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Ivan
2 years ago
5

How long will it take for a 40.0 gram sample of I-131 (half-life = 8.4 days) to decay to 1/16 its original mass?

Chemistry
1 answer:
Shtirlitz [24]2 years ago
6 0

Answer:

42 days

Explanation:

Half life = 8.4 days

Starting mass = 40.0 g

Time = ?

Final Mass = 1/16 * 40 = 2.5 g

First Half life;

Remaining mass = 40 / 2 = 20g

Second Half life;

Remaining mass = 20 / 2 = 10g

Third Half life;

Remaining mass = 10 / 2 = 5g

Fourth Half life;

Remaining mass = 5 / 2 = 2.5g

Time = Number of half lives * Duration of half life = 5 * 8.4 = 42 days

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Find the % composition for each element in Zn(CIO3)2
bezimeni [28]

Zn = 28.15%

Cl = 30.53%

O = 41.32%

<h3>Further explanation</h3>

Given

Zn(CIO3)2 compound

Required

The % composition

Solution

Ar Zn = 65.38

Ar Cl = 35,453

Ar O = 15,999

MW Zn(CIO3)2 = 232.3

Zn = 65,38/232.3 x 100% = 28.15%

Cl = (2 x 35.453) / 232.3 x 100% = 30.53%

O = (6 x 15.999) / 232.3 x 100% = 41.32%

7 0
2 years ago
Hydrogen gas and fluorine gas will react to form hydrogen fluoride gas. What is the standard free energy change for this reactio
Marta_Voda [28]

Answer:

\Delta G=-541.4kJ/mol

Explanation:

Hello there!

In this case, according to the given information, it turns out firstly necessary to write out the described chemical reaction as shown below:

H_2+F_2\rightarrow 2HF

Now, we set up the expression for the calculation of the standard free energy change, considering the free energy of formation of each species, specially those of H2 and F2 which are both 0 because they are pure elements:

\Delta G=2\Delta G_f^{HF}-(\Delta G_f^{H_2}+\Delta G_f^{F_2})\\\\\Delta G=2*-270.70kJ/mol-(0kJ/mol+0kJ/mol)\\\\\Delta G=-541.4kJ/mol

Regards!

4 0
2 years ago
2. A sample of oxygen gas is placed in a rigid 1.5L glass container at STP. If the gas is
sladkih [1.3K]

The new pressure : P₂ = 1038.39 mmHg

<h3>Further explanation</h3>

Given

1.5 L container at STP

Heated to 100 °C

Required

The new pressure

Solution

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure).

So P₁ =  1 atm = 760 mmHg

T₁ = 273 K

T₂ = 100 °C+273 = 373 K

Gay Lussac's Law  

When the volume is not changed, the gas pressure is proportional to its absolute temperature  

\tt \dfrac{P_1}{T_1}=\dfrac{P_2}{T_2}

Input the value :

P₂=(P₁.T₂)/T₁

P₂=(760 x 373)/273

P₂ = 1038.39 mmHg

7 0
2 years ago
HNO3 is an Arrhenius ______________ and increases the concentration of __________ when added to water.
poizon [28]
HNO3 and H2SO4 are Arrhenius acids which will increase the concentration of H+ when dissolved in water.

KOH and Ca(OH)2 are Arrhenius bases that increase the concentration of OH- when dissociated in water.

4 0
3 years ago
Sapphires and Rubies are composed of ? <br>A. olive<br>B. turquoise<br>C. corundum<br>D. quartz​
Aleonysh [2.5K]

Answer:

c

Explanation:

it is corundum now please follow me

8 0
3 years ago
Read 2 more answers
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