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Talja [164]
3 years ago
8

Naturally occurring neon exists as three isotopes. 90.51% is ne-20 with a mass of 19.99 amu, 0.27% is ne-21 with a mass of 20.99

amu, and 9.22% is ne-22 with a mass of 21.99 amu. what is the atomic mass of neon?
Chemistry
1 answer:
gregori [183]3 years ago
3 0

The atomic mass of an element is the average relative mass of its atoms as compared with an atom of carbon-12 whose mass is taken as 12. In terms of percentages of different isotopes, the average atomic mass can be determined as follows: A_{average} = ∑(p_{i}X A_{i})/100. Where, p_{i} is the percentage abundance of isotope with atomic number A_{i}.

So, average atomic mass of neon = \frac{(90.51 X 19.99) + (0.27 X 20.99) + (9.22 X 21.99)}{100} = 20.177 amu.

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<u>Answer:</u> The increase in pressure is 0.003 atm

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\Delta H = Enthalpy change of the reaction = 28.8 kJ/mol = 28800 J/mol     (Conversion factor: 1 kJ = 1000 J)

R = Gas constant = 8.314 J/mol K

T_1 = initial temperature = 801^oC=[801+273]K=1074K

T_2 = final temperature = (801+1.00)^oC=802.00=[802+273]K=1075K

Putting values in above equation, we get:

\ln(\frac{P_2}{1})=\frac{28800J/mol}{8.314J/mol.K}[\frac{1}{1074}-\frac{1}{1075}]\\\\\ln P_2=3\times 10^{-3}atm\\\\P_2=e^{3\times 10^{-3}}=1.003atm

Change in pressure = P_2-P_1=1.003-1.00=0.003atm

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When 18.5 g of HgO(s) is decomposed to form Hg(l) and O2(g), 7.75 kJ of heat is absorbed at standard-state conditions. What is t
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From the given,

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For the formation of 1 mol of HgO , 90.7 kJ of energy is release

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