Problem 103 - Chemistry The Central Science

Question

Nickel carbonyl, Ni(CO) \(_{4},\) is one of the most toxic substances known. The present maximum allowable concentration in laboratory air during an 8 -hr workday is 1 ppb (parts per billion) by volume, which means that there is one mole of \(\mathrm{Ni}(\mathrm{CO})_{4}\) for every \(10^{9}\) moles of gas. Assume \(24^{\circ} \mathrm{C}\) and 1.00 atm pressure. What mass of \(\mathrm{Ni}(\mathrm{CO})_{4}\) is allowable in a laboratory room that is 12 \(\mathrm{ft} \times 20 \mathrm{ft} \times 9 \mathrm{ft}\) ?

Step-by-Step Solution

Answer

The mass of allowable Nickel carbonyl (Ni(CO)4) in the laboratory room with dimensions 12 ft x 20 ft x 9 ft, at 24°C and 1.00 atm pressure, is approximately 0.000424 g.

Step 1: Calculate the Volume of Room in Liters

First, we need to convert the dimensions from feet to meters and then calculate the volume in liters (L). The conversion factors are: 1 foot = 0.3048 meters 1 cubic meter = 1000 liters Room dimensions = 12 ft × 20 ft × 9 ft = 2160 cubic feet. Convert to cubic meters: 2160 cubic feet × (0.3048 m / foot)^3 = \( 61.1323 \) cubic meters Convert to liters: \( 61.1323 \) cubic meters × 1000 L / cubic meter = 61132.3 L

Step 2: Calculate Moles of Gas in the Room using Ideal Gas Law

Use the ideal gas law equation: PV = nRT Where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. We are given P = 1.00 atm, V = 61132.3 L, R = 0.0821 (atm·L) / (K·mol), and T is given in Celsius, we need to convert it to Kelvin: T = 24 + 273.15 = 297.15 K Solve for n (the number of moles of gas in the room): n = PV / RT n = (1.00 atm × 61132.3 L) / (0.0821 (atm·L) / (K·mol) × 297.15 K) n ≈ 2486.681 moles of gas

Step 3: Find Moles of Ni(CO)4 Based on Maximum Allowable Concentration

Given one mole of Ni(CO)4 for every 10^9 moles of gas. Calculate the number of moles of Ni(CO)4: moles of Ni(CO)4 = (moles of gas) / 10^9 moles of Ni(CO)4 = 2486.681 / 10^9 moles of Ni(CO)4 ≈ 2.4867 × 10^(-6) moles

Step 4: Calculate the Mass of Allowable Ni(CO)4

Use the molar mass of Ni(CO)4 to find its mass: Molar Mass of Ni(CO)4 = 58.69 (Ni) + 4 (12.01 (C) + 16.00 (O)) = 170.49 g/mol Mass = moles × molar mass Mass = 2.4867 × 10^(-6) moles × 170.49 g/mol ≈ 0.000424 g So, the mass of allowable Nickel carbonyl (Ni(CO)4) in the laboratory room is approximately 0.000424 g.

Key Concepts

Nickel carbonyl

Nickel carbonyl, scientifically known as Ni(CO) _{4}, is a coordination compound formed by nickel and carbon monoxide. It appears as a colorless liquid with a powerful, unpleasant odor. This compound is notorious for its high toxicity and volatile nature. In industrial processes, nickel carbonyl is used primarily in the purification of nickel, in a procedure known as the Mond process. Here, impure nickel reacts with carbon monoxide to form nickel carbonyl, which decomposes to pure nickel upon heating.

When working with nickel carbonyl, safety is of utmost importance because it is highly poisonous. Even minimal exposure can result in serious health issues. Hence, the lab safety norms dictate stringent measures to control exposure, keeping it below 1 part per billion (ppb) by volume in an 8-hour work environment.

Due to its toxicity, handling and storage of nickel carbonyl require advanced safety measures, including adequate ventilation and personal protective equipment. Incorporating specialised equipment to monitor air quality is crucial to ensure that the concentration of nickel carbonyl remains within permissible limits.

Toxic substances

Toxic substances are chemicals that can cause harm to living organisms. The degree of toxicity can vary greatly between substances and depends on the amount of exposure and the method of entry into the body. With nickel carbonyl being one of the most toxic compounds, understanding its effects is vital.

Inhalation is the most common route of exposure for nickel carbonyl, leading to symptoms such as headaches, dizziness, and in severe cases, respiratory issues or even death. Therefore, exposure limits are established to protect individuals from adverse health effects. These limits, such as the parts per billion (ppb) for nickel carbonyl, define the maximum concentration allowed.

• Exposure limits are crucial in industrial and laboratory settings to protect humans.
• Toxicity depends on various factors including dosage, duration of exposure, and individual susceptibility.
• Safety protocols, including the use of personal protective equipment and regular monitoring, are essential to minimize risks associated with toxic substances.

Molar mass calculation

Calculating the molar mass of a compound is a fundamental step in chemistry. It involves summing up the atomic masses of all the atoms in a molecule. This is crucial for converting moles into grams, enabling precise measurement of substances in a chemical reaction.

In the case of nickel carbonyl, Ni(CO) _{4}, we calculate the molar mass by adding the atomic mass of nickel (58.69 g/mol) to the combined atomic masses of four carbon (totaling 48.04 g/mol) and four oxygen atoms (64.00 g/mol). Altogether, the molar mass comes to approximately 170.49 g/mol.

Understanding molar mass is pivotal in chemical calculations and allows for conversions between mass and moles, a necessary step when applying the ideal gas law. In the original exercise, the calculated molar mass helped determine the permissible mass of nickel carbonyl vapors in a given volume of air.

Using the equation:

• Mass = moles × molar mass

students can easily find the necessary weights of substances involved, providing a clear pathway from theoretical calculations to practical laboratory applications.