Which material does not melt at any temperature? wood, a mixture of different substances ethanol, a molecular compound sodium chloride, an ionic compound iron, a metallic element description?

Answers

Answer 1
The material, which does not melt at any temperature is WOOD.
Wood is made up of many substances including lignin, water, cellulose and other organic materials. When wood is heated, it normally oxidizes in the presence of oxygen before it has the chance to melt. The physical structure of the wood is typically destroyed during this process and the original material can not be obtain again.This irreversible breakdown of wood makes it impossible for wood to melt. 

Related Questions

Which of the following compounds has the highest boiling point?

2-pentanone

pentene

chloropentane

pentane

Answers

the answer is chloropentane

Answer: chloropentane

Explanation:

When a hydrocarbon has a halogen atom, its properties will change because this group has a higher molecular weight and a higher polar moment that will be hard to defeat in order to reach the boiling point.

The Boiling point of the pentene is 30°C // pentane is 36,1°C //  2-pentanone is 101°C and chloropentane 108°C.

Simple hydrocarbons have lower boiling points compare with those with a functional group like the Oxygen in the 2-pentanone and the Chlorine in the  chloropentane. On the other heand,  Oxygen is not as electronegative and heavy like Chlorine, thus the chloropentane is the one with higher boiling point.

NaCl + AgNO3 —> AgCl + NaNO3

How much AgNO3 is consumed during the reaction with 78 g of NaCl?

Answers

Answer is: 226,88 grams of AgNO₃ is consumed.
Chemical reaction: NaCl + AgNO₃ → AgCl + NaNO₃.
m(NaCl) = 78 g.
n(NaCl) = m(NaCl) ÷ M(NaCl).
n(NaCl) = 78 g ÷ 58,4 g/mol.
n(NaCl) = 1,335 mol.
From chemical reaction: n(NaCl) : n(AgNO₃) = 1 : 1.
n(AgNO₃) = 1,335 mol.
m(AgNO₃) = 1,335 mol · 169,87 g/mol.
m(AgNO₃) = 226,88 g.

Final answer:

To find the amount of AgNO₃ consumed, calculate the moles of NaCl present in 78 g and use the one-to-one mole ratio of the reactants to determine the moles and then the mass of  AgNO₃ consumed, which is 226.86 grams.

Explanation:

To calculate how much  AgNO₃ is consumed in the reaction with 78 g of NaCl, we first need to understand the stoichiometry of the reaction. The balanced chemical equation is:

NaCl (aq) +  AgNO₃ (aq) → AgCl (s) + NaNO₃ (aq)

This indicates that 1 mole of NaCl reacts with 1 mole of  AgNO₃ to produce 1 mole of AgCl and 1 mole of NaNO₃.

First, we must examine the reaction stoichiometry, which is a one-to-one ratio. Therefore, we need to calculate the number of moles of NaCl:

Find the molar mass of NaCl: Na (22.99 g/mol) + Cl (35.45 g/mol) = 58.44 g/molCalculate the moles of NaCl: 78 g NaCl ÷ 58.44 g/mol = 1.335 moles NaCl

Since the stoichiometry is one-to-one, the moles of NaCl will equal the moles of  AgNO₃ that react:

1.335 moles NaCl = 1.335 moles  AgNO₃ consumedFind the molar mass of  AgNO₃: Ag (107.87 g/mol) + N (14.01 g/mol) + 3×O (16 g/mol each) = 169.87 g/molCalculate the mass of  AgNO₃ consumed: 1.335 moles × 169.87 g/mol = 226.86 grams  AgNO₃

Therefore, 226.86 grams of  AgNO₃ is consumed when 78 grams of NaCl react.

Valence electrons are responsiblefor the makeup of chemical properties of elements true or false

Answers

Answer:

WRONG-the answer is TRUE

Explanation:

The ionization of pure water forms _____.

Answers

Answer: The ionization of pure water forms hydroxide and hydronium ions.

Explanation:

Ionization is a reaction in the pure water in which water breaks down into its constituting ions that hydronium ion and hydroxide ions.

[tex]H_2O+H_2O\rightleftharpoons H_3O^++OH^-[/tex]

One molecule of water looses its proton to form hydroxide ion and l=the lost protons get associated with another water molecule to form hydronium ion.

Which of the following is essential for a theory to become widely accepted within the scientific community? (2 points)
A theory must include a valid scientific model.

A theory must be supported by many different experiments.

A theory is an educated guess based on multiple observations.

A theory must change over time regardless of the scientific data.

Answers

A theory must be supported by many different experiments.

Answer:

A theory must be supported by many different experiments.

Explanation:

It is important for a theory to be tested by different independent science labs. When the same data are observed only then the theory reaches a consensus in the scientific community. A theory is based on evidence and not on educated guess. A scientific theory withstands rigorous scrutiny before it becomes accepted by the scientific community. Hence option B in correct.

If 5.10 g of acetic acid is reacted, how many grams of water can form?

Answers

To determine how much water can form would depend on what the acetic acid is reacting with. However, a very common reaction of acetic acid that leads to the formation of water is the condensation that occurs during the esterification process. We can react acetic acid with an alcohol, such as methanol, and form the ester and water.

CH₃CO₂H + CH₃OH → CH₃CO₂CH₃ + H₂O

The mole ratio of water to acetic acid is 1:1. We can now use the mass of acetic acid to find the moles, which we can convert to moles of water:

5.10 g CH₃CO₂H / 60 g/mol = 0.085 mol CH₃CO₂H x 1 mol H₂O/1 mol CH₃CO₂H = 0.085 mol H₂O

0.085 mol H₂O x 18 g/mol = 1.53 g H₂O

In the reaction provided, assuming the reaction goes to completion, 5.10 g of acetic acid can form 1.53 g of water.

Write a chemical equation that illustrates the autoionization of water -g.com

Answers

The equation is H2O (l) + H2O(l)  OH- (aq) + H3O+(aq) 
We have to know how it could be when the acid donates the H+ and the base accept the H+.
So here we assume that one of H2O is acid and the other H2O in the equation is a base, then the first H2O loses H+ and the second H2O gain the H+. 

When substances go through chemical changes, which of the following will always happen? A. Exactly one new substance will form and one will be destroyed. B. One or more substances with different chemical properties will form. C. One or more substances will be completely destroyed. D. A gas will form or a white solid will precipitate.

Answers

i think b is the answer 
B. one or more new substances form with different chemical properties.

Consider the data presented below. time (s) 0 40 80 120 160 moles of a 0.100 0.067 0.045 0.030 0.020 part a part complete determine whether the reaction is first order or second order. determine whether the reaction is first order or second order. this is the first order reaction. this is the second order reaction. submitprevious answers correct part b what is the rate constant?

Answers

Final answer:

The reaction is likely first order as indicated by the provided rate constant which aligns with the characteristics of a first-order reaction.

Explanation:

To determine whether the reaction is first order or second order, we need to consider the rate at which the concentration of A changes over time. For a first order reaction, the rate of reaction is directly proportional to the concentration of the reactant. This means that if you were to plot the natural logarithm (ln) of the concentration of A versus time, you would see a linear relationship.

In contrast, a second order reaction implies that the rate is proportional to the square of the concentration of the reactant. Here, plotting the inverse of the concentration of A versus time would yield a linear relationship.

Given that the rate constant for the reaction is expressed as k = 1.0 × 107 L mol−1 min−1, this is indicative of a first order reaction, as it does not include a squared concentration term. Therefore, based on the provided information, the reaction is first order.

In bowen's discontinuous reaction series, the first mineral to crystallize out of a mafic melt is __________ .

Answers

The Olivine normally crystalizes first from the magma of the mafic minerals, It crystalizes at between 1200°C and 1300°C. when the temperature of magma drops and there is a silica still remains in the magma so the olivine reacts with this silica to form pyroxene.and by more cooling of the temperature of magma and there is a silica still remains in magma pyroxene change to amphibole, and amphibole to biotite.when the pyroxene strat to form the plagioclase feldspar also forms. 

Final answer:

The correct answer is "olivine". In Bowen's discontinuous reaction series, olivine is the first mineral to crystallize from a mafic melt. It later reacts to form pyroxene as the magma cools. This series helps us understand mineral crystallization and the formation of igneous rocks.

Explanation:

In Bowen's discontinuous reaction series, the first mineral to crystallize from a mafic melt is olivine. The process of crystallization in a cooling magma begins with high-temperature minerals like olivine. As the temperature of the magma decreases, different minerals begin to crystallize while others become unstable, with olivine reacting with silica to form pyroxene at lower temperatures. This reaction is represented by the equation Mg2SiO4 + SiO2 > 2MgSiO3, turning olivine into pyroxene. Through Bowen's reaction series, we understand that the crystallization of minerals removes elements such as magnesium (Mg) and iron (Fe) from the magma, altering its composition over time. These early-formed minerals are known as phenocrysts, and their formation is sequential based on the cooling of the magma. Bowen's reaction series not only informs us about mineral crystallization sequences but also about the formation of different igneous rocks and their compositions.

One way the modern atomic model differs from Thomson's atomic model is that electrons are no longer scattered throughout and atom's positive matter like chocolate chips in a cookie dough. instead, each electron is outside of the nucleus occupying a specific ___

Answers

Hello!

One way the modern atomic model differs from Thomson's atomic model is that electrons are no longer scattered throughout an atom's positive matter like chocolate chips in a cookie dough. instead, each electron is outside of the nucleus occupying a specific Energy Level.

The modern atomic model is also called the Schrodinger's model or the Quantum Mechanical model. Although atoms are commonly depicted like planets with electrons orbiting it like satellites, in reality, electrons aren't in fixed orbits but there are clouds where there is a bigger probability of finding an electron. This area is called an Energy Level. 

Have a nice day!

Sea anemones are predatory invertebrates with stinging tentacles that can paralyze many sea animals. The clownfish is immune to the sting of the sea anemone and actually lives among its tentacles. The relationship is mutually beneficial—the clownfish often lures meat-eating animals over to the anemone, and the anemone benefits from the meal. The clownfish often gets to eat leftovers from the anemone’s meal.

When the clown fish is ready to lay eggs, it lays them near a sea anemone. How’s this a reproductive strategy?

The sea anemone protects the clownfish’s eggs from predators.
The sea anemone fertilizes the clownfish’s eggs.
The sea anemone provides nourishment for the clownfish’s eggs.
The sea anemone uses the clownfish’s eggs to lure prey.
The sea anemone lets the clownfish rest on it.
NextReset

Answers

Nature is full of wonders and one of the most impressive of them are symbiotic relationships (mutually beneficial relationships). Despite the competition in the kingdom of life, here 2 actors help each other to gain more than they could individually. Let's look at the answers. The sea anemone can't possibly fertilize the clownfish's eggs, only another clownfish can do that. The 4th choice might be correct but it does not help the clownfish; The 5th choice is also correct but it is not related to the offspring of the clownfish. For the 3rd choice, we have that the anemone sometimes provides leftovers for the fish, but the fish' eggs cannot use this source of nutrients. However, we know that the 1st assertion holds; the poisonous tentacles of the sea anemone protect the eggs from potential predators.

Clownfish lay their eggs near sea anemones as a reproductive strategy because the anemones' stinging tentacles protect the eggs from predators.

When clownfish are ready to lay eggs, they do so near a sea anemone to leverage the anemone's natural defenses as part of their reproductive strategy.

Sea anemones have stinging tentacles that can immobilize or deter potential predators. This interaction is a classic example of mutualism, a type of symbiotic relationship between two organisms where both benefit.

For clownfish, laying eggs near the sea anemone means the eggs are protected by the anemone's stinging capabilities, which significantly reduces the likelihood of predators consuming them. The correct answer to how this is a reproductive strategy is that the sea anemone protects the clownfish's eggs from predators.

Although clownfish and anemones do have a mutually beneficial relationship overall, in this specific case, the anemone does not fertilize, nourish the eggs, or use them to lure prey, nor does it provide a resting place for clownfish.

convert 4540 grams of gold to moles of gold

Answers

The atomic mass of gold is 79g/mol
Therefore, 4540 grams will have
4540/79 = 57.46835
Therefore; 
 = 57.468 moles

To calculate moles , we divide mass of the substance given by the molar mass of the substance.

That can be mathematically represented as:

[tex] Number of moles of a substance= \frac{Given mass of a substance}{ Molar mass of substance} [/tex]

Here given mass of substance is 4540 g

Molar mass of the substance is 196 g mol⁻¹

So number of moles can be calculated as:

[tex] Number of moles of a substance= \frac{Given mass of a substance}{ Molar mass of substance} [/tex]

[tex] Number of moles of gold= \frac{4540}{196} [/tex]

So number of moles of gold =23.16 mol

Which of the following can explain the daily change in sea level observed along a coast?
A. The gravitational pull of the moon on the water near the coast
B. The speed of the ocean's conveyor belt near the coast
C. Earthquakes and volcanoes near the coast
D. The concentration of salt in the water near the coast

Answers

The answer for the question above is A. the gravitational pull of the moon on the water near the coast. The sun and and the moon are responsible for the rising and falling of the ocean tides. The gravitational pull of the moon and the sun makes the water in the oceans bulge, causing a continuous change between high and low tide. 

Predict the bond present between carbon and hydrogen in polyethylene

Answers

it is an alkene: CnH2n (n=number of the atoms of carbon)
in ethylene there are two carbons so:
C2H4 just like the picture

Which of the following statements best describes Kepler's law of ellipses?

Each planet orbits the sun in an elliptical shape with the sun at one of the ellipse's two focal points.
An ellipse has two focal points. The sun is at one focal point of an ellipse. The other focal point is the planet that orbits the sun.
The planets orbit the sun in a perfect circle. The sun is an elliptical shape.
Planets must orbit the sun in an elliptical shape because an ellipse has two focal points.

Answers

The answer is "Each planet orbits the sun in an elliptical shape with the sun at one of the ellipse's two focal points." The first option refers to Kepler's First Law which contradicts Ptolemy and Copernicus' assumption that orbits are "perfectly" shaped. In Kepler's concept of the ellipse, planets orbit in an elliptical path with the sun at one of the two focal points since the other focus is empty.

Answer : Each planet orbits the sun in an elliptical shape with the sun at one of the ellipse's two focal points.

Explanation:

Kepler's Law of ellipses: This law explains the path of the planet around the sun

The orbit of the planet around the sun is an ellipse shape, where sun is present on the one of the focus.

From the given options the correct option is:

Each planet orbits the sun in an elliptical shape with the sun at one of the ellipse's two focal points.

Which of these choices is a goal of the Soil and Water Resources Conservation Act?

A. To establish a federal bureau that regulates the use of federal areas
B. To establish air-quality standards and regulate emissions of air pollutants
C. To assess the conservation of soil and water resources on private lands
D. To limit the carbon emissions of fossil fuel power plants

Answers

The correct answer is C.
The aim of the Soil and Water Resources Conservation Act from 1977 is to assess the conservation of soil and water resources on private lands. 
It provides for the United States Department of Agriculture to estimate the status and trends of soil, waters and similar resources, as well as improve and protect them through the necessary programs and policies. 

Answer:

A

Explanation:

How does hydrogen bonding affect the physical properties of substances?

Answers

The melting and boiling point depend on the strength of the ihydrogen bonds. Hydrogen bonding will cause the higher the melting and boiling points because more energy is needed to break bonds between molecules.
Hydrogen bonds affect solubility in water, molecules with hydrogen bonds dissolve better in water.

Final answer:

Hydrogen bonding affects the physical properties of substances such as water and carboxylic acids by increasing their boiling point, melting point, solubility, heat capacity, surface tension, and viscosity due to the additional attractive intermolecular forces these bonds provide.

Explanation:

Hydrogen bonding significantly influences the physical properties of substances. These intermolecular forces occur when a hydrogen atom bonded to a strongly electronegative atom, like oxygen or nitrogen, is attracted to another electronegative atom in a nearby molecule. This attraction leads to a type of bond that, while not as strong as a covalent bond, significantly affects a substance's physical characteristics.

For instance, in water molecules, hydrogen bonds form between the positively charged hydrogen atom of one molecule and the negatively charged oxygen atom of another. This results in a network of bonds that increase the melting point and boiling point of water, compared to what would be expected based on its molecular weight alone. It's also the reason why water has a high heat capacity, surface tension, and viscosity.

In the case of carboxylic acids, hydrogen bonding allows these molecules to dimerize (form pairs), which enhances their boiling points and makes them more soluble in water than comparable hydrocarbons. When carboxylic acids dissolve in water, the hydrogen bonding facilitates the interaction between acid molecules and water, which is crucial for their dissolution and the resultant physical properties.

How much energy is evolved during the formation of 197 g of fe, according to the reaction below? fe2o3(s) + al(s) → al2o3(s) + fe(s) δh°rxn = -852 kj?

Answers

Answer is: 1,51·10³ kJ is evolved during the formation.
Chemical reaction: Fe₂O₃(s) + Al(s) → Al₂O₃(s) + Fe(s); ΔH°rxn = -852 kJ.
m(Fe) = 197 g.
n(Fe) = m(Fe) ÷ M(Fe).
n(Fe) = 197 g ÷ 55,85 g/mol.
n(Fe) = 3,527 mol.
Use proportion: 2 mol(Fe) : -854 kJ = 3,527 mol(Fe) : ΔH°rxn.
ΔH°rxn = -854 kJ · 3,527 mol ÷ 2 mol.
ΔH°rxn = -1510 kJ = -1,51·10³ kJ.

Answer : The energy evolved in the reaction is 1499.52 kJ

Explanation :  Given,

Mass of Fe = 197 g

Molar mass of Fe = 56 g/mole

Enthalpy of reaction = -852 kJ

First we have to calculate the moles of Fe.

[tex]\text{ Moles of Fe}=\frac{\text{ Mass of Fe}}{\text{ Molar mass of Fe}}=\frac{197g}{56g/mole}=3.52moles[/tex]

Now we have to calculate the energy evolved in the reaction.

From the balanced chemical reaction we conclude that,

As, 2 mole of Fe evolved energy = 852 kJ

So, 3.52 mole of Fe evolved energy = [tex]\frac{3.52}{2}\times 852kJ[/tex]

                                                         = 1499.52 kJ

Therefore, the energy evolved in the reaction is 1499.52 kJ

Consider separate 1.0-l gaseous samples of h2, xe, cl2, and o2 all at stp.
a. rank the gases in order of increasing average kinetic energy.
b. rank the gases in order of increasing average velocity.
c. how can separate 1.0-l samples of o2 and h2 each have the same average velocity?

Answers

1) I think all the gases have the same kinetic energy. Since kinetic energy depends only on temperature and since all are at STP. Kinetic energy is the energy possessed by a body or molecules in motion, for gases the kinetic energy increases with increase in temperature due to increased vibration of gas molecules.

2) Kinetic energy is given by the formula 1/2mv^2, where m is the mass and v is the velocity. All the gases have the same kinetic energy, mass and velocity are inversely proportional. Therefore, the most massive molecules will have the lowest average speed. H2 is the fastest, Xe is the slowest.
Xe, Cl2, O2, H2, in the order of increasing speed. 

3) Two separate gases will have the same kinetic energy at the same temperature, but not the same average speeds. To have the same average speed the two gases will not be at the same temperature. 
Final answer:

All gases at the same temperature have the same average kinetic energy. The average velocity of gases increases with decreasing molar mass. Thus, 1.0-L samples of O2 and H2 can have the same velocity because velocity is also affected by temperature.

Explanation:

The kinetic energy of a gas is determined by its temperature, not by the identity of the gas itself. This is explained by the Kinetic Molecular Theory. Because all four gases are at the same temperature (standard temperature), they have the same average kinetic energy.

However, the average velocity of the gases varies depending upon the molar mass of the gas. The lighter the gas (lower molar mass), the faster it moves. Thus, the order of increasing velocity is Xe < Cl2 < O2 < H2.

To answer part c, the reason why 1.0-L samples of O2 and H2 can each have the same average velocity despite being different substances is because the average velocity of a gas depends not only on its mass, but also the temperature at which it is measured. As these two samples are both at the same temperature, they can have the same average velocity.

Learn more about Kinetic Energy and Velocity of Gases here:

https://brainly.com/question/20299120

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What pressure will be exerted by 0.650 mol of a gas at 30.0C if it is contained in a 0.700 L vessel?

Answers

I believe you need to use the ideal gas constant which is Pv=nRT and P is the pressure so if you solve for P you get P=(nRT)/v and you can then just plug in n= number of moles T=temp in kelvins v=volume in liters R= is a constant of .08206 L*atm/K*mol

A student is told that both energy and mass must be conserved in every chemical reaction. She measures the mass of Hydrochloric acid and a zinc strip separately. She then places the zinc strip into the acid and bubbles form as the zinc looks like it disappears. The combined mass afterward is less than the original.

Answers

I think the combined mass was less afterward than the original mass due to escape of hydrogen gas in the atmosphere. According to the law of conservation of mass, mass is conserved and does not change in a chemical reaction which occurs in a closed system. However in an open system the mass may not be conserved and may change due to release of gases to the atmosphere. Like in this case, hydrogen gas produced in the reaction was released to the atmosphere thus reducing the final mass.

Answer:

Explanation:

When we react Hydrochlorid Acid with zinc we have the following reaction:

2HCl(aq) + Zn(s) --> ZnCl2(aq) + H2(g)

The hydrogen gas formed is lost to the environment, so we can affirme that in the start we have the mass for all the H, Cl and Zn atoms in the solution, but after the reaction occurs, we have only the mass for the Cl and Zn atoms.

That's why the mass is less than the original.

The law that the student was told is only applied to closed environments.

If a balloon at 10 oC goes from 30L to 2L, what is the final temperature?

Question 4 options:

18.87


4.72


0.21


16,980.00


8490.00

Answers

I think its the 3rd one 0.21

Which of these equations demonstrates energetic coupling in a cell? equation 1: atp + h2o → adp + pi δg1 = –7 kcal/mol equation 2: phosphoenolpyruvate + h2o → pyruvate + pi δg2 = –14.8 kcal/mol equation 3: glucose + pi → glucose-6-phosphate + h2o δg3 = +3.3 kcal/mol equation 4: adp + pi → atp + h2o δg3 = +7 kcal/mol?

Answers

I believe the most appropriate equations are 1 and 3; that is 
ATP + H2O = ADP + Pi ΔGI =- 7 kcal/mol and 
Glucose + Pi = Glucose-6-phosphate  +H2O ΔG3 = +3.3 kcal/mol
Reaction coupling is a strategy used by cells in which an energetically favorable reaction such as hydrolysis of ATP is directly linked with an energetically unfavorable reaction.

Final answer:

Energetic coupling in a cell is demonstrated when the energy from an exergonic reaction, like ATP hydrolysis (Equation 1), is used to drive an endergonic reaction, such as the phosphorylation of glucose (Equation 3). ment.

Explanation:

Energetic coupling is a process where the energy released by an exergonic reaction (such as ATP hydrolysis) is used to drive an endergonic reaction, making the coupled process energetically favorable. To identify energetic coupling, we look for equations that pair an exergonic reaction with an endergonic reaction.

Equation 1: ATP + H2O → ADP + Pi; ΔG1 = –7 kcal/mol. This equation represents the hydrolysis of ATP, an exergonic reaction releasing energy.

Equation 3: glucose + Pi → glucose-6-phosphate + H2O; ΔG3 = +3.3 kcal/mol. This equation represents the endergonic process of phosphorylating glucose, which requires input of energy.

The coupling of ATP hydrolysis (Equation 1) to drive the phosphorylation of glucose (Equation 3) in cellular metabolism demonstrates energetic coupling. Here, the energy released from ATP is used to phosphorylate glucose, a process critical for cellular metabolism and an example of how cells harness energy from exergonic reactions to power endergonic reactions. Such coupling is central to cellular bioenergetics and metabolic pathways.

I WILL MARK BRAINLIEST How could this sentence be re-written to convey the active voice?
The landscape was carefully painted by the artist.
A) The landscape was painted.
B) The landscape was painted by the artist.
C) The artist carefully painted the landscape.
D) The beautiful landscape was carefully painted by the talented artist.

Answers

Active voice means that the person/object initiating the action is the subject of the sentence.

For example, 
He threw the book away (active voice) vs The book was thrown away by him. passive voice.

For the given sentence, the action was painting.  So go ahead and choose the sentence which indicates that the artist is the subject of the sentence.

Answer:

The answer is C) The artist carefully painted the landscape.

Explanation:

Assuming complete dissociation, what is the molality of k+, br− in an aqueous solution of kbr whose freezing point is -2.53 ∘c? the molal freezing-point-depression constant of water is 1.86 (∘c⋅kg)/mol.

Answers

Dissociation of potassium bromide: KBr(aq) → K⁺(aq) + Br⁻(aq).
ΔT = 2,53°C.
Kf = 1,86°C·kg/mol.
i - Van 't Hoff factor. Because dissociate on one cation and one anions, potassium bromide has i = 2.
b - molality.
ΔT = Kf · b(solution) · i.
2,53°C = 1,86°C·kg/mol · b(solution) · 2.
b(KBr) = 0,68 m = 0,68 mol/kg.
b(KBr) = b(K⁺) = b(Br⁻) = 0,68 m.
Answer: 0.68 m

Explanation:

1) The molality of the solution is found using the depression freezing-point colligative property formula:

ΔTf = i * m * Kf.

2) i is the van't Hoof factor. Which accounts for the dissociation of the KBr.

Since 1 molecule of KBr dissociates into 2 iones, 1 K+ and 1 Br-, this constant is 2., i = 2.

3) ΔTf = Tf water - Tf solution = 0 °C - (- 2.53°C) = 2.53°C

4) Kf is given: Kf = 1.86 [°C kg/mol]

5) => m = ΔTf / (i * Kf)

m = 2.53°C / (2 * 1.86°C / kg/mol) = 0.68 mol/kg = 0.68 m

6) Since, there is one mole of K+ and one mole of Br per every mole of KBr, then the molality of one of them is the same molality of the soluton

m of K+ = m of Br- = m of KBr = 0.68 m

How are greenhouse gases like carbon dioxide and methane different from other atmospheric gases like nitrogen and oxygen?

Answers

Greenhouse gases are more efficient at absorbing thermal energy and re-radiating it than the other atmospheric gases.

#1: Jim, Jane, Ann, and Bill measure an object’s length, density, mass, and volume, respectively. Which student’s measurement might be in centimeters?

A. Bill’s

B. Jane’s

C. Jim’s

D. Ann’s
**MY answer: C. Jim's

#2: How many centimeters are in 0.05 kilometers?

A. 50

B. 500

C. 5,000

D. 50,000
***My answer: C. 5,000

Answers

1. The student with a measurement that might be in centimeters is A. Bill.
2. Centimeters  in 0.05 kilometers is C. 5,000
solution:
0.05 km x (1000 meters/ 1 km)
= 50 meters x (100 cm/ 1 meter) 
=5000 cm

Check my answers please? Only 5 multiple choice questions. I'm really confused. Any and all help is appreciated! Will give medal!

1. Which of the following is a correctly written thermochemical equation?

NH4Cl NH4+ + Cl
2C8H18 + 25O2 16CO2 + 18H2O, H = 5,471 kJ/mol
Fe (s) + O2 (g) Fe2O3 (s), H = 3,926 kJ
-->C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol
2. How does a phase change affect a thermochemical equation?

It alters the moles of reactants.
-->It can affect the (delta) H value.
It alters the products.
It affects the balance of the equation.

Answers

For question number, the correct answer is
C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol

For question number 2, the correct answer is It can affect the (delta) H value.

This means that you are correct with your choices.

How many more valence electrons does oxygen need to have a full outer valence shell?

Answers

Oxygen is in group 16 of the PTOE, so it has 6 valence electrons. In order to have a full outer shell it would need 2 more electrons. (second shell can hold a max of 8 electrons)
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