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3 years ago

Just those 2 questions on the picture please ASAP

Chemistry

1 answer:

natka813 [3]3 years ago

5 0

7. Tungsten is a conductor, the rest listed are insulators.

8. Thermal Energy

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Hydrogen atoms absorb energy so that the electrons are excited to n=4. Calculate the wavelength, in

FromTheMoon [43]

Answer:

the wavelength, in nm, of the photon is 487.5 nm

Explanation:

Given:

n = 4 (excited)

n = 2 (relaxes)

Question: Calculate the wavelength, in nm, λ = ?

First, it is important to calculate the energy of the electron when it excited and then when it relaxes.

$E_{1} =\frac{-13.6}{n^{2} } =\frac{-13.6}{4^{2} } =-0.85eV$ (excited)

$E_{2} =\frac{-13.6}{2^{2} } =-3.4eV$ (relaxes)

The change of energy

ΔE = E₁ - E₂=-0.85 - (-3.4) = 2.55 eV = 4.08x10⁻¹⁹J

For a photon, the wavelength emitted

$\lambda =\frac{hc}{delta(E)}$

Here

h = Planck's constant = 6.63x10⁻³⁴J s

c = speed of light = 3x10⁸m/s

Substituting values:

$\lambda =\frac{6.63x10^{-34}*3x10^{8} }{4.08x10^{-19} } =4.875x10^{-7} m=487.5nm$

8 0

3 years ago

How many grams of CO are needed to react with an excess of Fe2O3 to produce (210.3 g Fe) 209.7 g Fe? Show your work.

Fed [463]

Explanation:

$3CO(g)+Fe_2O_3(s)\rightarrow 2Fe(s)+3CO_2(g)$

1)Mass of CO when 210.3 g of Fe produced.

Number of moles of $Fe$ in 210.3 g=

$\frac{\text{Given mass of Fe}}{\text{Molar mass of Fe}}$

$=\frac{210.3}{55.84 g/mol}=3.76 mol$

According to reaction, 2 moles of Fe are obtained from 3 moles of CO, then 3.76 moles of Fe will be obtained from : $\frac{3}{2}\times 3.76 moles$ of CO that is 5.64 moles.

Mass of CO in 5.64 moles =

$\text{Number of moles}\times \text{molar mass of CO}=5.46\times 28 g/mol=157.92 g$

2)Mass of CO when 209.7 g of Fe produced.

Number of moles of $Fe$ in 209.7 g=

$\frac{\text{Given mass of Fe}}{\text{Molar mass of Fe}}$

$=\frac{209.7}{55.84 g/mol}=3.75 mol$

According to reaction, 2 moles of Fe are obtained from 3 moles of CO, then 3.75 moles of Fe will be obtained from : $\frac{3}{2}\times 3.75 moles$ of CO that is 5.625 moles.

Mass of CO in 5.625 moles =

$\text{Number of moles}\times \text{molar mass of CO}=5.625\times 28 g/mol=157.5 g$

4 0

3 years ago

Read 2 more answers

The ease with which the charge distribution in a molecule can be distorted by an external electric field is called the___. A) el

muminat

Answer:

Question 1

C) polarizability

Question 2

C) London dispersion forces

Question 3:

D)Kr

Question 4:

E) strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other

4 0

3 years ago

4. The volume of a sample of a gas at STP is 200.0 ml. If the pressure is increased to 4.00 atmospheres (temperature constant),

Elina [12.6K]

Answer : The value of new volume is, 50.0 mL

Explanation :

Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

$P\propto \frac{1}{V}$

or,

$P_1V_1=P_2V_2$

where,

$P_1$ = initial pressure at STP = 1 atm

$P_2$ = final pressure = 4.00 atm

$V_1$ = initial volume at STP = 200.0 mL

$V_2$ = final volume = ?

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

$1atm\times 200.0mL=4.00atm\times V_2$

$V_2=50.0mL$

Therefore, the value of new volume is, 50.0 mL

6 0

4 years ago

What happened when bromine reacted with aluminum?

-Dominant- [34]

Answer:

The reaction begins and builds up heat. This heat causes the aluminum to melt and float on top of the liquid bromine. Wherever the two elements meet, sparks, heat, and light are given off.

Explanation:

4 0

3 years ago