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3 years ago

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A certain element has 2 naturally occurring isotopes. One isotope has a mass of 35 and an abundance of 75.77%, and the other has

a mass of 37 and an abundance of 24.23%. Find the average atomic mass rounded to the hundredths place.

1 answer:

Lorico [155]3 years ago

7 0

Answer: 35.5

Explanation: Please see attachment for explanation. Thanks!

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The radioactivity due to carbon-14 measured in a piece of a wooden casket from an ancient burial site was found to produce 20 co

Mrrafil [7]

Answer:

17202.6 years

Explanation:

Activity of the living sample (Ao) = 160 counts per minute

Activity of the wood sample (A) = 20 counts per minute

Half life of carbon-14 = 5730 years

t= age of the artifact

From;

0.693/t1/2= 2.303/t log Ao/A

Then;

0.693/ 5730= 2.303/t log Ao/A

Substituting values;

0.693/5730= 2.303/t log (160/20)

Then we obtain;

1.209×10^-4 = 2.0798/t

t= 2.0798/1.209×10^-4

Thus;

t= 17202.6 years

Therefore the artifact is 17202.6 years old.

8 0

3 years ago

If the atomic number of an element is 9 and the mass number is 19, how many neutrons does the atom have?

sammy [17]

To find the number of neutrons.....

NEUTRONS = MASS NUMBER - ATOMIC NUMBER ( PROTONS)

NEUTRONS = 19 - 9

So this element has 10 neutrons

5 0

3 years ago

What volume in liters of chlorine gas would be fully required to react to 125 g of Nal

Ivahew [28]

Volume of Cl₂ = 9.34 L

<h3>Further explanation</h3>

Reaction

2NaI + Cl₂ ⇒ 2NaCl + I₂

mol NaI (MW=149,89 g/mol) :

$\tt \dfrac{125}{149,89}=0.834$

mol Cl₂ : mol NaI = 1 : 2

mol Cl₂ :

$\tt \dfrac{1}{2}\times 0.834=0.417$

Assumptions at STP(1 mol=22.4 L) :

$\tt 0.417\times 22.4~L=9.34~L$

4 0

3 years ago

Kruka [31]

Answer:

.

Explanation:

8 0

3 years ago

For a reaction for which AH = +29.3 kJ/mol and AS = +106 J/mol•K, which of the following statements is true? A) The reaction is

umka2103 [35]

Answer: A) The reaction is spontaneous above 276 K.

Explanation:

According to Gibb's equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$ = Gibbs free energy

$\Delta H$ = enthalpy change = +29.3 kJ/mol =29300 J/mol

$\Delta S$ = entropy change = +106 J/molK

T = temperature in Kelvin

$\Delta G$ = +ve, reaction is non spontaneous

$\Delta G$ = -ve, reaction is spontaneous

$\Delta G$ = 0, reaction is in equilibrium

$\Delta G=(+ve)-T(+ve)$

$\Delta G=(+ve)(-ve)$

$T\Delta S>\Delta H$ for reaction to be spontaneous

$T\times 106 J/molK>29300J/mol$

$T>276K$

Thus the Reaction is spontaneous when temperature is above 276 K.

8 0

3 years ago