What happens when a chemical hand warmer is unwrapped and starts to work?
A. A physical change absorbs thermal energy.
B. A chemical reaction absorbs thermal energy.
C. A physical change releases thermal energy.
D. A chemical reaction releases thermal energy.

Answers

Answer 1
D ur. Welcome :)))))))))
Answer 2

Answer: D. A chemical reaction releases thermal energy.

Explanation:  

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Related Questions

What is the final temperature, in degrees Celsius, when the pressure is 768 mmHg , with no change in the volume and amount of gas

Answers

The final temperature, in degrees Celsius, of the gas is 34.62 °C

Gas laws

From the question, we are to determine the final temperature, in degrees Celsius

From the Pressure law or Gay-Lussac's law

We have that, for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly proportional to its absolute temperature.

Using the formula,

[tex]\frac{P_{1} }{T_{1}} = \frac{P_{2} }{T_{2}}[/tex]

Where P₁ is the initial pressure

T₁ is the initial temperature

P₂ is the final pressure

and T₂ is the final temperature

From the given information,

P₁ = 739 mmHg

T₁ = 23 °C = 23 + 273.15 = 296.15 K

P₂ = 768 mmHg

T₂ = ?

Putting the parameters into the formula, we get

[tex]\frac{739}{296.15}=\frac{768}{T_{2} }[/tex]

Then,

[tex]T_{2} = \frac{768 \times 296.15}{739}[/tex]

T₂ = 307.77 K

Therefore,

T₂ = 307.77 - 273.15 = 34.62 °C

Hence, the final temperature, in degrees Celsius, of the gas is 34.62 °C

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Here is the complete question:

A gas sample has a pressure of 739 mmHg when the temperature is 23 °C. What is the final temperature, in degrees Celsius, when the pressure is 768 mmHg, with no change in the volume or amount of gas?

Find the molecular mass of NH4Cl​
Full explanation

Answers

Answer:

Explanation:

1 * N = 14

3 * H = 3

Cl =   35.5

Total 52.5

Answer:

Ammonium chloride is the correct answer

hello people ~
Name two items that are made from coconut fiber​

Answers

Answer:

Items that are made from coconut fibers are:

Floor mats, brushes, mattresses, etc.

(You can choose from the options)

Explanation:

Hope this helps

Im new to brainly ^^

Answer: Breads and cakes

PLEASE HELP

If you were a robotics engineer, how would you design a prosthetic limb that stretches and releases? Explain the different parts of your design. Think about the following elements in your design:

Apply the relationship between electricity and magnetism to design a simple motor.


Apply the relationship between electricity and magnetism to design a simple motor.


Explain how the motor would cause the tendon to stretch and release.

Answers

Answer:

Massachusetts Institute of Technology

Summary:

A new surgical technique could allow prosthetic limbs to feel much more like natural limbs. Through coordination of the patient's prosthetic limb, existing nerves, and an artificial muscle graft, amputees would be able to sense where their limbs are in space and to feel how much force is being applied to them.

Share:

Answer:

The function of tendons can be classified into two categories: tensile force transmission, and storage and release of elastic energy during locomotion. The action of tendons in storing and releasing energy is mainly seen in sports activities with stretch‐shortening cycles (SSCs). The more intense the SSC movements are (jumping‐like activities), the more frequently tendon problems are observed. High SSC movements impose high loads on tendons. Consequently, tendons that frequently deal with high SSC motion require a high energy‐absorbing capacity to store and release this large amount of elastic energy. As the elasticity of tendon structures is a leading factor in the amount of stored energy, prevention and rehabilitation programmes for tendon injuries should focus on increasing this tendon elasticity in athletes performing high SSC movements. Recently, it has been shown that ballistic stretching can significantly increase tendon elasticity. These findings have important clinical implications for treatment and prevention of tendon injuries.

Explanation:

When two atoms form a covalent bond they share electrons. What are the electrons of one atom being attracted to in the other atom that allows them to bond?​

Answers

Answer:

The electrons are attracted to the nuclei of both atoms.

Explanation:

Electrons are attracted to nuclei because nuclei are positively charged and electrons are negatively charged. Opposites attract

When an atom loses electrons it becomes _____.

Answers

It becomes positively charged! It has more protons than electrons at this point

How much heat is needed to raise the temperature of 50 g of a substance by 15°C when the specific heat is 0.92 J/g-°C?

A.) 65 J
B.) 250 J
C.) 345 J
D.) 690 J

Answers

Answer:

690j

Explanation:

Use the formula

q

=

m

C

Δ

T

q = heat absorbed or released, in joules (J)

m = mass

C = specific heat capacity

ΔT = change in temperature

Plug known values into the formula.

q

=

50

(

.92

)

(

15

)

q

=

690

therefore, 690 joules of heat energy are needed.

How many grams of hydrogen peroxide are needed to produce 90. 0 g of water?

2H202 (1) ► 2H20() + O2(g)

Answers

Put the numbers into your calculator to find the answer! 90 x 32, then divide by 18.02 x 2. Estimation can tell me that the answer is 79.9, or 80!

After a day at the beach, bodysurfing and hunting for shark teeth, your parent’s yell that it is time to leave. You grab your sandals and towel and run towards the parking lot. Thirty seconds later you feel like you are walking on hot coals. Explain the sudden change

Answers

Answer:

There was a change in temperature on the surface you were walking on. It is possible that "you" were walking on cool, wet sand and when your parents said it was time to leave, you ran barefoot towards the parking lot (away from the sand) and got a burning coal sensation on your feet.

Explanation:

1. If a ball was rolling on a carpet, friction would exert energy
O the same direction the ball is going
O the opposite direction the ball is going

Answers

Answer:same direction

Explanation:

What type of chemical bond is the strongest type of bond?


covalent

ionic

metallic

polar

Answers

Answer:

Covalent

Explanation:

Covalent Bonds. Another type of strong chemical bond between two or more atoms is a covalent bond. These bonds form when an electron is shared between two elements and are the strongest and most common form of chemical bond in living organisms.

Iodine adds to the double bonds in fatty acids (one iodine molecule per double bond). How many double bonds are in a molecule of arachidonic acid (Molar mass

Answers

Answer:

To test if a lipid is saturated or unsaturated iodine is added. If the iodine changes from brown to clear the lipid is unsaturated. If the iodine does not change colors the lipid is saturated. To test for the degree of lipid saturation iodine is added to the unsaturated lipid.

Explanation:

Which of the following is not a benefit of using a scientific model?
А Models allow you to formulate hypotheses about processes.
B Models allow you to study processes that cannot be duplicated.
C Models are often simplified to help explain complex concepts.
D Models make it possible to duplicate the real thing.​

Answers

Answer:

Benifits of scientific modeling

Explanation:

When students are engaged in scientific modeling, they are able to notice patterns and develop and revise representations that become useful models to predict and explain--making their own scientific knowledge stronger, helping them to think critically, and helping them know more about the nature of science.

A student sets up an experiment to determine how much time will elapse before equal samples of water at 20°C become solid if placed in freezers at four different temperatures. Which are the independent and dependent variables in this experiment? A. the starting temperature of the water, and the water containers used B. the starting temperature of the water, and the time it takes the water to freeze C. the various temperatures in the freezers, and the water containers used D. the various temperatures in the freezers, and the time it takes the water to freeze

Answers

Answer:

D. the various temperatures in the freezers, and the time it takes water to freeze

Explanation:

The dependent variable is the variable in an experiment that is subject to being tested and put under observation.  

The independent variable is the variable that is changed and altered in order to bring certain effect on the dependent variable.  

The various temperatures in the freezers is the independent variable that is subject to change and alteration while the time it takes water to freeze is the dependent variable.

science / which phrase describes the differences between these two liquid ?

Answers

Answer:

viscosity

Explanation:

one one left is mercury and the other one is honey right?

Answer:

high surface tension versus low surface tension

Explanation:

hope this helps!^^

what is the final temperature of 520.1 g of water (specific heat =4.18 J/g × °C) at 24.2 °C that absorbed 950 J of heat​

Answers

Answer:

The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs. 

Explanation:

The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs. 

¿Qué tipo de Inter conversión existe en una celda galvánica o en una celda electrolítica? a) de energía química a energía eléctrica y viceversa b) de energía eléctrica a energía química c) de energía química a energía eléctrica d) de energía lumínica a energía eléctrica

Answers

Answer:

Opción a)

Explanation:

En este caso, vamos a explicartelo descartando opciones. Para empezar el proceso que existe en una celda galvánica o electrolítica, es lo que uno llama un proceso de Electroquímica, y permite manipular y usar la energía electrica para generar una reacción.

En este caso, yo tengo por ejemplo una celda galvánica con dos componentes como hierro y cobre conectados mediante una celda. El proceso de reacción entre ellos es lo que ayudará a que se genere energia electrica y esto, encendería un bombillo de luz. También puede ocurrir lo contrario. Con electricidad, se genera una reacción química. En estos casos, se genera una reacción de tipo REDOX (Oxido reducción).

Tomando en cuenta esto, la respuesta correcta sería la opción a). Veamos por que las otras opciones no son:

b) Energía eléctrica a química

Esta opción es falsa, porque estaría supeditando que una reacción solo puede darse por medio de una manipulación de la energía electrica y en las celdas galvánicas no ocurre eso, sino al revés.

c) Energía química a eléctrica

Falsa, porque es igual que la anterior, solo está supeditado a que ocurra este tipo de reacciones y no es así.

d) energía lumínica a eléctrica

Falso porque la energía lumínica proviene tambien de la electricidad, y en el caso de una celda galvánica se genera una reacción por lo que existe otro tipo de energía.

Espero esto te ayude.

A car is traveling 76.4 kilometers per hour. What is its speed in miles per minute?

Answers

Explanation:

speed

76.4/1.609 kilometres to mile =47.47

1hour to minutes=1×60

=60

speed in miles per minute 47.47mile per minute or mph

Two blocks of platinum have a temperature of 200°C. One block has a mass of 10 g, the other block has a mass of 100 g. Do the blocks have the same amount of thermal energy? Explain.

Answers

The two blocks have the same amount of thermal energy.

Effect of temperature on different mass objects

Due to platinum metal, the thermal energy is equally distributed in the whole metal so that's equal distribution the thermal energy of both blocks will be the same so we can conclude that the two blocks have the same amount of thermal energy.

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In what ways will the addition of earth worms most likely affect the terrarium?

Answers

significantly modify the physical, chemical and biological properties of the soil profile.

Answer: The soil biota benefits soil productivity and contributes to the sustainable function of all ecosystems. The cycling of nutrients is a critical function that is essential to life on earth. Earthworms (EWs) are a major component of soil fauna communities in most ecosystems and comprise a large proportion of macrofauna biomass. Their activity is beneficial because it can enhance soil nutrient cycling through the rapid incorporation of detritus into mineral soils. In addition to this mixing effect, mucus production associated with water excretion in earthworm guts also enhances the activity of other beneficial soil microorganisms. This is followed by the production of organic matter. So, in the short term, a more significant effect is the concentration of large quantities of nutrients (N, P, K, and Ca) that are easily assimilable by plants in fresh cast depositions. In addition, earthworms seem to accelerate the mineralization as well as the turnover of soil organic matter. Earthworms are known also to increase nitrogen mineralization, through direct and indirect effects on the microbial community. The increased transfer of organic C and N into soil aggregates indicates the potential for earthworms to facilitate soil organic matter stabilization and accumulation in agricultural systems, and that their influence depends greatly on differences in land management practices. This paper summarises information on published data on the described subjects.

Explanation: Protection of the soil habitat is the first step towards sustainable management of its biological properties that determine long-term quality and productivity. It is generally accepted that soil biota benefits soil productivity but very little is known about the organisms that live in the soil and the functioning of the soil ecosystem. The role of earthworms (EWs) in soil fertility is known since 1881, when Darwin (1809–1882) published his last scientific book entitled “The formation of vegetable mould through the action of worms with observations on their habits.’’ Since then, several studies have been undertaken to highlight the soil organisms contribution to the sustainable function of all ecosystems [1]. Soil macrofauna, such as EWs, modify the soil and litter environment indirectly by the accumulation of their biogenic structures (casts, pellets, galleries, etc.) (Table 1). The cycling of nutrients is a critical ecosystem function that is essential to life on earth. Studies in the recent years have shown increasing interest in the development of productive farming systems with a high efficiency of internal resource use and thus lower input requirement and cost [2, 3]. At present, there is increasing evidence that soil macroinvertebrates play a key role in SOM transformations and nutrient dynamics at different spatial and temporal scales through perturbation and the production of biogenic structures for the improvement of soil fertility and land productivity [4, 5]. EWs are a major component of soil fauna communities in most natural ecosystems of the humid tropics and comprise a large proportion of macrofauna biomass [6]. In cultivated tropical soils, where organic matter is frequently related to fertility and productivity, the communities of invertebrates—especially EWs—could play an important role in (SOM) dynamics by the regulation of the mineralization and humification processes [7–9]. The effects of EWs on soil biological processes and fertility level differ in ecological categories [12]. Anecic species build permanent burrows into the deep mineral layers of the soil; they drag organic matter from the soil surface into their burrows for food. Endogeic species live exclusively and build extensive nonpermanent burrows in the upper mineral layer of soil, mainly ingested mineral soil matter, and are known as “ecological engineers,’’ or “ecosystem engineers.’’ They produce physical structures through which they can modify the availability or accessibility of a resource for other organisms [13]. Epigeic species live on the soil surface, form no permanent burrows, and mainly ingest litter and humus, as well as on decaying organic matter, and do not mix organic and inorganic matter [14]. In the majority of habitats and ecosystems (Table 2), it is usually a combination of these ecological categories which together or individually are responsible for maintaining the fertility of soils [15–17]. EWs influence the supply of nutrients through their tissues but largely through their burrowing activities; they produce aggregates and pores (i.e., biostructures) in the

Fill in the coefficients that will balance the following reaction:
__C₂H₂+__O2–>__CO2 +__H2O

Answers

Explanation:

C3H8 + 5O2 -> 3CO2 + 4H2O

C2H2 + 2.5O2 -> 2CO2 + H2O

Which issue poses the greatest long-term challenge in the development of new nuclear power plants? controlling carbon dioxide emissions storage of radioactive waste controlling fission reactions mining of uranium

Answers

The issue which is the greatest long-term challenge in the development of new nuclear power plants is the storage of radioactive waste.

What are nuclear power plants?

Nuclear power plants are also known as thermal power station as in this plants heat is generated through the nuclear reactors which in turn produces electricity.

In the nuclear reactors, nuclear fission of radioactive substances takes place, as a result of which high amount of waste of radioactive substances are produced which may harm the other living organism as they produces dangerous rays.

Hence option (B) is correct.

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Answer:

it's b

Explanation:

other person said so

what is galvanic or voltaic cell?​

Answers

Answer:

An electrochemical cell that converts the chemical energy of spontaneous redox reactions into electrical energy is known as a galvanic cell or a voltaic cell. Galvanic cell Voltaic cell is an electrochemical cell that makes use of chemical reactions to generate electrical energy....




HOPE THIS HELPS, HAVE A GREAT DAY!!

Explanation:

Answer:

A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous Oxidation-Reduction reactions.

From internet..hope it helps you:)

Explanation:

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What is a vapor?
A. A substance that forms a gas, but only at very high temperatures
OB. A substance that is always in the solid or liquid phase at room
temperature
C. A substance that has a much higher melting point and boiling
point than other similar substances
D. A substance that is in the gas phase at a temperature at which it
would normally be a solid or liquid

Answers

According to the research, a vapor is a substance that is in the gas phase at a temperature at which it would normally be a solid or liquid.

What is a vapor?

It is the state in which a gas is found when it is at a level below its critical point.

A vapor is the result of heating an element that, at room temperature, is usually a solid or liquid.

Therefore, we can conclude that according to the research, a vapor is a substance that is in the gas phase at a temperature at which it would normally be a solid or liquid.

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Alcohol is removed by the _________ blank at a constant rate of 0.25 to 0.30 ounce of ethanol per hour

Answers

Answer:

Liver

Explanation:

Some of these intermediate metabolites can have harmful effects on the body. Most of the ethanol in the body is broken down in the liver by an enzyme called alcohol dehydrogenase (ADH), which transforms ethanol into a toxic compound called acetaldehyde (CH3CHO), a known carcinogen.

If an asteroid were going to impact Earth, would you prefer to know in advance or let the NEO remain a mystery until impact? Why?

Answers

Answer:

I think you're supposed to answer that yourself because it's asking your personal opinion. I'd personally like to know in advance

Remain a mystery, because what am I suppose to do if I know it? I’m not rich and I don’t have a bunker to hind in ( except for tr*mp ). Also, without knowing there’s no panic and it can happen quick; like the dinosaurs.

In the combustion of methane, 810 kilojoules per mole (16 grams) is released. Compare this with the fission of uranium-235. The fission of uranium-235 releases 107 kilojoules per mole.

How much mass is lost in the fission reaction?


∆m = E/C2 (where c = 3.00 × 108 m/s)

Answers

1.189 x 10⁻¹² kg is lost when uranium-235 undergoes fission

In a fission reaction, the nucleus of an atom is broken down into two smaller particles. This is usually seen in heavy and unstable nuclei

The fission of uranium-235 releases 107 kJ/mol

We know that the formula for mass-energy equivalence is

                                              E=mc²

c = 3 x 10⁸ m/s

107000 J= m x  (3 x 10⁸ m/s)²

107000 = m x 9 x 10¹⁶

m = 1.189 x 10⁻¹² kg

In the fission of 1 mole of uranium,   1.189 x 10⁻¹² kg is lost in the reaction

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Answer:

edmentum sample answer

Explanation:

If energy can only be converted from one type to another, the energy you observe when the tortilla chip burned must have come from another type. Where do you think the energy you observe when the tortilla chip burned came from? What type of energy was it originally?

Answers

When you burned the chip, The original source of energy conversions was chemical energy. Which then converted to light, thermal, sound, and kinetic energy.

How do isotopes of a givin element similar

Answers

Different isotopes of an element have the same number of protons in the nucleus, giving them the same atomic number, but a different number of neutrons giving each elemental isotope a different atomic weight.

Someone help me please!!

Answers

Answer: See below

Explanation:

For the first molecule, Al3H, there are:

3 bond pairs and 0 lone pairs on the main atom The total number of electron pairs is 3.So, the hybridization of the molecule will be sp2, and the shape according to VSEPR theory will be a trigonal planar

For the second molecule, CH2F2, there are:

4 bond pairs and 0 lone pair on the central atom. TThere are 4 electron pairs Therefore, the hybridization of the molecule will be sp2, and the shape will be tetrahedral

For the third molecule, PH3, there are

3 bond pairs and 1 lone pair. 4 electron pairs. So, the hybridization of the molecule will be sp3. However, the 4th spot on the molecule will be occupied by a lone pair, so the overall shape will be trigonal pyramidal and not tetrahedral

For the final molecule, O3, there are:

2 bond pairs and 1 lone pairs. The number of electron pairs is 3. Hence, the hybridization of the molecule will be sp2. But due to the 3rd position being taken by a lone pair, and the VSEPR theory assuming that electron pairs will sort themselves to decrease the effects of repulsion, the overall shape will be bent and not linear.
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