what are chemical changes in chemistry

Answers

Answer 1

a usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical properties or composition, resulting in the formation of at least one new substance: The formation of rust on iron is a chemical change. Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.


Related Questions

1
How many atoms of carbon would be present in a molecule of CCl4?
A
5
B
1
С
2
D 4

Answers

Answer:

There are 5! goodluck,

Explanation:

During photosynthesis and cellular respiration plus carry out processes that involve both light and energy and chemical energy. Sort each tile into the correct column.

-Used to directly power cell growth
-Used to directly power photosynthesis
-Released through cellular respiration
-Captured by chloroplyll

Answers

Chemical energy power cell growth, solar radiation power photosynthesis and is captured by chlorophyll, and carbon dioxide is released through cellular respiration.

Photosynthesis and Respiration

During photosynthesis, solar radiation is captured by chlorophyll in green plants, and this is used to fix inorganic carbon dioxide and water to produce plant food in the form of carbohydrates.

During respiration, the carbohydrates synthesized via photosynthesis are broken down chemically to extract the energy locked in them. Carbon dioxide is produced as a by-product.

The energy extracted by respiration is used to power metabolic processes in plants.

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The following flow of energy takes place in one ecosystem: alga → insect → larva flatworm → fish.

Which trophic level has the most energy to pass on to the next?


A) insect larva

B) fish

C) flatworm

D) alga

Answers

Answer: D. Alga

Explanation:

As the atomic number of elements within Group 2 increases, the metallic character of each successive element
(1) decreases
(2) increases
(3) remains the same

Answers

Answer: (2), increases

Explanation: Metals are substances which readily loose electrons.

1. How many formula units are contained in 270.2 g of zinc nitrate, Zn(NO3)2?
50 POINTS

Answers

Zinc nitrate has 1 molecule of zinc (Zn), 2 molecules of nitrogen (N) and 6 molecules of oxygen (O).

Calculate the molecular mass of zinc nitrate by adding the molecular weights for all molecules in the compound.

Here are the molecular weights for each element:

Zn=65.38 g/mol

N=14.01 g/mol

O=16.00 g/mol

The molecular weight of zinc nitrate is then: 1*(65.38)+2*(14.01)+6*(16.00)=189.40 g/mol.

Using a conversion formula to calculate moles of zinc nitrate:

163.97gZn(NO

3

)

2

189.40gZn(NO

3

)

2

1molZn(NO

3

)

2

=0.866molZn(NO

3

)

2

 

There are 0.866 moles of zinc nitrate.

Note: These numbers may vary slightly due to the source of the molecular weight data and the number of decimal places used.

8.588 x 10^23 formula units

Questlon 2 of 10
Which of these describes a reason why nuclear power is important?
• A. Solar technology can be installed to provide any home with power.
• B. Solar and wind technologies are both "green."
• C. Solar and wind technologies are location specific.
• D. It's important to use "green" energy to protect our environment.

Answers

Answer:

c

Explanation:

its the only one with a downside to solar and wind.

Balance the equation for a half-reaction that occurs in acidic solution. Use e− as the symbol for an electron

Answers

The balanced half-reaction equation is [tex]MnO_4^- + 4H^+ --- > MnO_2 + 2H_2O + 3e^-[/tex]

What is a redox reaction?

The term redox reaction has to do with a reaction in which there is a loss or gain of electrons. In this reaction, one specie accepts electrons while another species loses electrons.

The balanced half-reaction equation in acid is;

[tex]MnO_4^- + 4H^+ --- > MnO_2 + 2H_2O + 3e^-[/tex]

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Based on your observations, do you think any of the samples are the same substance?

Yes
Yes

No
No
Explain your answer below.

Answers

can we get a picture please?

Enter an equation to show how h2po3− can act as a base with hs− acting as an acid

Answers

The base is the species that accept hydrogen, and the acids donate hydrogen ions. Dihydrogen phosphite acts as a base and hydrosulfide sulfanide act as an acid.

What are acids and bases?

Acids are molecules or chemical species that can donate a proton or a hydrogen ion to another chemical species.

Bases are the ions or molecules that accept a proton or hydrogen ion and release a hydroxide ion.

The acid and base relationship is shown as,

[tex]\rm H2PO_{3}^{-} + HS^{-} \leftrightarrows S^{-} + H_{3}PO_{3}[/tex]

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How many grams of nacl are present in 350 ml of a 0. 277 m solution of sodium chloride? a 1. 66 g b 16. 2 g c none of these d 97. 0 g e 5. 67 g

Answers

A NaCl solution of 350 mL volume and a concentration of 0.277 M will contain 5.67 grams of the salt.

Mole calculation

Recall that:

Mole = molarity x volume.

Also:

Mass = mole x molar mass

Hence;

Mole of 350 mL, 0.277 NaCl = 0.350 x 0.277 = 0.097 moles

Mass of 0.097 moles NaCl = 0.097 x 58.44 = 5.67 grams

Thus, a 350 mL, 0.277 M NaCl solution will contain 5.67 grams of the salt.

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How many molecules are in 368 g of potassium hydroxide (KOH)?

Answers

Answer: 6.559055381954511

Explanation:

Fe +0₂--Fe₂O3
35. What type of reaction is given

Answers

synthesis because the elements all come together

A mixture of helium, nitrogen and oxygen has a total pressure of 821 mmHg. The partial pressure of helium is 105 mmHg, and the partial pressure of nitrogen is 312 mmHg. What is the partial pressure (in mmHg) of oxygen in the mixture?

Answers

Answer:

Total partial pressure, Pt = 821 mm Hg

Partial pressure of Helium, P1 = 105 mm Hg

Partial pressure of Nitrogen, P2 = 312 mm Hg

Partial pressure of Oxygen, P3 = ? mm Hg

According to Dalton's law of Partial pressures,

Pt = P1 + P2 + P3

So, P3 = 404 mm Hg

What occurs as energy is transferred through the radiative zone of the sun? check all that apply. gamma rays are produced. photons are absorbed and reemitted. energy is transferred through the large-scale movement of material. photons are scattered in many directions. energy is released into the photosphere.

Answers

Answers:

1) Photons are absorbed by hot gas atoms.

2) Energy is transferred through large-scale movement of material.

3) Energy is released into the photosphere.

The Sun interior is divided into three regions: the inner core, the radiative zone and the convection zone.

The inner core is the central region of the Sun and all solar energy is produced in the core by nuclear fusion.

Radiative zone is around the inner core and in this area energy is transported by radiation.

The convection zone is the outer-most layer of the interior and in this area energy is transported by convection.

HELP PLEASE I BEG OF YOU


14-karat gold is 58 percent gold and 42 percent copper. calculate the actual amount of gold in a 65-g 14 karat gold chain.

Answers

Answer:

37.7%

Explanation:

58% of 65 is 37.7%

How many moles of hydrogen are required to react with 2 moles of oxygen?​

Answers

Answer:

4 moles of H2

Explanation:

From the equation, twice as many

2 moles of O2   requires 4 moles of H2

1mol of Oxygen requires 2 moles of Hydrogen

Moles of oxygen=2

Moles of Hydrogen

2(2)4moles

An ecosystem where all organisms have niches and habitats will be
balanced.
unbalanced.

Answers

Answer:

balenced.

Explanation:

An ecosystem where all organisms have niches and habitats will be balanced.

What is an ecosystem ?

An ecosystem consists of all the organisms and the physical environment with which they interact.

What is a niche ?

Niche describes the role an organism plays in a community. A species' niche encompasses both the physical and environmental conditions it requires and the interactions it has with other species.

What is a habitat ?

Habitat is the area and resources used by a particular species.

A balanced ecosystem represents a sustainable habitat of interdependent animals, plants, and microorganisms and their environment.

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list the symbols for the noble gases

Answers

Answer:here:

Explanation:helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).

Please help!!!
what is the name of pb(no3)2? explain how you determined the bond type and the steps you used to determine the naming convention for the compound.

Answers

Lead (II) Nitrate. Ionic bond since lead is a metal and nitrate is a polyatomic ion. NO3 has a charge of -1. Since there are 2, the overall charge is -2. Ionic must always have a net charge of 0, so Pb must have a charge of +2.

Naming- keep the first name the same, change the second to end with —ide (chlorine —> chloride) unless a polyatomic ion which stays the same.

The cation part is named first in an ionic compound and the anionic part is named with the suffix of ate, id etc. The name of the ionic compound Pb (NO₃)₂ is lead nitrate.

What are ionic compounds?

Ionic compounds are formed between metals and nonmetals. Metals are electron rich and can easily lose electrons to form  positively charged ions called cations.

Non-metals with electron-deficiency will gain electron from the metals and acquires a negative charge to form anions. The electrostatic force of this negative clouds and positive cloud from the cation is called ionic bonding.

For ionic compounds, the cation or metals are named first. Pb is a metal with two valence electrons and NO₃ group has a negative charge. Thus, Pb donates its two electrons each to each nitrate groups and the anionic part nitrate is named last.

Therefore, the compound name is lead nitrate.

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Which model states that an acid is a substance that contains hydrogen and ionizes to produce hydrogen ions?.

Answers

Answer:

The Arrhenius model

Explanation:

The Arrhenius state that an acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution.

Some greenhouse gases, such as fluorocarbons (CFCs, HFCs, PFCs, etc.), are human-made. Others, such as water, methane, and carbon dioxide, are naturally produced. Which type of greenhouse gas (human-made or natural) is more difficult to control and eliminate? Which types are easier? In three to five sentences, provide evidence for your argument.(4 points)

Answers

The natural types of greenhouse gases are more difficult to control and eliminate while the human-made type are easier.

What are greenhouse gases?

Greenhouse gases are specific type of gases that have the ability to trap and release heat in their bonds.

Greenhouse gases are the cause of global warming, which is the gradual increase in temperature of the Earth's atmosphere.

However, greenhouse gases can either occur naturally or be synthesized artificially. The naturally-occuring greenhouse gases like CO2 are more difficult to control because they are not produced by humans.

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How many total atoms are in one molecule of cobalt hydroxide?

Answers

Answer: Hello! I'm Jungkook. Here is your answer.....

1 Atom.

Explanation:

Hope this helps! Anneyong/Bye!

xoxoKookie

How many atoms of oxygen are in 2. 50 moles of so2?

Answers

The number of atoms of oxygen are present in 2.50 moles of sulfur dioxide is 30.110 × 10²³.

What is Avogadro's number?

Avogadro's number is define as the number of atoms present in one mole of any substance and it is equal to 6.022 × 10²³.

In the 1 mole of SO₂ 2 moles of oxygen are present. So that in 2 moles of SO₂, 2(2.5) = 5 moles of oxygen is present.

No. of atoms of oxygen in 5 moles of oxygen will be calculated as:

No. of atoms = 5 mole × 6.022 × 10²³atoms per mole = 30.110 × 10²³atoms

Hence number of atoms of oxygen is 30.110 × 10²³.

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How many moles of hydrogen gas would be required to produce 25 moles of H2O?

Answers

Answer:

There would be 25 moles

Explanation:

This is the equation for water (synthesis):

2H₂   +   O₂   →    2H₂O

Since there are 25 moles of water, the moles of hydrogen gas will have 25 moles.

Which reaction is endothermic? hcl naoh right arrow. nacl h2o 58 kj 6co2 12h2o energy right arrow. c6h12o6 6o2 6h2o 2na cl2 right arrow. 2nacl energy 2c2h6 7o2 right arrow. 4co2 6h2o 2,502 kj

Answers

Endothermic reactions are those in which heat is absorbed from the surroundings.

What are endothermic reactions?

They are reactions in which heat is absorbed from the surrounding, making the reaction vessels become colder.

It is unlike exothermic reactions in which heat is released into the surrounding, making the reaction vessel to be warmer.

For endothermic reactions, the enthalpy change is always positive because heat is absorbed. It is however negative for exothermic reactions because heat is evolved.

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Answer:

B. 6CO2 + 12H2O + energy =  C6H12O6 + 6O2 + 6H2O

Explanation:

What is the ph of a 0. 571 m solution of hydrosulfuric acid, h2s?

Answers

pH is the potential of the hydrogen in the aqueous solution. The pH of the hydrosulfuric acid is 0.6.

What is pH?

pH is the hydrogen or the hydronium ion concentration in the aqueous solution. The formula to calculate pH is given as,

[tex]\rm pH = \rm - log [H^{+}][/tex]

Since hydrosulfuric acid is diprotic the concentration of the hydrogen ion will be:

[tex]\begin{aligned} \rm [H^{+}] &= 2 \times 0. 571 \;\rm M \\\\&= 1.142\end{aligned}[/tex]

Now, pH is calculated as:

[tex]\begin{aligned} \rm pH &= \rm - log [H^{+}]\\\\&= \rm - log [1.142]\\\\&= 0.06\end{aligned}[/tex]

Therefore, 0.6 is the pH of the hydrosulfuric acid solution.

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The pressure inside of the chem-101 laboratory is 751 mm Hg. Calculate the pressure in units of atmospheres? (760 mm Hg = 1.00 atm)

Answers

751/760 x 1 atm = 0.988 atm

A 78.0 sample of gold at 175°C is put in a foam cup calorimeter with 25.0 g of water at 25.0°C. Calculate the specific heat of the gold if the final temperature is 38.18°C and the specific heat of water is 4.18 J/g°C. Show your work.

Thanks for the help!!​

Answers

The answer is the specific heat of the gold is 0.129 J/gC .

What is Calorimetry ?

It is an experimental method that allows one to calculate the heat change in a chemical process.

Calorimeter is just a reaction vessel. It could be a foam cup, a soda can, or a commercially available bomb calorimeter

Where q represents the heat change in the reaction, the calorimeter and the water. Since you are only measuring temperature, you will need to calculate the heat using it.

The change in heat of the gold is given by:

[tex]\rm q_{gold} = m c_{gold}\Delta T[/tex]

[tex]=78 \times c_{p}\times (175-38.18)[/tex]

The change in heat of the water is given by:

[tex]\rm q_{water} = mc_{p}\Delta T[/tex]

m is the mass of water in the calorimeter in grams,

and delta T is the change in temperature.

where [tex]\rm c_{p}[/tex] is the specific heat of water, which is 4.184 J/gC

mass of water =  25 g of water.

Temperature T₁ = 25°C

Final Temperature = 38.18 °C

Difference between temperature = 13.18 °C

[tex]\rm q_{water} = 25 \times 4.18\times 13.18[/tex]

For a Foam Cup Calorimeter

[tex]\rm q_{water} = q_{cal}\\\\\\\rm 25\times4.18\times13.318 = 78 \times c_{p}\times (175-38.18)\\\\\\On \;solving\; this \;we \;get \;c_{p} = 0.129[/tex]

Therefore the  the specific heat of the gold is 0.129 J/gC

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How many moles is 3.48 g of carbon?

Answers

[tex]\text{No. of moles } = \dfrac{\text{Mass of substance(C)} }{\text{Molar mass of substance(C)}}\\\\\\~~~~~~~~~~~~~~~~~~~=\dfrac{3.48}{12}~ \text{mol}\\\\\\~~~~~~~~~~~~~~~~~~~=0.29~ \text{mol}[/tex]

A chemist wants to extract copper metal from copper chloride solution. The chemist places 0.50 grams of aluminum foil in a solution containing 0.75 grams of copper (II) chloride. A single replacement reaction takes place. Which statement explains the maximum amount of copper that the chemist can extract using this reaction?

Unbalanced equation: CuCl2 + Al → AlCl3 + Cu

A. Approximately 0.36 grams, because copper (II) chloride acts as a limiting reactant
B. Approximately 1.8 grams, because copper (II) chloride acts as a limiting reactant
C. Approximately 0.36 grams, because aluminum acts as a limiting reactant
D. Approximately 1.8 grams, because aluminum acts as a limiting reactant

Answers

Approximately 0.36 grams of Cu are produced because copper (II) chloride acts as a limiting reactant.

What is an Equation ?

A representation of a chemical reaction using symbols of the elements to indicate the amount of substance, usually in moles, of each reactant and product.

Based on the balanced equation of reaction and the reacting masses, approximately 0.36 grams of Cu are produced because copper (II) chloride acts as a limiting reactant.

The amount of copper produced is determined from the balanced equation of the reaction.

The equation of the reaction is given below:

3 CuCl₂ + 2 Al → 2 AlCl₃ + 3 Cu

molar mass of CuCl₂ = 132 g/mol

molar mass of Al = 27.0 g

molar mass of Cu = 64.0 g

moles of aluminium in 0.50 g = 0.50 / 27 = 0.018 moles

moles of CuCl₂ in 0.75 g = 0.75/132 = 0.00568 moles

Therefore, CuCl₂ is the limiting reactant

3 moles of CuCl₂ produces 3 moles of Cu

0.00568 moles of CuCl₂ will produce 0.00568 moles of Cu

Mass of 0.005  moles of Cu = 0.00568 * 64 = 0.36 g of Cu

Therefore, approximately 0.36 grams of Cu are produced because copper (II) chloride acts as a limiting reactant.

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What is the coefficient of x in 2x+3?Please answer? Which of the following statements about the expected value of a random experiment is true? A. The expected value is the value you will get after one trial. B. The expected value is the average of the values after 100 trials. C. As the number of trials gets larger, the average of the trials approaches the expected value. D. The expected value never actually equals the average of the trials. Please select the best answer from the choices provided A B C D pls factorize 4(2x-3)(5x+2)=0 9. Look at the engine block shown in the figure. The engine shown in this figure is alanO A. eight-cylinder, V-type engine.O B. six-cylinder, V-type engine.O C. four-cylinder, in-line engine.O D.four-cylinder, horizontally opposed engine. A data analyst at a construction company is working on a report for a quickly approaching deadline. Why might they choose to analyze only historical data Mitchell received a stipend at the beginning of the semester to buy textbooks. During the semester, he spent $430.84 on textbooks. He had $136.04 of the stipend left at the end of the semester.x - $430.84 = $136.04How much was Mitchell's stipend? A. $566.88 B. $702.92 C. $362.82 D. $294.80 Use the method of completing the square to determine the exact values of x for the equation x2-8x+6=0. [4.8] 1 can find the area of a sector. A major fishing company does its fishing in a local lake. The first year of the company's operations it managed to catch 154,000 fish. Due to population decreases, the number of fish the company was able to catch decreased by 5% each year. How many total fish did the company catch over the first 10 years, to the nearest whole number? Select all of the factors that affect the level of wages. Select 4 correct answer(s)level of immigrationconsumer protection regulationsproduction possibilities frontierskills & abilitiessize of the labor pooldiminishing marginal utilityactions of labor unions Ernie is worried about his friend Haley. She has been drinking a lot and engaging in some other high-risk behavior. They have been friends for years, and this is not really like her. He wants to talk to her about his concerns, but he is not sure what the most effective way to influence her behavior is. Give three ways he could encourage her to pursue healthier behavior. Are your actions free or determined? Fully explain your answer. Mei Mei invested $1700 in an account that pays 3% interest compounded annually.Assuming no deposits or withdrawals are made, find how much money Mei Meiwould have in the account 16 years after her initial investment. Round to the nearesttenth (if necessary). Even though both crimes are notorious in American history, how had things changed between the time of the assassination of Lincoln and themurder of Nicole Brown Simpson and Ron Goldberg?O A Punishment for murder had become much more serious.B. Weapons had advanced significantly from swords to guns.OC Television had been invented, allowing everyone to watch the trial.OD. Racism became a motive for murder. What was ronald reagans basic belief about economic growth? he thought greater government involvement in business would fix the nations economic problems. he felt that more regulations would help to create more jobs. he believed that decreasing government spending would eventually lead to economic growth. he thought that higher taxes would provide incentives for growth. Please help a solution of potassium hydroxide (koh) was titrated against a solution of hydrochloric acid. how many moles of potassium hydroxide would react with 1 mole of hydrochloric acid? (hint: it may help to write out a balanced symbol equation for the reaction.) Please give coordinates :) Simplify the expression given below.x+2/x^3+2x^2-9x-18/3x+1/x^2-9 Express y in terms of x! Find the value of y when x = 1.1/6x + 3/4y =4 The Cold War era was marked by the rivalry between the US and the Soviet Union, the time of tension was pushed on because of the fact that the two countries never actually went to war. When else would this term apply in US history if at all? What might have happened if there would have been a "hot" war with the Soviet Union.