4.93 | How many milliliters of a 0.1500-M solution of KOH will be required to titrate 40.00 mL of a

The Glaser Tutoring Company
24 Feb 202210:18
EducationalLearning
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TLDRThis educational video script explains the process of titrating a weak acid, phosphoric acid (H3PO4), with a strong base, potassium hydroxide (KOH). The presenter clarifies that the simple titration formula mA = mB (molarity times volume) is not applicable due to the weak acid's nature. Instead, the script guides through stoichiometry using the balanced chemical equation, converting volumes to liters, calculating moles, and finally determining the required milliliters of KOH solution to neutralize the given volume of phosphoric acid. The explanation emphasizes the importance of significant figures and the correct application of stoichiometric ratios.

Takeaways
  • 🔍 The video discusses a titration problem involving a weak acid (phosphoric acid, H3PO4) and a strong base (potassium hydroxide, KOH).
  • 📚 It's noted that the titration formula m_a V_a = m_b V_b, typically used for strong acids and bases, cannot be applied here due to the presence of a weak acid.
  • 🧪 The balanced chemical equation for the reaction between H3PO4 and KOH is provided, indicating that 1 mole of H3PO4 reacts with 2 moles of KOH.
  • 📉 The problem involves calculating the volume of KOH solution required to titrate a given volume of H3PO4 solution with a known molarity.
  • ⚖️ The molarity of the H3PO4 solution is 0.0656 M, and the volume is 40.00 mL.
  • 📏 Conversion from mL to L is necessary for the calculation, which is done by dividing by 1000.
  • 🧮 Moles of H3PO4 are calculated using the formula: molarity × volume in liters.
  • 🔄 Stoichiometry is used to determine the moles of KOH needed based on the moles of H3PO4, with a 1:2 ratio from the balanced equation.
  • 📉 The molarity of the KOH solution is given as 0.1500 M, and the goal is to find the volume in mL required for the titration.
  • 🧩 The calculation for the volume of KOH needed involves using the formula: liters = moles / molarity, and then converting liters to mL by multiplying by 1000.
  • 📝 The final answer is that 35.0 mL of 0.1500 M KOH solution is required to titrate the 40.00 mL of 0.0656 M H3PO4 solution.
Q & A

  • What is the purpose of the video script?

    -The purpose of the video script is to demonstrate the process of calculating the volume of a KOH solution required to titrate a given volume of a phosphoric acid solution, using stoichiometry and the balanced chemical equation.

  • Why can't the formula m_aV_a = m_bV_b be used in this scenario?

    -The formula m_aV_a = m_bV_b can't be used here because it is most applicable for titrations involving a strong acid and a strong base. Phosphoric acid (H3PO4) is a weak acid, and the formula does not accurately represent the stoichiometry in such cases.

  • What is the balanced chemical equation given in the script?

    -The balanced chemical equation provided in the script is H3PO4 + 2KOH → K2HPO4 + 2H2O, which shows the reaction between phosphoric acid and potassium hydroxide.

  • How is the molarity of a solution related to the number of moles and volume?

    -The molarity of a solution is defined as the number of moles of solute divided by the volume of the solution in liters (Molarity = Moles / Liters).

  • What is the initial volume of the phosphoric acid solution given in the script?

    -The initial volume of the phosphoric acid solution is 40.00 milliliters.

  • What is the molarity of the phosphoric acid solution mentioned in the script?

    -The molarity of the phosphoric acid solution is 0.0656 M.

  • How many moles of phosphoric acid are present in the 40.00 mL solution?

    -To find the moles of phosphoric acid, multiply the molarity (0.0656 M) by the volume in liters (0.0400 L), resulting in 0.002624 moles.

  • What is the molarity of the KOH solution that needs to be calculated?

    -The molarity of the KOH solution is given as 0.1500 M.

  • How are the moles of KOH related to the moles of H3PO4 in the balanced equation?

    -According to the balanced equation, for every mole of H3PO4, two moles of KOH are required, hence the moles of KOH will be twice the moles of H3PO4.

  • What is the final volume of KOH solution in milliliters required to titrate the given volume of phosphoric acid?

    -The final volume of KOH solution required is 35.0 milliliters.

  • What is the significance of using stoichiometry in this titration problem?

    -Stoichiometry is used to relate the amounts of reactants and products in a chemical reaction, allowing for the calculation of the required volume of one reactant based on the given volume and molarity of another.

Outlines
00:00
🧪 Chemistry Titration Problem with Phosphoric Acid and KOH

The paragraph introduces a chemistry titration problem involving phosphoric acid (H3PO4) and potassium hydroxide (KOH). The script explains that the typical titration formula cannot be used due to the presence of a weak acid (phosphoric acid) and a strong base (potassium hydroxide). The balanced chemical equation for the reaction is provided, and the process begins with calculating the moles of phosphoric acid present in a 40 mL solution with a molarity of 0.0656 M. The calculation is detailed, resulting in 0.002624 moles of H3PO4.

05:01
📚 Stoichiometric Calculations for Acid-Base Reaction

This paragraph continues the chemistry lesson by focusing on stoichiometric calculations to determine the moles of KOH required to neutralize the given amount of phosphoric acid. Using the balanced chemical equation, it's established that two moles of KOH are needed for every mole of H3PO4. The moles of KOH are calculated to be 0.005248 moles based on the moles of H3PO4. The script then demonstrates how to convert these moles into liters and subsequently into milliliters of the KOH solution needed for the titration, concluding that 35 mL of 0.15 M KOH is required.

10:03
👋 Closing Remarks and Encouragement to Share the Educational Resource

In the final paragraph, the script wraps up the chemistry lesson with a summary of the titration process and the result. The instructor expresses hope that the lesson was helpful and encourages viewers to share the educational channel and its services with others. The closing is friendly and aims to foster a community of learners, inviting feedback and promoting further engagement in the subject matter.

Mindmap
Keywords
💡Titrate
Titration is a laboratory technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration. In the video, titration is the process of mixing an acid (phosphoric acid) with a base (potassium hydroxide) to reach a neutralization point. The script mentions titrating 40.00 mL of a 0.0656 M solution of H3PO4 with a 0.1500 M solution of KOH.
💡Molarity
Molarity is a measure of concentration that indicates the number of moles of a solute dissolved in one liter of solution. It is central to the script's theme of calculating the required volume of KOH to neutralize a given volume of phosphoric acid. The script uses molarity to calculate the moles of H3PO4 and subsequently the moles of KOH needed for the titration.
💡Phosphoric Acid (H3PO4)
Phosphoric acid is a weak acid with the chemical formula H3PO4. In the script, it is the acid that is being titrated with KOH. The video explains that it cannot be treated as a strong acid in the calculation, which affects the approach to determining the required amount of KOH.
💡Potassium Hydroxide (KOH)
Potassium hydroxide is a strong base with the chemical formula KOH. The script discusses its use in the titration process to neutralize phosphoric acid. The molarity of the KOH solution is given as 0.1500 M, which is crucial for calculating the volume needed for the titration.
💡Balanced Equation
A balanced chemical equation represents a chemical reaction where the number of atoms for each element is the same on both sides of the equation. In the script, the balanced equation for the reaction between phosphoric acid and potassium hydroxide is provided to understand the stoichiometric relationship between the reactants.
💡Stoichiometry
Stoichiometry is the calculation of the quantities of reactants and products in a chemical reaction based on the balanced equation. The script uses stoichiometry to relate the moles of H3PO4 to the moles of KOH needed for the titration, with a focus on the coefficients in the balanced equation.
💡Moles
Moles are a unit of measurement used in chemistry to express amounts of a chemical substance. The script calculates the moles of phosphoric acid present in the given volume and molarity, which is essential for determining the required moles of KOH for the titration.
💡Dimensional Analysis
Dimensional analysis is a systematic approach to converting between different units of measurement using a chain of relationships. In the script, dimensional analysis is used to convert moles to liters and then to milliliters, which is necessary to find the volume of KOH solution required.
💡Significant Figures
Significant figures are the digits in a number that carry meaning contributing to its precision. The script mentions significant figures in the context of ensuring the calculated volume of KOH has the correct level of precision, adhering to the rules of significant figures in scientific reporting.
💡Neutralization
Neutralization is a chemical reaction in which an acid and a base react to form a neutral substance. The script's theme revolves around the neutralization reaction between phosphoric acid and potassium hydroxide, aiming to find the exact amount of KOH needed to neutralize the given amount of H3PO4.
💡Concentration
Concentration refers to the amount of a substance present in a given volume. In the context of the script, the concentrations of both the acid (H3PO4) and the base (KOH) are essential for calculating the volume of KOH needed to neutralize the acid completely.
Highlights

The problem involves titrating phosphoric acid with potassium hydroxide.

The balanced chemical equation for the reaction is provided.

The titration formula m_a * v_a = m_b * v_b is not applicable due to the weak acid nature of phosphoric acid.

The formula molarity = moles / liters is used to find moles from molarity and volume.

Conversion from milliliters to liters is necessary by dividing by 1000.

Calculation of moles of phosphoric acid using its molarity and volume.

Dimensional analysis is used to relate moles of phosphoric acid to moles of potassium hydroxide.

The balanced equation shows a 1:2 molar ratio between phosphoric acid and potassium hydroxide.

Multiplying the moles of phosphoric acid by two gives the moles of potassium hydroxide required.

The molarity equation is rearranged to find the volume of potassium hydroxide solution needed.

Conversion from liters to milliliters is done by multiplying by 1000.

The final calculation shows that 35 milliliters of potassium hydroxide solution is required to titrate the phosphoric acid.

The importance of using stoichiometry and the balanced chemical equation for the calculation is emphasized.

The video provides a step-by-step guide on how to approach the titration problem.

The video concludes with a summary of the steps taken to solve the problem.

The video encourages viewers to share the content and seek help if needed.

Transcripts

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TitrationStoichiometryChemistryAcid BaseKOHPhosphoric AcidMolarityMolesNeutralizationEducational