When do chemical reactions occur?

Answers

Answer 1

Answer:

When the molecular composition changes.

Explanation:

A physical change is a change in size or appearance that can usually be reversed; a chemical change cannot be reversed easily and changes the atomic composition of something.


Related Questions

Scientists discover remains of wooden structures near a Celtic runes site. What kind of testing will indicate when the stones were moved into place by the Celts?

Carbon dating

Radioactive dating

Answers

Answer:

Carbon

Explanation:

Bc i got this question on my test

Answer:

A. Carbon dating

Explanation:

I took the test proof

                                 

What happens to the gravitational potential energy of an object if you bring it higher with respect to the ground? *

Answers

Answer:

Increases

Explanation:

The gravitational potential energy of an object increases as you bring it higher with respect to the ground.

Gravitational potential energy depends on the mass, height and gravity between two bodies;

   Gravitational potential energy  = mgh

m is the mass

g is the height

h is the height

We can clearly see that the higher the elevation, the more the value of the gravitational potential energy.

please help me out I need some ideas for cell city project or comic strip by tonight or if you did it already lemme copy it={​

Answers

Answer:

Can you give me your snap, so I can send you the foto

[H3O+] = 2.6 x 10-3 M calculate OH

Answers

Answer:

3.85E-12

Explanation:

from

KW=[H3O+]×[OH]

BUT KW=1E-14

9.
Which of the following molecules has (have) polar bonds?
a water
b carbon dioxide
c formaldehyde
d two of the above

Answers

Answer: A) Water Explanation: Water molecules are polar molecules

Answer:

two of the above

Explanation:

cK-12 Bond Polarity

If an atom has 25 protons how many electrons will it have orbiting its nucleus?
ОО
O 25
O 12
Electrons don't orbit the nucleus

Answers

Answer:

If the atom is nuetral it will have 25 electrons as there is the same number of electrons and protons if the atom is nuetral. Yes electrons do orbit the nucleas. Electrons orbit in orbitals which have corresponding energy levels.

Explanation:

I have a masters in Algebra II

Which best describs the energy transformation in a battery powered flash light ?

a
Chemical, to electrical, to thermal, to radiant
b
nuclear, to electrical, to thermal, to radiant
c
Mechanical, to electrical, to Thermal, to radiant
d
Chemical, to electrical, to mechanical, to radiant

Answers

Answer:

I think it's C

Explanation:

Sorry if its wrong

Answer:

C

Explanation:

Is calcium oxide a Element or compound or mixture?

Answers

Answer:

compound

Explanation:

Answer:

The answer is compound

Explanation:

HURRY PLSsss if right gets brilliant

Answers

Answer:    C hope this helps Have a wonderful day :)    

Explanation:

Consider the following equilibrium.
NH3(aq) + H2O(l) equilibrium reaction arrow NH4+(aq) + OH −(aq)
What will happen to the equilibrium constant if the concentration of OH − increases through the addition of a small amount of NaOH(aq)?

Answers

Answer:

It will remain the same

Explanation:

The equilibrium constant of the reaction will remain the same if the concentration of the OH is increased.

Changes in concentration values of any of the reactant does not affect the value of the equilibrium constant.

The equilibrium constant is a constant at a given temperature. It is temperature dependent. Since we have no change in temperature, therefore, the equilibrium constant will not change.

The equilibrium constant if the concentration of OH − increases through the addition of a small amount of NaOH(aq) is :

- Remains same.

Equilibrium Reaction

The equilibrium constant of the response will stay the same in case the concentration of the OH is increased.

Changes in concentration values of any of the reactant does not influence the esteem of the equilibrium constant.

The equilibrium constant may be a consistent at a given temperature.

It is temperature dependent. Since we have no alter in temperature.

Learn more about "Equilibrium":

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The maximum speed limit on a highway is 55 miles per hour. What is that speed in meters per second? (mi = 1.609 km)

Answers

Answer:

24.5872 meters per second

Rouned 24.6 or 25

WILL MARK BRAINLIEST:
Identify the dichotomous key: plz answer:::: Each of these aliens belongs to the same genus. What is their genus?

Answers

Answer:

Alienus

Explanation:

How many days will it take for 80 grams of Iodine-131 to decay to 5 grams?

Answers

32 days

Further explanation

General formulas used in decay:  

[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]

t = duration of decay  

t 1/2 = half-life  

N₀ = the number of initial radioactive atoms  

Nt = the number of radioactive atoms left after decaying during T time  

The half-life of iodine-131 is 8 days

No=80 g

Nt=5 g

[tex]\tt 5=80(\dfrac{1}{2})^{t/8}\\\\\dfrac{5}{80}=\dfrac{1}{2}^{t/8}\\\\\dfrac{1}{2}^4=\dfrac{1}{2}^{t/8}\\\\4=\dfrac{t}{8}\rightarrow 32~days[/tex]

What is a goal of environmentalists? O A. Conservation of the environment O B. Protection of the environment O C. Public awareness of the environment O D. All of the above​

Answers

Answer:

B?\

Explanation:

A goal of environmentalists is the protection of the environment.

What is an environment?The biotic and abiotic factors which surrounds living organisms are known as environment. To put it in simple word, it is a community of organisms living in a particular environment and the physical elements in that environment with which they interact.What is the role of environmentalists?

Environmentalist preserve the air and water; as well as conserve and protect entire ecosystems compromising of animals, plants and humans found in different habitats throughout our planet.

Environmentalists help the public make informed decisions about the use of limited natural resources. They do research, produce reports, write articles, campaign etc.

Hence, option b is the correct answer.

To learn more about environment and environmentalists here

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Need help!!
A sample of water is currently boiling. What phase(s) is/are present?
gas
Liquid
solid

Answers

Answer:

a

Explanation:

You could validate both liquid and gas as not all the water has evaporated to gas form

When comparing plant and animal cells which statement is least accurate?
Plant cells have a cell wall and animal cells do not.
Plant cells have chloroplasts and animal cells do not.
Plant cells have a large central vacuole and animal cells do not.
Plant cells have cell membranes and animal cells do not.

Answers

Here is a diagram comparing both plant and animal cells.
Hope it helps:)

J.J. Thomson's plum pudding model of the atom followed the discovery of
A)
negatively charged particles with a very small mass.
B)
positively charged particles with a very large mass.
0)
negative electrons that revolved around a positive nucleus.
D)
positively charged protons that were contained in a concentrated area.

Answers

the answer is A i think from the options though the answers are worded a bit weird

J.J. Thomson's plum pudding model of the atom followed the discovery of negatively charged particles with a very small mass. Thus, the correct option for this question is A.

Who was J. J. Thomson?

J.J. Thomson was a British physicist who discovered sub-atomic particles known as electrons within an atom. He also announced that atoms are made up of smaller components.

The plum pudding model is defined by Thomson in order to demonstrate that negatively charged sub-atomic particles known as electrons are surrounded by a volume of positively charged particles known as protons. It is one of the historical scientific model of the atom that governs all sorts of properties of sub-atomic particles.

Therefore, "negatively charged particles with a very small mass" is the discovery that follows J.J. Thomson's plum pudding model of the atom. Thus, the correct option for this question is A.

To learn more about the Plum pudding model, refer to the link:

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THIS QUESTION IS HARD BUT I NEED HELP AND ITS DUE IN 20 MINS. YOU HAVE TO ANSWER A AND B FOR EVERYTHING TO BE CORRECT. I KNOW YALL ARE SMART PLSS HELP. THANKS!!

Answers

With the batteries wire and paper clips you can make a spare to have a fire if use a compass to tell where I’m located the strong and leak magnet and put it under your hand put 2 nails on your hand and it will show you where your strongest magnetic force is.

0.954 mol bromine is added to 1 L reaction vessel that contains 1.22 mole of hydrogen and 1 mole of HBr at 1500K. What is the partial pressure of hydrogen, bromine and HBr at equilibrium?

Answers

Answer:

Partial pressure of H₂ →  149.9 atm

Partial pressure of Br₂ → 117.2 atm

Partial pressure of HBr → 112.8 atm

Explanation:

The problem can be solved by the Ideal Gases Law.

In a mixture of gases we know that the sum of partial pressures values the total pressure in the vessel. And the total pressure in the vessel is generated by the total moles which are presennt.

Total moles = 0.954 moles + 1.22 moles + 1 mol = 3.174 moles

Let's apply the Law to determine the total pressure.

P . 1 L = 3.174 moles . 0.082 . 1500 K

P = 390.4 atm

Now we apply the mole fraction concept

Mole fraction (1) →  moles of gas / total moles

Mole fraction (2) → partial pressure of gas / total pressure

In conclussion 1 = 2

Partial pressure of H₂ →  (1.22 / 3.174) . 390.4 atm = 149.9 atm

Partial pressure of Br₂ → (0.954 / 3.174) . 390.4 atm = 117.2 atm

Partial pressure of HBr → (1 / 3.174) . 390.4 atm = 112.8 atm

How many grams of copper (II) hydroxide can be prepared from 2.4 grams of copper (II) nitrate (Cu(NO3)2 ) and excess sodium hydroxide?

Answers

Answer:

percentage yield = 67%

Explanation:

Mass of Cu(NO₃)₂  = 15.25 g

Mass of NaOH   = 12.75 g

Percentage yield = ?

Solution:

Cu(NO₃)₂ + 2NaOH   →  Cu(OH)₂ + 2NaNO₃

Moles of Cu(NO₃)₂:

Number of moles = mass/ molar mass

Number of moles = 15.25 g /187.56 g/mol

Number of moles = 0.08 mol

Moles of NaOH :

Number of moles = mass/ molar mass

Number of moles = 12.75 g / 40 g/mol

Number of moles = 0.32 mol

Now we will compare the moles of Cu(OH)₂ with NaOH and Cu(NO₃)₂.      NaOH             :      Cu(OH)₂

                               2                   :          1

                               0.32              :           1/2×0.32 = 0.16 mol

                            Cu(NO₃)₂         :           Cu(OH)₂

                                  1                  :               1

                             0.08                :              0.08

The number of moles produced by  Cu(NO₃)₂  are less so it will limiting reactant.

Mass of Cu(OH)₂:

Mass = number of moles × molar mass

Mass = 0.08 mol × 97.6 g/mol

Mass = 7.808 g

Theoretical yield = 7.808 g

Percent yield:

percentage yield = Actual yield/ theoretical yield ×  100

percentage yield = 5.23 g/  7.808 g ×  100

percentage yield = 0.67 ×  100

percentage yield = 67%

1.3 grams of copper (II) hydroxide can be prepared from 2.4 grams of copper (II) nitrate (Cu(NO₃)₂) and excess sodium hydroxide.

Let's consider the following balanced double displacement reaction.

Cu(NO₃)₂ + 2 NaOH ⇒ Cu(OH)₂ + 2 NaNO₃

2.4 g of Cu(NO₃)₂ (molar mass 187.56 g/mol) react. The reacting moles of Cu(NO₃)₂ are:

[tex]2.4 g \times \frac{1mol}{187.56g} = 0.013 mol[/tex]

The molar ratio of Cu(NO₃)₂ to Cu(OH)₂ is 1:1. The moles of Cu(OH)₂ produced from 0.013 moles of Cu(OH)₂ are:

[tex]0.013molCu(NO_3)_2 \times \frac{1molCu(OH)_2}{1molCu(NO_3)_2} = 0.013 molCu(OH)_2[/tex]

The molar mass of Cu(OH)₂ is 97.56 g/mol. The mass corresponding to 0.013 moles of Cu(OH)₂ is:

[tex]0.013 mol \times \frac{97.56g}{mol} = 1.3 g[/tex]

1.3 grams of copper (II) hydroxide can be prepared from 2.4 grams of copper (II) nitrate (Cu(NO₃)₂) and excess sodium hydroxide.

You can learn more about stoichiometry here: https://brainly.com/question/22288091

A very new item just arrived in the market. It is very good for construction, and other things. Now, this item has chemicals, and in every drop, there are 400 grams of NaCI. If there are 10 drops in this item, how many grams of NaCI are in one bottle?

Answers

Answer: 4,000 grams of NaCI

Explanation:

We know that there are 400g of NaCI in one drop.

This bottle has 10 drops of this item.

So, we have to multiply the amount of NaCI in a drop by the amount of drops.

400 x 10 = 4,000.

The answer to the question is 4,000. Hope this helps!

Which is NOT an agent of chemical weathering?
A. water
C. carbon dioxide
B. oxygen
D. wind

Answers

Answer:

water is a water, but is also known as water. water means water, and the synonym of water is water, and antonym of water is non-water. water is located in earth. water's friends are pure water, salt water, dirty water and ice water. water's best friend is pure water, because when water gives water to pure water, pure water uses the water and gives back the water to the water.

thank you for enjoying my story

Explanation:

What is the characteristic of all ions

Answers

Answer:

They have one overall charge

Explanation:

Negative or positive

what do seismic waves do

Answers

Answer:

Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs. ... Earthquakes radiate seismic energy as both body and surface waves.

Answer:

they are caused from earthquakes

Explanation:

Earthquakes and underground explosions can release a lot of energy. That energy ripples away from its source in a variety of ways. Some of those vibrations will move forward  and back through the material they travel through . Other waves travel just like ocean waves, where they make the material they pass through move up and down compared to the direction the wave is traveling. And while some of these waves travel deep within the planet, still others move only along the surface. Studying where these various flavors of waves are and how they move not only can help scientists pinpoint where an earthquake or explosion occurred, but also can shed light on the structure of our inner planet.

Rank the following in order from the lowest to highest ionization energy?
Bi, Cs, Ba

Answers

Answer:

Cs,Ba, Bi

Explanation:

Ionization energy increases across the period from left to right on the periodic table

A. The chemical formula for iron (III) sulfate is Fe2(SO4)3. How many atoms of each element are present?

2 iron, 3 sulfur, 12 oxygen
3 iron, 3 sulfur, 12 oxygen
2 iron, 1 sulfur, 4 oxygen
6 iron, 3 sulfur, 12 oxygen
B.How many moles of hydrogen are in 1.8 mole(s) of quinine?

Express your answer using two significant figures.

C. How many moles of carbon are in 5.4 moles of quinine?

Express your answer using two significant figures.

D. How many moles of nitrogen are in 2.0×10−2 mole of quinine?

Express your answer using two significant figures.

Answers

Answer:

A. 2 Fe, 3 S and 12 O

B. 43 moles of H

C. 1.0×10² moles of C

Explanation:

A. Formula for iron (III) sulfate is Fe₂(SO₄)₃

This salt has 2 atoms of iron and 3 sulfates, so in total we have:

2 Fe, 3 S and 12 O

Pay attention to the subscripts

B. Formula for quinine is: C₂₀H₂₄N₂O₂

If we continue with the example before we can say that 1 mol of Iron (III) sulfate contains 2 moles of Fe, 3 moles of S and 12 moles of O

Then, 1 mol of quinine contains 24 moles of H

So 1.8 moles of quinine, may contain (1.8 . 24) /1 = 43 moles of H

C.  1 mol of quinine contains 20 moles of C

5.4 moles of quinine may contain (5.4 . 20) /1 = 1.0×10²

(As the answer must be in 2 significant figures and the real answer is 108, I had to use scientific notation)

How many atom of oxygen are in 2mole of O2​

Answers

Answer:

12.044  × 10²³ atoms of oxygen

Explanation:

Given data:

Number of atoms of oxygen = ?

Moles of oxygen = 2 mol

Solution:

Avogadro number:

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms of oxygen

2 mole × 6.022 × 10²³ atoms of oxygen / 1 mole

12.044  × 10²³ atoms of oxygen

I WILL GIVE YOU A BRAINLIEST: Bryce observes that the sun always seems to rise in the east. He talks with others and finds that everyone has the same observation. Which term describes this equation? A) the sun rises in the east B) Why does the sunrise in the east? C) The sun appears in the east because of Earth’s rotation pattern. D) If the sun appears in the east, then I am in the Western Hemisphere.

Answers

Answer: C

Explanation:

No matter the location on Earth, the sun always rises in the east due to its rotation pattern.

A 500.0-mL buffer solution is 0.100 M in HNO2 and 0.150 M in KNO2. Determine if each addition would exceed the capacity of the buffer to neutralize it.

a. 250 mg NaOH
b. 350 mg KOH
c. 125 g HBr
d. 1.35g Hl

Answers

Answer:

no one additions exceed the capacity of the buffer

Explanation:

given

Volume buffer = 500.0 mL = 0.5 L

mol HNO₂ = 0.5 L × 0.100 mol/L = 0.05 mol HNO₂

mol NO₂⁻ = 0.5 L × 0.150 mol/L = 0.075 mol NO₂⁻

solution

we know when any base more than 0.05 (HNO2) than exceed buffer capacity

and when any base more than 0.075 (KNO2) than exceed buffer capacity

when we add 250 mg NaOH (0.250 g)

than molar mass NaOH =40 g/mol

and mol NaOH = 0.250 g ÷ 40g/mol

mol NaOH  = 0.00625 mol

0.00625 mol NaOH will be neutralized by 0.00625 mol HNO₂

so it would not exceed the capacity of the buffer.

and

when we add 350 mg KOH (0.350 g)

than molar mass KOH =56.10 g

and mol KOH = 0.350 g ÷ 56.10 g/mol

mol KOH = 0.0062 mol

here also capacity of the buffer will not be exceeded

and

now we  add 1.25 g HBr

than molar mass HBr = 80.91 g/mol

and mol HBr = 1.25 g  ÷ 80.91 g/mol

mol HBr = 0.015 mol

0.015 mol Hbr will neutralize 0.015 mol NO₂⁻  

so the capacity will not be exceeded.

and

we add 1.35 g HI  

molar mass HI = 127.91 g/mol

so mol HI = 1.35 g ÷ 127.91 g/mol

mol HI = 0.011 mol

capacity of the buffer will not be exceed

What happens when the particles of a gas collide?
A. They vibrate in place
B. They stick to one another
C. They become particles of a solid
D. They bounce off one another

Answers

Answer:

A

Explanation:

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What effects the destruction of the rain forest? Who was running the Mexican government when Stephen F Austin arrived to discuss the resolutions?a General Csb. Antonio Lpez de Santa AnnaC. Ramon Musquizd. Valentin Gmez Farias resumen dela parabola del buen samaritano respondan rapido que es una tarea 2p(9p 1) pls help will give brainiest The smallest possible particle of an element is a(n) . Consider the following sequence of successive numbers of the 2k -th power: 1, 2^k , 3^k , 4^ k , 5^k , ... Show that the difference between the numbers in this sequence is odd for all k N. A computer manufacturer built a new facility for assembling computers. There were construction and new equipment costs. The company paid for these costs and made combined profits of $40 million after 4 years, while profits increased $30 million per year. Select the correct graph of this function. (2 points)A)There is a graph of a line that has a y intercept that is approximately $80 million and passes through the point of approximately x equals 2 years and y equals $140 million.B)There is a graph of a line that has a y intercept that is approximately negative $80 million and an x intercept that is approximately 2.7 years.C)There is a graph of a line that has a y intercept that is approximately negative $45 million and an x intercept that is approximately 2 years.D)There is a graph of a line that has a y intercept that is approximately negative $45 million and an x intercept that is approximately 0.6 years. Someone help me with this ASAP A scientist is breeding orange butterflies in the laboratory she notices a white butterfly in the latest generation of animals she sequences the genome of this butterfly in notices a mutation in the genes that calls for pigment in the wings. Explain how this mutation would result in a white butterfly. Which of the following is true about Baroque music? The quartering of troops was addressed in the Constitution with which amendment? Where did the Magyars live in relation to what was then known as Europe? Please help will give brainliest ( hey please help ) Which statement concerning colonists attitudes concerning the British Acts of 1764 and 1765 is most accurate? What territory did the British receive from France at the conclusion of the Seven Years War (French and Indian War)?French Canada, Spanish Florida, and all territory east of the Mississippi River, except for New OrleansSpanish Florida and New Orleansall of French Canada, New Orleans, and French territory west of the MississippiFrench Canada and all territory north of the Ohio River and east of the Mississippi River What value(s) of x will make x2 = 36 true? An oil refinery uses a Venturi tube to measure the flow rate of gasoline. The density of the gasoline is = 7.40 102 kg/m3, the inlet and outlet tubes, respectively, have a radius of 3.74 cm and 1.87 cm, and the difference in input and output pressure is P1 P2 = 1.20 kPa.a) find the speed of the gasoline as it leaves the hoseb) find the fluid flow rate in cubic meters per second How does Hurricane Katrina illustrate the problem with insurance? In a survey of 2,300 people who owned a certain type of car, 1,150 said they would buy that type of car again. What percent of the people surveyed were satisfied with the car? Point C(3.6, -0.4) divides in the ratio 3 : 2. If the coordinates of A are (-6, 5), the coordinates of point B are . If point D divides in the ratio 4 : 5, the coordinates of point D are .