The symbol ∆hf0 stands for

Answers

Answer 1

Answer:

standard heat of formation for compound

Explanation:


Related Questions

Pressure increases from Earth’s surface toward the center of Earth.

True Or False

Answers

Answer:

True

Explanation:

The center receives pressure which is what creates convection currents

Need help on #1 thank youu!

Answers

oil , water , wood im pretty sure

Answer:

Oil---> Wood---> Water

Explanation:

Denser things always go on bottom. Since oil is on top is the least dense among those, and then comes wood and then finally water.

Which type of crystal is typified by a sea of delocalized electrons
surrounding the lattice?
O A. lonic
B. Metallic
OC. Macromolecular
D. Chemical
Reset Selection

Answers

B.metallic is the answer hope this helped

The correct answer is option B. Metallic.

What explains the structure of metals and delocalized electrons?

Metal is composed of a huge structure of atoms arranged in a regular pattern. Electrons from the outer shell of a metal atom are delocalized and can move freely throughout the structure. This sharing of delocalized electrons results in strong metal bonds.

Metallic bonds are electrostatic attraction between metal cations and the negatively charged ocean of delocalized electrons. The sea of ​​delocalized electrons contains only valence electrons, not core electrons.

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a student is asked to draw an atom of sulfur on a board. the pictures below represents what the student drew. what is wrong with this sulfur atom

plzzzz help i need to finish up

Answers

Ur momma eheheheheheh

Classify the following as an element, compound, homogeneous mixture, or heterogeneous


mixture: salt water

A. Element
B. Compound
C. Homogeneous mixture
D. Heterogenous mixture

Answers

The answer is D. Heterogeneous mixture

A. Element
B. Compound
C homogenous mixture
D heterogenous mixture

Answers

Is the letter A is an element

What is pressure?
O A. The heat required to change the temperature of a gas
OB. The force of gas molecules hitting their container
O C. The mixing of gas molecules due to random motion
D. The space occupied by gas molecules moving around

Answers

Answer:

B.

Explanation:

The force of gas molecules hitting their container is pressure.

Because pressure = force/area.

B) the force of gas molecules hitting their container

PLEASE HELP WILL GIVE 100 points


Record the data from each trial in the data chart below. Be sure to fill in the chart completely.
Test One
Parent 1: FF
Parent 2: FF
Phenotype ratio:
short fur: long fur
Test Two
Parent 1: Ff
Parent 2: FF
Phenotype ratio:
short fur: long fur
Test Three
Parent l: ff
Parent 2: ff
Phenotype ratio:
short fur: long fur

Answers

Answer: Test One

Parent 1: FF

Parent 2: FF

Phenotype ratio:

short fur: long fur

Test Two

Parent 1: Ff

Parent 2: FF

Phenotype ratio:

short fur: long fur

Test Three

Parent l: ff

Parent 2: ff

Phenotype ratio:

short fur: long fur

Explanation:

How many grams of aluminum oxide would be produced from the reaction of 0.25 grams of aluminum with excess oxygen gas?

Answers

Answer:

0.472 grams of aluminum oxide would be produced from the reaction of 0.25 grams of aluminum with excess oxygen gas.

Explanation:

First of all, you should know that the balanced reaction that occurs:

4 Al + 3 O₂ → 2 Al₂O₃

Then, by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts are produced in moles:

Al: 4 molesO₂: 3 molesAl₂O₃: 2 moles

Being:

Al: 27 g/moleO: 16 g/mole

The molar mass of the compounds participating in the reaction is:

Al: 27 g/moleO₂: 2*16 g/mole= 32 g/moleAl₂O₃: 2*27 g/mole + 3*16 g/mole= 102 g/mole

Then, by stoichiometry of the reaction, the following amounts of mass react and are produced:

Al: 4 moles*27 g/mole= 108 gO₂: 3 moles*32 g/mole= 96 gAl₂O₃: 2 moles*102 g/mole= 204 g

 

Now it is possible to apply the following rule of three: if 108 grams of Al produce 204 grams of Al₂O₃, 0.25 grams of aluminum how much mass of Al₂O₃ will it produce?

[tex]mass of Al_{2} O_{3} =\frac{0.25 grams of Al*204 grams of Al_{2} O_{3} }{108 grams of Al}[/tex]

mass of Al₂O₃=0.472 grams

0.472 grams of aluminum oxide would be produced from the reaction of 0.25 grams of aluminum with excess oxygen gas.

Answer:

D

Explanation:

what are the steps to go from the names of compounds to the formulas

Answers

Answer:

Explanation:

write down the formulas, use the expressions and formulas to convert

HELP ME ILL GIVE YOU 40 POINTS JUST HELP MEEEEEEEEEEE

What causes blood pressure?
A.the strength of the muscles in the walls of the capillaries
B.the speed at which oxygen is returned to blood in the lungs
C. the force with which the ventricles contract
D. the rate at which blood flows through the heart

Answers

Answer:

C

Explanation:

What causes blood pressure?

C

To pump blood around the body, the heart contracts and then relaxes through the cardiac cycle. The cycle begins with the contraction of the two atria, which push blood into the ventricles. Then, the ventricles contract, which forces the blood out of the heart.

When the heart pushes blood around the body during systole, the pressure placed on the vessels increases. This is called systolic pressure.

When the heart relaxes between beats and refills with blood, the blood pressure drops. This is called diastolic pressure.

The English system is used as the International System of Measurement. Please select the best answer from the choices provided T F

Answers

FALSE


explanation: the English system of measurement is mainly only used in England. The metric system is the international system of measurement.
False it’s the metric system

What does the law of conservation of matter show?
A. That the total number of atoms in matter will never change.
B. That matter can never change form.
C. That atoms will combine in the simplest possible arrangement.
D. That atoms in matter can never be rearranged.

Answers

Answer: A) That the total number of atoms in matter will never change.

Explanation: Matter cannot be destroyed nor created. Matter is made up of atoms. The amount of atoms in an object will never change, even when changed into a different form.

Ex. When ice cubes melt there is still the same amount of water just in a different form.

Answer:

A

Explanation:

In the reaction, HCl + H2O produces H3O + Cl, what is the conjugate acid

Answers

Answer:

Conjugate acid is H3O

Explanation:

HCl + H2O = H3O + Cl

HCl = H+ and Cl- = Acid

H2O = OH- and H+ = Neutral as equal OH- and H+

H3O = H3O+ = Acid also known as Hydronium

Cl = Just free floating Chlorine = Cl-

Conjugate acid is H3O

Acid = A solution with more H+ ions than OH- ions.

Using the activity series provided. Which reactants will form products? Na > Mg > Al > Mn > Zn > Cr > Fe > Cd > Co > Ni > Sn > Pb > H > Sb > Bi > Cu > Ag Ag +NaNO3 Right arrow. Fe + Al2O3 Right arrow. Ni + NaCl Right arrow. Fe + Cu(NO3)2 Right arrow.

Answers

Answer:

D

Explanation:

To solve this we must be knowing each and every concept related to  activity series. Therefore, Fe + Cu(NO[tex]_3[/tex])[tex]_2[/tex] reactants will form products. The correct option is option D.

What is activity series?

We refer to the metal series in the image above as the activity series. This serves as a guide so that we can identify the byproducts of a metal displacement process. For displacement to take place, a metal must be placed over the other metallic combination.

Ag is significantly lower than Na in the series so, nothing happens. Since Al is above Fe, there is no response. Ni is below Na, hence no reaction will take place. A displacing reaction will happen because Fe is a greater active metal than copper.

Therefore, Fe + Cu(NO[tex]_3[/tex])[tex]_2[/tex] reactants will form products. The correct option is option D.

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The topmost layer of the Earth is made up of large pieces that fit together like a puzzle. However, these pieces don't stay still, and sometimes they rub against each other. When these large sections of the Earth’s crust, called tectonic plates, hit each other, they send vibrations through the surface of the Earth. These vibrations are seismic waves. Seismic waves are just like the ripples in a pond. But instead of traveling through water, they travel through the Earth. When they reach the Earth's surface, they make the ground shake. That's an earthquake.
Earthquakes are the result of?
A ripples traveling through water.
B Earth’s topmost layer sinking.
C vibrations from seismic waves.
D tectonic plates staying still.

Answers

Answer:

C- vibrations from seismic waves

Answer:

C vibrations from seismic waves.

Explanation:

The shifting rock in an earthquake causes vibrations called seismic waves.

Latent heat of vaporization is used to (1 Point) (a) overcome the forces of attraction between molecules in solid-state. (b) increase the kinetic energy of molecules in a liquid state. (c) overcome the forces of attraction between molecules in a liquid state. (d) increase the kinetic energy of molecules in the vapour state.

Answers

Answer:

Not sure what the answer is

Explanation:

I did this a while ago and dont remember sorry

Why you cannot add 0.3 moles of calcium fluoride directly to 1L of water to make a 0.3 M solution ? please only 5 mins left

Answers

Answer:

Because it's not soluble in water, need to be heated acidic solution

Explanation:

Calcium Fluoride Formula: CaF2  Comprises of Ca2+ and F−

H2O = Water H+ O2- OH-

Insoluble in water

In order to dissolve a salt, you have to break apart the ions and hydrate them via a solvent.

Need to read

HSAB concept( Pearson acid-base concept) is an initialism for "hard and soft (Lewis) acids and bases"

So F- is a Halogen which is a Hard Base

And OH- is a Hard base as well

And H- is a soft base

So soft acids react best with soft bases and hard acids react best with hard bases.

Bases don't react with other bases.

What does Avogadro's law say about a gas atSTP? A; 1 L of any gas contains 22.4 moles at STP B; 1 L of any gas has a pressure of 22.4 atm at STP C; All gases are at 22.4 atm at STP D; 1 mole of any gas has a volume of 22.4 L at STP

Answers

Answer: 1 mole of any gas has a volume of 22.4 L at STP

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 1 atm (at STP)

V = Volume of gas = ?

n = number of moles = 1

R = gas constant =[tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]273K[/tex]  (at STP)

[tex]V=\frac{nRT}{P}[/tex]

[tex]V=\frac{1mol\times 0.0820 L atm/K mol\times 273K}{1atm}=22.4L[/tex]

Thus 1 mole of every gas occupies 22.4 L at STP

Answer:

1 mole of any gas has a volume of 22.4 L at STP

Explanation:

ap3xx

I'll give brainliest
In going through the three physical states of matter, water would normally undergo changes in
A) composition.
B) density.
C) mass.
D) weight.

Answers

Answer:

COMPOSITION

Explanation:

Brainliest plz

Count then plot the total number of atoms in the reactants to total atoms
in the products for the equation 2H2 + O2 + 2H2O

Answers

answer C
explanation C

if the freezing point of a substance is 68°C, what is its melting point?

Answers

The melting point will be the freezing point times .14

The melting point of the substance has been [tex]\rm 68^\circ C[/tex].

The freezing point has been defined as the temperature above to which the substance exists in the liquid state, while below which the substance exist in the solid state.

Freezing point and melting point

The melting point has been the temperature at which the solid starts to convert into the liquid state. The melting point and freezing point for the substances has been the same temperature.

Thus, the melting point of the substance whose freezing point has been [tex]\rm 68^\circ C[/tex] has been [tex]\rm 68^\circ C[/tex].

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What is the answer to this I need help please

Answers

Answer : The boron-11 isotope is the most abundant.

Explanation :

As we are given that:

Average atomic mass of boron = 10.81 amu

Mass of boron-10 = 10.0129 amu

Mass of boron-11 = 11.0093 amu

As we know that the average atomic mass of an element is always closest to the most abundant isotope.

Out of the two boron isotopes, B-11 is closest in mass to the weighted average. Therefore, it is the most abundant.

Hence, the boron-11 isotope is the most abundant.

Carbon-14 is a common isotope of the element. How many electrons
does it contain?
O 14
O 12
O 8
O 6

Answers

i think 8 or 6 im not sure

these are easily extracted with a pH solution of greater than 7? which one

A) acid drugs
B) metabolites
C) base drugs
D) derivatives

Answers

Answer:

base drugs

Explanation:

The pH scale is a scale graduated from 0-14. It is used as an indicator of the degree of acidity or alkalinity. A pH of 0-6.9 indicates acidity. A pH of 7 indicates that the solution is neutral. A solution of pH above 7 indicates that the substance is basic.

It is thus a correct statement to say that any substance that dissolves in solution to produce a solution of pH greater than 7.0 is a basic substance.

If we look at the options closely, it is only a basic drug that will dissolve in water to yield a basic solution of pH greater than 7.0 hence the answer.

do rainforests have hot summers and cold winters?

Answers

Answer:

No, rainforests have long wet winters and short dry summers.

Tropical rainforests are lush and warm all year long! Temperatures don't even change much between night and day. The average temperature in tropical rainforests ranges from 70 to 85°F (21 to 30°C).

Which of the following is an example of a mixture?
A. NaCl
B. CO2 + H2 + O2
Ос. Са
D. C6H1206
Reset Selection

Answers

Answer:

B.

Explanation:

CO2 + H2 + O2 - are 3 individual substances.

CAN I PLEASE GET SOME HELP PLEASE PLEASE HELP ME I WOULD APPRECIATE IT AND THANK YOU!! WICH of the following is an expression of Avogadro's law (k=constant) A)V=kn B)V=k/n C)nV=k D)V=k no

Answers

Answer:

Vn = k

Explanation:

[tex]Vn = k[/tex]

From the web :

Avogadro's Law is stated mathematically as follows: Vn=k, where V is the volume of the gas, n is the number of moles of the gas, and k is a proportionality constant

Avogadro's Law is stated mathematically as follows: Vn=k, where V is the volume of the gas, n is the number of moles of the gas, and k is a proportionality constant.

What is Avagrado's law?

According to Avogadro's Law, all gases have an identical number of molecules in an equal volume at a given temperature and pressure. Amedeo Avogadro, an Italian chemist and physicist, first described the law in 1811.

At 0 °C and 1 abm pressure, the molar volume of all ideal gases is 22.4 litres.  If a gas's temperature and pressure remain constant, its volume will also grow as its amount increases.

If a gas's pressure and temperature are both constant, its volume falls as its volume of gas does. Every time you blow a balloon up, you demonstrate Avogadro's Law.

Therefore, Avogadro's Law is stated mathematically as follows: Vn=k, where V is the volume of the gas, n is the number of moles of the gas, and k is a proportionality constant.

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Nonrenewable resources are ?

Answers

DescriptionA non-renewable resource is a natural resource that cannot be readily replaced by natural means at a quick enough pace to keep up with consumption. An example is carbon-based fossil fuel

Answer:

limited resources

Explanation:

nonrenewable resources are those resources found inside the earth that are in a fixed amount. They are being used at a faster rate, and cannot be renewed. These resources include fossil fuels,natural gas, and coal.

// have a great day //

What is one way in which chemistry affects your everyday life?
A. Refrigerators use energy more efficiently than they did 10 years
ago.
B. Tap water is safe to drink because it is monitored for harmful
substances.
c. Weather forecasts are now more accurate because of radar.
D. Watches are now more accurate because they are digitalized.

Answers

Answer: B

Explanation: Water is filtered with a bunch of chemicals which makes it drinkable.

B, the filtration system used to make drinking water safe consists of chemistry
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