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3 years ago

How to combine elements to make compounds?

1 answer:

6 0

Elements combine to form chemical compounds that are often divided into two categories. Metals often react with nonmetals to form ionic compounds. These compounds are composed of positive and negative ions formed by adding or subtracting electrons from neutral atoms and molecules.

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- a) write the formula unit of calcium fluoride.

8090 [49]

Answer:

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3 years ago

Why are animals so impportant to our lifes

ivann1987 [24]

Answer:

Animals are important because without them we wouldnt have any food

Explanation:

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2 years ago

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Electronic transitions (i.e., absorption of uv or visible light) of the conjugated molecule butadiene can be approximated using

dlinn [17]

Answer:

2.51 Angstroms

Explanation:

For a particle in a one dimensional box, the energy level, En, is given by the expression:

En = n²π² ħ² / 2ma²

where n is the energy level, ħ² is Planck constant divided into 2π, m is the mass of the electron ( 9.1 x 10⁻³¹ Kg ), and a is the length of the one dimensional box.

We can calculate the change in energy, ΔE, from n = 2 to n= 3 since we know the wavelength of the transition ( ΔE = h c/λ ) and then substitute this value for the expresion of the ΔE for a particle in a box and solve for the length a.

λ = 207 nm x 1 x 10⁻⁹ m/nm = 2.07 x 10⁻⁷ m ( SI units )

ΔE = 6.626 x 10⁻³⁴ J·s x 3 x 10⁸ m/s / 2.07 x 10⁻⁷ m

ΔE = 9.60 x 10⁻¹⁹ J

ΔE(2⇒3) = ( 3 - 2 ) x π² x ( 6.626 x 10⁻³⁴ J·s / 2π )² / ( 2 x 9.1 x 10⁻³¹ Kg x a² )

9.60 x 10⁻¹⁹ J = π² x( 6.626 x 10⁻³⁴ J·s / 2π )² / ( 2 x 9.1 x 10⁻³¹ Kg x a² )

⇒ a = 2.51 x 10⁻¹⁰ m

Converting to Angstroms:

a = 2.51 x 10⁻¹⁰ m x 1 x 10¹⁰ Angstrom / m = 2.51 Angstroms

6 0

4 years ago

A sample of gas occupies 6. 8 L at 327 c what will be it volume at 27 c if the pressure and number of particles do not change

Vitek1552 [10]

A sample of gas occupies 6. 8 L at 327 c and the volume at 27 c if the pressure and number of particles do not change is 3.401 L.

<h3>What is volume?</h3>

Volume is a measurement of the three-dimensional space that is occupied. Numerous imperial units or the SI-derived units, such as the cubic meter and liter, are frequently used to quantify it numerically (such as the gallon, quart, cubic inch). Volume and the length (cubed) have a symbiotic relationship. The volume of a container is typically thought of as its capacity, not as the amount of the space it takes up. In the other words, the volume is the amount of fluid (liquid or gas) that the container may hold.

Volume was initially measured using naturally occurring vessels of a comparable shape and then with standardized containers. Arithmetic formulas can be used to quickly calculate the volume of the several straightforward three-dimensional shapes. If a formula for shape's boundary is known, it is possible to use integral calculus to determine the volumes of more complex shapes. No object in dimensions of zero, one, or two has volume; in the dimensions of four and above, the hypervolume is a concept similar to the standard volume.

In solving the any gas law problems, kelvin temperature will be used.

kelvin = degree celsius + 273.15

Kelvin = 327 + 273.15

= 600.15 K

Kelvin = 27 + 273.15

= 300.15 K

Given Data;

$V_{1}$ (the initial volume) = 6.8 L $V_{2}$ (the final volume) = ? unknown

$T_{1}$ (the initial temperature = 327 °C $T_{2}$ (the final temperature) = 27 °C

=( 600.15 K) = (300.15 K)

This problem can be solve using the Charles' Law which states that volume is directly proportional to kelvin temperature of gases if amount of gas and pressure are constant. If the temperature decreases, volume decreases.

Formula of the Charles' Law is $\frac{V_{1} }{T_{1} }= \frac{V_{2} }{T_{2} }$

To solve for V2, we can used formula $V_{2} =\frac{V_{1}T_{2} }{T_{1} }$

$V_{2} =\frac{V_{1}T_{2} }{T_{1} }$

= 6.8 L × 300.15 K / 600.15 K (cancel the unit kelvin)

= 2041.02 L / 600.15

$V_{2}$ = 3.401 L

Therefore, volume is 3.401 L

To know more about volume visit: brainly.com/question/1578538

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5 0

1 year ago

PLEASE HELP ASAP!!!!!!!!!!!!!!!!!!!!

iris [78.8K]

The answer is D, wavelength

Hope I helped!

7 0

3 years ago