What is chemical energy? (2 points)

a
Energy that is stored or released during a chemical reaction

b
Energy that is destroyed during a physical change

c
Energy that is released during a phase change

d
Energy that is created when a substance is being burned

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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Answer:

V₂ = 87.24 L

Explanation:

Charle's law states that at constant pressure, the volume of the gas is directly proportional to the temperature. Its mathematical form is given by :

[tex]\dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}[/tex]

We have, V₁ = 75, T₁ = 245 K, T₂ = 285, V₂ = ?

Putting all the values, we get :

[tex]V_2=\dfrac{V_1T_2}{T_1}\\\\V_2=\dfrac{75\times 285}{245}\\\\V_2=87.24\ L[/tex]

So, the new volume is 87.24 L.

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

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

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:

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:

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. H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)

b. 0.603 M

Explanation:

Step 1: Write the neutralization reaction

H₂CO₃(aq) + KOH(aq) ⇄ K₂CO₃(aq) + H₂O(l)

Step 2: Calculate the reacting moles of KOH

22.9 mL of 1.430 M KOH react.

0.0229 L × (1.430 mol/L) = 0.0327 mol

Step 3: Calculate the reacting moles of H₂CO₃

The molar ratio of H₂CO₃ to KOH is 1:1. The reacting moles of H₂CO₃ are 1/1 × 0.0327 mol = 0.0327 mol.

Step 4: Calculate the molarity of H₂CO₃

0.0327 moles of H₂CO₃ are in a volume of 54.2 mL. The molarity of H₂CO₃ is:

M = 0.0327 mol/0.0542 L = 0.603 M

Answer:

The answer is true

Explanation:

bc I took this on edgeunity

Answer:

try dividing the grams and the volume and see what number matches up with your answer

Answer:

Thus, at convergent boundaries, continental crust is created and oceanic crust is destroyed. Two plates sliding past each other forms a transform plate boundary. Natural or human-made structures that cross a transform boundary are offset—split into pieces and carried in opposite directions.

Explanation:

Answer:

Even though oxygen is transported via the blood, you may recall that oxygen is not very soluble in liquids. A small amount of oxygen does dissolve in the blood and is transported in the bloodstream, but it is only about 1.5% of the total amount. The majority of oxygen molecules are carried from the lungs to the body’s tissues by a specialized transport system, which relies on the erythrocyte—the red blood cell. Erythrocytes contain a metalloprotein, hemoglobin, which serves to bind oxygen molecules to the erythrocyte (Figure 1). Heme is the portion of hemoglobin that contains iron, and it is heme that binds oxygen. One hemoglobin molecule contains iron-containing Heme molecules, and because of this, each hemoglobin molecule is capable of carrying up to four molecules of oxygen. As oxygen diffuses across the respiratory membrane from the alveolus to the capillary, it also diffuses into the red blood cell and is bound by hemoglobin. The following reversible chemical reaction describes the production of the final product, oxyhemoglobin (Hb–O2), which is formed when oxygen binds to hemoglobin. Oxyhemoglobin is a bright red-colored molecule that contributes to the bright red color of oxygenated blood.

Hb + O2 ↔ Hb − O2

Answer:

d

Explanation:

collagen is made of proteins

Answer: It's gravity keeps the Moon orbiting around the Earth.

Explanation:

Complete Question

The complete question is shown in the first uploaded image

Answer:

So the math expression is  

             [tex]heat  =  \frac{ 35. 7  KJ *  1900 \ gram }{ 1 \ gram }[/tex]

Explanation:

From the question we are told that

  The heat released for 1 gram of reactant consumed is  [tex]H  =  37.5 \ KJ/g [/tex]

   The mass of reactant considered is  [tex]m =  1.9 \ kg  =  1900 \  g[/tex]

So  if

             [tex]37.5 \ KJ [/tex] is produced for  1 gram

Then

              x kJ is produced for  1900 g  

=>   [tex]x  =  \frac{ 35. 7  KJ *  1900 \ gram }{ 1 \ gram }[/tex]

So the heat released is  

       [tex]heat  =  \frac{ 35. 7  KJ *  1900 \ gram }{ 1 \ gram }[/tex]

Answer:

There are three basic types of chemical formula, the empirical formula, the molecular formula, and the structural formula.

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 Group 1 elements in the periodic table are known as the alkali metals. They include lithium, sodium and potassium, which all react vigorously with water to produce an alkaline solution.

Explanation:

Answer:

1) easy compressed

2) fills its container

3) far more space

Explanation:

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:

1.05  × 10^-20 microlitres

Explanation:

The computation of the volume of a molybdenum atom in micro liters is shown below:

As we know that

1 litre  = 1000cm^3

1 microlitre= 10^-6 litre

Therefore

1 cm^3 =  10^3 microlitres.

hence,

1.05 × 10^-23 cm^3 = 1.05  × 10^-20 microlitres

Hence, the volume of a molybdenum atom in micro liters is 1.05  × 10^-20 microlitres

The same is to be considered

Answer:

f and a. That is reagents f[HNO3, H2SO4] is used first then followed by reagent a[Br2, FeBr3]

Explanation:

So, in the production of m-bromonitrobenzene[3-Nitro-1-bromobenzene/1-Bromo-3-nitrobenzene] from benzene from the reagents provided by using the fastest reagents that is to say the reagent with the minimum number of steps, we are going to make use of reagents in option 'f' followed by reagents in  option 'a'.

STEP ONE: The first step in the production of m-bromonitrobenzene[3-Nitro-1-bromobenzene/1-Bromo-3-nitrobenzene] from benzene to give the minimum number of steps from the reagents given is nitration by using the reagents in option 'f'' that is  HNO3, H2SO4 to give nitrobenzene. The equation for the chemical reaction is given below as:

C₆H₆ +  HNO₃, H₂SO₄ -------------------------------------------------------> C6H5NO2.

It is the N⁺O₂ that is been used in the reaction mechanism [from the reaction:  HNO₃ + H₂SO₄ < -----------------> N⁺O₂ + HSO₄⁻ + H₂O].

STEP TWO: The next thing to do is to react the nitrobenzene got from the nitration of benzene in step one above with the reagents in option 'a'[Br2, FeBr3]. This step is known as the bromination of nitrobenzene.

C₆H₅NO₂ + Br₂, FeBr3 ------------------------------------------------> C₆H₄BrNO₂.

Answer:

True

Explanation:

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

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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As air undergoes conduction better in tile than in carpet, hence a carpeted floor feel warmer to bare feet than tile or wood even though all surfaces are the same temperature.

Conduction is defined as a process as a means of which heat is transferred from the hotter end of the body to it's cooler end.Heat flows spontaneously from a body which is hot to a body which is cold.

In the process of conduction,heat flow is within the body and through itself.In solids the conduction of heat is due to the vibrations and collisions of molecules while in liquids and gases it is due to the random motion of the molecules .

When conduction takes place, heat is usually transferred from one molecule to another as they are in direct contact with each other.There are 2 types of conduction:1) steady state conduction 2) transient conduction.According to the type of energy conduction is of three types:

1) heat conduction

2) electrical conduction

3)sound conduction

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Answer:

Definition: Fluid that can act as a liquid or as a solid depending on the pressure applied on it.

Explanation:

A fluid that incorporates time in a solid and liquid model is a non-Newtonian fluid. This type of fluid can behave as a solid or as a liquid depending on the pressure that is applied on it. This is different from normal fluids that remain the same regardless of the pressure they are subjected to. In the case of non-Newtonian fluids, when submitted to pressure, they are presented as solids, but without pressure, they are presented as liquids. This feature can be seen even within the same system.