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3 years ago

Calculate the energy of the lasers in a Blu-ray player, which emit at a wavelength of 4.05x10−7 m.

Chemistry

1 answer:

Komok [63]3 years ago

4 0

Answer:

4.907 × 10^-19 J

Explanation:

The energy of the lasers in a Blu-ray player can be calculated by using;

E = hf

Where;

E = Energy of laser (J)

h = Planck's constant (6.626 × 10^-34 J/s)

f = frequency (Hz)

However, the frequency must be known first in order to calculate the energy. The frequency can be calculated using the formula:

f = v/λ

Where:

λ = wavelength (4.05x10−7 m.)

v = speed of light (3 × 10^8m/s)

f = frequency (Hz)

f = 3 × 10^8 ÷ 4.05 x 10^−7

f = 0.7407 × 10^(8 + 7)

f = 0.7407 × 10^15

f = 7.407 × 10^14 Hz

Using E = hf

E = 6.626 × 10^-34 × 7.407 × 10^14

E = 49.07 × 10^(-34 + 14)

E = 49.07 × 10^-20

E = 4.907 × 10^-19 J

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Which sample of matter is classified as a solution? 1. H2O(s) 2. H2O(l) 3. CO2(g) 4. CO2(aq)

lys-0071 [83]

Answer : Option 4) $CO_{2}_{(aq)}$

Explanation : $CO_{2}_{(aq)}$ is the only sample of matter which can be classified as a solution. As the solution can be defined as a liquid mixture which contains a minor component (the solute) that is uniformly distributed within the major component (the solvent).

In this case, the solute is $CO_{2}$ which is dissolved in water which acts as an solvent. Also, it has a subscript which is aq. which means aqueous, is often given to the solution in which the solvent is water.

Therefore, $CO_{2}_{(aq)}$ is the correct answer.

4 0

3 years ago

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Hardness in groundwater is due to the presence of metal ions, primarily Mg2 and Ca2 . Hardness is generally reported as ppm CaCO

Maslowich

Answer:

0.0144 M

1440 ppm

Explanation:

Ca(In)²⁺ + EDTA → Ca(EDTA)²⁺ + In

We use the volume of EDTA consumed in the titration to calculate the moles of Ca⁺² ions:

0.012 L * 0.0600 M * $\frac{1molCa^{+2}}{1molEDTA}$ = 7.20x10⁻⁴ mol Ca⁺²

Now we calculate the molarity:

7.20x10⁻⁴ mol Ca⁺² / 0.050 L = 0.0144 M

To calculate in ppm, we use the moles of Ca⁺² and convert to mg of CaCO₃:

7.20x10⁻⁴ mol Ca⁺² = 7.20x10⁻⁴ mol CaCO₃

7.20x10⁻⁴ mol CaCO₃ * 100g/mol * $\frac{1000mg}{1g}$ = 72 mg CaCO₃

Finally, the concentration in ppm is:

72 mg CaCO₃ / 0.050L = 1440 ppm

5 0

2 years ago

7. How many liters of NH3, at STP will react with 10.6 g O2 to form NO2 and water? 4NH3(g) + 7O2(g) → 4NO2(g) + 6H2O(g) *

Alexus [3.1K]

7) Answer is: c. 4.24 L.

Balanced chemical reaction: 4NH₃(g) + 7O₂(g) → 4NO₂(g) + 6H₂O(g).

m(O₂) = 10.6 g; mass of oxygen.

n(O₂) = m(O₂) ÷ M(O₂).

n(O₂) = 10.6 g ÷ 32 g/mol.

n(O₂) = 0.33 mol; amount of oxygen.

Vm = 22.4 L/mol; molar volume at STP (Standard Temperature and Pressure).

At STP one mole of gas occupies 22.4 liters of volume.

V(O₂) = n(O₂) · Vm.

V(O₂) = 0.33 mol · 22.4 L/mol.

V(O₂) = 7.42 L; volume of oxygen.

From balanced chemical reaction: n(O₂) : n(NH₃) = 7 : 4.

n(NH₃) = 4 · 0.33 mol ÷ 7.

n(NH₃) = 0.188 mol; amount of ammonia.

V(NH₃) = 0.188 mol · 22.4 L/mol.

V(NH₃) = 4.24 L.

8) Answer is: a. 3.7 g.

Balanced chemical reaction: P₄(g) + 6H₂(g) → 4PH₃(g).

m(P₄) = 3.4 g; mass of phosphorous.

n(P₄) = m(P₄) ÷ M(P₄).

n(P₄) = 3.4 g ÷ 123.9 g/mol.

n(P₄) = 0.0274 mol; limiting reactant.

n(H₂) = 4 g ÷ 2 g/mol.

n(H₂) = 2 mol; amount of hydrogen.

From balanced chemical reaction: n(P₄) : n(PH₃) = 1 : 4.

n(PH₃) = 4 · 0.0274 mol.

n(PH₃) = 0.1096 mol.

m(PH₃) = 0.1096 mol · 34 g/mol.

m(PH₃) = 3.726 g.

9) Answer is: d. Percent yield is the ratio of theoretical yield to actual yield expressed as a percent.

Percent yield = actual yield / theoretical yield.

Theoretical yield is the maximum amount of product that can be produced from limiting reactant and actual yield is a product that is obtained by experimentation.

For example:

the percent yield = 250 g ÷ 294.24 g · 100%.

the percent yield = 84.5 %.

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3 years ago

Show your calculation by uploading a picture. Calculate the molar mass of ammonia, NH3

Cloud [144]

Answer:

17.04 g/mol

Explanation:

Molar Mass of NH₃

we know that

Nitrogen has 14.01 gram/mol

And Hydrogen has 1.01 gram/mol

but we have 3 Hydrogens So we multiply

1.01 by 3 i.e., 3.03

Now, add

14.01

+ 3.03

17.04

So, The molar mass of ammonia, NH₃ is

17.04 g/mol

-TheUnknownScientist

5 0

3 years ago

How is electromagnetic energy fromthe microwave transformed into heat energy

zysi [14]

Answer:

First, the microwaves transmit kinetic energy to the water molecules of the food, heating the water molecules. Only, those that are not very deep into the food.

Second, the hot water molecules transmit heat by conduction to the other parts of the food.

Explanation:

1) Microwaves are a form of electromagnetic radiation. The same as any wave, they carry energy.

2) The wave length of microwaves are in the range of 0.001 mm to 1 m (shorter than radio waves and longer than infrared)

3) The microwaves of an oven, used to heat food, have a wave length aroun 12 cm.

4) The microwaves transmit energy to the water molecules in the food, by increasing the kinetic energy of water molecules. As result, the water molecules get hotter. Microwaves only penetrate about 1 cm inside the food (a potato for example) and from that the heat is transferred by conduction to the inner parts of the food.

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3 years ago

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