Question

Hydrogen sulfide, H2S, has a very strong rotten egg odor. Methyl salicylate has a wintergreen odor, and benzaldehyde has a pleasant almond odor. If the vapors for these three substances were released at the same time from across a room.

a. List the order of oder that would reach you first to last and why? (quantitatively)?
b. If the rate of effusion of hydrogen sulfide is 1.375. What is the rate of effusion of benzaldehyde and Methyl salicylate?
c. If it took Hydrogen sulfide 10 seconds to reach you across the room. How long would it take for Benzaldehyde to reach your nose?

Answer 1

a. The order of odor that would reach you first to last is as follows:

Hydrogen sulfide (H2S)

Benzaldehyde (C7H6O)

Methyl salicylate (C7H8O3)

What is the order of odour that would reach you first to last, and why?

The order of odor that would reach you first to last is as follows:

Hydrogen sulfide (H2S)

Benzaldehyde (C7H6O)

Methyl salicylate (C7H8O3)

This is because the rate of effusion of a gas is inversely proportional to the square root of its molar mass. Hydrogen sulfide has the smallest molar mass of the three substances, so it will effuse the fastest and reach your nose first. Benzaldehyde has the next smallest molar mass, so it will reach your nose second. Methyl salicylate has the largest molar mass, so it will reach your nose last.

b. The rate of effusion of a gas can be calculated using Graham's law of effusion:

Rate of effusion =
`\sqrt{}`(M1 / M2) * Rate of effusion of substance 1

where:

M1 is the molar mass of substance 1

M2 is the molar mass of substance 2

The molar mass of hydrogen sulfide is 34.08 g/mol. The molar mass of benzaldehyde is 106.12 g/mol. Plugging these values into Graham's law, we get:

Rate of effusion of benzaldehyde =
`\sqrt{}`(34.08 g/mol / 106.12 g/mol) * 1.375 Pa m/s = 0.79 Pa m/s

The molar mass of methyl salicylate is 152.14 g/mol. Plugging this value into Graham's law, we get:

Rate of effusion of methyl salicylate =
`\sqrt{}` (34.08 g/mol / 152.14 g/mol) * 1.375 Pa m/s = 0.57 Pa m/s

Therefore, the rate of effusion of benzaldehyde is 0.79 Pa m/s and the rate of effusion of methyl salicylate is 0.57 Pa m/s.

c. The time it takes for a gas to effuse a certain distance can be calculated using the following equation:

Time = Distance / (Rate of effusion * Cross-sectional area)

where:

Distance is the distance the gas needs to travel

Rate of effusion is the rate of effusion of the gas

Cross-sectional area is the cross-sectional area of the orifice through which the gas is effusing

Let's assume that the distance to your nose is 1 meter and that the cross-sectional area of the orifice is 1 cm². Plugging in these values and the rate of effusion of hydrogen sulfide, we get:

Time = 1 meter / (1.375 Pa m/s * 1 cm²) = 726.4 seconds

Since the rate of effusion of benzaldehyde is 0.79 Pa m/s, the time it would take for benzaldehyde to reach your nose is:

Time = 1 meter / (0.79 Pa m/s * 1 cm²) = 1265.8 seconds

Therefore, it would take approximately 1265.8 seconds for benzaldehyde to reach your nose.