Reactivo Limitante y en Exceso (Paso a Paso)

Summary

In this educational chemistry video, the process of calculating the limiting and excess reagents, as well as the mass of a product and the percentage yield, is demonstrated. Starting with a balanced chemical equation, the video explains how to determine the molecular weights of sodium bicarbonate (NaHCO₃) and hydrochloric acid (HCl), calculate their moles, and identify the limiting reagent. The video also covers how to calculate the mass of sodium chloride (NaCl) produced and how to compute the percentage yield, with a detailed step-by-step approach and practical examples. The video aims to help viewers understand these key stoichiometric concepts.

Takeaways

• 😀 The script explains how to calculate limiting reagents and excess reagents in a chemical reaction.
• 😀 The first step is to ensure the chemical equation is balanced, which is confirmed in this example.
• 😀 The molecular weights of sodium bicarbonate (NaHCO3) and hydrochloric acid (HCl) are calculated using the periodic table.
• 😀 The molar mass of sodium bicarbonate is 84 grams, and the molar mass of hydrochloric acid is 36.5 grams.
• 😀 The script uses the formula for calculating moles: mass divided by molar mass, giving moles for each reactant.
• 😀 After calculating the moles of each reactant, the limiting reagent and excess reagent are determined by comparing their ratios.
• 😀 If the ratio of the limiting reagent decreases, it indicates it is the limiting reagent, while the other is in excess.
• 😀 The limiting reagent in this example is sodium bicarbonate (NaHCO3), while hydrochloric acid (HCl) is the excess reagent.
• 😀 The script explains how to calculate the mass of sodium chloride (NaCl) as a product of the reaction using the limiting reagent.
• 😀 The formula for percentage yield is given as the ratio of actual yield to theoretical yield, multiplied by 100.
• 😀 The theoretical yield of NaCl is calculated as 13.92 grams, and the actual yield is 13.9 grams, resulting in a 99.8% yield.

Q & A

What is the first step in solving the given chemical reaction problem?

The first step is to check if the chemical equation is balanced. This is important because, in a balanced equation, the number of atoms of each element on both sides of the equation should be equal.

How can you tell if a chemical equation is balanced?

A chemical equation is balanced if the number of atoms of each element is the same on both sides of the equation. For example, if one side has 2 hydrogen atoms, the other side must also have 2 hydrogen atoms.

What does it mean when a number is not written in a chemical formula?

When a number is not written in a chemical formula, it implies that the coefficient is 1. For example, in the formula NaCl, the '1' in front of Na and Cl is not written, but it is understood to be there.

What is the molecular weight of sodium bicarbonate (NaHCO3) as calculated in the video?

The molecular weight of sodium bicarbonate (NaHCO3) is calculated as 84 grams, which is derived by adding the atomic masses of sodium (23), hydrogen (1), carbon (12), and three oxygens (16 each).

How do you calculate moles from the mass of a substance?

To calculate moles, divide the given mass of the substance by its molecular weight. For example, if you have 20 grams of sodium bicarbonate (NaHCO3), and its molecular weight is 84 grams, the number of moles would be 20 / 84 = 0.238 moles.

What is the purpose of calculating the limiting reactant?

The limiting reactant is the substance that runs out first in a chemical reaction, determining the maximum amount of product that can be formed. Identifying it allows us to calculate how much of the other reactant will be in excess.

How do you determine which reactant is in excess and which is limiting?

To determine the limiting and excess reactants, compare the moles of each reactant based on the balanced equation. If the ratio of the available moles does not match the ratio in the equation, the one in the smaller ratio is limiting, and the other is in excess.

How do you calculate the mass of sodium chloride (NaCl) produced?

To calculate the mass of sodium chloride (NaCl), first find the moles of the limiting reactant (sodium bicarbonate). Then, use stoichiometry based on the balanced equation to calculate the moles of NaCl produced and finally convert this to mass by multiplying by the molecular weight of NaCl (58.5 grams).

What is the formula for calculating the percentage yield of a chemical reaction?

The percentage yield is calculated by dividing the actual yield (the amount of product obtained from the experiment) by the theoretical yield (the amount of product that should be produced based on calculations), and then multiplying by 100. In the video, the actual yield is 13.9 grams, and the theoretical yield is 13.92 grams, giving a yield of 99.8%.

Why is it important to calculate the limiting reactant in a chemical reaction?

It is important to calculate the limiting reactant because it determines how much product can be formed. Without knowing the limiting reactant, you can't accurately predict how much product will be produced or how much of the other reactant will remain unreacted.