required practicals p2 Flashcards
1
Q
Rates of Reaction
A
- Use a measuring cylinder to put 10cm3 of sodium thiosulfate solution into a conical flask
- Place the conical flask onto a printed black cross
- Add 10cm3 of HCl to the conical flask
- Swirl the solution and start a stopwatch
- Look down through the top of the flask and stop the clock when the cross can no longer be seen
- Repeat steps 1-5 using lower concentrations of sodium thiosulfate solution
2
Q
Chromatography
A
- Use a ruler to draw a horizontal line about 2cm from the bottom of the chromatography paper
- Mark 5 pencil spots at equal spaces across the line
- Use a capillary tube to put a small spot of each of the known food colours and the unknown colours onto the pencil spots
- Pour water into a beaker aprrox 1cm depth
- Attach the paper to a glass rod using tape
- Lower the paper into the beaker
- Remove the paper once the water has travelled around 3/4 up and use a pencil to mark where the water reached
- Leave the paper to dry
3
Q
Water - checking if pure
A
Potable water = safe to drink
Pure water = contains no dissolved solids
1. Use a balance to weigh an empty evaporating basin and record the mass
2. Fill the evaporating basin with the water sample
3. Place on a tripod and gauze and use a bunsen burner to gently heat until it all evaporates
4. Allow the evaporating basin to cool
5. Re-weigh the evaporating basin
6. If the mass of the evaporating basin increased, the water contained dissolved solids bc they wouldve formed crystals on the bottom of the evaporating basin
4
Q
Water - purifying it
A
- Use apparatus - conical flask on tripod and gauze, conical flask attached to delivery tube pointed into a test tube containing ice and water
- Gently heat water using bunsen burner
- The water vapour will travel along the delivery tube
- When the water vapour enters the cold test tube, it will condenses back into liquid water
- This is distilled water which contains no dissolved substances so is pure
