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garri49 [273]
3 years ago
9

After decaying for 48 hours, l/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this

radioisotope?
Chemistry
1 answer:
ivolga24 [154]3 years ago
3 0

After the first half-life, 1/2 is unchanged. After the 2nd one, 1/4 remains. After the 4th one, 1/16 remains. So you have 4 half-lives in 48 hours, the half-life is thus 12 hours.
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What are the boiling points and freezing points (in oC) of a solution of 50.3 g of I2 in 350 g of chloroform? The kb = 3.63 oC/m
patriot [66]

Answer:

Boiling point: 63.3°C

Freezing point: -66.2°C.

Explanation:

The boiling point of a solution increases regard to boiling point of the pure solvent. In the same way, freezing point decreases regard to pure solvent. The equations are:

<em>Boiling point increasing:</em>

ΔT = kb*m*i

<em>Freezing point depression:</em>

ΔT = kf*m*i

ΔT are the °C that change boiling or freezing point.

m is molality of the solution (moles / kg)

And i is Van't Hoff factor (1 for I₂ in chloroform)

Molality of 50.3g of I₂ in 350g of chloroform is:

50.3g * (1mol / 253.8g) = 0.198 moles in 350g = 0.350kg:

0.198 moles / 0.350kg = 0.566m

Replacing:

<em>Boiling point:</em>

ΔT = kb*m*i

ΔT = 3.63°C/m*0.566m*1

ΔT = 2.1°C

As boiling point of pure substance is 61.2°C, boiling point of the solution is:

61.2°C + 2.1°C = 63.3°C

<em>Freezing point:</em>

ΔT = kf*m*i

ΔT = 4.70°C/m*0.566m*1

ΔT = 2.7°C

As freezing point is -63.5°C, the freezing point of the solution is:

-63.5°C - 2.7°C = -66.2°C

7 0
3 years ago
In examples where the volume of a system is under constant pressure, which of
grin007 [14]
Answer:

D


Explanation:


At constant volume, the heat of reaction is equal to the change in the internal energy of the system. ... Most chemical reactions occur at constant pressure, so enthalpy is more often used to measure heats of reaction than internal energy.
6 0
3 years ago
How are the carbon, nitrogen, and oxygen cycles different?
k0ka [10]
The CNO cycle<span> (for </span>carbon–nitrogen–oxygen<span>) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the </span>other<span> being the proton–proton chain reaction. Unlike the latter, the CNO </span>cycle<span> is a catalytic </span>cycle<span>.</span>
3 0
3 years ago
Help anyone can help me do this question,I will mark brainlest.​
Anettt [7]

Answer:

12 grams

Explanation:

if  you used the transformation equation  you would end up with 12 grams

4 0
3 years ago
If you fill your car tire to a pressure of 32 psi (pounds per square inch) on a hot summer day when the temperature is 35°C (95°
Murrr4er [49]
By Gay Lussacs law you can find the pressure. First both temperatures of Celsius must change to Kelvin by adding 273. Temperature one will be 308K and temperature 2 will be 258K
With this info, you can now find the pressure with Lussacs law

P1 = P2
— —
T1 T2

Pressure 1 is given which is 32 psi so just plug it all in and find P2

32 = x
—— ——
308 258

308x = 8256 (Cross multiply)

X = 26.8 (divide both sides by 308)

Answer is 26.8 PSI

This makes sense because as temperature increases pressure increases, as well as when temperature decreases, pressure decreases. Since it’s a colder day the pressure will be lower.
4 0
3 years ago
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