The relative atomic mass of fluorine is 19. What is the mass of 3 mol of fluorine gas?

(A) 110g

(B) 112g

(C) 114g

(D) 120g

To find the mass of 3 moles of fluorine gas, we first need to understand the relationship between moles, atomic mass, and mass. The relative atomic mass of fluorine is given as 19, which means that one mole of fluorine atoms weighs 19 grams. Since fluorine gas (F₂) consists of two fluorine atoms, we need to adjust our calculations accordingly.

Calculating the Mass of Fluorine Gas

Here’s how we can break it down step by step:

• Determine the molar mass of fluorine gas (F₂): Since each fluorine atom has a relative atomic mass of 19, the molar mass of fluorine gas, which is diatomic (F₂), is calculated as follows:

Molar mass of F₂ = 2 × 19 g/mol = 38 g/mol

• Calculate the mass of 3 moles of fluorine gas: Now that we know the molar mass of fluorine gas, we can find the mass of 3 moles:

Mass = Number of moles × Molar mass

Mass = 3 mol × 38 g/mol = 114 g

Final Answer

Therefore, the mass of 3 moles of fluorine gas is 114 grams. The correct answer is (C) 114g.

Understanding Moles and Molar Mass

To further clarify, a mole is a unit that measures the amount of substance. One mole of any substance contains approximately 6.022 × 10²³ particles (Avogadro's number). The molar mass is the mass of one mole of a substance, expressed in grams per mole. This concept is crucial in chemistry as it allows us to convert between the number of moles and the mass of a substance easily.

In summary, when dealing with gases or any chemical substances, always remember to account for whether you are dealing with single atoms or molecules, as this will affect your calculations significantly. In this case, recognizing that fluorine gas is diatomic was key to arriving at the correct answer.