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3 years ago

An atom of a certain element has 12 protons, 14 neutrons, and 2 valence electrons. What is the name of this element?

Chemistry

1 answer:

DedPeter [7]3 years ago

5 0

Given :

An atom of a certain element has 12 protons, 14 neutrons, and 2 valence electrons.

To Find :

The name of this element.

Solution :

We know, element with atomic number ( number of protons ) 12 and valance electrons is Magnesium.

Now, isotope of magnesium of proton with 14 neutrons is Mg-16 .

Therefore, name of element is Mg-16 .

Hence, this is the required solution.

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3 years ago

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(I)how many atoms are present in 7g of lithium?

ICE Princess25 [194]

Answer :

(i) The number of atoms present in 7 g of lithium are, $6.07\times 10^{23}$

(ii) The number of atoms present in 7 g of lithium are, $1.204\times 10^{24}$

(iii) The number of moles of $F_2$ is, 1 mole

The number of moles of $CO_2$ is, 0.5 mole

The number of moles of $OH^-$ is, 1 mole

Explanation :

Part (i) :

First we have to calculate the moles of lithium.

$\text{Moles of }Li=\frac{\text{Mass of }Li}{\text{Molar mass of }Li}$

Molar mass of Li = 6.94 g/mole

$\text{Moles of }Li=\frac{7g}{6.94g/mol}=1.008mole$

Now we have to calculate the number of atoms present.

As, 1 mole of lithium contains $6.022\times 10^{23}$ number of atoms

So, 1.008 mole of lithium contains $1.008\times 6.022\times 10^{23}=6.07\times 10^{23}$ number of atoms

Thus, the number of atoms present in 7 g of lithium are, $6.07\times 10^{23}$

Part (ii) :

First we have to calculate the moles of carbon.

$\text{Moles of }C=\frac{\text{Mass of }C}{\text{Molar mass of }C}$

Molar mass of C = 12 g/mole

$\text{Moles of }C=\frac{24g}{12g/mol}=2mole$

Now we have to calculate the number of atoms present.

As, 1 mole of carbon contains $6.022\times 10^{23}$ number of atoms

So, 2 mole of carbon contains $2\times 6.022\times 10^{23}=1.204\times 10^{24}$ number of atoms

Thus, the number of atoms present in 7 g of lithium are, $1.204\times 10^{24}$

Part (iii) :

To calculate the moles of $F_2$ :

$\text{Moles of }F_2=\frac{\text{Mass of }F_2}{\text{Molar mass of }F_2}$

Molar mass of $F_2$ = 38 g/mole

$\text{Moles of }F_2=\frac{19g}{19g/mol}=1mole$

Thus, the number of moles of $F_2$ is, 1 mole

To calculate the moles of $CO_2$ :

$\text{Moles of }CO_2=\frac{\text{Mass of }CO_2}{\text{Molar mass of }CO_2}$

Molar mass of $CO_2$ = 44 g/mole

$\text{Moles of }CO_2=\frac{22g}{44g/mol}=0.5mole$

Thus, the number of moles of $CO_2$ is, 0.5 mole

To calculate the moles of $OH^-$ ions :

$\text{Moles of }OH^-=\frac{\text{Mass of }OH^-}{\text{Molar mass of }OH^-}$

Molar mass of $OH^-$ = 17 g/mole

$\text{Moles of }OH^-=\frac{17g}{17g/mol}=1mole$

Thus, the number of moles of $OH^-$ is, 1 mole

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3 years ago

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The residue of coal decomposition that is used in the manufacture of steel is called: 1. coal gas 2. coke 3. coal tar

bagirrra123 [75]

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3 years ago

Marcela dissolves 80.0 g of ammonium nitrate in 50.0 mL of water at room temperature and notes that the temperature of the solut

seraphim [82]

Answer: The correct answer is A

Explanation:

On addition of the ammonium nitrate to 50 ml of water the temperature decreases which means that reaction between the ammonium nitrate and water is an endothermic reaction.The value of $\Delta H$ is positive for an endothermic reactions.

$\Delta H>0$

Entropy is a degree of randomness of the system.

On addition of the ammonium nitrate to water ammonium nitrate break down into ions which means that entropy is increased.

$\Delta S>0$

$\Delta G=\Delta H-T\Delta S$ (Gibb's free energy)

Since, ammonium nitrate is getting dissolved in water which means that this reaction is spontaneous and $\Delta G$ of spontaneous reaction is negative that is:

$\Delta G$

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3 years ago

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