Which describes the enthalpy change associated with an endothermic reaction? *
2 points
ΔH is negative
ΔH is zero
ΔH is positive

Answers

Answer 1

Answer:

It is negative because the enthalpy of the products is greater than the enthalpy of the reactants.


Related Questions

A compound has a molecular weight of 112. 124 atomic mass units and the empirical formula C3H4O. What is the molecular formula of the compound? Use the periodic table to help you. A. C6H8O B. C9H12O3 C. C8H4O2 D. C4H8O2 E. C6H8O2.

Answers

The molecular formula of the compound which has a molecular weight of 112.124 atomic mass units is C₆H₈O₂.

What is molecular formula?

Molecular formula of any compound tells about the composition and numbers of each entities present in that molecule.

Steps involved in the prediction of molecular formula:

First we predict the molar mass of given emperical formula as:

      Molar mass of C₃H₄O = 3(12) + 4(1) + 16 = 56

Now we divide the given mass by the calculated mass of empirical formula:

        112.124/56 = 2

Now we multiply the subscripts of given empirical formula by this whole number and we get:

        Molecular formula = (C₃H₄O)₂ = C₆H₈O₂

Hence correct option is (E).

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In Lhasa, Tibet, the elevation is 12,000 feet. The altimeter reading in an airplane is 19. 50 in Hg.

This pressure is equal to ___psi.

Answers

Given the data from the question, the reading (i.e pressure) of the altimeter in psi is 9.57 psi

Conversion scale

1 inHg = 0.491 psi

Data obtained from the question Pressure (inHg) = 19.50 inHgPressure (psi) =?

How to determine the pressure in psi

The pressure of the altimeter in psi can be obtained as illustrated below:

1 inHg = 0.491 psi

Therefore,

19.50 inHg = 19.50 × 0.491

19.50 inHg = 9.57 psi

Thus, 19.50 inHg is equivalent to 9.57 psi

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How many liters of carbon gas are in 13.7 moles of carbon dioxide gas at STP?

Answers

At STP

1 mol weighs 22.4L

No of moles=13.7mol

Total volume:-

13.7(22.4)306.88L[/tex]

The volume of gas occupied by 13.7 moles at STP is 306.88L.

What is STP?

STP stands for standard temperature and pressure. STP refers to a specific pressure and temperature used to report on the properties of matter.

According to IUPAC( International Union of Pure and Applied Chemistry), it is defined as -

Temperature of 0 degree celsius (273K)Pressure of 1 atm

It is generally needed to test and compare physical and chemical processes where temperature and pressure plays an important role as they keep on varying from one place to another.

One mole of a gas under STP conditions occupies a volume of 22.4L.

Given,

Moles of carbon dioxide gas = 13.7 moles

We know that,

1 mole of a gas occupies 22.4 L of volume at STP.

Thus, 13.7 moles will occupy 13.7 × 22.4 L

                                              = 306.88 L

Therefore, the volume of gas occupied at STP is 306.88L.

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Using standard thermodynamic data at 298k, calculate the free energy change when 2. 34 moles of nh3(g) react at standard conditions

Answers

For a thermodynamic data at 298k, when 2. 34 moles of nh3(g) react at standard conditions, the free energy change is mathematically given as

dG'−213.174KJ

What is the free energy change?

Generally, the equation for the Chemical Reaction   is mathematically given as

HCL+NH3----->NH4Cl

Therefore

dG=-202.9-[-16.5+(95.3)]

dG=-91.1KJ/mol

In conclusion, For 2.34 moles

dG'=-91.1KJ/mol*2.34

dG'−213.174KJ

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The free energy change when 2.34 moles of NH₃(g) react at standard conditions is -213.174 kJ.

How do we calculate free energy change?

Free energy change of any chemical reaction will be calculated by using the following chemical reaction:

ΔG = Free energy of products - Free energy of reactants

Given chemical reaction is:

NH₃ + HCl → NH₄Cl

From the stoichiometry of the reaction it is clear that same moles of ammonium chloride is produced by the same moles of ammonia & hydrochloric acid.

Free enrgy of NH₄Cl = -202.9 kJ/mol

Free enrgy of NH₃ = -16.5 kJ/mol

Free enrgy of HCl = 95.3 kJ/mol

On putting values in the above equation, we get

ΔG = -202.9-[-16.5+(95.3)]

ΔG = -91.1KJ/mol

For 2.34 moles, ΔG will be:

ΔG = (2.34)(-91.1) = -213.174 kJ

Hence required amount of free eenrgy is -213.174 kJ.

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what is the difference between melting point and boiling point?​

Answers

The melting point is the temperature a substance must reach to go into its liquid phase (or solid) and a boiling point is the temperature a substance must reach to go into its gas phase (or liquid). For example, water must be 0ºC to melt or freeze and 100ºC to boil.

The melting point is a certain temperature a thing has to be at to melt or to turn into a liquid and the boiling point is the same thing its just with gas

zinc sulfide with oxygen has (O2) to yield zinc oxide and sulfur oxide.
(i need the formula)

Answers

Answer:

The reaction between zinc sulphide and oxygen gives zinc oxide and sulfur dioxide. The chemical equation of the reaction is: 2ZnS + 3O2 → 2ZnO + 2SO2 2 moles of ZnS react with 3 moles of O2 to form 2 moles of ZnO and 2 moles of SO2

Explanation:

60 points please help me i will appreciate it!

Answers

Answer:

This is a pretty straightforward example of how an ideal gas law problem looks like.

Your strategy here will be to use the ideal gas law to find the pressure of the gas, but not before making sure that the units given to you match those used by the universal gas constant.

So, the ideal gas law equation looks like this

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

P

V

=

n

R

T

a

a

−−−−−−−−−−−−−−−

Here you have

P

- the pressure of the gas

V

- the volume it occupies

n

- the number of moles of gas

R

- the universal gas constant, usually given as

0.0821

atm

L

mol

K

T

- the absolute temperature of the gas

Take a look at the units given to you for the volume and temperature of the gas and compare them with the ones used in the expression of

R

.

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Liters, L

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Kelvin, K

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Celsius,

C

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×

Notice that the temperature of the gas must be expressed in Kelvin in order to work, so make sure that you convert it before plugging it into the ideal gas law equation

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

T

[

K

]

=

t

[

C

]

+

273.15

a

a

−−−−−−−−−−−−−−−−−−−−−−−−

Rearrange the ideal gas law equation to solve for

P

P

V

=

n

R

T

P

=

n

R

T

V

Plug in your values to find

P

=

0.325

moles

0.0821

atm

L

mol

K

(

35

+

273.15

)

K

4.08

L

P

=

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

2.0 atm

a

a

−−−−−−−−−−−

The answer is rounded to two sig figs, the number of sig figs you have for the temperature of the gas.

Answer:

[tex]\huge\boxed{\sf P = 1.68 \ atm}[/tex]

Explanation:

Given:

Moles = n = 0.6 mol

Volume = v = 9.13 L

Temperature = T = 38 °C + 273 = 311 K

Gas constant = R = 0.08206 L atm K⁻¹ mol⁻¹

Required:

Pressure = P = ?

Formula:

Pv = nRT

Solution:

Rearranging formula

[tex]\displaystyle P = \frac{nRT}{v} \\\\P = \frac{(0.6)(0.08206)(311)}{9.13} \\\\P = \frac{15.3}{9.13} \\\\P = 1.68 \ atm\\\\\rule[225]{225}{2}[/tex]

Which of these is a ball and stick model?

Answers

the answer is C i did that before

At the top of a hill, an athlete on a skateboard has X joules of mechanical energy. How much mechanical energy will she have at the bottom of the hill? Ignore the effects of friction. X joules less than X joules more than X joules There is not enough information to know.

Answers

If an athlete has X joules of mechanical energy at the top of the hill, he will have the same X amount of energy at the bottom of the hill.

What is mechanical energy?

Mechanical energy is the addition of kinetic and potential energy. It can be either kinetic or potential energy.

It is the energy possessed by the position or the motion of the body.

It is the energy present to perform any work.

So, the athlete will have X joule of energy at the top and bottom of the hill.

Thus, the correct option is a, X joules.

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Answer:

X Joules

Explanation:

4. The students predict that the reaction between hydrogen and sulfur will release a lot of energy. What question could help
provide support for the prediction?

Answers

Let's see

[tex]\\ \rm\rightarrowtail H_2+S=H_2S+Heat[/tex]

So

Observe the equation

it releases heat means it's exothermic

So

Question may include+Heatmay include ∆H=+ve

What does the energy hill represent on an energy diagram?
A. The potential energy gained by the products when a reaction
happens
B. The potential energy the reactants have stored in molecular bonds
O C. The additional potential energy the reactants must gain in order to
react
D. The final amount of potential energy of the products of the
reaction

Answers

B.The potential energy the reactants have stored in molecular bonds

Tear off a small, flat sheet of waxed paper. Use the pipette to dispense a drop of water on the waxed paper. Now, dry the pipette, and use it to dispense a drop of oil on the waxed paper next to the water drop. Be sure the two drops are not touching. Compare and describe the appearance of both drops.

Answers

Answer:

Explanation:

When comparing the drops of oil and water, one thing I noticed was the shape. The water drop was more defined, whereas the drop of oil began to spread and was much flatter. This may be due to the waxy material, and how both oil and water react to the wax.

Can someone please help its due today and im so bad at chemistry

Answers

what’s the question

The compound below is treated with chlorine in the presence of light. Draw the structure for the organic radical species produced by reaction of the compound with a chlorine atom. Assume reaction occurs at the weakest c-h bond.

Answers

Explanation:

A carbon radical is a reaction intermediate, which is produced during a free-radical reaction. These carbon radicals contain one unpaired electron on a carbon atom. Hence, these radicals are highly reactive in nature.

A free-radical reaction results in the production of a carbon radical as a reaction intermediate.

What is radical in chemistry?

A radical in chemistry is indeed an atom, molecule, and ion that possesses one least one unpaired electron electron. The term "radical" is sometimes used to refer to a free radical. These unpaired electrons provide radicals, with a few exceptions, a high degree of chemical reactivity. Radicals frequently dimerize on their own. The majority of organic radicals have brief lives.

A free-radical reaction results in the production of a carbon radical as a reaction intermediate. One unpaired electron is present on the carbon atom in these radical forms of carbon. As a result, the nature of these radicals is very reactive.

Therefore, a free-radical reaction results in the production of a carbon radical as a reaction intermediate.

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How many moles of O2 are required for the complete reaction of 1.60 moles of C2H4 to form CO2 and H2O? Use the balanced equation: C2H4 + 3O2 --> 2CO2 + 2H2O

113 mol
4.80 mol
48.0 mol
0.64 mol

Answers

Answer:

4.80 mol is the answer

Explanation:

please mark me as brainlist..

4.8 moles

Balanced equation: C₂H₄ + 3O₂ --> 2CO₂ + 2H₂O

C₂H₄  : 1.60 moles

use molar ratio:

3O₂ : C₂H₄

3 : 1

moles of O₂ : 3 * 1.6 = 4.8 moles

How many moles are in 4. 75 x 1025 molecules of O2?

Answers

Answer: 78.9 moles

Explanation:

4.75 x 10^25 molecules (1 mole / 6.02 x 10^23 molecules) = 78.9 moles :)

Which substance is known as the universal solvent because it dissolves more solutes than any other solvent?.

Answers

Answer:

Water(H20)

Explanation:

Water is called the universal solvent because more substances dissolve in water than in any other chemical. This has to do with the polarity of each water molecule. The hydrogen side of each water (H2O) molecule carries a slight positive electric charge, while the oxygen side carries a slight negative electric charge.

hello people ~
Identify the type of plastic that can best be used to make electrical switches.

A. PVC

B. Polythene

C. PET

D. Bakelite

Answers

Answer:

Bakelite

Explanation:

Bakelite is a non recyclable plasticSimilar to Melamine it has some of very bad heat and electricity conducter.So it's used in electrical switches

What does a coefficient tell you?

Answers

 The coefficient tells you how many molecules of that substance there is. 

What happens to a catalyst as the result of a chemical reaction?

A.) It slows a chemical reaction.
B.) It is not consumed.
C.) It is consumed.
D.) It changes to something else.

Answers

I’m pretty sure a catalyst speed up a chemical reaction.

The answer is b

The catalyst is recovered unchanged in amount and chemical composition at the end of a reaction. It speeds up only a spontaneous reaction, not a spontaneous one. It is not consumed in a reaction. The correct option is B.

What is a catalyst?

A substance which increases the rate of a reaction without itself undergoing any permanent change chemically or quantitatively is defined as the catalyst and the phenomenon is known as the catalysis. It is believed that a catalyst actually participates in the chemical reaction that it speeds up.

A catalyst does not affect the position of equilibrium of a reversible reaction and thus do not alter its equilibrium constant. This is because it speeds up the forward and backward reactions to the same extent. It shows some specificity in its action.

It does not alter the Gibbs energy.

Thus the correct option is B.

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Based on the results of testing colorless solutions with indicators, which solution is most acidic?

Answers

A solution in which methyl orange is red indicates the most acidic substance.

What is an Indicator?

This is defined as a substance that gives a visible sign, usually by a colour change when a chemical species is added.

On litmus paper, the redder the color is, the more acidic it is which was why methyl orange changing to darker red signifies most acidity.

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How does this visual help to explain hazards from volcanoes that can hurt people even when they are not erupting?

Answers

Answer:

The visual seems to be showcasing an erupting volcano, so I don't believe the two are related.

Explanation:

Through the acid rain because after the eruption there will be a eruption cloud that contains gas and acid rain.

what are the properties of aluminium and their use​

Answers

Answer: Answers are in bulleted lists.

Explanation: Aluminum...

has a low densityis non-toxichas a high thermal conductivityhas excellent corrosion resistancecan be easily cast, whether it's machined or formed.

Uses:

Aeroplane PartsCansWindow framesBeer kegsFoils Kitchen utensils

Have a great day! :)

NEED HELP ASAP PLEASE !!!

Answers

Explanation:

H2S is the limiting reagent

H2S= 1/8 (least value)

O2= 1/4

use shorthand method to represent the electrochemical reaction in a lead storage battery.

Answers

The shorthand equation shows us in a glance what happens in the electrochemical reaction. For a lead storage battery, we have; PbSO4(s)/H2O//Pb (s) ,PbO2(s) /H2SO4

What is an electrochemical reaction?

An electrochemical reaction is one in which electrical energy is produced from a chemical reaction. The equations in a lead storage battery are;

Anode: Pb (s) + HSO4- → PbSO4(s) + H+ + 2 e-

Cathode: PbO2(s) + HSO4- + 3 H+ + 2 e- → PbSO4(s) + 2 H2O

Overall: Pb (s) + PbO2(s) + 2 HSO4- + 2 H+ → 2 PbSO4(s) + 2 H2O

Hence, the shorthand notation of this reaction is;

PbSO4(s)/H2O//Pb (s) ,PbO2(s) /H2SO4

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really need help with this

Answers

This is a microscope.

Hope this clears that up for you.

According to the kinetic theory of gases, an ideal gas molecule

Answers

Answer:

According to the kinetic theory of gases, in an ideal gas between two successive collisions, a gas molecule travels in a straight line.

According to the kinetic theory of gases, an ideal gas molecule move in a straight line between two successive collisions.

What is the kinetic theory of the gases?

The kinetic theory of gases says that the gas is many large numbers of subatomic particles, which randomly motion always.

They move on a straight plane and only change their path when they collide with other molecules or the container's walls.

Thus, according to the kinetic theory of gases, an ideal gas molecule move in a straight line between two successive collisions.

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Given the following equation: Cu + 2 AgNO3 ---> Cu(NO3)2 + 2
Ag How many grams of Cu are needed to react with 262g moles of
AgNO3?

Answers

Given the following equation; Cu + 2AgNO3 = Cu(NO3)2 + 2Ag, 48.97 grams of Cu are needed to react with 262g of AgNO3.

How to calculate mass of substances?

The mass of a substance can be calculated using the following steps:

Cu + 2AgNO3 = Cu(NO3)2 + 2Ag

1 mole of Cu react with 2 moles of AgNO3

Molar mass of AgNO3 = 169.87 g/molMolar mass of Cu = 63.5g/mol

moles of AgNO3 = 262g/169.87g/mol = 1.54mol

1.54 moles of AgNO3 will react with 0.77 moles of Cu.

mass of Cu = 0.77 × 63.5 = 48.97g

Therefore, given the following equation; Cu + 2AgNO3 = Cu(NO3)2 + 2Ag, 48.97 grams of Cu are needed to react with 262g of AgNO3.

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Which of the following elements has the largest electronegativity?
Fluorine (F)
Bromine (Br)
Lithium (LI)
Calcium (Ca)

Answers

Answer:

FLUORINE

Explanation:

It has 5 electrons In Its 2P shell!

Answer:

Fluorine

Explanation:

because it has a score of 4.0 which is the highest possible

Why do different elements produce distinct colors in the flame test

Answers

Answer:

Their electrons have different allowed energy levels

Explanation:

Elements are the pure form that only consists of the atoms of the same proton number. Distinct colors are produced in the flame test as their electrons have different energy levels.

What is the Flame test?

A flame test is a procedure that detects the presence of chemical substances based on a spectrum and colors emitted by the elements in the flame.

The energy levels of the different elements vary and are defined by the movement of the electrons in the spectra. The energy released and the flame produced by different electrons are different.

Therefore, electrons with various energy levels release flames of different colors.

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