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4 years ago

Why is red the last color seen at sunset?

1 answer:

8 0

Within the visible range of light, red light waves are scattered the least by atmospheric gas molecules. So at sunrise and sunset, when the sunlight travels a long path through the atmosphere to reach our eyes, the blue light has been mostly removed, leaving mostly red and yellow light remaining.

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Is a CAS number a physical or chemical property

katrin [286]

Chemical

Hope that helps

5 0

3 years ago

A mixture of gases with a pressure of 800.0 mm hg contains 60% nitrogen and 40% oxygen by volume. What is the partial pressure o

larisa86 [58]

Answer:

The partial pressure of oxygen in the mixture is 320.0 mm Hg

Explanation:

1) Take a base of 100 liters of mixture:

N: 60% × 100 liter = 60 liter

O: 40 % × 100 liter = 40 liter.

2) Volume fraction:

At constant pressure and temperature, the volume of a gas is proportional to the number of molecules.

Then, the mole ratio is equal to the volume ratio. Callin n₁ and n₂, the number of moles of nitrogen and oxygen, respectively, and V₁, V₂ the volume of the respective gases you can set the proportion:

V₁ / V₂ = n₁ / n₂

That means that the mole ratio is equal to the volume ratio, and the mole fraction is equal to the volume fraction.

Then, since the law of partial pressures of gases states that the partial pressure of each gas is equal to the mole fraction of the gas multiplied by the total pressure, you can draw the conclusion that the partial pressure of each gas is equal to the volume fraction of the gas in the mixture multiplied by the total pressure.

Then calculate the volume fractions:

Volume fraction of a gas = volume of the gas / volume of the mixture

N: 60 liter / 100 liter = 0.6 liter

V: 40 liter / 100 liter = 0.4 liter

3) Partial pressures:

These are the final calculations and results:

Partial pressure = volume fraction × total pressure

Partial pressure of N = 0.6 × 800.0 mm Hg = 480.0 mm Hg

Partial pressure of O = 0.4 × 800.0 mm Hg = 320.0 mm Hg

8 0

3 years ago

Tema: Métodos de Separação de Misturas – Homogêneas e Heterogêneas;

seraphim [82]

Answer:

fjskeowkcnekvo Dee five votes come vote for dog even r

4 0

3 years ago

Why do elements have different properties?

Ann [662]

I think because each element has its own number of protons and neutrons, giving it its own atomic number and mass (correct me if I’m wrong please)

3 0

3 years ago

Over-the-counter hydrogen peroxide solutions are 3% (w/v). What is this concentration in moles per liter?

Marina CMI [18]

1 ml of water weighs 1 gram so 1 liter (1000 ml) weighs 1000 grams. A 3% solution (3% = 0.03) of hydrogen peroxide (w/v) would contain 1000 grams x 0.03 or 30 grams. The chemical formula of hydrogen peroxide is H2O2 and a mole weighs 34.0147 grams/mole. So 30 grams of H2O2 divided by 34.0147 grams/mole equals 0.88 moles of H2O2. The concentration of a 3% (w/v) hydrogen peroxide solution therefore contains 30 grams of H202 (or 0.88 moles of H202) per in a liter of water (or 1000 grams H20) would thus be 0.88 moles H2O2 per liter (0.88 moles H2O2/l) .

5 0

3 years ago