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3 years ago

The half-life of francium-212 is 19 minutes. How many minutes will it take for 100 gram

Chemistry

1 answer:

vagabundo [1.1K]3 years ago

7 0

Answer:

57 mins

Explanation:

From the question given above, the following data were obtained:

Half life (t₁/₂) = 19 mins

Original amount (N₀) = 100 g

Amount remaining (N) = 12.5 g

Time (t) =?

Next, we shall determine the number of half-lives (n) that wound have elapse for 12.5 g of the sample to remain. This can be obtained as follow:

Original amount (N₀) = 100 g

Amount remaining (N) = 12.5 g

Number of half-lives (n) =?

N = 1/2ⁿ × N₀

12.5 = 1/2ⁿ × 100

Cross multiply

12.5 × 2ⁿ = 100

Divide both side by 12.5

2ⁿ = 100 /12.5

2ⁿ = 8

Express 8 index with 2 as the base

2ⁿ = 2³

n = 3

Finally, we shall determine the time taken for 100 g of the isotope to decay to 12.5 g. This can be obtained as follow:

Half life (t₁/₂) = 19 mins

Number of half-lives (n) = 3

Time (t) =?

t = n × t₁/₂

t = 3 × 19

t = 57 mins

Thus, it will take 57 mins 100 g of the isotope to decay to 12.5 g.

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If 45 mL of a 6 M solution is diluted to a final volume of 250 mL, what is concentration of the final solution?

Andrew [12]

Answer:

1.08 M

Explanation:

From the question given above, the following data were obtained:

Initial volume (V₁) = 45 mL

Initial concentration (C₁) = 6 M

Final volume (V₂) = 250 mL

Final concentration (C₂) =?

The final concentration of the solution can be obtained by using the dilution formula as illustrated below:

C₁V₁ = C₂V₂

6 × 45 = C₂ × 250

270 = C₂ × 250

Divide both side by 250

C₂ = 270 / 250

C₂ = 1.08 M

Therefore, the final concentration of the solution is 1.08 M.

5 0

3 years ago

1. A sulfur atom has 16 protons, 18 neutrons, and 16

Gnom [1K]

Answer:

b. 16 protons, 18 neutrons, and 18 electrons

Explanation:

Things to be remembered

Negative charge on any ionic species indicates gained the electrons

Positive charge on any ionic species indicates lost the electrons

A sulfur atom has 16 protons, 18 neutrons, and 16 electrons, A sulfide ion has a 2– charge which indicates that sulphur has gained two electron from any other atom, ion or species!

Thanks for joining brainly community!

8 0

3 years ago

Read 2 more answers

Balance each of the following in BASE: Show work

kupik [55]

Answer : The balanced chemical equation in a basic solution are,

(A) $2CrO_4^{2-}+8H_2O+3Cu\rightarrow 2Cr(OH)_3+4OH^-+3Cu(OH)_2$

(B) $2NO_2+2OH^-\rightarrow NO_3^-+H_2O+NO_2^-$

(C) $4Zn+7OH^-+NO_3^-+6H_2O\rightarrow 4[Zn(OH)_4]^{2-}+NH_3$

(D) $Br_2+12OH^-+5Br_2\rightarrow 2BrO_3^-+6H_2O+10Br^-$

Explanation :

(A) The given chemical reaction is :

$CrO_4^{2-}(aq)+Cu(s)\rightarrow Cr(OH)_3(s)+Cu(OH)_2(s)$

The oxidation-reduction half reaction will be :

Oxidation : $Cu\rightarrow Cu^{2+}+2e^-$

Reduction : $CrO_4^{2-}+4H_2O+3e^-\rightarrow Cr^{3+}+8OH^-$

In order to balance the electrons, we multiply the oxidation reaction by 3 and reduction reaction by 2 then added both equation, we get the balanced redox reaction.

The balanced chemical equation in a basic solution will be,

$2CrO_4^{2-}+8H_2O+3Cu\rightarrow 2Cr^{3+}+16OH^-+3Cu^{2+}$