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3 years ago

What is the the heat of reaction, delta, in kJ/mol?

Chemistry

1 answer:

wariber [46]3 years ago

5 0

Answer:

b) -25 kJ/mol.

Explanation:

Hello there!

In this case, since the general definition of the enthalpy of reaction involves the subtraction of the energy of the products and the energy of the reactants:

$\Delta H=H_{prod}-H_{react}$

Thus, since the graph shows that the energy of the products is 20 kJ/mol and that of reactants 45 kJ/mol, we will obtain:

$\Delta H=20kJ/mol-45kJ/mol\\\\\Delta H=-25kJ/mol$

Which means it is exothermic.

Regards!

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Single stranded___ molecules translate he code for making protein

Radda [10]

Answer:

RNA

Explanation:

Central dogma is the process of the formation of protein from the sequence of nucleotide on DNA. It consists of two further processes Transcription and translation.

During Transcription, the information from the DNA sequence is transcripted in a sequence of RNA, that is single stranded and contains Uracil instead of Thymine. During Translation, the information from the RNA sequence is translated into a sequence of amino-acid, and a protein.

Hope it helps!

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3 years ago

What is the last element in the periodic table?

borishaifa [10]

Answer:

Ununoctium

Explanation:

It's at the very end of the periodic table

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3 years ago

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An atom has 8 electrons and a mass of 17. What would the correct symbol be?

irakobra [83]

I believe the answer is A.

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3 years ago

A zinc salt, E when

Naily [24]

Answer:

The salt is Zn(NO3)2

When the residue is allowed to cool, its colour changes from yellow to white

The equation of the reaction is; 2Zn(NO3)2(s) --->2ZnO(s) + 4NO2(g) + O2(g)

Explanation:

Decomposition of Zn(NO3)2 is one of the routes by which ZnO is obtained. ZnO is a white insoluble powder which has a yellow colour when hot and a white colour when cold. It is an amphoteric substance used as a white pigment in paints and as a filler for rubber.

In a very pure form, it is used in cosmetic powders and creams as well as in medicinal ointments and lotions.

Also recall that NO2 is a brown gas and oxygen gas rekindles a glowing splint.

6 0

3 years ago

Compute the atomic density (the number of atoms per cm3 ... rather than the mass density g/cm3) for a perfect crystal of silicon

serious [3.7K]

Answer:

$\large\boxed{\large\boxed{5.00\times 10^{22}atoms/cm^3}}$

Explanation:

You can convert the density into atomic density using the atomic weight and Avogadro's number

A dimensional analysis is very helpful:

$\dfrac{g}{cm^3}\times \dfrac{mol}{g}\times \dfrac{atoms}{mol}=\dfrac{atoms}{cm^3}$

Follow the chain: g cancels with g, mol cancels with mol; at the end, what remains is atoms/cm³, which is what you want.

Use that with your data:

$\dfrac{2.33g}{cm^3}\times \dfrac{1mol}{28.09g}\times \dfrac{6.022\times 10^{23}atoms}{mol}=\approx 5.00\times10^{22}atoms/cm^3$

3 0

3 years ago