Iron reacts with oxygen in the air to form rust. Predict the signs of enthalpy, entropy, and Gibbs free energy change for this process (for the system). Explain the sign for each one

Answers

Answer 1
4Fe + 3O2 —> 2Fe2O3

enthalpy will be negative as this is an oxidation process and all oxidation process has negative enthalpy (releasing energy that’s why we feel the heat)

entropy will be negative as we can see in the equation the reactants are 4 molecules of solid (Fe) and 3 molecules of gas (O2) but the product is only 2 molecules of solid which has lower entropy, hence the net entropy is negative

Gibbs free energy will depend on the temperature. at higher temperature the gibbs will be negative

Related Questions

The following picture would be best described us

Answers

Answer:

I think its B because yeah lol but I hope you get it right

The following can be best described as a gaseous compound. The correct option is C.

What are states of matter?

A state of matter is one of the various forms that matter can take in physics. In everyday life, four states of matter are visible: solid, liquid, gas, and plasma.

The elements those are gases basically at standard temperature as well as pressure are referred to as gaseous elements. The periodic table contains 11 gaseous elements.

A gas is a sample of matter that conforms to the shape of the container in which it is held and acquires a uniform density inside the container, even when gravity is present and regardless of the amount of substance in the container.

The given image depicts that the molecules of particles are at some distance from each other, this usually implies for gaseous compound.

Thus, the correct option is C.

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13. Find the total number of atoms present in the following molecules.
a. 5 H₂O
b. Zn Cl₂​

Answers

Answer:

zxcdfzdg

Explanation:

zszghzd

heterogeneous mixture homogeneous
How are they similar?

Answers

Answer:

By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers. Each of the layers is called a phase.

Explanation:


Using the ruler, what is the value of A considering significant
figures?

Answers

Answer:

13.7 cm

Explanation:

If the number is between two whole numbers then that means it is going to be a decimal, how to determine the decimal is by how many ticks/lines are between it, so if you count from 13 cm and count each line as 1 you get to the number 7 and since that number is between the whole number it becomes 13.7

6. How many meters are in 0.00253 kilometers?

Answers

Answer:

2.53 kilometers

This picture shows students working in a
chemistry laboratory. What could they do to make
their lab safer?
Label the test tubes and plastic cups.
Move the fire extinguisher closer to their
table.
Wear chemical protective gloves.
Reduce the clutter on the table.
Stand at the table instead of sitting. Tie long hair back.
DONE

Answers

Answer:

yes it is true they apply necessary safety measures

Answer: Label the test tubes, wear chemical protective gloves, tie long hair back

Explanation:

Just got it wrong

Calculate the maximum mass of iron that can be obtained from 240 tonnes of iron oxide

Answers

Answer:

167.86 tonnes

Explanation:.

I am assuming the iron oxide is Fe2O3 (Haematite) which is the most common form of iron oxide.

From the atomic masses:

Maximum Mass of iron = 240 *  2*55.845 / (2*55.845 + 3*15.999))

= 240 * 111.69 / (159.687)

= 167.86 tonnes

Describe what must be happening to the particles above as the change is happening

Answers

Answer:

d

Explanation:

solids the modicual are tightly packed

liquid, more room to move around  aka not so tightly packed

gas, can move where ever it wants  aka not paked at all

D. The space between the particles is becoming larger

Hehe someone help I have put down heat but I think there is another

Answers

Answer:

chemical potential enery

Mark brainliest

As discussed during the lecture, the enzyme HIV-1 reverse transcriptae (HIV-RT) plays a significant role for the HIV virus and is an important drug target. Assume a concentration [E] of 2.00 µM (i.e. 2.00 x 10-6 mol/l) for HIV-RT. Two potential drug molecules, D1 and D2, were identified, which form stable complexes with the HIV-RT.
The dissociation constant of the complex ED1 formed by HIV-RT and the drug D1 is 1.00 nM (i.e. 1.00 x 10-9 mol/l). The dissociation constant of the complex ED2 formed by HIV-RT and the drug D2 is 100 nM (i.e. 1.00 x 10-7 mol/l).
1. Compute the total concentration of [D1]tot that is needed to bind 90% of the HIV-RT at the given concentration [E]tot. Provide your answer as a numerical expression with 3 significant figures in the unit mol/l. You do NOT have to consider competition betwwen the drugs D1 and D2! They are administered separately.
2. Compute the total concentration of [D2]tot that is needed to bind 90% of the HIV-RT at the given concentration [E]tot. Provide your answer as a numerical expression with 3 significant figures in the unit mol/l.You do NOT have to consider competition betwwen the drugs D1 and D2! They are administered separately.

Answers

Answer:

C)[D]/[ED] = 5.20

D)[D]/[ED] = 5.20

E)[D']_T = 1.495* 10 ^-7 M

F)[D'] / [ED']  = 0.0579

Explanation:

E = 250 nM =2.5* 10 ^-7 mol/L , T=298.15 K

Dissociation constant of K_D = 1.3 μM (1.3 *10 ^-6 M)

E + D ⇄ ED → K_a = [ED] / [D][E]   (association constant)

ED ⇄ E + D → K_D = [E][D] / [ED]  (dissociation constant)

C)

[E] =2.5*10^-7 mol/L

K_D = 1.3* 10^-6 M

K_D = [E][D] / [ED] → [D]/[ED] = K_D / [E]

= [D]/[ED] = 1.3* 10 ^-6 / 2.5 *10^-7

= 13/25 * 10

=130/25 = 5.20

[D]/[ED] = 5.20

D)

ΔG =RTln Kd

ΔG_2 for E and D = 1.987 * 298.15 * ln 1.3*10^-6

ΔG_2 592.454 * [ln 1.3 +ln 10^-6]

ΔG_1 = 592.424 [0.2623 - 13.8155]

ΔG_2 = -592.424 * 13.553

ΔG_1 = -8184.633 cal/ mol

ΔG_1 = -8184.633  * 4.18 J/mol = -34244.508 J?mol

ΔG_1 = -34.245 KL/mol

so, ΔG_2 = ΔG_1 - 10.5 KJ/mol

ΔG_2 = -34.245 - 10.5

ΔG_2 = -44.745KJ / mol

ΔG_2 =RT ln K_D

-44.745 *10^3

=8.314 *298.15 lnK_D

lnK_D' = - 44745 / 2478.81 g

ln K_D' = -18.051

K_D' = -18.051

K_D' = e^-18.051

[D]/[ED] = 5.20

E)

[E] = 2.5* 10 ^-7 mol/ L = a

K_D' = [E][D] / [ED']                                  E +D' → ED'

K_D' = a/2(x-(a/2) / (a/2)

KD' = x - a/2

=2.447 *10^-8 = (2.5/2) * 10^-7

x=2.447 * 10^-8 + 1.25 * 10^-7

x = 2.447 *10^-8 + 1.25 * 10 ^-7

x= 10^-7 [1.25 + 0.2447]

x = 1.4947 * 10^-7

[D']_T = 1.495* 10 ^-7 M

F)

K_D' = [E][D'] / [ED']

[D'] / [ED'] = KD' / [E]

[D'] / [ED'] = 1.447 *10^-8 / 2.5* 10^-7

[D'] / [ED'] = 0.5788 * 10^-1

[D'] / [ED']  = 0.0579

Explanation:

...

Solid calcium oxide and gaseous water are produced by the decomposition of solid calcium oxide hydroxide. Write a balanced chemical equation for this reaction.​

Answers

[tex]\boxed{\sf {Ca(OH)_2(s)\atop Calcium\:Hydroxide}\longrightarrow {CaO(s)\atop Calcium\;oxide}+{H_2O(g)\atop water}}[/tex]

On reactant side

Hydrogen= 2atomsOxygen=2atomsCalcium=1atom

On product side

Hydrogen=Oxygen=2atomsCalcium=1atom.

hence balanced.

A popular car has a gas tank that holds a maximum of 14.5 gallons of fuel. What is
the size of the tank in liters ?

Answers

Answer:

54.883, so rougly about 54.9 liters.

Explanation:

To convert gallons to liters, multiply the amount of gallons by 3.785.

14.5 * 3.785 = 54.883

Taking into account the change of units, the size of the tank is 54.88 liters.

In first place, the rule of three is a tool used to quickly solve problems involving a proportional relationship between two variables.

The rule of three is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other), the direct rule of three should be applied.

The rule of three is applied as follows, with A, B and C being known values ​​and D being an unknown value: if A maintains a certain relationship with B, and it is known that C and D have the same relationship, it is possible to calculate the unknown value D using the following expression:

[tex]D=\frac{CxB}{A}[/tex]

In this case, the rule of three can be applied as follows: if 1 gallon is equal to 3.785 liters, 14.5 gallons are equal to how many liters?

[tex]D=\frac{14.5 gallonsx3.785 liters}{1 gallon}[/tex]

Solving:

D= 54.88 liters

In summary, the size of the tank is 54.88 liters.

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If you change the number of neutrons in an atom, you will also change its -
charge
element.
o
number
d
isotope.

Answers

isotope… without changing electrons/atomic nimber, the atom remains the same changing neutron will cause it to become isotope

When 47.1 J of heat is added to 14.0 g of a liquid, its temperature rises by 1.80 ∘C. What is the heat capacity of the liquid?

Answers

Answer:

[tex]\boxed {\boxed {\sf 1.87 \J/g \textdegree C}}[/tex]

Explanation:

We are asked to find the specific heat capacity of a liquid. We are given the heat added, the mass, and the change in temperature, so we will use the following formula.

[tex]q= mc\Delta T[/tex]

The heat added (q) is 47.1 Joules. The mass (m) of the liquid is 14.0 grams. The specific heat (c) is unknown. The change in temperature (ΔT) is 1.80 °C.

q= 47.1 J m= 14.0 g ΔT= 1.80 °C

Substitute these values into the formula.

[tex]47.1 \ J = (14.0 \ g) * c * (1.80 \textdegree C)[/tex]

Multiply the 2 numbers in parentheses on the right side of the equation.

[tex]47.1 \ J = (14.0 \ g * 1.80 \textdegree C)*c[/tex]

[tex]47.1 \ J = (25.2 \ g*\textdegree C) *c[/tex]

We are solving for the heat capacity of the liquid, so we must isolate the variable c. It is being multiplied by 25.2 grams * degrees Celsius. The inverse operation of multiplication is division, so we divide both sides of the equation by (25.2 g * °C).

[tex]\frac {47.1 \ J}{(25.2 g *\textdegree C)} = \frac {(25.2 g *\textdegree C)*c}{{(25.2 g *\textdegree C)}}[/tex]

[tex]\frac {47.1 \ J}{(25.2 g *\textdegree C)} =c[/tex]

[tex]1.869047619 \ J/g *\textdegree C = c[/tex]

The original measurements of heat, mass, and temperature all have 3 significant figures, so our answer must have the same. For the number we found that is the hundredth place. The 9 in the thousandth place to the right tells us to round the 6 up to a 7.

[tex]1.87 \ J/ g * \textdegree C =c[/tex]

The heat capacity of the liquid is approximately 1.87 J/g°C.

How to find out how many neutrons an isotope has

Answers

Answer:

To find the number of neutrons in an isotope, subtract the number of protons from the atomic mass of the isotope. The atomic number of the element equals the number of protons.

How many decigrams (dg) are in 0.779 kg?

Answers

Answer:

7790

Explanation:

Answer:

7790 decigrams

Explanation:

Someone answer this please

To convert something in kilojoules to joules, you need to:

Multiply by 1,000
1
Divide by 1,000
2
Multiply by 1,000,000 3
Divide by 1,000,000
4

Answers

Answer:

Divide by 1000

Explanation:

Have a good day

Hope I helped

Multiply by 1000 .

I HOPE IT WILL HELP YOU.

HOPE your day goes great.

What is an atomic number

Answers

Answer:

the number of protons is called the atomic number

hope it helps you buddy

Answer: number of protons in an atom

Explanation:

What is the reason for the emission of light after the gas in a discharge tube is excited?
A)
photo-electric emission
Eliminate
B)
spontaneous radioactive reaction
C)
energy jumps by electrons due to excitation
D)
high energy reaction of the gas inside the tube

Answers

Answer:

c

Explanation:

took test on usa testprep

When gas in a discharge tube is excited to higher energy level after some seconds they return to the ground level by releasing energy in the form of light. Thus energy jumps by electron due to excitation is correct option.

What is gas discharge tube?

A gas discharge tube is an electronic devise containing inert gases that ionizes and conducts results in  emission of light.

When a potential  is applied between the electrodes in a gas discharge tube, and the pressure is reduced, the gas particles inside forms a plasma of ions.

The electrons released when excited to higher energy level by absorbing energy and returns to the initial state by emitting energy in the form of light, the discharge tube glows.

The color emitted by the discharge tube vary based on the gas in the tube. Each type of gaseous ions emit different colors.

Therefore, the light emission in gas discharge tube is due to energy hike during electron excitation and then relaxing by emitting the light energy. Thus, option c is correct.

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Arrange the following aqueous solutions in order of increasing boiling points.
0.050 m Mg(NO 3) 2; 0.100 m ethanol; 0.090 m NaCl
a. Mg(NO3) < NaCl < ethanol
b. ethanol < Mg(NO3)2 < NaCl
c. ethanol < NaCl < Mg(NO3)2
d. NaCl < ethanol < Mg(NO3)2
e. Mg(NO3)2 < ethanol < NaCl

Answers

Answer:

The correct choice is option b. ethanol < Mg(NO3)2 < NaCl

Explanation:

Ethanol = 0.100 m

Mg(NO3)2 = 0.15 m

NaCl = 0.18 m

The molar concentration of NaCl is the highest, which is why its boiling point will be the highest, too.

Calculate the force needed to accelerate a 300 kg mass at 5
mls acceleration.

Answers

Explanation:

Force=mass *acceleration

F=300*5

f

F=1500N

Calculate the number of kilograms of sodium fluoride needed per year for a city of 100,000 people if the daily consumption of water per person is 150.0 gallons.

Answers

Fluoridation is the process of adding fluorine to drinking water to avoid tooth decay.

The question is incomplete; the complete question is;

Fluoridation is the process of adding fluorine compounds to drinking water to help fight tooth decay. A concentration of 1 ppm of fluorine is sufficient for the purpose. (1 ppm means one part per million, or 1 g of fluorine per 1 million g of water.) The compound normally chosen for fluoridation is sodium fluoride, which is also added to some toothpastes. Calculate the quantity of sodium fluoride in kilograms needed per year for a city of 50,000 people if the daily consumption of water per person is 150 gallons.

(Sodium fluoride is 45.0 percent fluorine by mass. 1 gallon = 3.79 L; 1 year = 365 days; 1 ton = 2000 lb; I lb = 453.6 g; density of water = 1.0 g/mL.)

The quantity of sodium fluoride in kilograms needed per year for a city of 50,000 people if the daily consumption of water per person is 150 gallons is [tex]9.32 * 10^9 Kg[/tex].

From the question, we know that;

Daily consumption of water per person = 150 gallons.

Population of the city = 100,000 people

Total daily city consumption =[tex]100,000 *  150 gallons = 15 * 10^6 gallons[/tex]

Annual water consumption = [tex]15 * 10^6 gallons * 365 = 5.475 * 10^9 gallons[/tex]

1 gallon = 3.785 L = 3.785 kg

[tex]5.475 * 10^9 gallons = 5.475 * 10^9 gallons * 3.785 kg/ 1 gallon = 2.1 * 10^10 Kg[/tex]

Since sodium fluoride accounts for 45% by mass of water

Mass of sodium fluoride= [tex]0.45 * 2.1 * 10^10 Kg= 9.32 * 10^9 Kg[/tex]

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what happens when an acid dissolves

Answers

Explanation:

When an acid is dissolved in water it forms hydrogen ions (H+) that combine with water to form the hydronium ion (H3O+) .

Answer:

Acids are substances that when dissolved in water release hydrogen ions, H+(aq). ... When dissolved, bases release hydroxide ions, OH-(aq) into solution. Water is the product of an acid and base reacting. Chemists say that the acid and base cancel or neutralise each other, hence the reaction is known as "neutralisation".

Explanation:

What causes the pressure in a gas

Answers

Answer:

Gas pressure is caused when gas particles hit the walls of their container. The more often the particles hit the walls, and the faster they are moving when they do this, the higher the pressure. This is why the pressure in a tyre or balloon goes up when more air is pumped in.

Answer
Choice A
Answer
Choice B
Answer
Choice C
Question
A scientist hypothesizes that a new medication can reduce
the chances of catching a cold Which of these would most
likely be the dependent variable in a study involving this
medication?
//
The participants
who do not receive
the medication
Color PURPLE
The number of
participants who
catch a cold
Color YELLOW
The age of the
participants
Color GRAY
Tt remains the
T+ is purposely
It is used for

Answers

Answer:

what is the question????

How many joules are equivalent to 450 calories?

Answers

Answer:

Below

Explanation:

To convert calories to joules, you need to multiply the value by 4184

     450 x 4184 = 1882800 J

If your teacher requires you to round to significant figures, you would round to 2 sig figs as 450 only has 2 sig figs

     450 x 4184 = 1.9 x 10^6

Hope this helps! Best of luck <3

HELP! 100 points if you give a valid answer and brainliest if it's detailed!

Answers

Explanation:

The extract of plant is not done in fixed proportion

it is heterogeneous

How many moles of Al2O3 are contained in 45.1 g of Al2O3?

Answers

Answer:

0.44mol

Explanation:

1mol/102g=xmol/45.1g

-> x=(45.1x1)/102

x=0.44mol

Which of the following best describes the make up of Saturn's rings?(1 point) solid bands of sand and dust that formed from the start of the universe solid bands of sand and dust that formed from the start of the universe material from comets that have passed through Saturn's atmosphere material from comets that have passed through Saturn's atmosphere dust, rock, and ice particles that orbit due to Saturn's gravity dust, rock, and ice particles that orbit due to Saturn's gravity debris and rocks from other planets that orbit around Saturn

Answers

Answer:

Which of the following best describes the make up of Saturn's rings?(1 point) solid bands of sand and dust that formed from the start of the universe solid bands of sand and dust that formed from the start of the universe material from comets that have passed through Saturn's atmosphere material from comets that have passed through Saturn's atmosphere dust, rock, and ice particles that orbit due to Saturn's gravity dust, rock, and ice particles that orbit due to Saturn's gravity debris and rocks from other planets that orbit around Saturn

The make up of Saturn's ring are dust, rock, and ice particles that orbit due to Saturn's gravity"

Saturn is one of the 9 planets of the solar system. It is considered to be the second largest planet.

Saturn has seven large rings orbiting around it. These rings are believed to be pieces of comets, asteroids, or shattered moons that broke up before they reached the planet. And this shattered comets or asteroid are believed to be torn apart by Saturn's powerful gravity.

These comets or asteroids are made of billions of small chunks of ice and rocks which are covered or coated with other small materials such as dust particles.

Thus, the correct option that matches the above explanation is "dust, rock, and ice particles that orbit due to Saturn's gravity"

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Each roman numeral represents a sample of a substance. Each circle represents an atom. Considering what qualifies as a pure substance, which image(s) would be considered pure substances?

III and V


V


II and IV


I and III

Answers

Answer:

III and V

Explanation:

Both of them are evenly spread homogenous mixtures.

The images that would be considered pure substances are III and V. Thus, the correct option for this question is A.

What is a Pure substance?

A pure substance may be defined as a type of substance or matter that has a constant composition and properties that are constant throughout the sample.

It is scientifically found that a pure substance is typically made up of only one kind of particle and has a fixed or constant structure. According to the given diagram, images III and V signify the even distribution of the same type of atoms of molecules within the substances.

Apart from physical properties, pure substances also shares identical chemical properties as well.

Therefore, the images that would be considered pure substances are III and V. Thus, the correct option for this question is A.

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