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3 years ago

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A watt is a unit of power or energy per unit time (1 W = 1 J/s). A semiconductor laser in a CD player has an output wavelength o

f 780 nm and a power level of 0.120 mW. How many photons strike the CD surface during the playing of a CD 78 minutes in length?

1 answer:

GREYUIT [131]3 years ago

5 0

Answer:

n = 2.208x10¹⁸ photons

Explanation:

The energy of a photon( an elementary particle) is given by the equation:

E = nxhxf

Where n is the number of photons, h is plank constant (6,62x10⁻³⁴ J.s), and f is the frequency. Knowing that the power level is 0.120mW (1.2x10⁻⁴ W), the energy in J, for a time of 78 min (4680 s)

E = 1.2x10⁻⁴x4680 = 0.5616 J

The frequency of a photon is its velocity ( c= 3x10⁸ m/s) divided by its wavelength, which is 780 nm = 780x10⁻⁹ m

f = 3x10⁸/780x10⁻⁹

f = 3.846x10¹⁴ s⁻¹

Then, the number of photons is:

0.5616 = nx6,62x10⁻³⁴x3.846x10¹⁴

n = 2.208x10¹⁸ photons.

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Water is dissolved into n-butanol (a polar liquid). Which is the second step at the molecular level as water dissolves into n-bu

serg [7]

Answer:

Formation of intermolecular hydrogen bonding between water molecules and molecules of n-butanol

Explanation:

Low molecular weight alcohols are miscible with water in all proportions. The reason for this is that, when a low molecular weight alcohol is dissolved in water, intermolecular hydrogen bonds are formed between the low molecular weight alcohol and water molecules.

Low molecular weight alcohols such as n-butanol contain the polar -OH group which interacts with water via hydrogen bonding.

8 0

3 years ago

Identify the correct coefificients to balance it<br> -C3H8+O2 to -CO2 +-H2O

Iteru [2.4K]

Answer:

${\rm 1\; C_3H_8} + {\rm 5\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}$ .

Explanation:

${\rm ?\; C_3H_8} + {\rm ?\; O_2} \to {?\; \rm CO_2} + {?\; \rm H_2O}$ .

Among the four species in this reaction, $\rm C_3H_8$ is species with the largest number of atoms per molecule. Assume that the coefficient of this compound is $1$ .

${\rm 1\; C_3H_8} + {\rm ?\; O_2} \to {?\; \rm CO_2} + {?\; \rm H_2O}$ .

Number of atoms on the left-hand side of the reaction:

$\rm C$ : $1 \times 3 = 3$ .
$\rm H$ : $1 \times 8 = 8$ .
$\rm O$ : not found yet.

By the conservation of atoms, the number of atoms on the right-hand side of the reaction should match those on the left-hand side. In this reaction, $\rm CO_2$ is the only product with carbon atoms, whereas $\rm H_2O$ is the only product with hydrogen atoms. These $3$ carbon atoms and $8$ hydrogen atoms would correspond to:

$3 / 1 = 3$ $\rm CO_2$ molecules, and
$8 / 2 = 4$ $\rm H_2O$ molecules.

${\rm 1\; C_3H_8} + {\rm ?\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}$ .

Number of atoms on the right-hand side of the reaction:

$\rm C$ : $3 \times 1 = 3$ .
$\rm H$ : $4 \times 2 = 8$ .
$\rm O$ : $3 \times 2 + 4 \times 1 = 10$ .

The number of $\rm O$ atoms on the left-hand side should match those on the right-hand side. In this reaction, $\rm O_2$ is the only reactant with $\rm O\!$ atoms. These $10$ $\rm \! O$ atoms would correspond to:

$5$ $\rm O_2$ molecules.

${\rm 1\; C_3H_8} + {\rm 5\; O_2} \to {3\; \rm CO_2} + {4\; \rm H_2O}$ .

5 0

2 years ago

2) 183 cg =<br> kg<br> 5<br> .00183 kg<br> 0.0183 kg<br> .183 kg<br> 3) 0.25 kg =<br> g

OlgaM077 [116]

Answer:

183 cg = 0.00183 kg

0.25 kg = 250 g

Explanation:

Use conversion factors. 1kg is equal to 1 x 10^5 cg (100000) and 1 kg is equal to 1 x 10^3 grams (1000 grams).

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3 years ago

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Alecsey [184]

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