Substance B is hard, does not conduct electricity, and melts at 1200 °C. Substance B is likely a(n):
(a) ionic solid
(b) metallic solid
(c) molecular solid
(d) covalent network solid

Answer:

ΔH°rxn = -827.5 kJ

Explanation:

Let's consider the following balanced equation.

2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)

We can calculate the standard enthalpy of reaction (ΔH°rxn) from the standard enthalpies of formation (ΔH°f) using the following expression.

ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]

ΔH°rxn = [2 mol × ΔH°f(PbO(s)) + 2 mol × ΔH°f(SO₂(g) )] - [2 mol × ΔH°f(PbS(s)) + 3 mol × ΔH°f(O₂(g) )]

ΔH°rxn = [2 mol × (-217.32 kJ/mol) + 2 mol × (-296.83)] - [2 mol × (-100.4) + 3 mol × 0 kJ/mol]

ΔH°rxn = -827.5 kJ

The standard enthalpy of the reaction is -827.5 kJ/mol

The standard enthalpy of reaction [tex]\mathbf{\Delta H^0_{rxn}}[/tex] is the enthalpy change that happens in a system whenever one mole of the matter is converted through a chemical process under normal conditions.

The given reaction can be expressed as:

2PbS(s) + 3O₂(g) → 2PbO(s) + 2SO₂(g)

The standard enthalpy can be represented by the equation:

[tex]\mathbf{\Delta H^0_{rxn} = \sum \Delta _f ^0(products) - \sum \Delta _f^0(reactants)}[/tex]

At standard conditions, the standard enthalpies of formation of the given species are:

∴

[tex]\mathbf{ \Delta H^0_{rxn} = \Big[2 mol \times \Delta H^0_f(PbO(s)) + 2 mol \times \Delta H^0_ f(SO_2(g) )\Big] - \Big[2 mol \times \Delta H^0_f (PbS(s))} + \mathbf{ 3 mol \times \Delta H^0_f(O_2(g) )\Big] }}[/tex]

[tex]\mathbf{\Delta H^0rxn = [2 mol \times (-217.32 kJ/mol) + 2 mol \times (-296.83)] - [2 mol \times (-100.4)} \\ \mathbf{+ 3 mol \times 0 kJ/mol]}}[/tex]

[tex]\mathbf{\Delta H^0rxn = -827.5 \ kJ/mol}}[/tex]

Therefore, we can conclude that the standard enthalpy of the reaction is -827.5 kJ/mol

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It is critical to watch or observe what is happening with every step of your experiment

1) Both cells have a cell membrane.

2) A nucleus is present in only Eukaryote cells.

3) I'm pretty sure Prokaryote cells are bacteria.

Hope this helps!! :)

Answer:

True

Explanation:

Because atoms with the same number of valence electrons react in similar ways with other elements.

Answer:

11.023 pounds

Explanation:

Answer:

Explanation:

From the given information:

The equation for the reaction can be represented as:

[tex]2SO_2 + O_2 \to 2SO_3[/tex]

The I.C.E table can be represented as:

                     2SO₂              O₂                   2SO₃

Initial:             14                  2.6                     0

Change:        -2x                -x                      +2x

Equilibrium:   14 - 2x          2.6 - x                2x

However, Since the amount of sulfur trioxide gas to be 1.6 mol.

SO₃ = 2x,

then x = 1.6/2

x = 0.8 mol

For 2SO₂; we have 14 - 2x

= 14 - 2(0.8)

= 14 - 1.6

= 12.4 mol

For O₂; we have 2.6 - x

= 2.6 - 1.6

= 1.0 mol

Thus;

[SO₂] = moles / volume = ( 12.4/50) = 0.248 M ,

[O₂] = 1/50 = 0.02 M ,  

[SO₃] = 1.6/50 = 0.032 M

Kc = [SO₃]² / [SO₂]² [O₂]

= ( 0.032²) / ( 0.248² x 0.02)

= 0.8325

Recall that; the equilibrium constant for the reaction [tex]2SO_2 + O_2 \to 2SO_3[/tex] = 0.8325;

If we want to find:

[tex]SO_2 + \dfrac{1}{2}O_2 \to SO_3[/tex]

Then:

[tex]K_c = (0.8325)^{1/2}[/tex]

[tex]\mathbf{K_c = 0.912}[/tex]

Since no temperature is given to use in the question, it will be impossible to find the final temperature of the mixture.

Answer:

c

Explanation:

Answer:

A

Explanation:

Nuclear fusion is a much more powerful reaction than any of the others.

Nuclear fusion of two hydrogen isotopes would expect to produce the most energy. Therefore, option (A) is correct.

Nuclear fusion can be defined as when two or more nuclei fuse together to form a single heavier nucleus. In this reaction, the matter is generally not conserved due to some of the mass of the nuclei being converted to energy.

For nuclear fusion, the nuclei must be brought closer to the reaction occurring. Each star in the universe, including sun, is shining due to nuclear fusion reactions. They produce large amounts of energy in this process.

In the Sun's core, hydrogen nuclei are get transformed into helium nuclei which are known as nuclear fusion. It takes place when four hydrogen nuclei fuse into each helium nucleus. During the Nuclear fusion process, some of the mass of hydrogen nuclei is transformed into energy.

Therefore, nuclear fusion is where hydrogen atoms combined to form helium to produce the most energy.

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Answer:

The answer is "Option a".

Explanation:

Multiply the mass of the solutions by 3.17% to get the mass of [tex]BaCl_2[/tex]:

[tex]\to 427 \ g \times 0.0317 = 13.56\ g[/tex]

Divide this mass with BaCl2's molecular concentration to acquire the mole ratio:  

[tex]molar mass = 208.24 \frac{g}{mol}\\\\moles = \frac{13.56}{208.24} = 0.065 \ moles \\\\[/tex]

                       [tex]= 6.5 \times 10^{-2} \ moles[/tex]

A 427 g sample is 3.17% by mass barium chloride contains 6.5 × 10⁻² moles of BaCl₂.

A 427 g sample is 3.17% by mass barium chloride, that is, there are 3.17 g of barium chloride per 100 g of sample.

The mass of barium chloride in 427 g of the sample is:

[tex]427gSample \times \frac{3.17gBaCl_2}{100gSample} = 13.5gBaCl_2[/tex]

We can calculate the number of moles in 13.5 g of barium chloride using its molar mass (208.23 g/mol).

[tex]13.5 g \times \frac{1mol}{208.23g} = 6.5 \times 10^{-2} mol[/tex]

A 427 g sample is 3.17% by mass barium chloride contains 6.5 × 10⁻² moles of BaCl₂.

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Answer:

The answer is 16

Explanation:

Answer:

1.24 L of H₂ at STP .

Explanation:

2Al(s)    +6HCl(aq)    →    2AlCl₃(aq)   +    3H₂(g)

2 moles                                                  3 x 22.4 L

2 x 27 g of Al reacts to give  3 x 22.4 L of H₂ at STP .

1 g of Al will react to give 3 x 22.4 / ( 2 x 27 ) L of H₂ at STP .

= 1.24 L of H₂ at STP .

The volume of hydrogen produced by 1 grams of Al has been 1.24 L.

The balanced chemical reaction has been given as:

[tex]\rm 2\;Al\;+\;6\;HCl\;\rightarrow\;2\;AlCl_3\;+\;3\;H_2[/tex]

From the equation, 2 moles of Aluminum gives 3 moles of Hydrogen

The mass of the compound from moles can be given as:

Mass = moles × molecular mass

Mass of 2 moles Al = 2 × 27 g

Mass of 2  moles Al = 54 g

Mass of 3 moles hydrogen = 3 × 2 g

Mass of 3 moles hydrogen = 6 g

From the equation,

54 g aluminum gives = 6 grams hydrogen

[tex]\rm 1\;gram\;aluminum\;=\;\dfrac{6}{54}\;\times\;1[/tex]

1 gram Aluminum = 0.11 grams hydrogen

The mass of hydrogen produced by 1 gram Al has been 0.11g. The moles equivalent to 0.11g hydrogen has been given as:

Mass = moles × molecular mass

0.11 g = moles × 2 g/mol

Mole of hydrogen = 0.055 mol

The moles of hydrogen produced by 1 gram of Al has been 0.055 mol.

According to the ideal gas equation, any gas at STP has 1 mole equivalent to 22.4 L. So,

1 mol = 22.4 L

0.055 mol = 0.055 × 22.4 L

0.055 mol = 1.244 L.

The volume of hydrogen produced by 1 grams of Al has been 1.24 L.

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Answer:

The answer is true

Explanation:

bc I took this on edgeunity

Answer:

its C and D

C. The brown substance is molecular

D. The blue substance is ionic

Explanation:

did the test !

Two correct statements are B) The silver substance is ionic

C) The brown substance is molecular.

Silver is a chemical element with the symbol Ag and atomic wide variety 47. categorized as transition steel, Silver is stable at room temperature.

It is a molecular substance, that's a substance with or more atoms, the smallest gadgets of remember joined together via a covalent bond. A covalent bond is a hyperlink created via the sharing of electrons that holds these atoms collectively.

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Answer:

a)Weight of Y extracted from water in single extraction = 67.2 g

b) Total weight of Y extracted from water in two successive extractions = 70.9 g

Explanation:

Distribution coefficient, Kd = Cs / Cm

where Cs  is concentration of solute in methylene chloride; Cm is concentration of solute in water

a) Let x g of solute Y be extracted into methylene chloride

72.0 - x g of Y will be left in water

Kd = (x/180 mL of methylene chloride) / (72.0 - x/180 mL of water) = 14

14 = 180 * x / 180 * 72.0 - x

x = 14(72.0 - x)

x = 1008 - 14x

15x = 1008

x = 1008/15

x = 67.2 g

Weight of Y extracted from water in single extraction = 67.2 g

b) First extraction: Let x g of solute Y be extracted into methylene chloride

72.0 - x g of Y will be left in water

14 = x/90 / 72.0 - x/180

14 = 180x/ 90(72.0 - x)

14 = 2x/ 72.0 - x

2x = 14(72.0 - x)

2x =  1008 - 14x

16x = 1008

x = 63.0 g

Second extraction: Amount of solute left in water after first extraction = 72 - 63 = 9.0 g

Let x g of solute Y be extracted into methylene chloride

9.0 - x g of Y will be left in water

14 = x/90 / 9.0 - x/180

14 = 180x/ 90(9.0 - x)

14 = 2x/ 9.0 - x

2x = 14(9.0 - x)

2x =  126 - 14x

16x = 126

x = 7.90 g

Total weight of Y extracted = (63 + 7.90) g

Total weight of Y extracted from water in two successive extractions = 70.9 g

a) The Weight of Y extracted from water in single extraction is 67.2 g

b) The Total weight of Y extracted from water in two successive extractions should be 70.9 g

Here

The distribution coefficient, Kd should be

= Cs / Cm

where

Cs  should be a concentration of solute in methylene chloride;

Cm should be a concentration of solute in water

a) Let  us assume x g of solute Y that should be extracted into methylene chloride

So,

72.0 - x g of Y will be left in water

And, now

Kd = (x/180 mL of methylene chloride) / (72.0 - x/180 mL of water) = 14

So,

14 = 180 * x / 180 * 72.0 - x

x = 14(72.0 - x)

x = 1008 - 14x

15x = 1008

x = 1008/15

x = 67.2 g

b)

Now First extraction:

Let x g of solute Y be extracted into methylene chloride

So,

72.0 - x g of Y will be left in water

14 = x/90 / 72.0 - x/180

14 = 180x/ 90(72.0 - x)

14 = 2x/ 72.0 - x

2x = 14(72.0 - x)

2x =  1008 - 14x

16x = 1008

x = 63.0 g

Second extraction:

Amount of solute left in the water after the first extraction that should be

= 72 - 63

= 9.0 g

Now

Let x g of solute Y be extracted into methylene chloride

9.0 - x g of Y will be left in water

14 = x/90 / 9.0 - x/180

14 = 180x/ 90(9.0 - x)

14 = 2x/ 9.0 - x

2x = 14(9.0 - x)

2x =  126 - 14x

16x = 126

x = 7.90 g

Total weight of Y extracted = (63 + 7.90) g

= 70.9g

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Answer:

Reductions in available food and shelter

Explanation:

To solve this we must be knowing each and every concept related to population. Therefore, organisms in over-populated areas do not survive well due to reduction in available food and shelter.

The group of people from whom a quantitative sample is gathered for a research is referred to as a population. Therefore, a population is any collection of people who have anything in common.

A sample is a representative group of a population chosen at random. This is a smaller group that was selected from the population and possesses all of the population's traits. The observations and inferences drawn from the sample data then applied to the entire population.

Therefore, organisms in over-populated areas do not survive well due to reduction in available food and shelter.

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Answer:

21 is the max but with the bread ypu could make 22 if you had 3 more cheese

Answer:

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes.

Explanation:

Answer:

Hope this helped.

Explanation:

Cellulose is a molecule, consisting of hundreds – and sometimes even thousands – of carbon, hydrogen and oxygen atoms. Cellulose is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre.

Answer:

The sun's light is blocked by the moon.

Explanation:

During the eclipse, the moon rotates right in front of the sun, that's why the eclipse is so rare and only happens every four(?) years/

Answer:

[tex]\boxed {\tt 1.0 \ g/mL}[/tex]

Explanation:

Density can be found by dividing the mass by the volume.

[tex]d=\frac{m}{v}[/tex]

The mass of the water is 50.0 grams.

The volume of the water is 50.0 milliliters.

[tex]m= 50.0\ g \\v=50.0 \ mL[/tex]

Substitute the values into the formula.

[tex]d=\frac{50.0 \ g}{50.0 \ mL}[/tex]

Divide.

[tex]d= 1.0 \ g/mL[/tex]

The density of the water is 1.0 grams per milliliter. Also, remember that the density of pure water is always 1.0 g/mL or g/cm³

The mass number of an element is the sum of the protons and neutrons present in the nucleus of the atoms of the element.

The mass number of an element is the number obtained when the number of protons and neutrons in the nucleus of an atom of the element are summed together.

The sum of protons and neutrons in the nucleus of an atom is collectively known as the nucleon. Thus, the mass number of an atom can also be referred to as the nucleon of the atom.

This can be mathematically expressed as:

Mass number = number of protons + number of neutrons.

Atoms generally contain protons, neutrons, and electrons. The protons are positively charged and are located in the nucleus, the neutrons are also located in the neucleus but have no charges. The electrons, on the other hand, are located outside the nucleus in regions referred to as orbitals.

The sum of the protons and neutrons determine the mass of an atom because the contribution of electrons to the mass of atoms is negligible.

Thus, the mass number of an element is the sum of proton and neutron numbers present in the nucleus of the atoms of the element.

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Answer:

The given reaction has been the symbolization for replacement reaction. Thus, option D is correct.

The given general reaction has been:

[tex]\rm AB\;+\;CD\;\rightarrow\;AD\;+\;CB[/tex]

In the given reaction, there has presence of compound AB and CD. The reaction between the two results in the formulation of AD and CB. In the reaction, the B has been more attracted by C and forms bond with C by replacing D.

In the same way, A has been more attracted with D and forms bond with D replacing C.

The type of reaction in which the more reactive element replaces the less reactive element has been termed as replacement reaction. Thus, the given reaction has been the symbolization for replacement reaction. Thus, option D is correct.

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Answer:

the correct answer would be A. acidity

Answer:

The answer is A.) Acidity

Extremophiles are bacteria, archaea, as well as eukarya across all three domains of life. Cells make up every organisms.

Extremophiles contain bacteria, archaea, as well as eukarya from all three domains of life.

Any organic, biological system which works as a separate entity was referred to as an organism.

Extremophiles are organisms that can survive in harsh settings, such as those with high temperatures, radiation, salt, or pH levels. In the planet's evolutionary development, several creatures have been ecologically dominating.

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Answer:

Ka = 4.70x10⁻⁴M

Explanation:

The general dissociation of a weak acid, HX, is:

HX(aq) ⇄ H⁺(aq) + X⁻(aq)

And Ka is written as:

Ka = [H⁺] [X⁻] / [HX]

Where [] represents the molar concentration in equilibrium of each specie.

The equilibrium is reached when X of HX is dissociate in X H⁺ and X X⁻, that is:

[HX] = 0.0129M - X

[H⁺] = X

[X⁻] = X

As pH = -log [H⁺]:

10^-pH = [H⁺] = X  = 2.239x10⁻³M

Solving:

[HX] = 0.0129M - 2.239x10⁻³M = 0.01066M

[H⁺] = 2.239x10⁻³M

[X⁻] = 2.239x10⁻³M

Ka = [H⁺] [X⁻] / [HX]

Ka = [2.239x10⁻³M] [2.239x10⁻³M] / [0.01066M]

Answer:

Explanation:

pH = 10.3

[ H] = 10⁻¹⁰°³

= 5 x 10⁻¹¹ M

concentration of CsOH C = 3 M

pKa of carbonate = 6.35

Ka = 10⁻⁶°³⁵ = 4.46 x 10⁻⁷

Buffer capacity = 2.303 x C x Ka x [ H⁺] / ( Ka + [ H⁺]² )²

= 2.303 x 3 x 4.46 x 10⁻⁷  x 5 x 10⁻¹¹ / ( 4.46 x 10⁻⁷  + 25 x 10⁻²² )²

= 154 x 10⁻¹⁸ / 19.9 x 10⁻¹⁴

= 7.74 x 10⁻⁴ .

Answer:

0.133

Explanation:

reaction between KIO3 and KI in acidic medium

IO3⁻ +5I⁻ +6h⁺ → 3I₂ + 3H₂O

I₂ reacts with thiosulphate

NaS₂O₃  → 2Na⁺ + S₂O₃²⁻

net reaction

IO⁻₃ + 6H⁺ + 6S₂O₃³⁻ → I⁻ + 3S₄O₆²⁻ + 3H₂O

mole of KIO₃

= molarity x volume

[tex]\frac{0.02mol}{L} *0.01L[/tex]

= 0.00002mol

a mole of KIO₃ has reaction with 6 mol of S₂O₃²⁻

= 2x6x10⁻⁵

= 0.00012 mol

volume = 0.90 ml

1 ml = 0.001L

0.90ML  = 0.0009L

to get concentration,

molarity/volume

= 0.00012/0.0009

= 0.133m

The concentration of the standard sodium thiosulfate solution is ; 0.133

The net chemical reaction equation

IO₃⁻  +  6H⁺  +   6S₂O₃³⁻ ---->  I⁻  +  3S₄O₆²⁻  + 3H₂O

First step : Determine the moles of  KIO₃

number of moles = molarity * volume

                            = 0.02 mol / L * 0.01 L

                            = 0.00002 mol

From the net chemical reaction equation

one ( 1 ) mole of KIO₃ reacts with 6 moles of S₂O₃²⁻

∴ number of moles in the reaction = 6 * 0.00002 = 0.00012 mol.

Final step : Determine the concentration of sodium thiosulfate solution

Given Volume = 0.90 ml = 0.0009 L

∴ concentration of sodium thiosulfate solution

   =  0.00012 / 0.0009  =  0.133

Hence we can conclude that The concentration of the standard sodium thiosulfate solution is ; 0.133

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Answer:

Will be more acidic

Explanation:

The equilibrium of NH3 in water is:

NH3(aq) + H2O(l) ⇄ NH4⁺(aq) + OH⁻(aq).

Where equilibrium constant, Kb, is:

Kb = 1.85x10⁻⁵ = [NH4⁺] [OH⁻] / [NH3]

From 0.10M NH3, the reaction will produce X of NH4⁺ and X of OH⁻ and Kb will be:

1.85x10⁻⁵ = [X] [X] / [0.10M]

1.8x10⁻⁶ = X²

X = 1.34x10⁻³ = [OH⁻]

As pOH = -log[OH⁻] = 2.87

And as pH = 14 - pOH

pH of the 0.10M NH3 is 11.13

Now, to find the pH of the NH4Cl and NH3 we need to use H-H equation for bases:

pOH = pKb + log [NH4⁺] / [NH3]

Where pKb is -log Kb = 4.74 and [] are moles of both compounds.

Moles of [NH4⁺] = [NH3] = 60mL, 0.060L*0.22M = 0.0132moles:

pOH = 4.74 + log [0.0132] / [0.0132]

pOH = 4.74

pH = 14 - 4.74 = 9.26

That means the pH of the resulting solution will be more acidic