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Questions and Answers
During a titration experiment, a student finds that the endpoint is consistently surpassed, leading to an overestimation of the titrant volume required. Which of the following laboratory practices is most likely to contribute to this systematic error?
During a titration experiment, a student finds that the endpoint is consistently surpassed, leading to an overestimation of the titrant volume required. Which of the following laboratory practices is most likely to contribute to this systematic error?
- Rinsing the burette with distilled water instead of the titrant.
- Adding indicator solution excessively. (correct)
- Using a cracked beaker to hold the solution being titrated.
- Reading the titrant volume from the burette at an angle.
A researcher is preparing a standard solution of potassium permanganate ($KMnO_4$). Upon dissolving the $KMnO_4$ in distilled water, they observe that the solution's concentration changes slightly over a few days. Which factor most likely explains this phenomenon?
A researcher is preparing a standard solution of potassium permanganate ($KMnO_4$). Upon dissolving the $KMnO_4$ in distilled water, they observe that the solution's concentration changes slightly over a few days. Which factor most likely explains this phenomenon?
- Potassium permanganate reacts slowly with organic substances or reducing agents in the water. (correct)
- The potassium ions in $KMnO_4$ undergo radioactive decay.
- Potassium permanganate is hygroscopic and absorbs moisture from the air.
- The volumetric flask used was not properly calibrated.
In a chemical reaction between sodium hydroxide ($NaOH$) and hydrochloric acid ($HCl$), which of the following represents the correct balanced chemical equation?
In a chemical reaction between sodium hydroxide ($NaOH$) and hydrochloric acid ($HCl$), which of the following represents the correct balanced chemical equation?
- $NaOH + 2HCl \rightarrow NaCl_2 + 2H_2O$
- $NaOH + HCl \rightarrow NaClO + H_2$
- $NaOH + HCl \rightarrow NaCl + H_2O$ (correct)
- $2NaOH + HCl \rightarrow Na_2Cl + 2H_2O$
When performing a titration with a strong acid and a strong base using phenolphthalein as an indicator, at what pH would you expect the solution to change color at the endpoint?
When performing a titration with a strong acid and a strong base using phenolphthalein as an indicator, at what pH would you expect the solution to change color at the endpoint?
A student measures the pH of a solution and finds it to be 3.5. What is the hydrogen ion concentration $[H^+]$ of this solution?
A student measures the pH of a solution and finds it to be 3.5. What is the hydrogen ion concentration $[H^+]$ of this solution?
Why is it essential to use distilled or deionized water instead of tap water when preparing solutions for quantitative chemical analysis?
Why is it essential to use distilled or deionized water instead of tap water when preparing solutions for quantitative chemical analysis?
In a titration experiment, a student uses a burette to deliver the titrant. Before starting the titration, what is the most important step to ensure accurate results?
In a titration experiment, a student uses a burette to deliver the titrant. Before starting the titration, what is the most important step to ensure accurate results?
A student performs a litmus test on a solution and observes that the blue litmus paper turns red. What does this indicate about the solution?
A student performs a litmus test on a solution and observes that the blue litmus paper turns red. What does this indicate about the solution?
During the preparation of a solution with an accurate concentration, a student uses a volumetric flask. What is the primary function of a volumetric flask in this process?
During the preparation of a solution with an accurate concentration, a student uses a volumetric flask. What is the primary function of a volumetric flask in this process?
In a laboratory setting, which apparatus is most suitable for accurately transferring small volumes of liquid, typically less than 1 mL?
In a laboratory setting, which apparatus is most suitable for accurately transferring small volumes of liquid, typically less than 1 mL?
Flashcards
Heating apparatus
Heating apparatus
Beakers, Bunsen burners, tripods and gauze.
What are spatulas used for?
What are spatulas used for?
Used to transfer samples/chemicals from original containers to weighing bottles.
What are pipettes / droppers?
What are pipettes / droppers?
Apparatus used to move or transfer small amounts of liquid.
Standard Solution
Standard Solution
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Primary Standard Solution
Primary Standard Solution
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Endpoint in Titration
Endpoint in Titration
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What is a manometer?
What is a manometer?
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Study Notes
- Exam is for CHM 107, General Chemistry Practical 1
- The exam duration is 45 minutes.
- Instructions: Answer all questions.
- H= 1.00 amu
- Cl= 35.45 amu
- Na= 22.98 amu
- O= 15.99 amu
- C= 12.01 amu
- Fe= 55.84 amu
- S= 32.06 amu
Laboratory Apparatus
- Name two laboratory apparatus that can be used for heating.
- Identify the apparatus for transferring samples/chemicals from original containers to weighing bottles.
- Determine the apparatus used to move or transfer small amounts of liquid.
- Identify the apparatus used for measuring pressure.
Chemical Reactions and Equations
- Write a balanced equation for the reaction between sodium hydroxide and oxalic acid.
- HCl + NaOH → NaCl + H2O
Titration Calculations
- A student titrates 15.00 cm3 of hydrochloric acid with 10.00 cm3 of sodium hydroxide solution containing 4.60 g of NaOH in 500 cm3 of water should be used to calculate the concentration of hydrochloric acid in mol/dm3.
- Calculate the acid concentration from question 4 in g/dm3.
- Calculate the base concentration from question 4 in g/dm3.
- Determine the molar concentration of oxalic acid if 9.98 cm3 of the acid neutralizes 12.00 cm3 of 0.2M NaOH.
- Endpoint in titration
Solutions
- Define a standard solution.
- Define a primary standard solution.
pH and Ion Concentration
- Calculate the hydrogen ion concentration of a solution with a pH of 4.30.
- Calculate the pH of a solution with a hydronium ion concentration of 5.7 x 10-5 M.
Conversions
- Convert 140 mg of NaCl to kg.
- Convert 5.6 liters of H2O to cubic meters.
Chemical Indicators and Tests
- Describe the litmus test for CO2.
- Find the color of phenolphthalein indicator in the presence of an acid.
- Explain why lime water turns milky when carbon dioxide gas is passed through it.
Molar Mass
- Determine the molar mass of ferrous sulphate.
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