What concentration of benzoic acid will have a ph of 4.0? (for benzoic acid, pka=4.20)?
1 answer:
We are given the molar concentration of an aqueous solution of weak acid and the pH ofthe solution, and we are asked to determine the value of Ka for the acid.
The first step in solving any equilibrium problem is to write the equation for the equilibriumreaction. The ionization of benzoic acid can be written as seen in the attached image (1).
The equilibrium-constant expression is the equation number (2)
From the measured pH, we can calculate pH as seen in equation (3)
To determine the concentrations of the species involved in the equilibrium, we imagine that thesolution is initially 0.10 M in HCOOH molecules. We then consider the ionization of the acidinto H+ and HCOO-. For each HCOOH molecule that ionizes, one H+ ion and one HCOO- ionare produced in solution. Because the pH measurement indicates that [H+] = 1x 10^-4 M atequilibrium, we can construct the following table as seen in the equation number (4)
To find the value of Ka, please see equation (5):
We can now insert the equilibrium concentrations into the expression for Ka as seen in equation (6)
Therefore, 2.58x10^-4 M is the concentration of benzoic acid to have a pH of 4.0
The first step in solving any equilibrium problem is to write the equation for the equilibriumreaction. The ionization of benzoic acid can be written as seen in the attached image (1).
The equilibrium-constant expression is the equation number (2)
From the measured pH, we can calculate pH as seen in equation (3)
To determine the concentrations of the species involved in the equilibrium, we imagine that thesolution is initially 0.10 M in HCOOH molecules. We then consider the ionization of the acidinto H+ and HCOO-. For each HCOOH molecule that ionizes, one H+ ion and one HCOO- ionare produced in solution. Because the pH measurement indicates that [H+] = 1x 10^-4 M atequilibrium, we can construct the following table as seen in the equation number (4)
To find the value of Ka, please see equation (5):
We can now insert the equilibrium concentrations into the expression for Ka as seen in equation (6)
Therefore, 2.58x10^-4 M is the concentration of benzoic acid to have a pH of 4.0
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Complete Question
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Answer:
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Explanation:
The explanation is shown on the second uploaded image
The thermal decomposition of calcium carbonate will produce 14 g of calcium oxide. The stoichiometric ratio of calcium carbonate to calcium oxide is 1:1, therefore the number of moles of calcium carbonate decomposed is equal to the number of moles of calcium oxide formed.
Further Explanation:
To solve this problem, follow the steps below:
- Write the balanced chemical equation for the given reaction.
- Convert the mass of calcium carbonate into moles.
- Determine the number of moles of calcium oxide formed by using the stoichiometric ratio for calcium oxide and calcium carbonate based on the coefficient of the chemical equation.
- Convert the number of moles of calcium oxide into mass.
Solving the given problem using the steps above:
STEP 1: The balanced chemical equation for the given reaction is:
STEP 2: Convert the mass of calcium carbonate into moles using the molar mass of calcium carbonate.
STEP 3: Use the stoichiometric ratio to determine the number of moles of CaO formed.
For every mole of calcium carbonate decomposed, one more of a calcium oxide is formed. Therefore,
STEP 4: Convert the moles of CaO into mass of CaO using its molar mass.
Since there are only 2 significant figures in the given, the final answer must have the same number of significant figures.
Therefore,
Learn More
- Learn more about stoichiometry brainly.com/question/12979299
- Learn more about mole conversion brainly.com/question/12972204
- Learn more about limiting reactants brainly.com/question/12979491
Keywords: thermal decomposition, stoichiometry