Calculate the mass of citric acid required to make 50.0 mL of a 0.100 M solution. The formula of citric acid is H3C6H507. The formula weight of citric acid is Why must NaOH solutions be standardized before being used to do titrations? What indicator is used for the titrations of this experiment? What is its color change? • If you accidentally forgot to rinse out the 10mL graduated cylinder after measuring the citric acid, what effect would this have on the NaOH placed in the cylinder? Calculate the molarity of the citric acid solution prepared by dissolving 1.0 gram of citric acid in 50.0 mL of solution. The formula of citric acid is H3C6H507. Data and Results Table for the Titration of NaOH with citric acid Data or Calculation Trial 1 Trial 2 Trial 3 (if necessary) Vol Citric acid 3.0 ml 3.0 mL Moles citric acid (calc) Volume NaOH (initial reading) Volume NaOH (final reading) Volume NaOH used (calc) Moles NaOH (calc) Molarity NaOH (calc) Balance the chemical equation for the reaction of citric acid and sodium hydroxide. H3C6H507 + NaOH H2O + Na3C6H507 Show detailed calculations that include units for the following: Moles citric acid Moles NaOH Molarity of NaOH. Average Molarity of NaOH Data and Results Table for the Titration of Diluted Vinegar with NaOH Data or Calculation Trial 1 Trial 2 Trial 3 (if necessary) Volume diluted Vinegar Volume NaOH (initial) Volume NaOH (final) Volume NaOH used (calc) Moles NaOH (calc) Moles HC2H302 (calc) Molarity of HC2H302 (calc) Balance the chemical equation for the reaction of citric acid and sodium hydroxide. HC2H302 + NaOH H2O + NaC2H302 Show detailed calculations that include units for the following: Moles NaOH Moles acetic acid Molarity of acetic acid in diluted vinegar. Molarity of acetic acid in vinegar.
The Correct Answer and Explanation is :
Here’s the breakdown of the calculations and explanations for the provided chemistry questions:
1. Mass of Citric Acid Required
To make a 0.100 M solution of citric acid (H₃C₆H₅O₇), we use:
[
\text{Molarity (M)} = \frac{\text{moles}}{\text{volume (L)}}
]
Rearranging for moles:
[
\text{moles} = \text{Molarity} \times \text{volume (L)} = 0.100 \, \text{M} \times 0.0500 \, \text{L} = 0.00500 \, \text{moles}
]
Mass of citric acid:
[
\text{mass} = \text{moles} \times \text{molar mass (192.12 g/mol)} = 0.00500 \, \text{mol} \times 192.12 \, \text{g/mol} = 0.9606 \, \text{g}
]
Answer: 0.9606 g of citric acid is required.
2. Why Standardize NaOH?
NaOH is hygroscopic, meaning it absorbs moisture from the air, which can alter its concentration. Standardizing ensures the actual concentration is known for accurate titrations.
3. Indicator and Color Change
Phenolphthalein is commonly used. It changes from colorless (acidic) to pink (basic).
4. Effect of Not Rinsing Graduated Cylinder
Residual citric acid would react with NaOH, consuming more NaOH than necessary. This would lead to an overestimation of NaOH concentration.
5. Molarity of Citric Acid Solution
Given 1.0 g citric acid in 50.0 mL:
Moles of citric acid:
[
\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{1.0 \, \text{g}}{192.12 \, \text{g/mol}} = 0.00521 \, \text{mol}
]
Molarity:
[
\text{Molarity} = \frac{\text{moles}}{\text{volume (L)}} = \frac{0.00521 \, \text{mol}}{0.0500 \, \text{L}} = 0.1042 \, \text{M}
]
Answer: 0.104 M
6. Balanced Chemical Equations
- Citric acid with NaOH:
[
\text{H₃C₆H₅O₇ + 3NaOH → Na₃C₆H₅O₇ + 3H₂O}
] - Acetic acid with NaOH:
[
\text{HC₂H₃O₂ + NaOH → NaC₂H₃O₂ + H₂O}
]
7. Calculations for Titrations
Moles of Citric Acid:
[
\text{moles} = \text{Molarity} \times \text{volume (L)}
]
Moles of NaOH:
Using the reaction stoichiometry, 3 moles of NaOH react with 1 mole of citric acid.
Molarity of NaOH:
[
\text{Molarity (NaOH)} = \frac{\text{moles NaOH}}{\text{volume (L)}}
]
Average Molarity:
[
\text{Average Molarity} = \frac{\text{Sum of Molarities}}{\text{Number of Trials}}
]
8. Acetic Acid in Vinegar
Moles of NaOH:
[
\text{moles} = \text{Molarity} \times \text{volume (L)}
]
Moles of Acetic Acid:
1 mole NaOH reacts with 1 mole HC₂H₃O₂.
Molarity of Acetic Acid (Diluted):
[
\text{Molarity} = \frac{\text{moles}}{\text{volume (L)}}
]
Molarity of Acetic Acid (Original):
Account for dilution factor.
These calculations ensure precise results for titration experiments, highlighting the importance of standardization, clean equipment, and proper stoichiometric relationships.