CHEMISTRY MIDDLE SCHOOL

What does index fossil mean?

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Answer 1
Answer:

An index fossil is a  fossil that is useful for dating and correlating the strata in which it is found.

Or it is a fossil that helps you find the date where it has been found. I rephrased that.


Related Questions

MIDDLE SCHOOL

What three organelles do plant cells have that are different from animal cells

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Plant cells have a cell wall, a large central vacuole, and plastids such as chloroplasts and animal cells do not have any of those
MIDDLE SCHOOL

Moles/Mass/Molecules Practice Problem Worksheet Complete the following problems:

1. Convert 11.03 moles of calcium nitrate to grams.

2. How many molecules are contained in 103.4g of sulfuric acid?

3. 3.25 x 1024 molecules of dinitrogen pentoxide would be how many moles?

4. What would be the mass of 9.03 x 1021 molecules of hydrobromic acid?

5. A sample of iron (III) chloride has a mass of 26.29g. How many moles would this be?

Answers

1. Converting 11.03 moles of calcium nitrate to grams gives 1,809.89 grams.

2. The number of molecules that are contained in 103.4 g of sulfuric acid is    molecules.

3. Converting molecules of dinitrogen pentoxide to moles is equal to 5.3987 moles.

4. The mass of molecules of hydrobromic acid is 1.2135 grams.

5. The number of moles contained in 26.29 g of iron (III) chloride is 0.1621 moles.

Given the following data:

  • Number of moles of calcium nitrate = 11.03 moles
  • Mass of sulfuric acid = 103.4 grams
  • Number of molecules of dinitrogen pentoxide =
  • Number of molecules of hydrobromic acid =
  • Mass of iron (III) chloride = 26.29 grams

Scientific data:

  • The molar mass of calcium nitrate = 46.07 g/mol.
  • The molar mass of sulfuric acid = 98.079 g/mol.
  • The molar mass of hydrobromic acid = 80.91 g/mol.
  • The molar mass of iron (III) chloride = 162.2 g/mol.
  • Avogadro's number =

1. To convert 11.03 moles of calcium nitrate to grams:

Mass of calcium nitrate = 1,809.89 grams.

2. To calculate how many molecules are contained in 103.4 g of sulfuric acid:

First of all, we would determine the number of moles contained in 103.4 g of sulfuric acid.

Number of moles = 1.0543 moles

By stoichiometry:

1 mole of sulfuric acid =  molecules

1.0543 mole of sulfuric acid = X molecules

Cross-multiplying, we have:

X =  molecules

3. To convert molecules of dinitrogen pentoxide to moles:

By stoichiometry:

1 mole of dinitrogen pentoxide =  molecules

X mole of dinitrogen pentoxide = molecules

Cross-multiplying, we have:

X = 5.3987 moles

4. To calculate the mass of molecules of hydrobromic acid:

First of all, we would determine the number of moles contained in molecules of hydrobromic acid.

By stoichiometry:

1 mole of hydrobromic acid =  molecules

X mole of hydrobromic acid =   molecules

Cross-multiplying, we have:

X = 0.015 moles

Mass of hydrobromic acid = 1.2135 grams.

5. To calculate the number of moles contained in 26.29 g of iron (III) chloride:

Number of moles = 0.1621 moles.

Read more: brainly.com/question/16906167

Answer:

Explanation:

1) Convert 11.03 moles of calcium nitrate to grams.

Given data:

Number of moles = 11.03 mol

Mass of calcium nitrate = ?

Solution:

Formula:

Number of moles = mass / molar mass

Now we will rearrange the formula because we have to calculate the mass.

Mass = number of moles × molar mass

Molar mass of calcium nitrate =  164.088 g/mol

Mass = 11.03 mol ×  164.088 g/mol

Mass = 1809.89 g

2. How many molecules are contained in 103.4g of sulfuric acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules = ?

Mass of sulfuric acid = 103.4 g

Solution:

Formula:

Number of moles = mass / molar mass

Number of moles = 103.4 g/ 98.079 g/mol

Number of moles = 1.05 mol

1 mole =  6.022 × 10²³ molecules

1.05 mol × 6.022 × 10²³ molecules / 1mol

6.323 × 10²³ molecules of sulfuric acid

3. 3.25 x 1024 molecules of dinitrogen pentoxide would be how many moles?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of dinitrogen pentoxide = 3.25 × 10²⁴

Moles of dinitrogen pentoxide = ?

Solution:

1 mole =  6.022 × 10²³ molecules

1 mol  × 3.25 × 10²⁴ molecules / 6.022 × 10²³ molecules

5.4 moles

4. What would be the mass of 9.03 x 1021 molecules of hydrobromic acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of hydrobromic acid = 9.03 × 10²¹

Mass of hydrobromic acid = ?

Solution:

First of all we will calculate the moles of hydrobromic acid.

1 mole =  6.022 × 10²³ molecules

1 mol  × 9.03 × 10²¹ molecules / 6.022 × 10²³ molecules

0.015  moles

Mass of hydrobromic acid:

Mass =  number of moles × molar mass

Mass = 0.015 mol × 80.9 g/mol

Mass =1.21 g

5. A sample of iron (III) chloride has a mass of 26.29g. How many moles would this be?

Given data:

Number of moles =?

Mass of iron(III) chloride = 26.29 g

Solution:

Formula:

Number of moles = mass / molar mass

Molar mass of iron chloride  =  162.2 g/mol

Now we will put the values in formula.

Moles = 26.29 g/ 162.2 g/mol

Moles = 0.16 g

HIGH SCHOOL

If a sample contains 21.2 g N, how many moles of N does it contain? 0.66 mol 1.51 mol 14.01 mol 297.01 mol

Answers

M(N)=21.2 g
M(N)=14.007 g/mol

n(N)=m(N)/M(N)

n(N)=21.2g/(14.007g/mol)=1.51 mol

Hello!

If a sample contains 21.2 g N, how many moles of N does it contain?

0.66 mol

1.51 mol

14.01 mol

297.01 mol

We have the following data:  

m (mass) = 21.2 g

MM (Molar mass of Nitrogen) = 14 g / mol

n (number of moles) = ?

Formula:  

Solving:  

Answer:

1.51 mol

_______________________________

I Hope this helps, greetings ... Dexteright02! =)

HIGH SCHOOL

A decrease in height of a column in a mercury barometer means that

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Answer:

increase in the air pressure

Explanation:

The barometer is a device that is used for measuring the air pressure. It is a device that uses mercury in order to show the air pressure. The mercury reacts easily to the changes in the air pressure, so it is a nice indicator for it. The air pressure can simply be defined as the weight of the air masses, and the pressure they make it because of it on the objects. The lower the air pressure, the higher up the mercury will go, as it will experience less pressure from the air, and the higher the air pressure, the lower the mercury will drop, as it will experience more pressure from the air.

HIGH SCHOOL

An equilibrium mixture of PCl 5 ( g ) , PCl 3 ( g ) , and Cl 2 ( g ) has partial pressures of 217.0 Torr, 13.2 Torr, and 13.2 Torr, respectively. A quantity of Cl 2 ( g ) is injected into the mixture, and the total pressure jumps to 263.0 Torr. The appropriate chemical equation is PCl 3 ( g ) + Cl 2 ( g ) − ⇀ ↽ − PCl 5 ( g ) Calculate the new partial pressures after equilibrium is reestablished.

Answers

Answer: The new partial pressures of when equilibrium is re-established are 223.4 torr, 6.82 torr and 26.4 torr respectively.

Explanation:

For the given chemical reaction:

The expression of for above reaction follows:

        ........(1)

We are given:

Putting values in above equation, we get:

Now we have to calculate the new partial pressure of .

The reaction is re-established and proceed to right direction by Le-Chatelier's principle to cancel the effect of addition of .

Now, the equilibrium is shifting to the reactant side. The equation follows:

                       

Initial:             13.2         32.8            217.0

At eqm:         13.2-x      32.8-x         217.0+x

Putting values in expression 1, we get:

Neglecting the 40.4 value of 'x'  because pressure can not be more than initial partial pressure.

Thus, the value of 'x' will be, 6.38 torr.

Now we have to calculate the new partial pressures after equilibrium is reestablished.

Partial pressure of = (217.0+x) = (217.0+6.38) = 223.4 torr

Partial pressure of = (13.2-x) = (13.2-6.38) = 6.82 torr

Partial pressure of = (32.8-x) = (32.8-6.38) = 26.4 torr

Hence, the new partial pressures of when equilibrium is re-established are 223.4 torr, 6.82 torr and 26.4 torr respectively.

COLLEGE

Calculate the half-life of different radioactive sources.

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The rate at which a radioactive isotope decays is measured in half-life. The termhalf-life is defined as the time it takes for one-half of the atoms of a radioactive material to disintegrate. Half-lives for various radioisotopes can range from a few microseconds to billions of years.
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back at it again with that answer
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HIGH SCHOOL

Select all that apply. Which of the following are homogeneous solutions? salt water
air
sand and water
vinegar
cement

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Salt water and air are homogenous
MIDDLE SCHOOL

What is climate? (site 2)

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The weather conditions prevailing in an area in general or over a long period.
HIGH SCHOOL

What are some examples of colligative properties in real life?

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Firstly, colligative properties focus on the NUMBER of particles in the ratio of the solute to the solvent. Finally, examples of such are: the decreasing of vapor pressure, the increasing of one's material to its boiling point, the decreasing again of one's material to its freezing point, and osmotic pressure.
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