Preliminary Chemistry - Task 3: Practical Investigations
Aim – to plan and perform an investigation to identify and describe the effect of salt on the boiling point of water
Hypotenuse – If salt is added to boiling water, the boiling temperature of the solution will be increased. The higher the concentration of salt, the higher the boiling point temperature will be. This is because more energy is required as the salt is a non-volatile solute, therefore making the water an impure solvent, initially raising its boiling point.
Independent variable – concentration of salt
Dependant variable – boiling point of solution
Controlled variable – volume of the water, size of beaker, using the same thermometer, using the same scales, performing the experiment at the same height above sea level and using the same boiling point signs.
· Pen, paper and ruler
· Retort stand
· Bosshead and clamp
· Bunsen burner
· Gauze mat
· 5 x 250ml beakers
· Half a beaker of salt (5 and 10 grams)
· Measuring cylinder
· 3 x 100ml of cold tap water
· Safety goggles
· Lab coat
· Clean wipe
1. Collect equipment in descending order of materials list.
2. Draw up a results table using the pen, paper and ruler to accurately place results once the experiment has been performed.
3. Place the mat on the safest location on the lab bench, setting up the retort stand directly parallel to the mat, followed by attaching the bosshead and clamp approximately 2/3 to the top of the retort stand.
4. Position the Bunsen burner in the middle of the mat (without connecting it to the gas), then place the tripod directly on top of the Bunsen burner, also placing the gauze mat on the centre of the tripod.
5. Assemble the scales on a flat, stable surface with access to a power source, away from water or anything which may cause danger.
6. Using one of the four, 250ml beakers and the spoon fill the beaker approximately half way with salt, and then place it on your bench where it will not get knocked over or mixed with any other substances.
7. Set up the three of the four remaining beakers on the opposite side of the lab bench to where the experiment equipment is set up, spacing them evenly in order to remember which beaker contains which solution.
8. Fill up the measuring cylinder to precisely 100ml of cold tap water, then placing it in the most left beaker (which will be the plain water), once again fill up the measuring cylinder to exactly 100ml of cold tap water, except place it in the middle beaker (which will be the 5 grams of salt), fill up the measuring cylinder a final 100ml and place in the most right beaker (which will be the 10 grams of salt).
9. Turn on the scales, placing the final beaker on them. Press the ‘tare’ button on the scales returning the weight to 0.
10. Using the spoon carefully collect small spoonfuls of salt, placing...