Question

You know that chemical A reacts with chemical B. You react 10.0 g \(\mathrm{A}\) with \(10.0 \mathrm{g}\) B. What information do you need to know to determine the amount of product that will be produced? Explain.

Short answer

To determine the amount of product produced in the reaction between 10.0 g of chemical A and 10.0 g of chemical B, you need the balanced chemical equation, molar masses of the chemicals, calculate the number of moles of each reactant, determine the limiting reagent, and finally, calculate the amount of product produced using the stoichiometry from the balanced chemical equation and the molar mass of the product(s).

Step-by-step solution

Write the balanced chemical equation

To determine the amount of product produced from the reaction between chemical A and chemical B, a balanced chemical equation representing their reaction should be provided. The equation will show the stoichiometry, i.e., the ratio of the number of moles of the reactants consumed and products formed.

Find the molar mass of the chemicals

Calculate the molar mass of chemical A and chemical B using the periodic table. The molar mass of a substance (in grams) is equal to its molecular weight (atomic weights of all atoms in the molecule). It will help to determine the number of moles of each reactant.

Calculate the number of moles of each reactant

Utilize the given masses of the chemicals (10.0 g each) and their molar masses to calculate the number of moles present in both chemical A and chemical B, using the formula: Moles = \(\frac{\text{mass (g)}}{\mathrm{molar\,mass (g/mol)}}\)

Determine the limiting reagent

Based on the number of moles of each reactant and the stoichiometry of the balanced chemical equation, identify the limiting reagent. The limiting reagent is the reactant that will be completely consumed in the reaction and will therefore determine the amount of product formed.

Calculate the amount of product produced

Use the limiting reagent and the stoichiometry provided by the balanced chemical equation to calculate the number of moles of each product formed. Then, convert the moles of product(s) to grams using their respective molar masses. At this point, you will have determined the amount of product that will be produced in the reaction between chemical A and chemical B.

Key concepts

Balanced Chemical Equation

Understanding a balanced chemical equation is crucial to studying a chemical reaction. In essence, it represents a recipe for the chemical process, outlining exactly what reactants combine and in what ratio to form specific products.

For example, if chemical A reacts with chemical B, their reaction might be represented by the equation \(A + B \rightarrow AB\). This equation must be balanced, meaning the number of atoms for each element must be equal on both sides of the reaction arrow. A balanced equation might look like \(2A + 3B \rightarrow AB_3 + A_2B\).

The balance ensures the law of conservation of mass is upheld. It's important because it tells us how many moles of each reactant we need to produce a certain amount of product, and thus, plays a foundational role in stoichiometry.

Molar Mass Calculation

The molar mass of a substance is defined as the mass in grams of 1 mole of that substance. A mole is a unit of measurement used to express amounts of a chemical substance, defined as containing exactly \(6.022 \times 10^{23}\) particles, such as atoms or molecules.

To calculate the molar mass, one must sum up the atomic weights of all the atoms present in a molecule, using the values provided by the periodic table. For example, the molar mass of water \(H_2O\) is calculated by adding the atomic weights of two hydrogen atoms with one oxygen atom, yielding about 18.02 grams per mole.

This calculation enables us to convert between the mass of substance and the number of moles, a critical step for quantitatively describing chemical reactions.

Limiting Reagent

The concept of the limiting reagent is akin to that of a bottleneck in a process. It's the reactant that runs out first in a chemical reaction, thus determining the maximum amount of product that can be produced. In the kitchen, if you run out of eggs while baking cookies, you can't make more cookies, even if you have plenty of flour and sugar left; eggs are the limiting 'reagent' in this scenario.

In chemical reactions, we calculate the number of moles of all reactants and, based on the stoichiometry from the balanced equation, identify the limiting reagent. For example, if our balanced equation requires two moles of A for every three moles of B, and we have fewer moles of A than required, A will be the limiting reagent. Knowing this is pivotal as it allows us to predict accurately the quantity of the product.

Theoretical Yield Calculation

Calculating theoretical yield involves using the information from the balanced chemical equation and the identity of the limiting reagent to determine the amount of product that would be produced if every single reactant particle reacted. This the best-case scenario amount is called the theoretical yield.

To compute it, one must find the number of moles of the limiting reagent, use the stoichiometry to determine the number of moles of product that should form, and then convert this to grams using the molar mass of the product. This calculation provides a benchmark for understanding the efficiency of a reaction and is essential for practical laboratory work and industrial chemical processes, although actual yield is often less due to various real-world factors.