly, pOH is a measure of hydroxyl ions in a solution and is expressed as the logarithm of the concentration of OH⁻ ions, with the sign changed:

pOH= - log [OH⁻]

The following relationship can be established between pH and pOH:

pH + pOH= 14

In this case, you know that [OH⁻]= 4×10⁻⁵ M. For this concentration, the pOH is calculated as:

pOH= - log (4×10⁻⁵ M)

pOH= 4.398

Then, pH can be calculated as:

pH + 4.398= 14

pH= 14 - 4.398

pH= 9.602

So, the [H₃O⁺] is calculated as:

9.602= - log [H₃O⁺]

[H₃O⁺]= 10⁻⁹ ⁶⁰²

[H₃O⁺]= 2.5×10⁻¹⁰ M

Finally, the pH and [H₃O⁺] of the solution is 9.602 and 2.5×10⁻¹⁰ M respectively.

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Answer:

The wavelength of the energy that needs to be absorbed  = 52.36 nm

Explanation:

For this study;

Let consider the Rydgberg equation from Bohr's theory of atomic model:

i.e.

[tex]\dfrac{1}{\lambda} = R_H (Z^*)^2( \dfrac{1}{n_1^2}-\dfrac{1}{n_2^2})[/tex]

where

Z* = effective nuclear charge of atom = Z - σ = 6

n₁ = lower orbit = 3

n₂ = higher orbit = 4

[tex]R_H[/tex] = Rydyberg constant = 1.09 × 10⁷ m⁻¹

λ = wave length of the light absorbed

∴

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(6)^2( \dfrac{1}{3^2}-\dfrac{1}{4^2})[/tex]

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(36)( \dfrac{1}{9}-\dfrac{1}{16})[/tex]

[tex]\dfrac{1}{\lambda} = 392400000\times0.0486111111[/tex]

[tex]\dfrac{1}{\lambda} =19075000[/tex]

[tex]\lambda = \dfrac{1}{19075000}[/tex]

[tex]\lambda = \dfrac{1}{1.91\times 10^7 \ m^{-1}}[/tex]

[tex]\lambda = 5.236 \times 10^{-8} m[/tex]

[tex]\lambda = 52.36 \times 10^{-9} m[/tex]

[tex]\lambda = 52.36\ n m[/tex]

Therefore, the wavelength of the energy that needs to be absorbed  = 52.36 nm

Answer:hi

Explanation:

The final temperature = 36 °C

The balanced combustion reaction for C₆H₆

2C₆H₆(l)+15O₂(g)⇒ 12CO₂(g)+6H₂O(l)  +6542 kJ

MW C₆H₆ : 78.11 g/mol

mol C₆H₆ :

[tex]\tt \dfrac{8.5}{78.11}=0.109[/tex]

Heat released for 2 mol C₆H₆ =6542 kJ, so for 1 mol

[tex]\tt \dfrac{0.109}{2}\times 6542=356.539~kJ/mol[/tex]

Heat transferred to water :

Q=m.c.ΔT

[tex]\tt 356.539=5.691~kg\times 4.18~kj/kg^oC\times (t_2-21)\\\\t_2-21=15\rightarrow t_2=36^oC[/tex]

.

.

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b competition .

hope it helps u

Answer:

Mass is conserverd

Explanation:

Any chemical reaction must follow the law of conservation of mass. Meaning that mass cannot be created nor destroyed. Since all chemical reactions must follow this law, no matter what reaction happens, mass is conserved.

Answer:

its hydroxy and alkoxy

Explanation:

ester is mainly formed by substitution reaction of carboxylic acid and alcohol

The esters are generally produced as a result of the reaction called esterification. They are generally derived from carboxylic acids. The functional group present in ester is OR. The correct option is E.

The chemical compounds which are derived from an acid either organic or inorganic in which at least -OH ( hydroxyl group ) is replaced by an -O- alkyl group ( alkoxy ) group are called esters. Generally an ester can be represented as R - C = O - OR.

The chemical compounds that are formed by the reaction of an acid and alcohol by losing water molecule can be defined as the esters.

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Answer:

Light i think

Explanation:

light is a source of energy also

Answer:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

General Formulas and Concepts:

Explanation:

Step 1: RxN

Pb(NO₃)₂ (aq) + KI (aq) → PbI₂ (s) + KNO₃ (aq)

Step 2: Balance RxN

Pb(NO₃)₂ (aq) + 2KI (aq) → PbI₂ (s) + 2KNO₃ (aq)

Step 3: Ionic Equations

Total Ionic Equation:

Pb²⁺ (aq) + 2NO₃⁻ (aq) + 2K⁺ (aq) + 2I⁻ (aq) → PbI₂ (s) + 2K⁺ (aq) + 2NO₃⁻ (aq)

Cancel out spectator ions.

Net Ionic Equation:

Pb²⁺ (aq) + 2I⁻ (aq) → PbI₂ (s)

Answer:

a. Approximately [tex]1.3\; \rm mL[/tex].

b. Approximately [tex]7.2\; \rm mL[/tex].

Explanation:

The unit of concentration "[tex]\rm M[/tex]" is equivalent to "[tex]\rm mol \cdot L^{-1}[/tex]", which means "moles per liter."

However, the volume of both solutions were given in mililiters [tex]\rm mL[/tex]. Convert these volumes to liters:

[tex]\displaystyle 45\; \rm mL = 45\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.045\; \rm L[/tex].

[tex]\displaystyle 330\; \rm mL = 330\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.330\; \rm L[/tex].

In a solution of volume [tex]V[/tex] where the concentration of a solute is [tex]c[/tex], there would be [tex]c \cdot V[/tex] (moles of) formula units of this solute.

Calculate the number of moles of [tex]\rm NaCl[/tex] formula units in each of the two solutions:

Solution in a.:

[tex]n = c \cdot V = 0.045\; \rm L \times 0.10\; \rm mol \cdot L^{-1} = 0.0045\; \rm mol[/tex].

Solution in b.:

[tex]n = c \cdot V = 0.330\; \rm L \times 0.074\; \rm mol \cdot L^{-1} = 0.02442\; \rm mol[/tex].

What volume of that [tex]3.4\; \rm M[/tex] (same as [tex]3.4 \; \rm mol \cdot L^{-1}[/tex]) [tex]\rm NaCl[/tex] solution would contain that many

For the solution in a.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.0045\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0013\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0013\; \rm L = 0.0013\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 1.3\; \rm mL[/tex].

Similarly, for the solution in b.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.02442\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0072\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0072\; \rm L = 0.0072\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 7.2\; \rm mL[/tex].

The most plausible reason why your new patient, Elisa, is feeling tired all the time is:

According to the complete question, we can see that the cells which are in Elise's body are receiving oxygen and proteins, but they are not getting enough glucose, which can be gotten from breaking down starch.

As a result of this, we can see that the best diagnoses of why Elise is always getting tired is that she has diabetes because of the inability of the body to break down starch to provide enough glucose to the body.

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Answer: pH = 10

Explanation: First solve for pOH using the equation pOH=-log[OH-] = 4

Then plug the pOH in the equation, pH + pOH =14

then solve for pH. pH =14 - 4 = 10

Answer:

pH= 10

Explanation:

The pH really depends on what your solution is.

For example, if we are assuming that the concentration of 1.0M is of a strong monoprotic acid e.g. HCl, it would be safe to assume that almost all of the 1.0M acid has dissociated into its H+ ion, and its conjugate base. Thus, the pH can be determined by taking the negative log(to base 10), of the concentration.

Inversely, if the solution is of a strong base, the pOH value would be found, assuming the steps above. This pOH value can be used to infer a pH from the formula - pH + pOH = 14 then 14 - 4 = 10

Finally, come the weak acids/bases, which follow the rules above, except as they only partially dissociate, one needs its equilibrium constant to determine its extent of ionisation, to substitute into the negative log. This also is the case for the second, and higher order dissociation of polyprotic acids e.g. H2SO4.the answer is 10

Hope it helps

Answer:

check the image

Explanation:

Answer:

The new material Emily invented allows scratches to be repaired quickly, so it would be useful on cars and other surfaces that experience a lot of wear.

Explanation:

I got this right on Plato\Edmentum

Answer:

The new material Emily invented allows scratches to be repaired quickly, so it would be useful on cars and other surfaces that experience a lot of wear.

Explanation:

Answer:

[tex]\% Fe=11.4\%[/tex]

Explanation:

Hello!

In this case, for the described chemical reaction, we find it is:

[tex]8H^+(aq)+5Fe^{2+}(aq)+MnO_4^-(aq)\rightarrow 5Fe^{3+}(aq)+Mn^{2+}(aq)+4H_2O(l)[/tex]

Because it says that the iron is dissolved in a strong acid which provides addition hydrogen ions to the reaction media. Thus, for the questions attached on the figure we find:

- This a REDOX reaction because we see iron is being oxidized from 2+ to 3+ and manganese reduced from +7 to +2.

- Since it is a redox reaction and the oxidized species is that undergoing an oxidation number increase, we evidence iron goes from +2 to +3, which means iron is the oxidized species.

- In this case, for the used 59.2 mL (0.0592 L) of the 0.2000 M solution of potassium permanganate, we can compute the consumed grams of iron via stoichiometry including the 5:1 mole ratio between them in the chemical reaction:

[tex]m_{Fe^{2+}}=0.0592L*0.2000\frac{molMnO_4^-}{L}*\frac{5molFe^{2+}}{1molMnO_4^-} *\frac{55.85gFe^{2+}}{1molFe^{2+}} \\\\m_{Fe^{2+}}=3.31gFe^{2+}[/tex]

It means that the percent of iron in that sample is:

[tex]\% Fe=\frac{3.31g}{29.00g} *100\%\\\\\% Fe=11.4\%[/tex]

Best regards.

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question we have

[tex]density = \frac{690}{750} = \frac{69}{75} = \frac{23}{25} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

The work is -6,497.54 J

Explanation:

Work is the amount of energy transferred from one system to another by a force when a displacement occurs.

The work exchanged for a gas depends on the transformation it performs to go from the initial state to the final state.

The pressure - volume work done by a system that compresses or expands at constant pressure is given by the expression:

W= -P*ΔV

where

In this case:

Replacing:

W=  -570,459.8 Pa*0.01139 m³

Solving:

W=-6,497.54 J

The work is -6,497.54 J

Answer:

please brainlist answer

Explanation:

The addition of K 3 Fe(CN) 6 to a solution causes the formation of a deep blue precipitate which indicates that iron(II) ions are present.

The conclusive test for iron(II) ions is the test by the use of potassium hexacyanoferrate III solution.

In qualitative analysis certain reagents are used to test for the presence of certain cations or anions. Those reagents react in a certain way with those reagents. Usually, a positive test may involve a color change, formation of a precipitate or evolution of a gas.

In the case of iron(II) ions, potassium hexacyanoferrate III solution is used in the conclusive qualitative test for the ion. A positive test involves the appearance of a deep blue precipitate.

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Answer:

I ordered the tiles from left to right and top to bottom as the numbers kept increasing. The tiles were also organized based on the color and shape that they were. The tiles with the same color and shape were arranged in the same column.

Explanation:

In the modern periodic table, the elements are listed in order of increasing atomic number and elements having similar chemical properties naturally line up in the same column (group).

Answer:

A

Explanation:

Answer:

Because as the concentration is diminished, the capacity to transfer electricity is diminished as well.

Explanation:

Hello!

In this case, since electrolytes are substances that are able to conduct the electricity in aqueous media (solutions in which water is the the solvent) because they have the capacity to form ions with both positive and negative charges, due to the fact that HCl is a strong acid, we notice it is fully ionized in solution and therefore it is a strong electrolyte. However, when the concentration is diminished, we can notice that strength is diminished as well because less ions will have the capacity to transfer the electricity and therefore it'd become a poor conductor or weak electrolyte.

Best regards!

Answer:

C. Only 2s and 2p may hybridize; these orbitals contain valence electrons used in bonding.

Explanation:

Carbon has four valence electrons (2s² 2p²), in several organic compounds it forms four bonds and as this element has two types of orbitals to join, 2s and 2p, it is expected that a compound like methane has two types of C-H bonds, but this is not the case, as all its orbital atoms are the same.

In a process called hybridization, s orbitals and p orbitals are combined in an atom. Depending on the amount of p orbitals that are combined, the hybrid orbitals can be sp (one orbital 2s and one 2p are combined), sp² (the 2s orbital combines with two 2p orbitals) and sp³(the orbital 2s combines with three 2p orbitals).

The carbon atom has the presence of 6 electrons. The valence bond theory hybridized the 2s and 2p orbital for the bonding, as they have valence bonds.

The valence bond theory has been the atomic hybridization of the atoms that results in the formation of the bonds.

The carbon atom has 4 valence electrons present in the bonding valence orbitals. The orbitals combine as sp, sp2, sp3 orbital in order to form the bond.

Thus, since there has been the presence of valence electrons in the s and p orbitals, the 2s and 2p are involved in the hybridization. Hence, option C is correct.

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Answer:

C

Explanation:

Answer:

I think is A

Explanation:

Hope it helps

Answer:

1.70 L

Explanation:

From the question given above, the following data were obtained:

Pressure (P) = constant = 1.2 atm

Initial volume (V1) = 1.25 L

Initial temperature (T1) = 293 K

Final temperature (T2) = 398 K

Final volume (V2) =?

Since the pressure is constant, the gas is obeying Charles' law. Thus, we can obtain the new volume (V2) of the gas by applying the Charles' equation as shown below:

V1/T1 = V2/T2

1.25 / 293 = V2 /398

Cross multiply

293 × V2 = 1.25 × 398

293 × V2 = 497.5

Divide both side by 293

V2 = 497.5 / 293

V2 = 1.70 L

Therefore, the new volume of the gas is 1.70 L.

Answer: c. Water

Explanation:

Heat capacity can be defined as the physical property of the matter. It is the amount of heat which is required to produce a unit change in the temperature of the material.

Water requires more amount of energy per gram of the liquid to change its temperature as compare to any other liquid like ethanol and oil. Ethanol is a volatile liquid so it will require less heat to boil but heat capacity of oil will be more than the oil. The heat capacity of water will be the highest, and it will require more heat.

Answer:

Element Symbol # of Atoms

Sodium   Na   2

Cobalt   Co   3

Hydrogen  H  20

Oxygen   O   10

Explanation: