🔬 • Lesson 2.9 : Experiments and Chemical Analysis (Chem) Flashcards
Let’s take a trip down to the lab; learn about experimental design, apparatus for tests, acid-base titrations, chromatography, separation and purification, as well as identification of ions and gases.
What apparatus is used to measure time?
Stop-watch.
What apparatus is used to measure temperature?
Thermometer.
What apparatus is used to measure mass?
Balance.
What apparatus is used to measure volume in titration?
Burette.
What apparatus is used to measure a specific volume of liquid accurately?
Volumetric pipette.
What apparatus is used to measure approximate volumes of liquids?
Measuring cylinder.
What apparatus is used to measure the volume of gas?
Gas syringe.
What is a solvent?
A substance that dissolves a solute.
What is a solute?
A substance that is dissolved in a solvent.
What is a solution?
A mixture of one or more solutes dissolved in a solvent.
What is a saturated solution?
A solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature.
What is a residue?
A solid substance that remains after evaporation, distillation, filtration, or similar processes.
What is a filtrate?
A liquid or solution that has passed through a filter.
Name 3 of the apparatus used to perform an acid-base titration?
Burette, volumetric pipette, indicator
How is a burette used in an acid-base titration?
The volumetric pipette is used to measure an accurate volume of the solution to be titrated.
How is a volumetric pipette used in titration?
The volumetric pipette is used to measure an accurate volume of the solution to be titrated.
What is the role of an indicator in titration?
The indicator changes color at the end-point, showing when the reaction is complete.
What is paper chromatography used for?
Paper chromatography separates mixtures of soluble colored substances to identify their components.
How does paper chromatography separate substances?
Substances move at different speeds through a solvent based on their solubility and affinity for the paper.
How do you identify unknown substances in chromatography?
Compare the Rf values of the unknown substance with known substances to identify it.
How do you identify pure and impure substances in chromatography?
Pure substances have one spot on the chromatogram,
Impure substances show multiple spots.
What is the Rf equation in chromatography?
Rf = (distance traveled by substance) / (distance traveled by solvent).
The Rf value helps to identify substances.
How is separation and purification done using a suitable solvent?
A solvent dissolves the solute, separating it from the residue. After, the solution can be filtered or evaporated to purify.
How does filtration work for separation and purification?
Filtration separates solids from liquids using filter paper.
The liquid that passes through is called the filtrate.
How does crystallisation work for separation and purification?
Crystallisation separates a dissolved solid by cooling the solution, allowing crystals to form and be collected by filtration.
How does simple distillation work for separation and purification?
Simple distillation separates liquids based on boiling points.
The substance with a lower boiling point evaporates, condenses, and is collected.
How does fractional distillation work for separation and purification?
Fractional distillation separates mixtures of liquids with different boiling points by using a fractionating column to allow multiple distillations.
What separation technique would you use for a mixture of two liquids with different boiling points?
Fractional distillation is best for separating liquids with different boiling points.
How can purity be assessed from melting point and boiling point?
A pure substance has a sharp, specific melting and boiling point. Impurities lower the melting point and widen the boiling point range.
How do you test for carbonate ions (CO₃²⁻)?
Add dilute acid. If carbon dioxide (CO₂) is produced, bubble it through limewater, which will turn cloudy.
How do you test for chloride (Cl⁻), bromide (Br⁻), and iodide (I⁻) ions?
Acidify with dilute nitric acid, then add aqueous silver nitrate.
• Chloride: White precipitate (AgCl).
• Bromide: Cream precipitate (AgBr).
• Iodide: Yellow precipitate (AgI).
How do you test for nitrate ions (NO₃⁻)?
Add aluminum foil and aqueous sodium hydroxide, then warm.
If ammonia gas (NH₃) is produced, nitrate ions are present.
How do you test for sulfate ions (SO₄²⁻)?
Acidify with dilute nitric acid, then add aqueous barium nitrate.
A white precipitate (BaSO₄) indicates sulfate ions.
How do you test for ammonium ions (NH₄⁺)?
Add aqueous sodium hydroxide and warm.
If ammonia gas (NH₃) is released, ammonium ions are present.
How do you test for calcium ions (Ca²⁺)?
Add aqueous sodium hydroxide.
A white precipitate (Ca(OH)₂) indicates calcium ions.
How do you test for copper(II) ions (Cu²⁺)?
Add aqueous sodium hydroxide.
A blue precipitate (Cu(OH)₂) forms.
How do you test for iron(II) ions (Fe²⁺)?
Add aqueous sodium hydroxide.
A green precipitate (Fe(OH)₂) forms.
How do you test for iron(III) ions (Fe³⁺)?
Add aqueous sodium hydroxide.
A brown precipitate (Fe(OH)₃) forms.
How do you test for zinc ions (Zn²⁺)?
Add aqueous sodium hydroxide.
A white precipitate (Zn(OH)₂) forms, which dissolves in excess sodium hydroxide to form a colorless solution.
How do you test for ammonia gas (NH₃)?
Damp red litmus paper turns blue when exposed to ammonia gas.
How do you test for carbon dioxide (CO₂)?
Bubble CO₂ through limewater. It turns cloudy if CO₂ is present.
How do you test for chlorine gas (Cl₂)?
Damp litmus paper turns white when exposed to chlorine gas.
How do you test for hydrogen gas (H₂)?
Hold a lighted splint near hydrogen gas.
It will produce a pop sound.
How do you test for oxygen gas (O₂)?
Insert a glowing splint into the gas.
If oxygen is present, the splint will reignite.
How do you use a flame test to identify lithium ions (Li⁺)?
Lithium gives a crimson red flame.
How do you use a flame test to identify sodium ions (Na⁺)?
Sodium gives a yellow flame.
How do you use a flame test to identify potassium ions (K⁺)?
Potassium gives a lilac flame.
How do you use a flame test to identify copper(II) ions (Cu²⁺)?
Copper gives a green flame.
How do you test for carbon dioxide gas (CO₂) using a splint?
Light a splint and place it into a container of the gas.
The splint goes out. (This happens because CO₂ is not flammable and does not support combustion.)
How do you use a flame test to identify calcium ions (Ca²⁺)?
Calcium gives a orange-red flame.
