Chapter 19: Problem 64
The oxidation of
Short Answer
Expert verified
The molar concentration of is 0.156 M.
Step by step solution
01
Determine the balanced chemical equation
To balance the redox reaction, first balance the atoms other than O and H. Then, balance the oxygen atoms using water molecules, and hydrogen atoms using H⁺ ions. Afterward, balance the charges using electrons. The balanced equation is:
02
Calculate moles of K₂Cr₂O₇
The volume and molarity of are given: 26.0 mL and 0.0250 M. Convert the volume from mL to L by dividing by 1000, then calculate the moles of :
03
Relate moles of Cr₂O₇²⁻ to Fe²⁺
According to the balanced equation, 1 mole of reacts with 6 moles of . Therefore, the moles of are:
04
Calculate the molarity of Fe²⁺
Use the moles of calculated in Step 3 and the volume of the solution to find its molarity. Convert the given volume from mL to L: The molarity of is:
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Molarity Calculation
Molarity is an essential concept in chemistry that helps us understand the concentration of a solution. It is defined as the number of moles of a solute divided by the volume of the solution in liters. In this exercise, we calculated the molarity of ions after determining the moles present in the solution.
To calculate molarity, follow these steps: was found to be 0.156 M.
To calculate molarity, follow these steps:
- Calculate the moles of solute using the relation:
. - Determine the volume of the solution in liters by converting mL to L. Remember: 1 mL = 0.001 L.
- Calculate molarity using
.
Balancing Chemical Equations
Balancing chemical equations is crucial for understanding how substances react with each other. It involves making sure that the number of each type of atom on the reactant side equals the number on the product side. For this, one often uses the redox method, especially with redox reactions like ours.
Here are steps to balance oxidation-reduction reactions:
Here are steps to balance oxidation-reduction reactions:
- Separate the equation into two half-reactions: one for oxidation and one for reduction.
- For each half-reaction, balance the atoms other than O and H first.
- Then, balance oxygen atoms by adding water (
). - Balance hydrogen atoms by adding protons (
). - Finally, balance the electrons by ensuring equal charge on both sides of the half-reactions.
Stoichiometry
Stoichiometry involves calculating the quantities of reactants and products in a chemical reaction. It is pivotal for linking molarity to real-world reactions, as it relies on balancing chemical equations to find the mole ratio of reactants and products.
To apply stoichiometry effectively: reacted with in a 1:6 ratio. Using stoichiometry, we determined the moles of reacted given the moles of provided. Understanding stoichiometry is crucial for accurately predicting how much of each substance is needed or produced in a reaction.
To apply stoichiometry effectively:
- Use the balanced chemical equation to understand the mole ratio of each reactant and product.
- Convert all given information to moles (e.g., using molarity and volume).
- Apply the mole ratio from the balanced equation to find unknown quantities.
Acidic Solution
In chemistry, an acidic solution refers to any solution that has a higher concentration of hydrogen ions ( ) than pure water, which contributes to its acidic properties. This is often necessary for certain reactions, including many redox processes, as in our exercise.
Key aspects of acidic solutions in reactions: ions, as shown by the inclusion of in the balanced equation. Recognizing the conditions under which a reaction occurs can be vital for mastering chemistry concepts.
Key aspects of acidic solutions in reactions:
- The presence of
ions can help balance the reaction, especially for oxygen and hydrogen. - Acidic environments can alter the rate and equilibrium of reactions, making certain reductions or oxidations possible.
- Understanding the role of
assists in balancing redox equations and predicting product formation in reactions.