CHEMISTRY HIGH SCHOOL

An igneous rock originally has 3 grams of uranium 238 in it. When dated the rock only contains 1.8 grams. What are the parent and daughter concentrations (in percentages) and what is its age?

Answers

Answer 1

Answer:

Answer :

The parent and daughter concentrations (in percentages) is, 60 % and 40 % respectively.

The age of rock is $3.32* 10^9\text{ years}$

Explanation :

First we have to calculate the parent and daughter concentrations (in percentages).

$\text{Parent concentrations}=(1.8g)/(3g)* 100=60\%$

and,

$\text{Daughter concentrations}=((3-1.8)g)/(3g)* 100=40\%$

As we know that, the half-life of uranium-238 = $4.5* 10^9$ years

Now we have to calculate the rate constant, we use the formula :

$k=(0.693)/(t_(1/2))$

$k=\frac{0.693}{4.5* 10^9\text{ years}}$

$k=1.54* 10^(-10)\text{ years}^(-1)$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=(2.303)/(k)\log(a)/(a-x)$

where,

k = rate constant = $1.54* 10^(-10)\text{ years}^(-1)$

t = time passed by the sample = ?

a = initial amount of the reactant = 3 g

a - x = amount left after decay process = 1.8 g

Now put all the given values in above equation, we get

$t=(2.303)/(1.54* 10^(-10))\log(3)/(1.8)$

$t=3.32* 10^9\text{ years}$

Therefore, the age of rock is $3.32* 10^9\text{ years}$

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Dalton’s Law CalculationA mixture of H₂, N₂ and Ar gases is present in a steel cylinder. The total pressure within the cylinder is 675 mm Hg and the partial pressures of N₂ and Ar are, respectively, 354 mm Hg and 235 mm Hg. If CO₂ gas is added to the mixture, at constant temperature, until the total pressure reaches 842 mm Hg, what is the partial pressure, in mm Hg, of the following?A) CO₂, 167 B) N₂, 354 C) Ar, 235 D) H₂, 8629

Answers

Answer:

A) The partial presssure of CO₂ is 167 mm Hg

B) The partial presssure of N₂ is 354 mm Hg

C) The partial presssure of Ar is 235 mm Hg

D) The partial presssure of H₂ is 86 mm Hg

Explanation:

Dalton's law of partial pressures is basically expressed by the following statement:

The total pressure of a mixture is equal to the sum of the partial pressures of its components.

So initially we have:

$P_(T)$ = total presure of the system (675 mm Hg).

$P_(N_2)$ = partial pressure of N₂ (354 mm Hg).

$P_(Ar)$ = partial pressure of Ar (235 mm Hg).

Using Dalton's law we can find the partial pressure of H₂:

$P_(T)=P_(N_2)+P_(Ar)+P_(H_2)$

675 mm Hg=354 mm Hg + 235 mm Hg + $P_(H_2)$

$P_(H_2)$ = 675 mm Hg - 354 mm Hg - 235 mm Hg

$P_(H_2)$ =86 mm Hg

If CO₂ gas is added to the mixture, at constant temperature, and the volume is the same, the difference between the new total pressure and the previous total pressure is equal to the partial pressure of CO₂.

$P_(T)=P_(N_2)+P_(Ar)+P_(H_2)+P_(CO_2)$

842 mm Hg= 354 mm Hg + 235 mm Hg + 86 mm Hg + $P_(CO_2)$

$P_(CO_2)$ = 842 mm Hg - 354 mm Hg - 235 mm Hg - 86 mm Hg

$P_(CO_2)$ = 167 mm Hg

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Good Morning

Answer : A particle that orbits the nucleus in an atom is called an Electron

Hint : Electron, negatively charged particle orbiting the nucleus. Same number as protons in neutral atoms

I hope that's help !

Happy Sunday :)

This would be a proton.It has a positive charge and is found in the nucleus. Don't get it confused with an electron this is not inside the nucleus but floats around the nucleus.

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Answers

Below are the choices:

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The independent variable is the amount of energy available, and the dependent variable is the number of dry cells.

I think the answer is The independent variable is the number of dry cells, and the dependent variable is the amount of energy available.

Answer:

im not sure about the answer but i did the test and "The independent variable is the number of dry cells, and the dependent variable is the amount of energy available."is wrong

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Answers

Answer:

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Ionization energy is your answer I just took the test and passed

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Answers

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