STOIKIOMETRI SINTESIS BIOETANOL DARI SUKROSA

Summary

This video focuses on a chemistry practical session about synthesizing organic compounds, specifically ethanol from sucrose. The process involves calculating the molar masses of sucrose and water, determining their stoichiometric relationship in the reaction, and calculating the amount of ethanol produced. The lecturer explains the step-by-step approach to determine which reactant is consumed first (sucrose, in this case), and the correct stoichiometric calculations to determine the theoretical yield of ethanol. A follow-up question challenges students to calculate the minimum amounts of sucrose and water needed to produce 1000 mL of ethanol. The session encourages hands-on learning in chemical synthesis.

Takeaways

• 😀 The lecture focuses on the synthesis of ethanol, specifically from sucrose, which is a bioethanol source.
• 😀 The reaction discussed assumes complete conversion of reactants into products, allowing the calculation of ethanol production.
• 😀 The molar mass of sucrose (C12H22O11) is approximately 342 g/mol, and for water (H2O) it is 18 g/mol.
• 😀 To calculate the number of moles of sucrose, the mass is divided by its molar mass. For 100g of sucrose, this yields 0.292 mol.
• 😀 Similarly, for water, 100g yields 5.56 mol, based on the molar mass of 18 g/mol.
• 😀 The stoichiometric relationship between sucrose and ethanol is 1:4, meaning 1 mol of sucrose yields 4 mol of ethanol.
• 😀 Using this stoichiometric ratio, 0.292 mol of sucrose will theoretically produce 1.168 mol of ethanol.
• 😀 The molar mass of ethanol (C2H5OH) is 46 g/mol, so the mass of ethanol produced is 53.7g.
• 😀 When comparing the amount of reactants, the amount of water (5.56 mol) exceeds the amount of sucrose (0.292 mol), meaning water is in excess.
• 😀 The limiting reagent in this reaction is sucrose, as it will be consumed first, while water remains in excess.
• 😀 A follow-up question asks students to calculate the minimum amount of sucrose and water required to produce 1000 mL of ethanol, which is left as a task for the students.

Q & A

What is the main topic of the lecture discussed in the transcript?

The main topic of the lecture is the synthesis of ethanol from sucrose, with a focus on stoichiometry and calculations related to this process.

Why is ethanol derived from organic compounds often referred to as 'bioethanol'?

Ethanol derived from organic compounds like sucrose is often called 'bioethanol' because it is produced from renewable biological resources.

What is the molar mass of sucrose used in the calculations, and how is it determined?

The molar mass of sucrose is calculated as 342 grams per mole. This is determined by adding up the atomic masses of carbon (12), hydrogen (1), and oxygen (16) based on its chemical formula (C12H22O11).

How is the amount of ethanol produced calculated based on sucrose and water in the experiment?

The amount of ethanol produced is calculated by determining the moles of sucrose and water, then using the stoichiometric relationship between sucrose and ethanol (1 mol sucrose produces 4 mol ethanol). The number of moles of ethanol is calculated by multiplying the moles of sucrose by 4.

What is the stoichiometric ratio between sucrose and ethanol in this reaction?

The stoichiometric ratio is 1:4, meaning 1 mole of sucrose produces 4 moles of ethanol.

How is the mass of ethanol produced calculated from moles of ethanol?

The mass of ethanol is calculated by multiplying the moles of ethanol by its molar mass (46 grams per mole). For example, if 1.168 moles of ethanol are produced, the mass is 1.168 moles × 46 g/mol = 53.7 grams of ethanol.

Which reactant, sucrose or water, is consumed first in the reaction, and why?

Sucrose is consumed first because it is the limiting reactant. The molar amount of sucrose is less than that of water, meaning it will be used up before the water.

How are the moles of sucrose and water calculated in the experiment?

The moles of sucrose and water are calculated by dividing their masses by their respective molar masses. For example, 100 grams of sucrose divided by 342 grams per mole gives 0.292 moles of sucrose, and 100 grams of water divided by 18 grams per mole gives 5.56 moles of water.

What is the minimum amount of sucrose and water required to produce 1000 mL of ethanol in this experiment?

To produce 1000 mL of ethanol, the required amounts of sucrose and water depend on the stoichiometric relationship and the molar masses involved. The specific calculation is left as an exercise for the students to solve.

Why is it important to understand stoichiometry when conducting experiments like this?

Understanding stoichiometry is crucial because it allows chemists to calculate the correct amounts of reactants and predict the amount of product produced, ensuring the reaction proceeds efficiently and effectively.