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3 years ago

Thallium consists of 29.5%Th-203 and 70.5%Th-205. What is the relative atomic mass of thallium?

Chemistry

2 answers:

grin007 [14]3 years ago

7 0

0.295 * 203 = 53.885
0.705 * 205 = 144.525
53.885 + 144.525 = 204.41
The relative atomic mass of Thallium is 204.41

Viktor [21]3 years ago

5 0

Answer:

204.41 is the relative atomic mass of thallium.

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

We are given:

Mass of Thallium-203= 203 u

Percentage abundance of Thallium-203= 29.5%

Fractional abundance of Thallium-203= 0.295

Mass of Thallium-205 = 270.9 u

Percentage abundance of Thallium-205 = 70.5%

Fractional abundance of Thallium-203 = 0.705

Putting values in equation 1, we get:

$\text{Average atomic mass of Thallium}=\sum[(203 u\times 0.295)+(205 u\times 0.705)]$

$\text{Average atomic mass of Thallium}=204.41 u$

204.41 is the relative atomic mass of thallium.

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For a: The mass of acetic anhydride needed is 73.91 grams.

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Putting values in equation 1, we get:

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$C_7H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+CH_3COOH$

By stoichiometry of the reaction:

1 mole of salicylic acid reacts with 1 mole of acetic anhydride.

So, 0.724 moles of salicylic acid will react with = $\frac{1}{1}\times 0.724=0.724mol$ of acetic anhydride.

Now, to calculate the mass of acetic anhydride, we use equation 1:

Moles of acetic anhydride = 0.724 moles

Molar mass of acetic anhydride = 102.09 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of acetic anhydride}}{102.09g/mol}\\\\\text{Mass of acetic anhydride}=73.91g$

Hence, the mass of acetic anhydride needed is 73.91 grams.

For b:

By stoichiometry of the reaction:

1 mole of salicylic acid is producing 1 mole of aspirin.

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Now, to calculate the mass of aspirin, we use equation 1:

Moles of aspirin = 0.724 moles

Molar mass of aspirin = 180.158 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of aspirin}}{180.158g/mol}\\\\\text{Mass of aspirin}=130.43g$

Hence, the theoretical yield of aspirin is 130.43 grams.

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pychu [463]

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