Sec 1 Science Separation Techniques topical questions

Name the technique used for each job.

1. (a)Removing iron filings from sulfur powder[1]
2. (b)Removing sand from a mixture of sand and water[1]
3. (c)Obtaining salt from salt water, without keeping the water[1]

In filtration, state where you find the residue and where you find the filtrate.

State one difference between evaporation and distillation.

Give one use of paper chromatography outside the school lab.

State one reason water is treated as a precious resource in Singapore, and one way a student can use less of it.

A mixture contains sand, salt and water.

1. (a)Describe how to obtain dry sand.[2]
2. (b)Describe how to obtain salt crystals from the remaining liquid.[2]
3. (c)State why a magnet is no help with this mixture.[1]

Describe how distillation produces water from sea water. Name the liquid collected and what remains in the flask.

A student sets up paper chromatography of black ink.

1. (a)State two mistakes if she draws the start line in pen and pours solvent above the spot.[2]
2. (b)The ink splits into blue and yellow spots. What does this show?[1]
3. (c)Which spot travelled further, and what does that mean?[1]

Explain how a waterworks can use more than one separation technique on muddy river water that also contains dissolved salts. You want clearer water with fewer dissolved salts.

A scrap yard has iron cans mixed with aluminium cans. Explain whether a magnet separates them, and name the property you are using.

A student wants pure water and dry salt from salty water. She only evaporates the solution in an open dish. Explain what she obtains, what she loses, and what she should have done instead.

Two inks, P and Q, are compared by chromatography in the same solvent. P gives one spot. Q gives three spots, and one of those spots travels the same distance as P’s spot.

1. (a)What does the single spot from P suggest?[1]
2. (b)What does Q’s pattern show?[1]
3. (c)Why does the matching distance suggest one dye might be in both inks?[1]

A mixture contains iron filings, sand and salt, all dry to start with. Describe a full method to obtain each substance on its own. Include when you add water.

Explain why a desalination plant and a student who turns off a dripping tap are both part of looking after water, even though only one of them uses distillation.

A condenser is connected so cold water enters at the top and runs out at the bottom. Predict one problem, and state the correct connection.