Q: Which equation correctly defines specific gravity?

$$\text{Specific Gravity} = \frac{\text{mass of substance}}{\text{mass of an equal volume of water}}$$

Q: What is the formula to calculate the volume of air (in liters) needed for an industrial hygienist to reach a detection limit of 0.01 mg/m³ if the LOD is 0.01 mg?

$$V = \frac{0.01\, \text{mg}}{0.01\, \text{mg/m}^3} \times 1000 = 1,000\, \text{liters}$$

Q: A silica gel tube collected 200 mg of methanol before breakthrough occurred. If the breakthrough mass is 50 mg, what is the breakthrough rate?

$$\frac{50}{200} \times 100 = 25\%$$

Q: How many molecules of water do you drink if you consume 250 mL (or grams) of water? (MW of water = 18, Avogadro's number = $$6.022 \times 10$$^{23}$$)

$$\frac{250}{18} \times 6.022 \times 10$$^{23}$$ = 8.36 \times 10$$^{24}$$

Q: A filter collected 50 micrograms ($$\mug) of $$lead from 0.72 cubic meters of air. What is the airborne concentration of lead in $$\mug/m$$³?

$$\frac{50}{0.72} = 69.4\, \mu\text{g/m}^3$$

Question 1

Which of the following best describes the difference between grab sampling and integrated sampling?

Accepted Answer

Grab sampling collects a contaminant concentration at a specific point in time and location, while integrated sampling involves a larger volume of air over a period of time.

Question 2

A laboratory technician needs to determine if a sample contains a contaminant above the threshold limit value (TLV). Which type of sampling should be used?

Accepted Answer

Short term sampling

Question 3

Which equation correctly defines specific gravity?

Accepted Answer

$$	ext{Specific Gravity} = \frac{	ext{mass of substance}}{	ext{mass of an equal volume of water}}$$

Question 4

Which of the following is a primary standard in sampling?

Accepted Answer

A dry gas meter used for direct measurement

Question 5

Passive samplers differ from diffuse samplers in that:

Accepted Answer

Passive samplers collect contaminants based on diffusion without active air movement, while diffuse samplers depend on contaminant molecules diffusing across an open surface.

Question 6

What is the formula to calculate the volume of air (in liters) needed for an industrial hygienist to reach a detection limit of 0.01 mg/m³ if the LOD is 0.01 mg?

Accepted Answer

$$V = \frac{0.01\, 	ext{mg}}{0.01\, 	ext{mg/m}^3} 	imes 1000 = 1,000\, 	ext{liters}$$

Question 7

Which of the following best describes adsorption as used in industrial hygiene sampling?

Accepted Answer

Adsorption involves the retention of the sampled substance on the surface of the sorbent.

Question 8

A silica gel tube collected 200 mg of methanol before breakthrough occurred. If the breakthrough mass is 50 mg, what is the breakthrough rate?

Accepted Answer

$$\frac{50}{200} 	imes 100 = 25\%$$

Question 9

According to Raoult's law, what happens to the vapor pressure of an ideal solution when a volatile solute is added to a volatile solvent?

Accepted Answer

The vapor pressure is the sum of the partial pressures of each component.

Question 10

How many molecules of water do you drink if you consume 250 mL (or grams) of water? (MW of water = 18, Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$\frac{250}{18} 	imes 6.022 	imes 10$$^{23}$$ = 8.36 	imes 10$$^{24}$$

Question 11

A filter collected 50 micrograms ($$\mug) of $$lead from 0.72 cubic meters of air. What is the airborne concentration of lead in $$\mug/m$$³?

Accepted Answer

$$\frac{50}{0.72} = 69.4\, \mu	ext{g/m}^3$$

Question 12

Which analytical technique is commonly used to analyze lead in the laboratory?

Accepted Answer

Atomic absorption spectroscopy (AAS)

Question 13

What is the best way to monitor BTEX (benzene, toluene, ethylbenzene, and xylenes) in compounds exposure?

Accepted Answer

Using a portable photoionization detector (PID)

Question 14

Which of the following statements about sublimation is correct?

Accepted Answer

Sublimation is the process in which a substance changes from the solid state directly to the gas state.

Question 15

What is the main function of an impinger in air sampling?

Accepted Answer

To collect airborne contaminants by bubbling air through a liquid

Question 16

Which designation refers to a substance that is a Respiratory Sensitizer?

Accepted Answer

RSEN

Study Guidance for GOB Chemistry: Sampling, Mass, Moles, and Analytical Methods

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