What does Hess's law state? A. The enthalpy of a reaction is positive if it is endothermic and negative if exothermic. B. The enthalpy of a reaction is the sum of the enthalpies of intermediate reactions. C. The enthalpy of a reaction can be determined only from single- step reactions. D. The enthalpy of a reaction can be measured from heat produced in a calorimeter.​

Answers

Answer 1
B. The enthalpy change of a reaction is the sum of the enthalpies of intermediate reactions.
Answer 2

Hess's law gave the net change in enthalpy.  According to the law, the enthalpy of the reaction is the addition of the enthalpies of the intermediate reaction. Thus, option B is accurate.

What is Hess's law?

Hess's law or the law of constant heat summation is the measure of the heat or the enthalpy of the chemical reaction. It was given by the chemist, Germain Hess.

The law states that the enthalpy of the chemical reaction is the sum of the enthalpies involved in the reactants and the products of the reaction. It is independent of the steps involved in the reaction.

Therefore, option B. enthalpy of reaction is the summation of the enthalpy of the intermediates.

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Related Questions

Given a Ksp for AgBr of 5.0 * 10–13, what happens when 50 ml of 0.002 M AgNO3 and 50 mL of 0.002 M NaBr are mixed?

Answers

Answer:

A precipitate will be produced

Explanation:

The Ksp of AgBr is:

AgBr(s) → Ag⁺ + Br⁻

5.0x10⁻¹³ = [Ag⁺] Br⁻]

Where [] are the concentrations in equilibrium of each ion.

And if Q is:

Q = [Ag⁺] Br⁻]

Where the concentrations are actual concentrations of each ion

We can say:

IF Q >= Ksp, a precipitate will be produced

IF Q < Ksp, no precipitate will be produced.

the molar concentrations are:

[AgNO₃] = [Ag⁺] = 0.002M * (50mL / 100mL) = 0.001M

Because 50mL is the volume of the AgNO₃ solution and 100mL the volume of the mixture of both solutions.

[NaBr] = [Br⁻] = 0.002M * (50mL / 100mL) = 0.001M

Q = [0.001M] * [0.001M]

Q = 1x10⁻⁶

As Q > Ksp,

A precipitate will be produced


What is the temperature and pressure at STP?

Answers

Answer:

Since 1982, STP is defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 105 Pa (100 kPa, 1 bar).

Explanation:

I hope I helped

An object in space is made of gas and gives off light and heat energy. We can only see it at night. Which object is it? (2 points)
Earth
moon
star
sun

Answers

Answer:

stars

earth isn't made of gas. (and you can always see it)

moon us not gas, or give off heat

sun is only visible during the day

connect them please, dont guess ill give brainiest to the FIRST answer + 29 points

Answers

Answer:

I cant see it sorry

Explanation:

Post another one

A mixture of Oxygen and Hydrogen occupies a pressure of 101.3kPa. The pressure of Hydrogen is 56kpa. Calculate the pressure of oxygen.

Answers

Answer:

45.3 KPa

Explanation:

From the question given above, the following data were obtained:

Total pressure (Pₜ) = 101.3 KPa

Pressure of Hydrogen (Pₕ) = 56 KPa

Pressure of Oxygen (Pₒ) =?

The pressure of oxygen in the mixture can be obtained as follow:

Pₜ = Pₕ + Pₒ

101.3 = 56 + Pₒ

Collect like terms

101.3 – 56 = Pₒ

Pₒ = 45.3 KPa

Thus, the pressure of oxygen in the mixture is 45.3 KPa

Question 8 of 10
The half-life of carbon-14 is 5,730 years. If you start with 12 atoms of carbon-
14, how many atoms of carbon-14 will there be after 5,730 years?
A. 12 atoms
B. 3 atoms
ООО
C. 24 atoms
D. 6 atoms
SUBMIT

Answers

Answer:

6

Explanation:

if you start with 12 atoms of carbon and its called the half life of carbon what is half of 12

Answer:

6 Atoms

Explanation:

Ap3x

To what temperature must 20.2 g of hydrogen gas be heated at 110 kPa to occupy a volume of 4.45 x 10^-2 kL

Answers

Answer:

59K

Explanation:

Using the general gas law equation:

PV = nRT

Where;

P = pressure (atm)

V = volume (L)

n = number of moles (mol)

R = gas constant (0.0821 Latm/molK)

T = temperature (K)

According to the information given in the question;

- mass of hydrogen gas = 20.2g

mole = mass/molar mass

mole = 20.2/2.015

mole = 10.01mol

- Pressure = 110 Kpa

1 kilopascal = 0.00987 atmosphere

110kPa = 110 × 0.00987

= 1.09atm

- Volume = 4.45 x 10^-2 kL

1 kL = 1000L

4.45 x 10^-2 kL = 4.45 x 10^-2 × 10³

4.45 × 10¹

= 44.5L

Using PV = nRT

T = PV/nR

T = 1.09 × 44.5/0.0821 × 10.01

T = 48.505/0.821

T = 59.02

T = 59K

In a combustion reaction, pentane (molar mass (MM) = 72.17 g/mol) burns, in the presence of oxygen (MM = 32.00 g/mol), to produce carbon dioxide (MM = 44.01 g/mol) and water (MM = 18.02 g/mol).



The balanced reaction is shown here: C5H12 (l) + 8 O2 (g) à 5 CO2 (g) + 6 H2O (g)



If 4.0 mol of O2 is available, what is the maximum number of moles of water that can be produced (AKS 4f)?

A.
3.0 mol

B.
4.0 mol

C.
5.0 mol

D.
8.0 mol

E.
2.0 mol

Answers

The maximum number of mole of water that can be produced is 3 moles (Option A)

Balanced equation

C₅H₁₂ + 8O₂ —> 5CO₂ + 6H₂O

From the balanced equation above,

8 moles of O₂ reacted to produce 6 moles of H₂O

How to determine the mole of water produced

From the balanced equation above,

8 moles of O₂ reacted to produce 6 moles of H₂O.

Therefore,

4 moles  of O₂ will react to produce = (4 × 6) / 8 = 3 moles of H₂O.

Thus, we can conclude that the maximum mole of water produced is 3 moles

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Which of the following is NOT a feature found on the Moon?
A. Mountains
B. Valleys
C. Craters
D. Oceans

Answers

Answer:

D

Explanation:

no water fjkdbksfjgnkfjgdkufgkjdfghkdfjhdgfg

A chemical reaction can theoretically produce 137.5 grams of product, but it actually produced 112.9 grams. Which is the percent yield for this reaction? AKS 4f

Answers

Answer:

Explanation:

Zoom in we can't see it dude

answer: 26.6%

explanation: actual yield - theoretical yield x 100%
112.9-137.5x100%= 26.6%

The total volume of a soda can is 415 mL. Of this 415 mL, there is 60.0 mL of headspace(empty space aka volume) for the CO2 gas put in to carbonate the beverage. If a volume of 100.0 mL of gas at standard pressure is added to the can, what is the pressure in the can when it has been sealed?​

Answers

Answer:

0.6 atm

Explanation:

I'm not sure about this though...

NIST employs a 20 °C (293.15 K, 68 °F) temperature and a 1 ATM absolute pressure (14.696 psi, 101.325 kPa). This standard is also known as normal pressure and temperature (abbreviated as NTP).

Explain about the standard pressure?

Originally, the term "atmosphere" referred to the air pressure at sea level. Later, it was determined to be 1.01375 x 105 pascals. 100 kilopascals are the unit of pressure known as a bar. Consequently, 1 ATM = 1.01325 bar, or that one atmosphere is almost equal to one bar.

101,325 pascals, or newtons of force per square meter, is the equivalent of one standard atmosphere, sometimes referred to as one atmosphere (approximately 14.7 pounds per square inch). also see millibar The atmosphere and atmospheric pressure unit are related topics.

The answer is 0.6 ATM

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Which statement best describes the main conflict in "Wiley, His Mother, and the Hairy Man"?

Answers

Answer:

a. Wiley has to find a way out of the tree he ran up.

b. Wiley has to trick the Hairy Man into turning himself into animals.

c. Wiley has to ask his mama for help to defeat the Hairy Man.

d. Wiley has to defeat the Hairy Man three times to make him go away.

Answer:

Wiley has to defeat the Hairy man three times to make him go away

Explanation:

Which of the following is the conjugate base of HPO42-?

Answers

Answer:

A. PO4^3-

Explanation:

took the quiz on a pex

The conjugate base of HPO₄²⁻ is PO₄³⁻. Therefore, option (A) is correct.

What is the Bronsted-Lowry concept?

The Bronsted-Lowry concept can be explained as an acid-base reaction where base and acid react with each other and by an exchange of proton acid, forms its conjugate base and the base generates its conjugate acid.

The Bronsted-Lowry theory is an extended version of Arrhenius's theory of acid-base. According to this concept, acid can be defined as a substance that donates a hydrogen ion or a proton and produces its conjugate base and the base can be defined as a substance that accepts a proton and creates its conjugate acid.

Bronsted-Lowry acid in the dissociation form can be represented as:

Acid   ⇄   Conjugate base +   H⁺

The conjugate base of Bronsted-Lowry acid HPO₄²⁻ can be represented as follows:

HPO₄²⁻   ⇄  PO₄³⁻ +   H⁺

Therefore, PO₄³⁻ is the conjugate base of the Bronsted-Lowry acid HPO₄²⁻​.

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how do i found out how animals gain energy and from where​

Answers

Answer:

Animals gain energy from the food they eat. Some animals eat plants while others eat other animals. This is passing of energy from the sun to plants to animal to other animals is called a food chain

difference between combustible and non - combustible

Answers

Answer:

A substance which burns in air and tends to produce heat and light is known as Combustible substances. Non-combustible substances are certain substances which are not combustible in the presence of air. Will not burn on being exposed to flame.

Answer:

A substance which burns in air and tends to produce heat and light is known as Combustible substances. Non-combustible substances are certain substances which are not combustible in the presence of air. Will not burn on being exposed to flame.

Explanation:

La leche se considera un alimento basico por su elevado contenido de nutrientes su densidad es de 1,4g/ml. Si se hace una compra de 7 bolsas de leche cada una con un volumen de 900m cual es la masa total de la leche expresada en kilogramos?

Answers

Answer:

8.82 kg es la masa total de leche

Explanation:

Consideraremos que el volumen de cada bolsa de leche es de 900 mL.

Sabiendo que tenemos en total 7 bolsas, el volumen final en litros que tenemos disponible es de:

900 mL . 7 = 6300 mL

Utilizando la densidad podemos calcular la masa de leche que tenemos en el total de las 7 bolsas

Densidad = masa / volumen

Densidad . volumen = masa → 1.4 g/mL . 6300 mL = 8820 g

Convertimos la masa de gramos a kg

8820 g . 1 kg /1000g = 8.82 kg

HELPP ILL GUVE YOU LOTS OF POINTS EVERYTHING U WANT I REALLY NEED HELP ​​

Answers

Answer:

but what is your question? it's just like the moon going around earth while earth along with all the other planets revolve around the sun

Explanation:

For the autoionization of water at 25°C, H2O(l) <---> H+ (aq) + OH-(aq)

Kw is 1.0 X 10^-14. What is (Delta Gº) for the process? ​

Answers

Answer:

ΔG° = 80 Kj/mole

Explanation:

ΔG° = -R·T·ln(Kw)

R = 0.008314 Kj/mol·K

T = 25°C = 298K

Kw = 1 x 10⁻¹⁴

ΔG° = -R·T·ln(Kw) -(0.08314Kj/mol·K)(298K)ln(1 x 10⁻¹⁴)

= -(0.008314)(298)(-32.2)Kj/mole

= 79.78Kj/mole ≈ 80Kj/mole (1 sig.-fig.)

The change in free energy for the autoionization of water at 25°C is -79.9 KJ

Using the formula;

ΔG = -RTlnK

ΔG  = change in free energy = ?

R = gas constant = 8.314 J/K/mol

T = temperature = 298 K

K = equilibrium constant = 1.0 X 10^-14

Substituting into the given formula as;

ΔG = -  (8.314 J/K/mol × 298 K × ln(1.0 X 10^-14))

ΔG = -7.99 × 10^4 J/mol or -79.9 KJ/mol

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dissolving sugar into coffee is a chemical change

true or false

Answers

False because the sugar is just changing it’s form
False. Because no matter how it’s mixed it’s still the same substances. Freeze it and it’s still coffee and sugar. Evaporate the water and it’s still coffee and sugar.

Describe the distribution of mass within an atom

Answers

Answer:

The nuclei of most atoms also contain neutrons . The masses of subatomic particles are very tiny. ... Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.

There are 2 places where charge is located in the atom:

the nucleus contains neutrons (zero charge) and protons (positive charge)

Around the nucleus there are electrons located on electron shields and the charge of electrons is equal to the charge of protons in the nucleus, but have negative sign.

To sum it all up we can say that the charge of protons in the nucleus is reduced by the charge of electrons on the orbits to make the atom electrically neutral.

Protists are single-celled microscopic creatures that inhabit ponds and seawater. In which sphere do they live?

Answers

Answer:

The presence of a nucleus in all protist organisms means they are all eukaryotic. ... Whether an organism contains one or multiple cells, the nucleus – the first and ... Diatoms; Green Algae – can live in fresh or salt water and sometimes moist ... Microscopy studies can be as easy as using a pipette to drop pond water onto a ...Explanation:

Anyone who could help me would be great!!! Plss!!!

Answers

Answer:

I think its a.The hockey puck loses heat molecule's.

is lung cancer a physical property or chemical property?

Answers

Answer:

its a chemical property

Explanation:

something that is made of all the same atoms or groups of atoms

Answers

Answer:

Substance-I just did this

Explanation:

Something that is made of all the same atoms or groups of atoms is called element. Atoms from at least one or maybe more elements.

What is element?

A substance that's unable to be converted into another substance is known as an element. Each of the approximately 100 elements has a unique form of atom. Atoms from at least one or maybe more elements are present in everything in the cosmos.

All known elements are listed in the periodic table, with those with related properties being grouped together. The majority of elements are lustrous metals that are excellent conductors of electricity. Iron, gold, and aluminum are metals that are solid at ambient temperature.

Therefore, something that is made of all the same atoms or groups of atoms is called element.

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How many electrons does calcium donate to sulfur when calcium and sulfur form an ionic bond?​

Answers

Answer:

two valence electrons

Explanation:

what is a ecosystem. A. a squirrel and it physical surroundings. B.a squirrel and what it does. c. all squirrels. d.one squirrel. GIVE BRANLIYST​

Answers

Explanation:

A system formed by the interaction of a community of organism with their physical environment is called ecosystem.

A. a squirrel and it physical surroundings.

3. Convert 273.0 g of lead into moles.

Answers

Answer:

1.3175675675675604

Explanation:

does this need to be rounded?

which process helps guarantee that a species continues to involve over hundreds of years?

A. growth

B. nutrition

C. reproduction​

Answers

Answer:

C. reproduction​

Explanation:

Carefully complete the energy diagram by drawing a curve that accurately shows the progress of the reaction, beginning at the reactants, moving through the transition state, and ending at the final products. When adding the products to the diagram, be sure to use an energy level that is appropriate relative to the energy level of the reactants.

Answers

Answer:The images for the 3 sub-questions have been presented in the first, second and third attached image to this solution.

Explanation:

Energy diagram which is relative to the energy level of the reactants is attached in the picture below.

What is an energy level?

Electrons present in an atom revolve in different orbits which are stationary states and are also called as energy levels. The energy levels are numbered as integers which are also called as principal quantum numbers.

Energy of the stationary state is given as E= -R

1/n² where R

is the Rydberg's constant. When an electron is excited, and it moves from lower to higher energy levels there is absorption of energy, while when it moves from higher energy level to lower energy level it radiates or gives out energy in the form of radiation.

They can also be defined as the distances between electron and nucleus of an atom . Electrons present in K energy level have least energy .Energy level diagrams are studied to understand nature of bonding , placement of electrons in orbits and and elemental behavior under certain conditions.

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https://whereby.com/cherie16

Answers

What is this for????
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