All categories

3 years ago

22. Radon has a half-life of 3.83 days. How long will it take a 225 g sample to decay to 14.06 g? (3pts.)

Chemistry

1 answer:

prohojiy [21]3 years ago

8 0

Answer:

15.32 days

Explanation:

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

Half-life (t½) = 3.83 days

Original amount (N₀) = 225 g

Amount remaining (N) = 14.06 g

Time (t) =.?

Next, we shall determine the number of half-lives that has elapsed. This can be obtained as follow:

Original amount (N₀) = 225 g

Amount remaining (N) = 14.06 g

Number of half-lives (n) =?

N = N₀ / 2ⁿ

14.06 = 225 / 2ⁿ

Cross multiply

14.06 × 2ⁿ = 225

Divide both side by 14.06

2ⁿ = 225 / 14.06

2ⁿ = 16

Express 16 in index form with 2 as the base

2ⁿ = 2⁴

n = 4

Thus, 4 half-lives has elapsed.

Finally, we shall determine the time. This can be obtained as follow:

Half-life (t½) = 3.83 days

Number of half-lives (n) = 4

Time (t) =.?

n = t / t½

4 = t / 3.83

Cross multiply

t = 4 × 3.83

t = 15.32 days

Therefore the time for 225 g sample of Radon to decay to 14.06 g is 15.32 days

You might be interested in

A 2.500g sample of compound containing only Carbon and Hydrogen is found containing 2.002g of Carbon. Determine the empirical fo

Dima020 [189]

The empirical formula : CH₃

<h3>Further explanation</h3>

Given

2.5 g sample

2.002 g Carbon

Required

The empirical formula

Solution

Mass of Hydrogen :

= 2.5 - 2.002

= 0.498

Mol ratio C : H :

C : 2.002/12 = 0.167

H : 0.498/1 = 0.498

Divide by 0.167 :

C : H = 1 : 3

7 0

2 years ago

Planet A is an inner planet with no moon and hardly any atmosphere. Planet B is an inner planet with no moon but with a dense at

postnew [5]

I think the answers are Mars and Venus

7 0

3 years ago

Where was cell theory discovered ?

SVEN [57.7K]

Cell theory was discovered from the scientist

8 0

3 years ago

Explain why energy has to be supplied to turn a liquid into a gas

jeka94

Answer:

heat energy are absorbed by water molecules and it is used to change the molecules from liquid to gas? if thats what your asking.

Explanation:

7 0

3 years ago

Calculate the standard reaction Gibbs free energy for the following cell reactions: (a) 2 Ce41(aq) 1 3 I2(aq) S 2 Ce31(aq) 1 I32

Law Incorporation [45]

Answer:

For a: The standard Gibbs free energy of the reaction is -347.4 kJ

For b: The standard Gibbs free energy of the reaction is 746.91 kJ

Explanation:

Relationship between standard Gibbs free energy and standard electrode potential follows:

$\Delta G^o=-nFE^o_{cell}$ ............(1)

For a:

The given chemical equation follows:

$2Ce^{4+}(aq.)+3I^{-}(aq.)\rightarrow 2Ce^{3+}(aq.)+I_3^-(aq.)$

Oxidation half reaction: $Ce^{4+}(aq.)\rightarrow Ce^{3+}(aq.)+e^-$ ( × 2)

Reduction half reaction: $3I^_(aq.)+2e^-\rightarrow I_3^-(aq.)$

We are given:

$n=2\\E^o_{cell}=+1.08V\\F=96500$

Putting values in equation 1, we get:

$\Delta G^o=-2\times 96500\times (+1.80)=-347,400J=-347.4kJ$

Hence, the standard Gibbs free energy of the reaction is -347.4 kJ

For b:

The given chemical equation follows:

$6Fe^{3+}(aq.)+2Cr^{3+}+7H_2O(l)(aq.)\rightarrow 6Fe^{2+}(aq.)+Cr_2O_7^{2-}(aq.)+14H^+(aq.)$

Oxidation half reaction: $Fe^{3+}(aq.)\rightarrow Fe^{2+}(aq.)+e^-$ ( × 6)

Reduction half reaction: $2Cr^{2+}(aq.)+7H_2O(l)+6e^-\rightarrow Cr_2O_7^{2-}(aq.)+14H^+(aq.)$

We are given:

$n=6\\E^o_{cell}=-1.29V\\F=96500$

Putting values in equation 1, we get:

$\Delta G^o=-6\times 96500\times (-1.29)=746,910J=746.91kJ$

Hence, the standard Gibbs free energy of the reaction is 746.91 kJ

7 0

3 years ago