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iogann1982 [59]
2 years ago
12

A sample contains 16. 75 g of the radioisotope U-236 and 50. 25 g of its daughter isotope, Th-232. How long did it take for deca

y to take place if one half-life of U-236 is 23 million years? 46 million years 69 million years 92 million years 115 million years.
Chemistry
2 answers:
garri49 [273]2 years ago
8 0

The time taken for the isotope to decay is 46 million years.

We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:

  • Original amount (N₀) = 50.25 g
  • Amount remaining (N) = 16.75
  • Number of half-lives (n) =?

2ⁿ = N₀ / N

2ⁿ = N₀ / N

2ⁿ = 50.25 / 16.75

2ⁿ = 3

Take the log of both side

Log 2ⁿ = 3

nLog 2 = Log 3

Divide both side by log 2

n = Log 3 / Log 2

n = 2

Finally, we shall determine the time.

  • Half-life (t½) = 23 million years
  • Number of half-lives (n) = 2
  • Time (t) =?

t = n × t½

t = 2  × 23

t = 46 million years

Learn more about half-life: brainly.com/question/25927447

nekit [7.7K]2 years ago
3 0

Answer:

A.46 Million years

Explanation:

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How many molecules are in 7.34 g of Na2CO3
kenny6666 [7]

Answer:

The answer is 105.98844.

<h3>Explanation: </h3>

We assume you are converting between grams Na2CO3 and mole. You can view more details on each measurement unit: molecular weight of Na2CO3 or mol This compound is also known as Sodium Carbonate.

7 0
3 years ago
Which of the following is a unit of length? O A. A liter O B. A kilogram C. A meter O D. A degree​
sergeinik [125]

Answer:

C.) A meter

Explanation:

5 0
3 years ago
Titanium is a transition metal used in many alloys because it is extremely strong and lightweight. Titanium tetrachloride (TiCl4
vova2212 [387]

Answer:

a) 226.6 grams of Cl₂

b) 19.2 grams of C

c) 303.2 grams of TiCl₄ and 70.4 grams of CO₂

Explanation:

The balanced chemical reaction is the following:

TiO₂(s) + C(s) + 2 Cl₂(g) → TiCl₄(s) + CO₂(g)

(a) What mass of Cl₂ gas is needed to react with 1.60 mol TiO₂?

From the chemical equation, 1 mol of TiO₂ reacts with 2 moles of Cl₂. So, the stoichiometric ratio is 2 mol Cl₂/1 mol TiO₂. We multiply this ratio by the moles of TiO₂ we have to calculate the moles of Cl₂ we need:

1.60 mol TiO₂ x 2 mol Cl₂/1 mol TiO₂ = 3.2 mol Cl₂

Now, we convert from moles to mass by using the molecular weight (MW) of Cl₂:

MW(Cl₂) = 35.4 g/mol x 2 = 70.8 g/mol

mass of Cl₂= 3.2 mol x 70.8 g/mol = 226.6 g

<em>Therefore, 226.6 grams of Cl₂ are needed to react with 1.6 mol of TiO₂. </em>

(b) What mass of C is needed to react with 1.60 mol of TiO₂?

From the chemical equation, 1 mol of TiO₂ reacts with 1 moles of C(s). So, the stoichiometric ratio is 1 mol C/1 mol TiO₂. We multiply this ratio by the moles of TiO₂ we have to calculate the moles of C(s) we need:

1.60 mol TiO₂ x 1 mol C(s)/1 mol TiO₂ = 1.60 mol C(s)

So, we convert the moles of C(s) to grams as follows:

MW(C) = 12 g/mol

1.60 mol x 12 g/mol = 19.2 g C(s)

<em>Therefore, a mass of 19.2 grams of C is needed to react with 1.60 mol of TiO₂. </em>

(c) What is the mass of all the products formed by reaction with 1.60 mol of TiO₂?

From the chemical equation, we can notice that 1 mol of TiO₂ produces 1 mol of TiCl₄ and 1 mol of CO₂. So, from 1.60 moles of TiO₂, 1 mol of each product will be produced:

1 mol TiO₂/1 mol TiCl₄ ⇒ 1.60 mol TiO₂/1.60 mol TiCl₄

1 mol TiO₂/1 mol CO₂ ⇒ 1.60 mol TiO₂/1.60 mol CO₂

Finally, we convert the moles to grams by using the molecular weight of each compound:

MW(TiCl₄) = 47.9 g/mol Ti + (35.4 g/mol x 4 Cl) = 189.5 g/mol

1.60 mol x 189.5 g/mol = 303.2 g

MW(CO₂) = 12 g/mol C + (16 g/mol x 2 O) = 44 g/mol

1.60 mol x 44 g/mol = 70.4 g

<em>Therefore, from the reaction of 1.60 mol of TiO₂ are formed 303.2 grams of TiCl₄ and 70.4 grams of CO₂.</em>

3 0
3 years ago
How many molecules are in 145.5 grams of Be(OH)2
Zanzabum

Answer:

2.04 x 10²⁴ molecules

Explanation:

Given parameters:

Mass of Be(OH)₂ = 145.5g

To calculate the number of molecules in this mass of Be(OH)₂ we follow the following steps:

>> Calculate the number of moles first using the formula below:

Number of moles = mass/molarmass

Since we have been given the mass, let us derive the molar mass of Be(OH)₂

Atomic mass of Be = 9g

O = 16g

H = 1g

Molar Mass = 9 + 2(16 + 1)

= 9 + 34

= 43g/mol

Number of moles = 145.5/43 = 3.38mol

>>> We know that a mole is the amount of substance that contains Avogadro’s number of particles. The particles can be atoms, molecules, particles etc. Therefore we use the expression below to determine the number of molecules in 3.38mol of Be(OH)₂:

Number of

molecules= number of moles x 6.02 x 10²³

Number of molecules= 3.38 x 6.02 x 10²³

= 20.37 x 10²³ molecules

= 2.04 x 10²⁴ molecules

3 0
3 years ago
Atoms with a low electronegativity,like lithium,have a weak attractive force for electrons because
Murrr4er [49]

Answer:

they're close to filling their outer shell, fulfilling the octet rule

Explanation:

3 0
3 years ago
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