Secondary 1 Science - Chapter 4: Diversity — Separation Techniques

Flashcards covering the separation techniques, experimental procedures, and Singapore's water sustainability strategies as outlined in the Chapter 4 Diversity lecture notes.

Which separation technique is used to separate an insoluble solid from a liquid?

Filtration.

Define 'filtrate' and 'residue' as they relate to filtration.

Filtrate is the liquid that passes through the filter; residue is the solid particles that remain on the filter.

Why is the technique of evaporation to dryness not used to recover solutes like sugar?

Sugar can be easily damaged or decomposed by heating to dryness.

How does crystallization differ from evaporation for separating a soluble solid from a solution?

Crystallization involves evaporating some of the solvent to obtain a saturated solution, from which pure crystals form, rather than heating to total dryness.

What is a saturated solution?

A solution that will not dissolve any more solute at a particular temperature.

What is simple distillation used for?

To separate a single liquid from a solution (e.g., pure water from seawater).

What is the purpose of adding boiling chips into the distilling flask during distillation?

To ensure smooth boiling.

Where should the bulb of the thermometer be placed in a distillation setup?

At the inlet of the condenser to measure the temperature of the vapour entering it.

In a Liebig condenser, why must water enter from the bottom?

To ensure the entire jacket is filled with water and the coldest part of the condenser is located just before the vapour escapes, achieving more effective cooling.

When is fractional distillation used instead of simple distillation?

When separating two or more liquids that are miscible with one another and have different boiling points.

What is the function of the glass beads in a fractionating column?

They increase the surface area for vapour that has not reached its boiling point to condense back into the flask, ensuring components with different boiling points leave at different times.

Which separation technique is used for immiscible liquids like oil and water?

A separating funnel.

What property of matter does paper chromatography exploit to separate substances?

The different solubilities of solutes in the same solvent.

Why is a pencil used to draw the starting line in paper chromatography instead of ink?

Pencil contains graphite which is insoluble in most solvents, whereas ink is a mixture that can dissolve and interfere with the results.

What is a 'locating agent' in chromatography?

A chemical sprayed on a chromatogram to make colourless spots visible.

What are Singapore’s 'Four National Taps'?

1. Water from Local Catchment, 2. Imported Water, 3. NEWater (reclaimed water), and 4. Desalinated Water.

What are the three main stages of water treatment in a NEWater plant?

1. Microfiltration / Ultrafiltration, 2. Reverse Osmosis, and 3. Ultraviolet Disinfection.

What is the specific energy consumption for desalination at Singapore’s Tuas South Desalination Plant?

$$3.5\,kWh/m^3$$

How much water does Singapore currently consume per day, and what is the expected demand by 2065?

Singapore consumes about 440 million gallons per day; demand is expected to double by 2065.

According to the PUB study, which four activities constitute 81% of total household water usage?

Shower, flushing, kitchen, and laundry.