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2 years ago

What percentage of the mass of a carbon-12 atom is

Chemistry

1 answer:

Lynna [10]2 years ago

7 0

Answer:

% of mass of electrons in C = 0.0272

Explanation:

Atomic no. of carbon = 6

So, no. of electron = 6

Mass of an electron = $\frac{1}{1836} amu$

Mass of 6 electrons = $6 \times \frac{1}{1836} = 0.003268 amu$

Mass of C = 12.0107 u

% of mass of electrons in C = $\frac{Mass\ of\ all\ electrons}{Mass\ of\ C}\times 100$

% of mass of electrons in C = $\frac{0.003268}{12.0107}\times 100=0.0272 \%$

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Afina-wow [57]

The correct answer is A; or 9.38x10^-3.

Explanation:

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Once you divide those by each other, your answer is 9.83x10^-3

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saul85 [17]

<u>Answer:</u> The $\Deltas H^o_{formation}$ for the reaction is -1406.8 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The chemical reaction for the formation reaction of $AlCl_3$ is:

$2Al(s)+3Cl_2(g)\rightarrow 2AlCl_3 (s)$ $\Delta H^o_{formation}=?$

The intermediate balanced chemical reaction are:

(1) $HCl(g)\rightarrow HCl(aq.)$ $\Delta H_1=-74.8kJ$ ( × 6)

(2) $H_2(g)+Cl_2(g)\rightarrow 2HCl(g)$ $\Delta H_2=-185kJ$ ( × 3)

(3) $AlCl_3(aq.)\rightarrow AlCl_3(s)$ $\Delta H_3=+323kJ$ ( × 2)

(4) $2Al(s)+6HCl(aq.)\rightarrow 2AlCl_3(aq.)+3H_2(g)$ $\Delta H_4=-1049kJ$

The expression for enthalpy of formation of $AlCl_3$ is,

$\Delta H^o_{formation}=[6\times \Delta H_1]+[3\times \Delta H_2]+[2\times \Delta H_3]+[1\times \Delta H_4]$

Putting values in above equation, we get:

$\Delta H^o_{formation}=[(-74.8\times 6)+(-185\times 3)+(323\times 2)+(-1049\times 1)]=-1406.8kJ$

Hence, the $\Deltas H^o_{formation}$ for the reaction is -1406.8 kJ.

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2 years ago

Does a negative exponent mean that the number is less than 1 yes or no

Masja [62]

Answer:

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2 years ago

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ozzi

Answer:

Na2CO3 <==> 2Na^+ + CO3^2-

Explanation:

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