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2 years ago

Why is the mass in amu of a carbon-12 atom reported as 12.011 in the periodic table of the elements?

1 answer:

7 0

The mass of an element listed in the Periodic Table is the weighted average of all its naturally occurring isotopes.

Naturally occurring carbon is about

99 % carbon-12 (12.000 u) + 1 % carbon-13 (13.003 u).

That extra carbon-13 makes the <em>average atomic mass</em> greater than 12.000 u.

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The total mass of the atmosphere is about 5.00 x 1018 kg. How many moles each of air, O2, and CO2 are present in the atmosphere?

n200080 [17]

<u>Answer:</u> The moles of oxygen and carbon dioxide in air is $3.63\times 10^{19}mol$ and $7.18\times 10^{16}mol$ respectively

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of atmosphere = $5.00\times 10^{18}kg=5.00\times 10^{21}g$

Average molar mass of atmosphere = 28.96 g/mol

Putting values in above equation, we get:

$\text{Moles of atmosphere}=\frac{5.00\times 10^{21}g}{28.96g/mol}=1.73\times 10^{20}mol$

We know that:

Percent of oxygen in air = 21 %

Percent of carbon dioxide in air = 0.0415 %

Moles of oxygen in air = $\frac{21}{100}\times 1.73\times 10^{20}=3.63\times 10^{19}mol$

Moles of carbon dioxide in air = $\frac{0.0415}{100}\times 1.73\times 10^{20}=7.18\times 10^{16}mol$

Hence, the moles of oxygen and carbon dioxide in air is $3.63\times 10^{19}mol$ and $7.18\times 10^{16}mol$ respectively

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erma4kov [3.2K]

Lack of moisture :)

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In the experiment "Beer-Lambert’s Law and Spectrophotometry", you prepared a calibration plot similar to the one pictured below.

dexar [7]

Answer:

0.025M

Explanation:

As you must see in your graph, each concentration of the experiment has an absorbance. Following the Beer-Lambert's law that states "The absorbance of a solution is directely proportional to its concentration".

At 0.35 of absorbance, the plot has a concentration of:

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Tom [10]

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A HH, TT, HT, TH

B HHHT, HTTT, HHTT

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D HHHH, HTHH, HTTH, HTTT, TTTT

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Klio2033 [76]

The answer is c. because you have to increase concentration of h2

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