1) Which example shows a change in a state
of matter?
A. Liquid pouring
2
B. Wood Burning
1
C. Ice Melting

The enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ

The objective of this question is to determine the value of ΔH and ΔE of combustion is for 1 mole of methane.

If we look closely at the question, we will realize that at constant pressure, methane burns and produces heat of 804 kJ into the surroundings.

Since heat is released;

ΔH = -804 kJ

It also does a work of 3kJ, since work is done on the system

W = - 3kJ

According to the first law of thermodynamics;

ΔE = ΔH  -  W

ΔE = (-804 - (-3 )) kJ

ΔE = -801 kJ

Therefore, we can conclude that the in 1 mole of methane, the enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ

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Answer:

Answer:

see explanation

Explanation:

Given 0.100M NaOH + 50ml 0.100M HCl

If 50ml of 0.100M NaOH is added to 50ml 0.100M HCl => pH = 7

if less than 50ml of 0.100M NaOH => pH < 7

if more than 50ml of 0.100M NaOH => pH > 7.

Example:

50ml(0.100M NaOH) + 50ml(0.100MHCl) =>

      0.500mole NaCl + 0.500mole H₂O

In this mix, both NaOH and HCl are converted to NaCl and H₂O and NaOH or HCl are no longer present giving a neutral solution. Since neither Na⁺ nor Cl⁻ undergo hydrolysis, the pH is dependent upon H₂O ⇄ H⁺ + OH⁻ and [H⁺] = [OH⁻] = 10⁻⁷M => pH = -log[H⁺] = -log(10⁻⁷) = -(-7) = 7

If less than 50ml of 0.100M NaOH is added, the mix will have an excess of HCl and the pH will be acidic; i.e., less than 7.

If more than 50ml of 0.100M NaOH is added, the mix will have an excess of NaOH and the pH will be alkaline (basic); i.e., greater than 7.

Answer: it would be the stem and the roots of the plant

Explanation:

Answer:

Bromine

Mercury

Bromine (symbol Br and atomic number 35) is a reddish-brown liquid, with a melting point of 265.9 K. Mercury (symbol Hg and atomic number 80) is a toxic shiny silvery metal, with a melting point of 234.32 K.

Answer:

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Explanation:

A more dense liquid stays lower while a less dense liquid stays higher. since water is 13.6 times less dense than mercury, the column for a barometer using water would have to be 13.6 times taller.

Answer:

2.4 M

Explanation:

1. Suppose you have 100 mL solution:

Use density to find grams of solution:

100 mL solution x (1.10 g / 1 mL) = 110 g solution

2. FInd the amount of sodium chloride pure:

110 g solution x(13 g NaCl / 100 g solution) = 14.3 g NaCl

3. Change grams to mol:

14.3 g NaCl x ( 1 mol NaCl/ 58.44 g NaCl) = 0.24 mol NaCl

4. Molarity:

M = mol NaCl / L solution

M = 0.24 mol NaCl / 0.1 L = 2.4 M

Answer:

It is a covalent bond because both carbon and oxygen are nonmetals. The formula will be CO² because the electrons between the atoms are being shared equally.

Answer:

Option C

Explanation:

CO₂ is a covalent bond because we know that both elements are nonmetals. The carbon atoms shares 2 electrons with each oxygen atom and each oxygen atom shares two electrons with the carbon atom. CO₂ forms a nonpolar covalent bond, meaning that the electrons are shared equally.

Explanation:

During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe over the protection and protection in their relatives. As Britain's populace step by step expanded, so did the quantity of crimes tha…

During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe the protection and protection of their relatives.

Protection is any measure taken to guard a thing against damage.

During the 1800s in England, relations police, which became composed of male volunteers, became organised to observe the protection and protection in their relatives.

As Britain's populace step by step expanded, so did the number of crimes that had been committed. This intended that regulation and order additionally needed to improve.

The New York City Police Department (NYPD) originates withinside the Government of New York City and tries to manipulate growing crime in early to mid-nineteenth century New York City.

This expanded crime became because of an expanding populace, brought about usually through negative Irish immigrants starting withinside the 1820s.

Whereas, as societies have become greater heterogeneous and complex, the function of the police is turning greater demanding. To fulfil this function, law enforcement officials want numerous broadly acknowledged competencies and private qualities, however much less is thought approximately how they're valued through police recruits.

Thus, we've tested the perspectives of police recruits in six European nations on 3 skills or traits of regarded significance for police work: knowledge, leadership, and the cap potential to shape precise family members with residents.

We have additionally explored versions in perspectives of recruits in distinct businesses and modifications of their perspectives for the duration of their schooling. For those purposes, we used survey facts accumulated withinside the RECPOL project.

Since the facts had been accumulated from distinct populations and at distinct times, the evaluation is primarily based totally on dimension invariance methodology, and one of the objectives became to spotlight the significance of rigorous appraisal of the pleasant and comparison of comparable survey facts the use of such methods.

The consequences display each variation and similarities in perspectives of recruits withinside the surveyed nations and modifications for the duration of schooling.

Police lifestyle seems to be an extensive factor, as greater objects withinside the carried out device can be validly utilized in comparisons of recruits in businesses with comparable policy traditions.

The consequences additionally confirmed exciting contrasts, e.g. new recruits in Sweden rated precise family members with residents greater surprisingly than recruits in businesses with a greater army history, however, this sample was modified for the duration of schooling, probably because of the effects of the recruitment process, schooling and lifestyle in the businesses.

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Tap water is a mixture not compound due to presence of many substance.

Tap water is an example of mixture not compound because in tap water, water is not available in pure form, it has many substances mix with water and those substances make no bond with water.

It has dissolved compounds like calcium carbonate, magnesium and fluoride. Different elements or compounds are physically combined rather than chemically linked together so we can conclude that student A is correct that tap water is a mixture.

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All of these properties are due to the chemical structure of the compound. The chemical structure includes the bonding angle, the type of bonds, the size of the molecule, and the interactions between molecules. Slight changes in the chemical structure can drastically affect the properties of the compound.

The balanced equation for the complete combustion of heptane, [tex]C_{7}H_{16}[/tex] is given as,

[tex]C_{7}H16(g) + 11O_{2} (g)[/tex] → [tex]7CO_{2}(g) + 8H_{2}O(g)[/tex] + heat/light

The chemical equation in which number of atom each elements is equal in reactant and product of the reaction is called  balanced chemical equation.

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Answer:

Electronnegativity

Explanation:

There are three important structural features: Hybridization, Bond angels, and Electron Geometry.

The not so important structural feature found by the number of electron rich regions is electronegativity. Hence option c is correct.

Structural feature is defined as the modeled as a directed acyclic graph (DAG), with the variable names as pathways and the variable values as nodes. The study of the construction of biological molecules is known as structural biology. Scientists study molecules in three dimensions using a range of imaging techniques to examine how they are put together, how they work, and how they interact.

Electronegativity is defined as the propensity for atoms involved in covalent bonds to draw the bonding electrons. The negatively charged electrons are drawn to the positively charged protons in the nucleus. The electronegativity or attraction will rise with the number of protons in the nucleus. Therefore, in a row of the periodic table, electronegativity rises from left to right.

Thus, the not so important structural feature found by the number of electron rich regions is electronegativity. Hence option c is correct.

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I hope you feel better soon! :)

Answer:

it should be the second one since London dispersion causes interaction between molecules.

hope I helped.

Generally non ionic species with no polarity forms the London -dispersion bonds. London dispersion is weaker than the dipole-dipole interaction and hence it have less boiling  point.

Boiling point of  a substance is the temperature at which the substance changes from liquid state to gaseous state or vapor where, the two states are in equilibrium.

Boiling of a substance depends on the molecular weight, bond type,temperature, pressure as well as purity of the substance.

London dispersion force is formed between two non-polar atoms. These atoms when come closer they attains a temporary polar nature and gets bonded.

Dipole-dipole bond is formed between two atoms of permanent dipole moment and they are polar compounds. Thus dipole-dipole interaction is stronger than London dispersion interaction. A strong bond needs more energy to boil.

Hence, molecules with  Dipole-Dipole bond is having higher boiling point.

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Answer:

6.02 × 1023

The molar mass from the periodic table is 32.00 g O2 = 1 mol O2, and by definition, 1 mol O2 = 6.02 × 1023 molecules O2.

Answer:

Since water has a density of 1 gram per cubic centimeter, then the container would need to be 800 cubic centimeters. if this container were a perfect cube, then the length of the side of the container would be equal to the cube-root of 800, which is approximately 9.28 cm to a side, or 3.65 inches to aside.

Due to errors in volume and moles measurement by the student, the true value of the molar gas constant is less than the obtained value.

The Percent error is 1.39%

Percent error is defined as the ratio of error and true value of a measurement expressed as a percentage.

Error = |true value - measured value|

The error in the students measurement = |0.08206 - 0.0832|

Error = 0.00114

Percent error = (0.00114/0.08206) × 100%

Percent error = 1.39%

The formula to determine the molar gas constant R is given below:

[tex]R = \frac{PV}{nT}[/tex]

Since the student value is higher than the true value, the possible sources of error include:

Therefore, the true value of the molar gas constant is less than the obtained value.

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In the first dissociation of H2A:

molarity    H2A(aq)↔ (HA)^-(aq) + H^+(aq)

initial                0.05 m          0 m           0 m

change               -x                 +x               +x

equilibrium    0.05-x               x                 x

we can neglect X in [H2A] as it so small compared to the 0.05

so by substitution in Ka equation:

Ka1 = [HA][H] / [H2A]

2.2x10^-6 = X^2/0.05

X = √(2.2x10^-6)*(0.05)= 1.1x10^-7

X=   3.32x10^-4 m

∴ [H2A] = 0.05 - 3.32x10^-4 = 0.0497 m

[HA] = 3.32x10^-4 m

[H] = 3.32x10^-4 m

the second dissociation of H2A: when ka2 = 8.2x10^-9

                          HA-(aq)     ↔ A^2- (aq) + H+(aq)

at equilibrium   3.32x10^-4        y              3.32x10^-4

Ka2           = [H+][A^2-] / [HA]

8.2x10^-9 = Y(3.32x10^-4)/(3.32x10^-4)

∴y = 8.2x10^-9 m

∴[A] = 8.2x10^-9 m

PH= -㏒[H+]

   = -㏒(3.32x10^-4)= 3.479  

[A]=8.2x10^-9 m

[H2A] = 0.0497 ≈ 0.05 m

Answer:

1. thermal energy

2. the particles within the system will have greater motion, and the temp will increase.

3. attractions occur due to electrostatic forces. when particles move fast enough, these forces can no longer keep particles together.

4. for a phase change from a solid to liquid, the bonds do not break completely and particles call still slide past each other.

5. a sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C

Explanation:

hope this helps

Temperature is a measure of the average kinetic energy of molecules.

The particles of a substance are in constant random motion. As more thermal energy is added to the particles, the motion of the particles increases. If more energy is added to a system during phase change, the particles within the system will have greater motion, and the temperature will increase.

Attractions between particles is greater when the kinetic energy of molecules decreases. Therefore, a statement that correctly describes how attractions that hold particles break is; "attractions due to electrostatic forces. When particles move fast enough, these forces can no longer keep particles together."

The rubber analogy is commonly used to describe covalent bonds where stretching of bonds occur. This analogy is not apt in describing phase changes because for a phase change from a solid to liquid, the bonds do not break completely and particles call still slide past each other.

The average kinetic energy of molecules depend on temperature hence a  sample of liquid benzene at 80°C and a sample of gaseous benzene at 80°C will have the same average kinetic energy.

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The molecules of the two gases will have the same kinetic energy at room temperature.

The average kinetic energy of gaseous molecules can be calculated using the formula:

Kinetic Energy = 3/2RT, where R = constant and T = temperature in Kelvin

This means that the kinetic energy of a gaseous molecule is dependent on the temperature of the molecule only.

In other words, the molecular mass of molecules of gases has no bearing on the kinetic energy of each molecule.

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Answer:

2

Explanation:

4s2 has 2 valence electrons

Valence shell is the shell which is the outermost shell, that is filled in the last, before valence shell is penultimate shell. Therefore 2 valence electron are there in the valence shell.

Element generally consist of atoms or we can say atoms combine to form element. Atoms of an element is always same, means all the properties of all atoms of one type of element is same.

From our question the electronic configuration of element is given as

1s²2s²2p⁶3s²3p⁶4s²

Valence electron is the one which is present in the outermost shell or orbit. So, form above electronic configuration we can say that 4 is the outermost shell and in this shell 2 electron is present. Therefore 2 electron are there in the valence shell as valence electron.

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Answer:

Firstly, try to Go through your chapter and pay attention to main keywords.

secondly try to watch 'Uube' videos related to specific topic instead of chapter and pay attention to it closely and watch it with a keen interest.

Discuss topics that you find harder with your friends or peer group members, Because you learn faster when you study with the people of your age.

Answer:

i think the best way to learn chemistry is study over things that involve it

Explanation:

Answer:

77%

Explanation:

The formula for finding percent change is change/original.

So, you have to do 0.3/0.39

You have to divide this to get 0.769 which can be rounded 0.77

0.77 as a percentage is 77%

So, the percentage mass increase of the carrot is 77%

Answer:nuclear reaction

Explanation: Nuclear fusion is a type of nuclear reaction where two light nuclei collide together to form a single, heavier nucleus. Fusion results in a release of energy because the mass of the new nucleus is less than the sum of the original masses.

Fusion is the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy.

Answer:

The answer is 3

Explanation:

Hope this helps and have a wonderful day.

Answer:

12

Explanation:

There are 4 sulfur atoms in SO4

4×3=12

This means that it turns into 3×(SO4)

=3SO4

Answer:

B

Explanation:

percentage composition helps to determine the percentage of each element in a compound