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olga55 [171]
3 years ago
8

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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H+ and OCl-

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Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation isC7H6
prisoha [69]

<u>Answer:</u>

<u>For a:</u> The mass of acetic anhydride needed is 73.91 grams.

<u>For b:</u> The theoretical yield of aspirin is 130.43 grams.

<u>Explanation:</u>

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

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}   .....(1)

  • <u>For a:</u>

Given mass of salicylic acid = 1.00\times 10^2g=100g

Molar mass of salicylic acid = 138.121 g/mol

Putting values in equation 1, we get:

\text{Moles of salicylic acid}=\frac{100g}{138.121g/mol}=0.724mol

For the given chemical reaction:

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.

  • <u>For b:</u>

By stoichiometry of the reaction:

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

So, 0.724 moles of salicylic acid will produce = \frac{1}{1}\times 0.724=0.724mol of aspirin.

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.

4 0
3 years ago
Is the law of conservative mass observed in this equation CaCO3 + 2HCI --&gt;CaCI2 +H2O + CO2
pychu [463]

Answer:

The law is observed in the given equation.

Explanation:

CaCO₃ + 2HCI → CaCI₂ +H₂O + CO₂

In order to find out if the law of conservative mass is followed, we need to <u>count how many atoms of each element are there in both sides of the equation</u>:

  • Ca ⇒ 1 on the left, 1 on the right.
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As the numbers for all elements involved are the same, the law is observed in the given equation.

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Answer:

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Explanation:

Let y represent the number of moles present

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Hence, 0.049 moles of Ba(OH)2 contains y moles of OH- ions.

To get the y moles, we then do cross multiplication

1 mole *  y mole = 2 moles * 0.049 mole

y mole = 2 * 0.049 / 1

y mole =  0.098 moles of OH- ions.

1 mole of OH- can neutralize 1 mole of H+

Therefore, 0.098 moles of HNO₃ are present.

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