Problem 33 - Chemistry A Molecular Approach

Question

The mass ratio of sodium to fluorine in sodium fluoride is 1.21:1. A sample of sodium fluoride produces 28.8 g of sodium upon decomposition. How much fluorine (in grams) forms?

Step-by-Step Solution

Answer

Approximately 23.8 grams of fluorine forms.

Step 1: Identify the Mass Ratio

The mass ratio of sodium to fluorine in sodium fluoride is given as 1.21:1. This means that for every 1.21 grams of sodium, there is 1 gram of fluorine.

Step 2: Calculate the Mass of Fluorine

To find the mass of fluorine that forms, use the provided mass ratio. If 28.8 grams of sodium are produced, then the mass of fluorine will be the amount of sodium divided by the sodium to fluorine ratio. Mathematically, it is represented as \( mass_{fluorine} = \frac{mass_{sodium}}{ratio_{Na:F}} \).

Step 3: Solve for the Mass of Fluorine

Substitute the known values into the equation to obtain the mass of fluorine: \( mass_{fluorine} = \frac{28.8\, g}{1.21} \approx 23.8\, g \).

Key Concepts

Mass Ratio in Chemical Compounds

Understanding the mass ratio in chemical compounds is essential when dealing with stoichiometry problems. The mass ratio simply represents the relationship between the masses of different elements in a compound. For instance, if we look at a compound like sodium fluoride (NaF), we may be given a mass ratio that tells us how much sodium (Na) there is compared to fluorine (F).

In the provided exercise, the mass ratio of sodium to fluorine is 1.21:1. This tells us that for every 1 gram of fluorine, there is 1.21 grams of sodium. To make this concept more approachable, imagine having a mixture of two different types of nuts in a bag: for every 1 kilogram of almonds, there are 1.21 kilograms of peanuts. The concept is identical when dealing with chemical elements in a compound. When given the mass of one element, you can use the mass ratio to easily find the mass of the other element.

Mole Concept

The mole concept is a bridge between the macroscopic world of grams and kilograms that we can measure and the microscopic world of atoms and molecules. One mole is defined as exactly 6.022 x 10²³ (Avogadro's number) of something, whether that's atoms, molecules, or another specified entity.

To relate the mole concept back to the exercise, if you know the number of moles of sodium produced, you could find out the exact number of atoms of sodium present. From there, using the Mass Ratio and Avogadro's number, you could determine the corresponding number of moles of fluorine, and ultimately its mass in grams. This kind of calculation can be vital for precise scientific experiments where knowing the exact amount of substances is crucial. Although the mole concept is not directly applied in the expressed solution, it underpins much of the reasoning in stoichiometry problems like this one.

Chemical Decomposition

The process of chemical decomposition is fundamental to chemistry. Decomposition reactions involve the breaking down of a chemical compound into simpler substances or elements. In the context of our sodium fluoride (NaF) example, when it decomposes, it breaks down into its constituent elements, sodium (Na) and fluorine (F).

Understanding decomposition can help clarify why knowing the mass ratio is useful. When a compound decomposes, the amount of each element produced can be predicted by their mass ratio in the original compound. This is exactly what we did with the example exercise: by knowing the masses of sodium produced upon decomposition, the mass ratio allowed us to calculate the corresponding mass of fluorine released. This concept is not only important for solving homework problems, but also for practical applications in scientific research, where controlling and predicting the products of decomposition reactions is key.