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Ray Of Light [21]
2 years ago
15

A radioactive element reduces to 5.00% of its initial mass in

Chemistry
1 answer:
Stolb23 [73]2 years ago
8 0

The half-life in months of a radioactive element that reduce to 5.00% of its initial mass in 500.0 years is approximately 1389 months

To solve this question, we'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:

Amount remaining (N) = 5%

Original amount (N₀) = 100%

<h3>Number of half-lives (n) =?</h3>

N₀ × 2ⁿ = N  

5 × 2ⁿ = 100

2ⁿ = 100/5

2ⁿ = 20

Take the log of both side

Log 2ⁿ = log 20

nlog 2 = log 20

Divide both side by log 2

n = log 20 / log 2

<h3>n = 4.32</h3>

Thus, 4.32 half-lives gas elapsed.

Finally, we shall determine the half-life of the element. This can be obtained as follow.

Number of half-lives (n) = 4.32

Time (t) = 500 years

<h3>Half-life (t½) =? </h3>

t½ = t / n

t½ = 500 / 4.32

t½ = 115.74 years

Multiply by 12 to express in months

t½ = 115.74 × 12

<h3>t½ ≈ 1389 months </h3>

Therefore, the half-life of the radioactive element in months is approximately 1389 months

Learn more: brainly.com/question/24868345

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Yeast converts glucose to ethanol and carbon dioxide during a process known as anaerobic fermentation. The chemical reaction is
Korolek [52]

Answer:

102g

Explanation:

To find the mass of ethanol formed, we first need to ensure that we have a balanced chemical equation. A balanced chemical equation is where the number of atoms of each element is the same on both sides of the equation (reactants and products). This is useful as only when a chemical equation is balanced, we can understand the relationship of the amount (moles) of reactant and products, or to put it simply, their relationship with one another.

In this case, the given equation is already balanced.

\tex{C_6H_{12}O_6} \longrightarrow 2 \ C_2H_6O + 2 \ CO_2

From the equation, the amount of ethanol produced is twice the amount of yeast present, or the same amount of carbon dioxide produced. Do note that amount refers to the number of moles here.

Mole= Mass ÷Mr

Mass= Mole ×Mr

<u>Method 1: using the </u><u>mass of glucose</u>

Mr of glucose

= 6(12) +12(1) +6(16)

= 180

Moles of glucose reacted

= 200 ÷180

= \frac{10}{9} mol

Amount of ethanol formed: moles of glucose reacted= 2: 1

Amount of ethanol

= 2(\frac{10}{9} )

= \frac{20}{9} mol

Mass of ethanol

= \frac{20}{9} \times[2(12)+6+16]

= \frac{20}{9}(46)

= 102 g (3 s.f.)

<u>Method 2: using </u><u>mass of carbon dioxide</u><u> produced</u>

Mole of carbon dioxide produced

= 97.7 ÷[12 +2(16)]

= 97.7 ÷44

= \frac{977}{440} mol

Moles of ethanol: moles of carbon dioxide= 1: 1

Moles of ethanol formed= \frac{977}{440} mol

Mass of ethanol formed

= \frac{977}{440} \times[2(12)+6+16]

= 102 g (3 s.f.)

Thus, 102 g of ethanol are formed.

Additional:

For a similar question on mass and mole ratio, do check out the following!

  • brainly.com/question/1685725
8 0
2 years ago
A chemist must dilute 34.3mL of 1.72mM aqueous calcium sulfate solution until the concentration falls to 1.00mM. He'll do this b
EastWind [94]

Answer:

58.9mL

Explanation:

Given parameters:

Initial volume  = 34.3mL    = 0.0343dm³

Initial concentration  = 1.72mM   = 1.72 x 10⁻³moldm⁻³

Final concentration  = 1.00mM = 1 x 10⁻³ moldm⁻³

Unknown:

Final volume  =?

Solution:

Often times, the concentration of a standard solution may have to be diluted to a lower one by adding distilled water. To find the find the final volume, we must recognize that the number of moles of the substance in initial and final solutions are the same.

   Therefore;

              C₁V₁  =  C₂V₂

where C and V are concentration and 1 and 2 are initial and final states.

        now input the variables;

                      1.72 x 10⁻³ x  0.0343 = 1 x 10⁻³  x V₂

                        V₂ = 0.0589dm³ = 58.9mL

         

4 0
3 years ago
The elements least likely to form bonds are found in which group? 15, 16, 17, 18
Ipatiy [6.2K]

Answer:

D.18

Explanation:

Edgenuity

3 0
3 years ago
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An infectious disease is _____.
e-lub [12.9K]

Answer: caused by organismis

Explanation:

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3 years ago
On the basis of electronegativity, which of these pairs of elements is most likely to form monatomic ions?
mixer [17]

Answer is: Cl and Na.

sodium and chlorine are in third period and they have very different properties. Sodium is solid metal and chlorine is gaseous nonmetal.

They form compound NaCl (Sodium chloride), because sodium lost one valence electron and form cation Na⁺, chlorine gain one electron and form anion Cl⁻.

Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.

Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.

Other examples are metal-metal pairs and they do not form cation and anion.

8 0
3 years ago
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