What would cause the liquid in the thermometer to drop?

1 answer:

7 0

The kinetic energy of the water molecules decreases. The motion of the particles in the substance decreases, and the temperature of the substance increases

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serg [7]

13 half-lives have passed

<h3>Further explanation </h3>

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

T = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

t1/2 = 4 days

Nt=18 mg (0.01% of the original isotope)

18 mg (Nt) = 0.01% No

No = the original isotope :

$\tt No=\dfrac{100}{0.01}\times 18~mg=180,000$

The duration of decay (T) :

$\tt \dfrac{Nt}{No}=\dfrac{1}{2}^{T/4}\rightarrow Nt=0.01\%No$

$\tt 0.01\%=\dfrac{1}{2}^{T/4}\\\\10^{-4}=\dfrac{1}{2}^{T/4}\\\\(\dfrac{1}{2})^{13}=\dfrac{1}{2}^{T/4}\\\\13=T/4\rightarrow T=52~days$

Half-lives passed :

$\tt \dfrac{52}{4}=13~half-lives$

3 0

3 years ago

Cl2 + 2KBr - Br2 + 2KCI

marishachu [46]

The molar mass of potassium chloride is 74.5513g/mol, and the molar mass of potassium bromide is 119.002g/mol. You first need to find how many moles are in the given sample, so you divide the mass by the molar mass of potassium bromide. You don’t necessarily need to convert the mole ratio, since both the potassium chloride and potassium bromide have 2 moles in the chemical equation. Lastly, you multiply the moles at this point by the molar mass of potassium chloride, and you get your final answer.

Answer: 222.91g KCl