what does Hess’s law state?

What Does Hesss Law State?

Answers

Answer 1

Answer:

C. The enthalpy of a reaction is the sum of the enthalpies of intermediate reactions.

Explanation:

The heat of any reaction  ΔH∘f  for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction.

Answer 2
Hess's law states that the energy change in an overall chemical reaction is equal to the sum of the energy changes in the individual reactions comprising it. In other words, the enthalpy change of a chemical reaction (the heat of reaction at constant pressure) does not depend on the pathway between the initial and final states. The law is a variation of the first law of thermodynamics and conservation of energy.

Related Questions

How many moles of oxygen are in a sample of 29.1 moles of coal (C135H96O9NS)?

Answers

Answer:

2.19moles

Explanation:

mole = mass ÷ molar mass

Molar Mass of the compound, C135H96O9NS =

12(135) + 1(96) + 16(9) + 14 + 32

= 1620 + 96 + 144 + 14 + 32

= 1906g/mol

Next, we calculate the mass percent of Oxygen in the compound

O9 = 16(9) = 144g/mol

144/1906 × 100

= 0.0755 × 100

= 7.55%

This means that there are 0.0755g of Oxygen in 1 mole of the coal compound.

Hence, in 29.1 moles of coal, there would be 29.1 × 0.0755

= 2.19moles of Oxygen

What helps your heart beat? Will give brainlist to whoever answers first!!

Answers

Answer:

running helps my heart beat

Answer:

Exercise: The easiest and most effective way to achieve a lasting lower heart rate is to do regular exercise. 2. Stay hydrated: When the body is dehydrated, the heart has to work harder to stabilize blood flow. Throughout the day, drink plenty of sugar- and caffeine-free beverages, such as water and herbal tea.

How many moles of helium gas are present in 120 liters of STP

Answers

12 is the answer I got

14. HCOOH is an example of
A. alcohols.
B. aldehydes.
C. carboxylic acids.
D. ethers.
E. ketones.​

Answers

Answer:

carboxylic acid is the answer

Explanation:

Plz mark brainliest

Which science process skill uses numbers to describe objects​

Answers

Answer: Science process skills include observing qualities, measuring quantities, sorting/classifying, inferring, predicting, experimenting, and communicating.

Which of the following best describes the velocity of an object?
A B0 m/s
B 30 m east
C 30 m/s east
D 30 m/s2

Answers

The answer is c
30 m/s east

Answer:

[tex]\boxed {\boxed {\sf C. \ 30 \ m/s \ east}}[/tex]

Explanation:

Velocity is the vector measurement of the change in position over time. A vector measurement means the answer must include a magnitude (numerical value) and a direction.

Here are some units of velocity:

m/s (meters per second) kph (kilometers per hour) km/s (kilometers per second)

There are many other units, but m/s is the most common.

We can eliminate choice B and D, because the units (meters-m and meters per second squared-m/s²) are not for velocity.

We are left with choice A (30 m/s) and C (30 m/s east). Remember, velocity needs a number and a direction. C contains the direction east, so it must be the correct answer.  

Choose all that are correct about the elements in the column highlighted in blue
in the periodic table below (there are FOUR correct answers)

help !!!

Answers

Answer:

running a business is the best i have ever done to make a good friend of yours to get to the point where you have a lot to say

What is the charge of a beta particle?

Answers

Answer:

Beta particles have a charge of minus 1.

Explanation:

Hope this helps!

Answer:

MARK AS BRAINLIEST ANSWER

PLZ FOLLOW ME

Explanation:

Beta particles have a mass which is half of one thousandth of the mass of a proton and carry either a single negative (electron) or positive (positron) charge. As they have a small mass and can be released with high energy, they can reach relativistic speeds (close to the speed of light)

HOPE IT HELPS YOU

Daniel and Sanya are scientists. Daniel is studying whether the increasing frequency of tropical storms is affecting coastal erosion. Sanya is investigating whether the discharge from industrial plants has any impact on the pH concentration of freshwater swamps in the surrounding area. Which fields of science are Daniel's and Sanya's studies most closely related to?

Daniel's field of study is related to [biological, earth and space,or physical] science, and Sanya's field of study is related to [biology, chemistry, or physics].​

Answers

Answer:

- Daniel- Earth and Space

- Sanya- Chemistry

Explanation:

Daniel's study field is associated with the 'Earth and Space' as he is attempting to explore how the frequency of tropical storms(in the atmosphere) and coastal erosion(relation with land and ocean) are interconnected to each other. He studies how the two are associated and affect life on the planet.

While Sanya's field of study would be 'Chemistry' as she aims to study the composition and constitution of substances and the changes that they undergo as a consequence of alterations in the constitution of their molecules('whether the discharge from industrial plants has any impact on the pH concentration of freshwater swamps in the surrounding area').

The overall long-term effects of air pollution are not yet certain.

True
False

Answers

Answer:

its true

Explanation:

because I made sure it was true and it is

Question 3
The element with electron configuration 1s^2 2s^s 2p^6 3s^2 3p^2
S (Z = 16).
Mg (Z = 12).
C (Z = 6).
Si (Z = 14).

Answers

Answer:

I'm on the same question as you

What is the mass of .550 mL of alcohol (density = 82.0 g/mL)

Answers

Answer:

1.223 g/ml

Explanation:

45.1 ml of alcohol. Multiply 82 by .55 because it’s less than 1 ml

how different are the duck leeches offsprings from their parents

Answers

They are different because their appearance and general genology may differ greatly from the leeches parent.

How many milliliters of sodium metal, with a density of 0.97 g/mL, would be needed to produce 34.5 grams of sodium hydroxide in the single replacement reaction below?
Unbalanced equation: Na + H2O ---> NaOH + H2

Answers

Volume of Sodium metal : 20.454 ml

Further explanation

Reaction(balanced) :

2Na + 2H₂O → 2NaOH + H₂

mass NaOH = 34.5 g

mol NaOH(MW=40 g/mol) :

[tex]\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{34.5}{40}\\\\mol=0.8625[/tex]

From the equation, mol ratio of Na : NaOH = 2 : 2, so mol Na=mol NaOH=0.8625

Mass Na (Ar=23 g/mol):

[tex]\tt mass=mol\times MW\\\\mass=0.8625\times 23\\\\mass=19.84~g[/tex]

Volume Na :

[tex]\tt V=\dfrac{m}{\rho}\\\\V=\dfrac{19.84~g}{0.97~g/ml}\\\\V=20.454~ml[/tex]

are particles in gas close together ​

Answers

Answer:

Solid particles are close together not gas particles

A gas mixture with a total pressure of 745 mmHg contains each of the following gases at the indicated partial pressures: CO2, 125 mmHg; Ar, 214 mmHg; and O2, 187 mmHg. The mixture also contains helium gas. What is the partial pressure of the helium gas

Answers

Answer:

219 mmHg

Explanation:

The partial pressure of a gas refers to the pressure exerted by one of the gases in a mixture of gases.

The total pressure of a gas is the sum of all the partial pressures of all the gases in the mixture.

Since the total pressure = 745 mmHg

The partial pressure of helium is;

745 - (125 + 214 + 187)

Partial Pressure of helium gas= 219 mmHg

3. Which of the following is an example of a polyatomic ion?
a. NO
b. OP-
C. CI
d. Ca²+​

Answers

Answer:D

Explanation:polyatomic means more then one and it have more then 1 positive ion

Answer: B

Explanation:

A polyatomic ion needs to have two atoms, hence the word “poly,” so D and C are NOT correct. An ion also needs to be charged, so that makes B the correct answer.

What is the kinetic energy of a population of particles?

Answers

Answer/Explanation:

The kinetic energy of a particle is one-half the product of the particle's mass m and the square of its speed v: K=12mv2.

Draw the Lewis structure for SO2. How
many single bonds, double bonds, triple
bonds, and unshared pairs of electrons are
on the central atom, in that order?
1. 3, 0, 0, 1
2. 2, 1, 0, 0
3. 4, 0, 0, 0
4. 1, 1, 0, 1
5. 0, 0, 1, 1
6. None of these
7. 0, 1, 1, 0
8. 2, 0, 0, 2
9. 0, 2, 0, 0
10. 1, 0, 1, 0

Answers

Answer:

It should be 9

Explanation:

That’s how I remember drawing them I took chemistry last year. Tell me if it’s good.

Which pair of statements most accurately describes Earth's position relative to
the sun in late March and in late September?

Answers

Answer:

A

Explanation:

What is the mass of 3.25 miles of AsF5

Answers

Answer:

169.913616 g/mol

Explanation: This is weight of AsF5 molecular weight

how many moles of barium hydroxide would be required to react with 117 g hydrogen bromide?

Answers

0.725 mol barium hydroxide

SOMEONE HELP ME PLEASE ILL GIVE BRAINLY

Answers

answer: chemical change

step-by-step explanation: because if it’s changing through heat, the temperature could be different. Chemical changes happen on a molecular level when you have two or more molecules that interact. Chemical changes happen when atomic bonds are broken or created during chemical reactions. therefore physical change in this given situation isn’t possible.

hope this helped.

. How do metals and non-metals
Which two properties of metal enable us to use metal as electric wire

Answers

Answer:

it's ductility and it's conductivity

Explanation:

What is the similarity between teeth and eggshells?
*. Please answer

Answers

Answer: Eggshells have a similar chemical composition to our tooth enamel, making them react similarly with other chemicals. This can help us understand what stains tooth enamel. When we brush an eggshell with fluoridated toothpaste, it strengthens the shell and protects it from acid, just like it does for our tooth enamel

Explanation:

Answer: Eggshells have a similar chemical composition to our tooth enamel, making them react similarly with other chemicals. This can help us understand what stains tooth enamel. When we brush an eggshell with fluoridated toothpaste, it strengthens the shell and protects it from acid, just like it does for our tooth enamel.

How do electrons affect the state of an element?

Answers

Answer:

Explanation:

All matter is made up of atoms. ... These shells are actually different energy levels and within the energy levels, the electrons orbit the nucleus of the atom. The ground state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron.

What type of reaction takes place
when propene is formed from
propanol?
A. Condensation
B. Dehydration
C. Hydration
D. Hydrolysis
E. Oxidation​

Answers

Answer:

Hydration

Explanation:

* 2-propanol is converted to propene using heated alumina beads as the catalyst. The product gas is purified with a dry ice–propanol cold trap.

* the propene is hydrogenated to propane using a palladium catalyst in nearly 100% yield


Aluminium and oxygen react to produce aluminium oxide,
4 Al + 3 02 - 2 AL,O
How many kilograms of aluminium oxide are formed when 5,4 kg of aluminium react
with excess oxygen?
A 5,4 kg
B 88 kg
C 10.2 kg
D 33,6 kg

Answers

The balanced reaction is

4 Al + 3 O₂   →   2 Al₂O₃

so that for every 4 moles of Al and 3 moles of O2, you end up with 2 moles of Al₂O₃.

• Al has molar mass ≈ 26.982 g/mol

• O has molar mass ≈ 15.999 g/mol

• Al₂O₃ thus has molar mass ≈ 101.961 g/mol

You start with 5.4 kg = 5,400 g of Al, or

(5.4 kg Al) • (1/26.982 mol/g) ≈ 200.133 mol Al

Al₂O₃ is produced in a ratio of 2 moles to every 4 moles of Al, so you end up with about 100.067 mol Al₂O₃, which has a mass of

(100.067 mol Al₂O₃) • (101.961 g/mol) ≈ 10,202 g = 10.2 kg

so the answer is C.

When an atom becomes a negative ion, it

Answers

It becomes a positives atom. Since it loses electrons it has more of a positive charge than a normal atom.

it becomes positive right? im pretty sure

Which are long chains formed by the process of polymerization?
1. subunits
2. ethylenes
3. monomers
4. DNA strands

Answers

Answer:

Monomers are long chains formed by the process of polymerization

Explanation:

Answer:

monomers is the correct answer....(C)

Explanation:

hope this helps, the person above me is correct

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