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3 years ago

Define the standard heat of formation of mgco3

1 answer:

7 0

The standard heat of formation is the energy change that occurs when 1 mole of a substance is made from its elements in their standard states ( most stable form of the element at 1 bar of pressure and the specified temperature, usually 298 K or 25 degrees Celcius)
E.g for MgCO3
Mg (s) + C (s) + 3/2 O2 (g) = MgCO3

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How does carbon 14 work

Verdich [7]

Carbon-14 dating is a way of determining the age of certain archeological artifacts of a biological origin up to about 50,000 years old. It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities.

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3 years ago

The purpose of the salt bridge in an electrochemical cell is to ____.

IgorLugansk [536]

Answer:

A. maintain electrical neutrality in the half-cells via migration of ions

Explanation:

Salt bridge -

For an electrochemical reaction , involving an anode and a cathode , both the electrodes are connect via a salt bridge to complete the circuit for the reaction .

One of the very important use of a salt bridge is to maintain the electrical neutrality of the respective half cells , which is achieved by the movement of ions .

Hence , from the given options , the correct option is ( a ) .

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3 years ago

A small portion of a crystal lattice is sketched below. What is the name of the unit cell of this lattice? Your answer must be a

Nikolay [14]

This is an incomplete question, the given sketch is shown below.

Answer : The name of given unit cell is, FCC (face-centered cubic unit cell)

Explanation :

Unit cell : It is defined as the smallest 3-dimensional portion of a complete space lattice which when repeated over the and again in different directions produces the complete space lattice.

There are three types of unit cell.

SCC (simple-centered cubic unit cell)
BCC (body-centered cubic unit cell)
FCC (face-centered cubic unit cell)

In SCC, the atoms are arranged at the corners.

$Z=\frac{1}{8}\times 8=1$

The number of atoms of unit cell = Z = 1

In BCC, the atoms are arranged at the corners and the body center.

$Z=\frac{1}{8}\times 8+1=2$

The number of atoms of unit cell = Z = 2

The given unit cell is, FCC because the atoms are arranged at the corners and the center of the 6 faces.

$Z=\frac{1}{8}\times 8+\frac{1}{2}\times 6=4$

The number of atoms of unit cell = Z = 4

Thus, the name of given unit cell is, FCC (face-centered cubic unit cell)

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3 years ago

A meteor is moving 468 km per minute traveling in a south-to-north direction passed near Earth in 2013. Does this statement desc

HACTEHA [7]

Answer:

it's describes the velocity. since a direction was specifically given, that means it is displacement, and displacement is to velocity while distance is to speed

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3 years ago

Read 2 more answers

Calculate pH value in a solution that has a<br> concentration of 0.04 mol / dm^3 of H30+ ions?

Sergio039 [100]

Answer:288229262427020202625369201010910000000000000

Explanation: bcuz I said

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3 years ago