Which of the following is a description of an exothermic reaction?

A. releases heat
B. reactants have less enthalpy than the products
C. ∆H is positive
D. gets cold

Answers

Answer 1

A description of an exothermic reaction is it releases heat. The correct option is A.

What is an exothermic reaction?

An exothermic reaction is a reaction in which heat is released into the atmosphere. In these reactions, less energy is needed to start the reaction and the energy is released when bonds are made in the products. Delta H is always negative in these reactions.

Energy is always given off when the reaction happened, in the form of heat and light. Examples are burning of wood, melting of ice, combustion, corrosion, etc.

Thus, the correct option is A. releases heat regarding a description of an exothermic reaction.

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Related Questions

1. You bought a loaf of bread and on the way home, the loaf of bread was crushed. Is the density of the crushed bread the same density as the uncrushed bread? If the density of the crushed bread is different from the density of the uncrushed bread, tell which bread has the higher density. Explain how you know.

Answers

Answer:

No. It is more dense than the uncrushed bread.

Explanation:

The mass is the same, however the volume has been decreased on the crushed side, forcing more matter into one space, which increases the density.

The loaf of bread was crushed then the density of crushed bread and uncrushed bread is same.  

What is density?

Density is defined as a measurement of how tightly the material is packed together.

It can also be defined as mass of a unit volume of a material substance.

Density can be expressed as

Density = mass / volume

The density depends on mass and volume and mass and volume of crushed and uncrushed bread is same only surface area changes with structural deformation.

Thus, the loaf of bread was crushed then the density of crushed bread and uncrushed bread is same.  

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A certain substance X has a normal freezing point of −3.1°C and a molal freezing point depression constant =Kf·6.23°C·kgmol−1. Calculate the freezing point of a solution made of 12.3g of urea NH22CO dissolved in 300.g of X. Be sure your answer has the correct number of significant digits.

Answers

Answer:

Freezing T° of solution =  - 7.35 °C

Explanation:

This is about the freezing point depression, a colligative property which depends on solute.

The formula is: Freezing T° pure solvent - Freezing T° solution = m . Kf . i

Freezing T° of pure solvent is -3.1°C

At this case, i = 1. As an organic compound the urea does not ionize.

We determine the molality (mol/kg of solvent)

We convert mass to moles:

12.3 g . 1mol / 60.06 g = 0.205 moles

0.205 mol / 0.3 kg = 0.682 mol/kg

We replace data in the formula:

-3.1°C - Freezing T° of solution  = 0.682 mol/kg . 6.23 kg°C/mol . 1

Freezing T° of solution = 0.682 mol/kg . 6.23 kg°C/mol . 1 + 3.1°C

Freezing T° of solution =  - 7.35 °C

What is the average pressure exerted by the molecules on the walls of the container?

Answers

Answer:

This question appears to be incomplete

Explanation:

However, we know that one of the kinetic theories of gases is that gas molecules collide with one another and against the walls of the container (in which they are stored); hence exerting there pressure on the walls of this container.

Ideal gases are the most suitable for this theory because it's molecules are far apart and do not exert any attractive forces towards one another; hence it's molecules move "undisturbed" or "freely". For ideal gases, the average pressure exerted by by the gas molecules on the walls of the container can be calculated as

PV = nRT

Where P = pressure (in atmosphere, atm or kilopascal, KPa or millimeter mercury, mmHg)

V = volume (in liters)

n = number of molecules

R = ideal gas constant (8.3145 J·mol⁻¹·K⁻¹)

T = temperature (in kelvin)

How can pH go high over time

Answers

Factors that raise pH in a swimming pool. 1. Natural pH Rise: Carbon Dioxide Loss. The chemistry of pH sounds a lot more complicated than it is. In short, the less CO 2 in solution, the ... 2. Sanitizers and their pH Impact. 3. pH and alkalinity adjustment chemicals.


A high pH level can be caused by several factors, the main culprits being additional chlorine stabilizers and sudden increases in temperature. In addition, high pH runs a risk with your chlorine, as your chlorine will no longer disinfect fully. There are also physical consequences of high pH for swimmers.

Which lists the waves in order of frequency, from highest to lowest?
O X-rays, gamma rays ultraviolet
O radio waves, visible light, X-rays
O ultraviolet, microwaves, gamma rays
O visible light, infrared, microwaves

Answers

Visible light, infrared, microwaves. This is the waves in order of frequency, from highest to lowest. Therefore, the correct option is option D.

What is electromagnetic wave?

One of the various ways that energy moves through space is electromagnetic radiation. Electromagnetic radiation includes the heat from a blazing fire, the sun's light, the X-rays your doctor uses, and the energy used it to cook food inside a microwave. Although though these energies may appear to be very different from each other, they are connected by the fact that they all have characteristics of waves.

The amplitude of a wave is the vertical line between both the tip of the crest and the wave's axis. This is the characteristic linked to the wave's brightness or intensity. The wavelength of a wave is the horizontal separation of two succeeding crests or troughs. Visible light, infrared, microwaves. This is the waves in order of frequency, from highest to lowest.

Therefore, the correct option is option D.

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2. How do we identify bias and avoid thinking errors when evaluating online

information?

Answers

Answer:

We can identify bias and avoid thinking errors when evaluating online information when there is a certain degree of partiality in the way the information is given. The writer takes one side and doesn’t consider benefits of the other side/view.

We can identify bias and avoid thinking errors when evaluating online information by making our personal findings and research from other sources and then comparing the two.

someone help. what is the missing word?

Answers

a. acceleration

----------------------

is a light bulb chemical or physical change. State evidence why

Answers

Answer:

It is a chemical change.

Explanation:

When the electricity is off, the filament cools down to its original physical state. This physical process repeats every time the light is turned on and off. However, if the bulb is cracked and air is introduced, the oxygen in the air reacts with the tungsten filament which then undergoes a chemical change.

Which of the following are observations? Select all that apply.
A. Watching table salt dissolve in waters'
B. Feeling the sensation of ice held in the hand.
C. Smelling ammonia used in a cleaning solution.
D. Hearing a loud bang when a balloon filled with hydrogen gas is ignited.
E. Looking at the readout of a digital scale when measuring reagents for an experiment.

Answers

Answer:

A and E

Explanation:

Observing means looking or watching with the eyes etc..

Observation is the component of research and involves inspection of the hypothesis. Dissolving table salt and reading a digital scale is an example of observation. Thus, options A and E are correct.

What is an observation?

Observation is that the component of the experimental style that defines observance or the review of the activity that underwent sure conditions.

It will be seen as a press release supported hearing, vision, etc. The dissolving of the flavorer is associate degree noticeable task wherever one will see the salt gets dissolved within the water to create a combination.

Similarly, the digital scales are used to measure the substances and use a readouts to estimate the quantity of the reagents to be used by directly seeing on the digital screen of the machine.

Therefore, dissolving salt and digital scale is observable.Hence options A and E are correct.

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Which statement correctly defines pasteurization?​

Answers

Answer:

Pasteurization is the process by which liquids are heated to kill bacteria that may be present.

explanation I got the correct answer

Answer:

Pasteurization is the process by which liquids are heated to kill bacteria that may be present.

Explanation:

i just did that one

Please give me some answers not all and I’ll give points

Answers

Answer:

B) pH of water is independent. A) Number of tadpoles is dependent

Explanation:Because the pH can kill fish

Which ketone in each pair is more reactive?
a. 2-heptanone or 4-heptanone,
b. bromomethyl phenyl ketone or chloromethyl phenyl ketone

Answers

Answer:

a. 2-heptanone is more reactive than 4-heptanone

b. chloromethyl phenyl ketone is more reactive than bromomethyl phenyl ketone

Explanation:

The reactivity of the carbonyl compound (ketone ) is affected by the steric effect. The steric effect is a hindrance that occurs in the structure or reactivity of a molecule, which is affected by the physical size and the proximity of the adjacent parts of the molecule.

Between 2-heptanone or 4-heptanone, 2-heptanone is more reactive than 4-heptanone. This is because 2-heptanone is less affected by the steric hindrance, unlike the 4-heptanone.

Similarly, the reactivity of the carbonyl compound (ketone) is also affected by the polarity on the carbon compound, which is associated with how electronegative the substituent attached is to the carbonyl compound. From the periodic table, the electronegativity of the Halogen family decreases down the group. Therefore chlorine is more electronegative than bromine.

As such, chloromethyl phenyl ketone is more reactive than bromomethyl phenyl ketone.

Imagine that you are developing a TLC plate, but you get distracted and forget to take the TLC plate out. Later, when you remove your TLC plate from the developing chamber, you notice that the solvent front has reached the top of the TLC plate. How will the Rf values from this TLC plate compare with those of a student who stopped developing their TLC plate before the solvent front reached the top of the plate

Answers

Answer:

The full form of TLC is Thin layer chromatography which is used in separating non volatile mixtures.

Explanation:

In the context, the Rf values could not be read properly or determined properly and accurately if the solvent front flows to the top of the plate. If the solvent reaches the plate's top, then the Rf values reading will be different from the TLC plate where the solvent did not reach the plate's top.

If the solvent front reaches the top, then it is not possible to accurately determine draw the line and to determine how far the spot went. And thus it would be difficult to solve the ratio as the plate would keep advancing or developing and also the compound spot keeps rising. As a result, spots reaches higher or rises than the normal rise but the solvent front does not change, it remains same. Thus, the Rf value would be completely off.

Determine the equilibrium expression for the following reaction:
2NaHCO3(s)⇋Na2CO3(s)+H2O(g)+CO2(g)

Answers

Answer:

K = [Na2CO3] [H2O] [CO2] / [NaHCO3]²

Explanation:

2NaHCO3(s)⇋Na2CO3 (s) + H2O(g) + CO2(g)

To write an expression for equilibrium constant, K, for the above reaction, it is important that we have an idea of what equilibrium constant is all about and how we can determine it.

Equilibrium constant for a reaction is simply defined as the ratio of the concentration of the product raised to their coefficient to the concentration of the reactant raised to their coefficient.

Thus the expression for the equilibrium constant for the above equation can be written as follow:

K = [Na2CO3] [H2O] [CO2] / [NaHCO3]²

3 H2S + 2AuCl --> Au2S3 + 6 HCL is what type
of reaction

Answers

Answer:

Double Displacement (Metathesis)

Explanation:

Using the molecular weight (96.2 g/mol) determine the amount of mmol of (3S)-3,4- dimethylpentyne. Round to the tenths place.

Answers

Answer:

2.0 mmole

Explanation:

The computation fo the amount of mmol is shown below:

As we know that

[tex]Mole = \frac{Given\ mass}{molar\ mass}[/tex]

where,

Given mass is 0.2 gm

The Molar mass is 96.2g/mol

Now

put these values to the above formula

So,

[tex]= \frac{0.2}{y96.2} \\\\= \frac{1}{481} mole[/tex]

Mile mole is

[tex]= \frac{1}{481}\times 1,000[/tex]

= 2.079

= 2.0 mmole

As

mole = 1,000^-1 mili mole

We simply applied the above formula so that the amount of mmole could come

what is zirconium electron configuration

Answers

kr,5s2,4d2

Explanation:

as itis in the 2nd transition series

The density of ice is 0.917 g/cm3. What volume of ice does 52.75 g occupy?

Answers

Answer:

The answer is

57.52 mL

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} [/tex]

From the question

mass of ice = 52.75 g

density = 0.917 g/cm³

The volume of the ice is

[tex]volume = \frac{52.75}{0.917} \\ = 57.52453653[/tex]

We have the final answer as

57.52 mL

Hope this helps you

Which of the following is an extensive property? a. melting point b. hardness c. color d. volume e. temperature

Answers

The answer is d volume. This is because the melting point, color, temperature are all intensive properties. While hardness is neither extensive or intensive. Volume is the only one that is considered an extensive property.

I hope this helps ! <3

Answer: volume

explanation:

PLEASE HELP ME, I have no idea how to do this :(

Answers

Answer:

molar mass: 151.165

Explanation:

mass of Carbon is 12.011 amu

mass of Hydrogen is 1.008

mass of Nitrogen is 14.007

mass of Oxygen is 15.999

you make the calculations like this...

[tex](12.011 \times 8) + (1.008 \times 9) + (14.007) + (15.999 \times 2) = 151.165amu[/tex]

An octagonal pyramid ... how many faces are there, how many vertices and how many edges? A triangular prism ... how many faces are there, how many vertices and how many edges? a triangular pyramid ... how many faces are there, how many vertices and how many edges?​

Answers

Answer:

Hi Harshadvani!! These are the answers you need:

Octagonal Pyramid:

Faces - Eight (8)

Vertices - Nine (9)

Edges - Sixteen (16)

Triangular Prism:

Faces - Five (5)

Vertices - Three (3)

Edges - Eight (8)

Triangular Pyramid:

Faces - Four (4)

Vertices - Four (4)

Edges - Six (6)

Hope it helps!!

Thanks!!!☺✨

Answer:

hey there

An octagonal pyramid

8

9

16

A triangular prism

5

3

8

a triangular pyramid

4

4

6

need further explanation???

text me on the comments

You have 723 ml of 3.99 M HCl. Using a volumetric pipet, you take 326 ml of that solution and dilute it to 976 ml in a volumetric flask. Now you take 100.00 ml of that solution and dilute it to 119 ml in a volumetric flask. What is the concentration of hydrochloric acid in the final solution

Answers

Answer:

1.12M

Explanation:

The initial concentration of the HCl solution is 3.99M. You are doing 2 dilutions:

In the first you take 326mL and dilute the solution to 976mL; that means you are diluting the solution:

976mL / 326mL = 2.99 times.

The concentration of this solution is:

3.99M / 2.99 = 1.33M

Now, in the second dilution, you take 100mL of the diluted solution and dilute it to 119mL. The concentration of this final solution is:

119mL / 100mL = 1.19 times.

1.33M / 1.19 =

1.12M

The final concentration of hydrochloric acid present is 1.11 M.

In the first dilution;

M1V1 = M2V2

M2 = 3.99 M × 326 ml/976 ml

M2 = 1.33 M

In the second dilution:

M1V1 = M2V2

M2 = 1.33 M × 100.00 ml/119 ml

M2 = 1.11 M

Hence, the final concentration of hydrochloric acid present is 1.11 M.

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I can sort the way each object moves by

Answers

Answer:

By the way they move

Explanation:

hope this helps

or the solution containing Zn2+(aq), n is 2, so the MM/n ratio will be the molar mass of Zn divided by 2: MM/n = (65.39 g/mol) / 2 = 32.70 g/mol Compare this theoretical value with your experimental result. If the plating efficiency is significantly less than 1, say it is 0.55, how would the observed MM/n ratio compare to the theoretical value?

Answers

Answer:

MM/n will be less than the theoretical value

Explanation:

Provided that

The plating efficiency is proportional to the element weight

i.e.

[tex]\frac{Zn^2}{(aq)}[/tex]

That represents [tex]\frac{MM}{n\ value}[/tex]

So,

MM by N value is

= 65.39 g /mol ÷ 2

= 32.70 g/mol

Also, the experimental plating value is 0.55 that represents that it is much lesser than the normal value

So it would be concluded that the MM by N would be lower than the theoretical value

calculate the density, in g/mL, of a liquid that has a mass of 0.165 g and a volume of 0.000295 l

Answers

Answer:

The answer is

0.56 g/mL

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question

mass of liquid = 0.165 g

Next we change the volume from L to mL using the conversion

1 L = 1000 mL

We have

If 1 L = 1000 mL

Then 0.000295 l = 1000 × 0.000295

volume = 0.295 mL

The density is

[tex]density = \frac{0.165}{0.295} \\ = 0.55932203...[/tex]

We have the final answer as

0.56 g/mL

Hope this helps you

(7.31 x 10+4 g) + (3.2300 x 10+3 g) =

Calculator answer

Final answer

Answers

7g + 105.4

this is the question simplified correctly

Element T exists as three isotopes: T-12 (98.90%), T-13 (1.00%) and T-14 (0.10%). Calculate the
average atomic mass of the element T.
Answer choices:
- 12.01 amu
- 11.72 amu
- 1200 amu
- 13 amu

Answers

Answer:

-10.00amu

ok.......... !!!!!

The average atomic mass of the element T is 12.012 amu.

What is average atomic mass?

The average atomic mass is defined as the atoms' weighted average mass in a naturally occurring sample of the element.

It is also defined as the average atomic mass of all naturally occurring isotopes of all elements.

The average atomic mass  can be expressed as

Average atomic mass = f1m1 + f2m2 + f3m3

                                    = 0.989 x 12 + 0.01 x 13 + 0.001 x 14

                                    = 11.868 + 0.13 + 0.014

                                    = 12.012 amu

Thus, the average atomic mass of the element T is 12.012 amu.

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convert 5 liters into kiloliters

Answers

Answer:0.005

Explanation:kilo means 1000 do you divide 5 by 1000 and you get.005

Answer: 0.005 kilolitres

Explanation:

5 liters = 0.005 kilolitres

Why? Because liters - kilolitres:  ÷ 1000

How did incorporation of the Bill of Rights affect state governments​

Answers

Answer:

The effect of the incorporation of the bill of rights was that state governments were required to provide most bill of rights protections.

Explanation:

Which of the following correctly describes a way in which Earth's atmosphere interacts with the biosphere

Answers

Answer:

Living organisms breathe gases in the atmosphere.

Explanation:

Answer:

Living organisms breathe gases in the atmosphere.

Explanation:

Biosphere

the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms.

 Atmosphere

the envelope of gases surrounding the earth or another planet

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