Which of the following equations represents a double-displacement reaction?

How do you figure out sub shells please i need help

Tanya [424]

For any given shell the number of subshells can be found by l = n -1. This means that for n = 1, the first shell, there is only l = 1-1 = 0 subshells.

3 0

3 years ago

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 an

castortr0y [4]

Answer :

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

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

Explanation :

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

$\text{Parent concentrations}=\frac{1.8g}{3g}\times 100=60\%$

and,

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

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

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

$k=\frac{0.693}{t_{1/2}}$

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

$k=1.54\times 10^{-10}\text{ years}^{-1}$

Now we have to calculate the time passed.

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

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.54\times 10^{-10}\text{ years}^{-1}$

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

$t=\frac{2.303}{1.54\times 10^{-10}}\log\frac{3}{1.8}$

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

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

5 0

3 years ago

What is the chemistry of acid and base

dexar [7]

Answer:

Of what?

Explanation:

But uhh: An acid is a substance that donates protons or accepts a pair of valence electrons to form a bond. Bases can be thought of as the chemical opposite of acids.

4 0

3 years ago

How many calories of heat are necessary to raise the temperature of 378.2 g of water from 32.2 oC to the boiling point?

ivolga24 [154]

Answer: multiple apply them together then divide them

Explanation:

8 0

3 years ago

Rank the following gases in order of decreasing rate of effusion. Rank from the highest to lowest effusion rate. To rank items a

Alinara [238K]

Answer:

H2, He, PH3, F2, C5H10

Explanation:

From Graham's law, we understood that lighter gas will diffuse faster than heavier gas under same condition. Graham's law of diffusion states as follow:

The rate (R) of diffusion of a gas is inversely proportional to the square root of its density (D) provided temperature and pressure remains constant. Mathematically, it is represented as:

R & 1/√D

Recall:

Molar Mass (M) = 2 x vapour density (D)

M = 2D

R & 1/√M

From the above, we can see that the rate is inversely proportional to the square root of the molar mass of substance. This implies that lighter gas will diffuse faster.

Now, to rank the above from the highest to rate rate of effusion, let us determine the molecular weight of each substance. This is illustrated below:

Molar Mass of F2 = 19 x 2 = 38g/mol

Molar Mass of He = 4g/mol

Molar Mass of C5H10 = (12X5) + (10X1) = 70g/mol

Molar Mass of H2 = 2x1 = 2g/mol

Molar Mass of PH3 = 31 + (3x1) = 34g/mol

Now, we can rank the substance beginning from the highest to the lowest rate of effusion as follow:

Substance >> Molar Mass >> Rank

H2 >>>>>>>>> 2g/mol >>>>>> 1

He >>>>>>>>> 4g/mol >>>>>> 2

PH3 >>>>>>>> 34g/mol >>>>> 3

F2 >>>>>>>>>> 38g/mol >>>> 4

C5H10 >>>>>> 70g/mol >>>> 5

3 0

3 years ago