URGENT PLS HELP

An open system starts with 276 J of mechanical energy. The energy changes
to 267 J of mechanical energy and 8 J of thermal energy. What is the final
total energy of the system?

Answer:

540% according to an article I read on BBC

Explanation:

Answer:

No Specific question

Explanation:

Answer:

A: heating solid

B: melting

C: heating liquid

D: boiling

E: heating gas

F: melting point

Explanation: got it right

Answer:

133.333333333 cm^3

Explanation:

Volume = Mass/Density

Among various physical properties, vapor pressure does not generally increase with increasing strength of intermolecular forces.

Intermolecular forces refer to the forces between molecules that hold them together. When the strength of intermolecular forces increases, physical properties such as boiling point, melting point, and viscosity typically increase. However, vapor pressure behaves differently.

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. When intermolecular forces are stronger, it becomes harder for molecules to escape the liquid or solid phase and enter the gas phase. Therefore, fewer molecules transition to the gas phase, resulting in a lower vapor pressure.

In summary, vapor pressure does not increase with stronger intermolecular forces, but rather decreases.

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1) The dream of Mendeleev concerned the arrangement of the elements by mass

2) Periodicity is the changing properties of the elements

3)

Antoine Lavoisier - Arranged the elements by their properties

Johann Döbereiner - Arranged the elements into triads

John Newlands - Arranges the elements according to the order of increasing atomic mass

We define the periodic table as the arrangement of the elements in order of increasing atomic numbers. We know can see that several attempts have been made at the systematization of the elements and the approaches to the problem have taken different dimensions. In a dream, Mendeleev saw the elements line up in order of atomic masses and there was a visible pattern.

The term periodicity has to do with the regular repeating property of the elements and this can be seen when we follow the properties of the elements as they change down the group and across the period.

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The answer is 11.1 mol

The reaction is N2+3H2→2NH3

On reaction here, three moles of hydrogen form two moles of ammonia is formed.

45 g of H2 is equivalent to 45/2=22.5 moles

So the number of moles of ammonia formed is 22.5/2=11.1 mol

What is a mole?

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Answer:

Explanation:

Answer:

The answer is

Explanation:

The percentage error of the density can be found by using the formula

\(Percentage \: \: error(\%) = \frac{error}{actual \: \: number} \times 100 \\ \)

From the question

actual density = 1.59 g/cm³

error = 1.68 - 1.59 = 0.09

The percentage error is

\(P(\%) = \frac{0.09}{1.59} \times 100\% \\ = 5.66037735...\)

We have the final answer as

Hope this helps you

When 50 NBr3 molecules and 57 NaOH formula units react according to the given balanced equation, the result is the formation of 150 NaBr formula units.

According to the balanced equation provided:

2 NBr3 + 3 NaOH -> N2 + 3 NaBr + 3 HOBr

From the equation, we can see that 2 moles of NBr3 react with 3 moles of NaOH to form 3 moles of NaBr.

To determine the number of NaBr formula units formed, we need to convert the given quantities into moles.

Given:

Number of NBr3 molecules = 50

Number of NaOH formula units = 57

To convert the number of NBr3 molecules to moles, we need to divide the given quantity by Avogadro's number. Similarly, for NaOH formula units, we can directly consider them as moles.

Using Avogadro's number (6.022 x 10^23 molecules/mol), we can calculate the number of moles for NBr3 and NaOH:

Number of moles of NBr3 = 50 / (6.022 x 10^23)

Number of moles of NaOH = 57

Now, we can use the mole ratios from the balanced equation to determine the number of moles of NaBr formed. From the equation, we know that 2 moles of NBr3 react to form 3 moles of NaBr.

Number of moles of NaBr = (Number of moles of NBr3) x (3 moles of NaBr / 2 moles of NBr3)

Finally, we can convert the number of moles of NaBr to the number of NaBr formula units using Avogadro's number:

Number of NaBr formula units = (Number of moles of NaBr) x Avogadro's number

Calculating these values, we find that 50 NBr3 molecules and 57 NaOH formula units react to form 150 NaBr formula units.

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Answer

1.0 mol

Explanation

Given:

Volume, V = 5.0 L

Temperature, T = 215 K

Pressure, P = 342 kPa

The gas constant, R = 8.31 L kPa/mol K

What to find:

The number of moles of the gas sample.

Step-step-solution:

The number of moles of the gas can be determine using the ideal gas equation formula:

Put the given values into the formula and calculate for n:

The number of moles of the gas sample is 1.0 mol.

The toxic chemicals is different from the safe chemical because the stronger attraction between it's molecule than the safe chemical.it molecule now move away from each. The correct option is C

Toxic chemical can be defined as a substance that can be poisonous or cause health effects. Some examples of toxic chemical include ammonia, acid, bleach, chlorine, and carbon monoxide.

Therefore toxins are substances created by plants and animals that are poisonous to humans. Toxins may also include some medicines that are helpful in small doses but poisonous in large amounts.

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An ionic equation is balanced when the number of atoms of each element and the total charge is the same on both sides of the equation.

The question is incomplete but I will show you how to balance ionic equation.

Write the unbalanced ionic equation, including the charges of the ions.

Identify the species that are present on both sides of the equation and cancel out any ions that appear on both sides of the equation.

Balance the atoms of each element in the equation, using coefficients as needed to make sure that the same number of atoms appears on both sides of the equation.

Check that the overall charge is balanced by adding or removing electrons as needed. If electrons are added, they should be added to the side of the equation where the total charge is more positive, and if electrons are removed, they should be removed from the side of the equation where the total charge is more negative.

Check that the equation is fully balanced by making sure that the number of atoms of each element and the total charge is the same on both sides of the equation.

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Answer:

c

Explanation:

I looked the answer up it said it was geosphere

Answer:

the answer is geosphere

Explanation:

i hope it helps you

Answer:Answer:

40-18 fl =>40-cl+cl+0-1e sorry if im rong

Explanation:

When \(^1^8F\) undergoes positron emission, the product nucleus is, \(^1^8O\).

In positron emission, also called positive beta decay (β+ decay), a proton in the parent nucleus decays into a neutron that remains in the daughter nucleus, and the nucleus emits a neutrino and a positron, which is a positive particle like an ordinary electron in mass but of opposite charge.

When a proton is converted into a neutron then the positron emission takes place as follows.

\(^1_1p\;\rightarrow\;^1_0n\;+\;^0_+1e\)

A positron is represented by the symbol. Therefore, when a positron emission occurs then the resultant nuclei atomic number decreases by a unit mass.

The general equation representing positron emission is as follows.

\(^M_ZA\;\rightarrow\;^M_Z_-_1 B\;+\;^0_+1e\)

Hence, fluorine-18 decays by positron emission as follows.

\(^1^8_9F\;\rightarrow\;^1^8_8n\;+\;^0_+1e\)

Therefore, when \(^1^8F\) undergoes positron emission, the product nucleus is, \(^1^8O\).

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To solve this problem, let's use the definition for molarity:

Replacing the values of the problem:

Now, to find the mass, we multiply by the molecular weight of NaCl. (Which is about 58.44g/mol)

The answer is approximately 22.2g of NaCl

1- ΔH2 = -ΔH1 (The enthalpy change for the reverse reaction is the negative of the enthalpy change for the forward reaction.)

2- ΔH3 = 3ΔH1 (The enthalpy change for the reaction involving the formation of 6 moles of Al2O3 is three times the enthalpy change for the formation of 2 moles of Al2O3.)

3- ΔH4 = 0.5ΔH1 (The enthalpy change for the reaction involving the formation of one mole of Al2O3 is half the enthalpy change for the formation of 2 moles of Al2O3.)

To express the enthalpy of a reaction in terms of another reaction, we can use the concept of Hess's law. Hess's law states that the overall enthalpy change of a reaction is independent of the pathway taken and depends only on the initial and final states of the reaction.

Expressing ΔH2 in terms of ΔH1:

The reaction (ΔH2) is the reverse of the formation of aluminium oxide from aluminium and oxygen (ΔH1), so the enthalpy change for the reverse reaction will have the opposite sign. Therefore, we have:

ΔH2 = -ΔH1

Expressing ΔH3 in terms of ΔH1:

The reaction (ΔH3) involves the formation of 6 moles of Al2O3, whereas the formation of Al2O3 in ΔH1 involves the formation of 2 moles of Al2O3. Therefore, the enthalpy change for ΔH3 will be three times that of ΔH1. Hence:

ΔH3 = 3ΔH1

Expressing ΔH4 in terms of ΔH1:

The reaction (ΔH4) involves the formation of one mole of Al2O3, whereas the formation of Al2O3 in ΔH1 involves the formation of 2 moles of Al2O3. Therefore, the enthalpy change for ΔH4 will be half that of ΔH1. Hence:

ΔH4 = 0.5ΔH1

In summary:

ΔH2 = -ΔH1

ΔH3 = 3ΔH1

ΔH4 = 0.5ΔH1

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The bonds when surface tension occurs, water molecules form a weak bond with each other allowing a small bug to walk across the surface of a puddle. are referred to as hydrogen bonds.

Surface tension is the energy, often denoted as γ, necessary to increase the surface area of a liquid by a unit of area. Surface tension is a result of the cohesive forces that arise between the liquid's atoms and molecules. It's a property of liquids that makes them behave like an elastic sheet or membrane on their surface.

Hydrogen bonds are a type of chemical bond that occurs between a hydrogen atom bonded to an atom such as oxygen, nitrogen, or fluorine and another atom or electronegative group in a different molecule or chemical group.

The hydrogen bond is a type of dipole-dipole interaction that occurs when an electronegative atom or molecule attracts the positively charged hydrogen atom of another molecule or group. The hydrogen bond is a result of the difference in electronegativity between the hydrogen and the electronegative atom or group.

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Answer:

Explanation:

Answer:

the rays strike at a low level in the polar region

Explanation:

okay so since the polar zones lie between 66.50 north or south the polar regions are always so cold is because strike the low parts

hope this helped!

We can see here that when compared to sulfuric acid, carboxylic acids are weaker acids.

Sulfuric acid is a strong, highly corrosive acid with the chemical formula \(H_{2} SO_{4}\). It is one of the most important and widely used industrial chemicals. Sulfuric acid is known for its strong acidic properties and is often referred to as the "king of chemicals" due to its widespread applications in various industries.

Sulfuric acid is a dense, oily liquid that is colorless when pure. It is soluble in water, and when dissolved, it releases hydrogen ions (H+) to make the solution highly acidic.

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Discuss the similarities and differences in the behavior of metals tested with water relative to their positions in the periodic table.

The periodic table is organized by increasing atomic number and is divided into groups (vertical columns) and periods (horizontal rows). Metals in the same group have similar properties, while metals in the same period show varying properties.

The reactivity of metals with water generally increases as you move down a group and across a period from left to right. This trend is due to the increasing size of the atoms and the ease with which they lose electrons, as well as the relative reactivities of the metals.

Within a family (group), the reactivity with water increases as you move down the group. For example, in Group IA (alkali metals), lithium reacts with water relatively slowly, while cesium reacts explosively. Similarly, in Group IIA (alkaline earth metals), magnesium reacts with water slowly, whereas barium reacts more vigorously.

When comparing the same period, metals on the left side of the periodic table are more reactive with water than those on the right. For instance, sodium (Group IA) reacts more vigorously with water than magnesium (Group IIA).

Based on these trends, cesium, being lower in Group IA than lithium, is predicted to be much more reactive with water, potentially resulting in an explosive reaction.

Comparing the reactivities of Groups IIA and IIIA with dilute acids, Group IIA metals are generally more reactive due to their higher tendency to lose electrons and form positive ions. As a result, Group IIA metals will typically react more vigorously with dilute acids than Group IIIA metals.

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Answer:

thallophyta and bryophyte sometimes pteridophyta mark as brainliest please

The predication that is testable here is that of Raymond. Option D

We have to keep it at the back of our minds that science deals with data that is testable. In other words, science is an empirical discipline. What we mean by this is that we must be able to get at knowledge by testing the data that we have in controlled experiments.

Now, if we look at the responses of the students, we can see that the only one that has to do with something that we can test is the one that said that Ocean surface temperatures are warmer than water at deep-sea vents.

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Answer:

(A) Use volume displacement and the mass of the rock to calculate density.

Explanation:

The amount of concentrated solution needed is (0.286 M)(65 mL) / C M, and the amount of water needed is 65 mL minus the volume of the concentrated solution.

To calculate the molarity of Kool Aid desired, we need to determine the number of moles of Kool Aid powder and sugar in the package. Since the molecular formula for sugar is C12H22O11, we can calculate its molar mass as follows:

Molar mass of C12H22O11 = (12 * 12.01) + (22 * 1.01) + (11 * 16.00)

= 144.12 + 22.22 + 176.00

= 342.34 g/mol

Given that the package contains 4.25 grams of Kool Aid powder, we can calculate the number of moles of Kool Aid powder using its molar mass:

Number of moles of Kool Aid powder = Mass / Molar mass

= 4.25 g / 342.34 g/mol

≈ 0.0124 mol

Similarly, for the sugar, which has a molar mass of 342.34 g/mol, we can calculate the number of moles of sugar using its mass:

Number of moles of sugar = Mass / Molar mass

= 192.00 g / 342.34 g/mol

≈ 0.5612 mol

Now, to calculate the molarity of the desired Kool Aid solution, we need to determine the volume of water. Given that 1.06 quarts is equal to 1 liter, and we have 2.00 quarts of water, we can convert it to liters as follows:

Volume of water = 2.00 quarts * (1.06 liters / 1 quart)

= 2.12 liters

To find the molarity, we use the formula:

Molarity (M) = Number of moles / Volume (in liters)

Molarity of Kool Aid desired = (0.0124 mol + 0.5612 mol) / 2.12 L

≈ 0.286 M

To prepare 65 mL of the desired molarity, we can use dilution calculations. We need to determine the volume of concentrated solution and the volume of water needed.

Let's assume the concentration of the concentrated Kool Aid solution is C M. Using the dilution formula:

(C1)(V1) = (C2)(V2)where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.

Given that C1 = C M and V1 = V mL, and we want to prepare a final volume of 65 mL (V2 = 65 mL) with a final concentration of 0.286 M (C2 = 0.286 M), we can rearrange the formula to solve for the volume of the concentrated solution:

(C M)(V mL) = (0.286 M)(65 mL)

V mL = (0.286 M)(65 mL) / C M

So, the amount of concentrated solution needed is (0.286 M)(65 mL) / C M, and the amount of water needed is 65 mL minus the volume of the concentrated solution.

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Answer: A saturated solution, by definition, contains an amount of solute equal to the amount of dissolved solute in equilibrium with an undissolved solute. We could, however, make a supersaturated solution in which the solvent contains more solute than would be in equilibrium with undissolved.

Explanation:   More solute cannot be dissolved at a given temperature in a saturated solution. This is because the solute dissolves in a solvent due to the space between the solvent particles, but with the continuous addition of solute, the space between the solvent particles is filled. As a result, no more solute particles can dissolve in the solvent.

Answer:

saturated

Explanation:

The concentration of the new solution if 0.50 M solution of sodium thiosulfate is used to create a more dilute solution is 0.05M.

Molarity refers to the concentration of a substance in solution, expressed as the number moles of solute per litre of solution.

The concentration of a solution can be calculated using the following formula:

CaVa = CbVb

Where;

According to this question, if 250 mL of the concentrated solution is diluted to a volume of 2.5 L, the new concentration can be calculated as follows:

0.250 × 0.5 = 2.5 × Cb

0.125 = 2.5Cb

Cb = 0.05M

Therefore, 0.05M is the new concentration of the solution.

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Therefore, 5 moles of CO2 are produced from the combustion of 100 g of methane (CH4).Hence, the answer is 5.

For the reaction CH4 2O2 ---> CO2 2H2O, how many moles of carbon dioxide are produced from the combustion of 100. g of methane?

Explanation:

The balanced chemical reaction for the combustion of methane (CH4) in the presence of oxygen (O2) is given by the chemical equation,

CH4 + 2O2 → CO2 + 2H2O

This chemical equation means that for every one mole of methane gas that undergoes combustion, two moles of oxygen gas are required, and this will produce one mole of carbon dioxide gas and two moles of water vapor.

So from the equation, we can see that the stoichiometric coefficients of methane and carbon dioxide are equal, which means that one mole of methane will produce one mole of carbon dioxide.

Therefore, the molecular weight of CH4 is 16 g/mol + 1 g/mol x 4 = 16 + 4 = 20 g/mol.

Using the atomic weights, we can find out the molecular weight of CO2, which is 12 g/mol + 16 g/mol x 2 = 44 g/mol.

So, one mole of methane is 20 g and from the balanced chemical equation, it produces one mole of carbon dioxide.

To find out the number of moles of carbon dioxide produced from 100 g of methane, we will use the following formula:

Moles = mass / molar mass= 100 / 20= 5 moles

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Answer:

Explanation:

There are 6 32S atoms and 2 36S atoms

Their respective contributions to the average aomic mass is (6*32)=192, and (2*36)=72.  Added together, this makes 264 total.  Divide by the total number of atoms, 8.  (264/8) = 33.00

The weighted atomic mass of these S atoms is 33.00 amu (atomic mass units)

The student added sodium chloride in order to precipitate lead II chloride because this is a positive test for lead II ions.

Some times when we carry out an aqueous phase reaction, the products of the reaction would be found to be in the solid phase. This implies that one of the products of the reaction is insoluble in water and separates out of the solution.

In this case, the student knows that lead II chloride is insoluble in water thus it is obtained upon the addition of sodium chloride. This informed the addition of the sodium chloride solution.

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Missing parts;

A 50.0 mL unknown aqueous sample was tested in the laboratory. The unknown sample was identified

to be lead (II) ions by a precipitation reaction with sodium iodide. Since the unknown was identified to

have lead (II) ions in it, a student added excess sodium chloride (NaCl) to the 50.0 mL sample. A white

precipitate was made and was subsequently filtered, washed, and dried to completion. The precipitate

was measure to have a mass of 2.350 grams.

(a) How did the students determine through the addition of sodium iodide that the sample had lead (II)

ions in it?