⚛ Chemistry RPs

Question 1

chem: what is the method for the making salts required practical

Answer 1

1. measure 40 cm3 of sulfuric acid and put it in a 100cm3 beaker, set up a Bunsen burner, tripod, gauze and heatproof mat, put the beaker on the gauze and heat gently until almost boiling, turn off the burner
2. remove the beaker from the tripod and use a spatula to add a small amount of copper (II) oxide powder to the acid, stir with glass rod.
3. add more copper (II) oxide and stir again until the solution is blue and some of the copper (II) oxide does not react
4. set up a funnel and filter paper over the conical flask and filter the solution, place the filtrate in an evaporating basin
5. set up the water bath using the 250 cm3 beaker on the tripod and gauze evaporate the filtrate gently
6. when crystals begin to form pour the remaining solution into the crystalizing dish, leave it for 24 hours, remove crystals and pat dry between 2 pieces of filter paper

Question 2

Chem: how do you do the titrations required practical

Answer 2

1. Use a pipette to measure 25 cm3 of sodium hydroxide solution into the conical flask and pit it on a white tile
2. Clamp the burette vertically in the clamp stand, there should be just enough space for the council flask and the tile, close the burette tap
3. Use a small funnel to carefully fill the burette with dilute sulfuric acid, put a beaker under the tap open it and allow liquid to fill the tap before closing and filling the burette up to the 0 cm3 line
4. Put 5 - 10 drops of phenolphthalein indicator into the conical flask and swirl it until the contents turn pink
5. Open the burette tap until 10 cm3 of sulfuric acid slowly seeps out into the flask while swirling, then add the acid until the solution turns from pink to colourless, shut the tap immediately
6. Record the volume in the burette to 2 d.p and repeat

Question 3

Chem: how do you do the electrolysis rp

Answer 3

1. Pour approx 50 cm3 of copper (II) chloride solution into the beaker add the Petri dish lidd and insert the carbon rods through the holes, **they must not touch
2. Add crocodile clips with their leads and rods to the electrodes, connect the rods to dc of a low voltage power supply
3. Select 4v on the power supply and activate it, look at the electrodes and record results
4. Use a piece of blue litmus paper to the solution next to the anode (pos) write observations in the table

Question 4

Chem: how do you do the temperature changes required practical

Answer 4

1. Measure 30cm3 of dilute hydrochloric acid and put it into a polystyrene cup
2. Stand the cup up inside the beaker for stability
3. Use a thermometer to measure the temp of the acid, measure 5 cm3 of sodium hydroxide solution then pout it into the cup
4. Pour sodium hydroxide into the polystyrene cup, fit the lid and gently stir the solution with the thermometer through the hole, watch the temp rise, when it stops rising record the highest temp reached
5. Repeat adding more sodium hydroxide into the cup each time and record the amount of sodium hydroxide and the max temp reached, do this until 40 cm3 of sodium hydroxide, wash out each time

Question 5

Chem: how do you do the rate of reaction (concentration) required practical

Answer 5

1. Measure 50 cm3 of 1 mol/dm3 of hydrochloric acid using one of the measuring cylinders, pour the acid into the conical flask, fit the bung and delivery tube to the top of the flask
2. Half fill the bowl with water as shown below
3. Fill the measuring cylinder with water and make sure it stays full when you invert it and add a single 3 cm piece of magnesium ribbon to the flask and put the bung back on as quickly as possible
4. Record the volume of hydrogen gas given off every 10 seconds
5. Repeat the experiment with 1.5 mol solution

Question 6

Chem: how do you do the concentration of sodium thiosulfate affect the rate of reaction

Answer 6

1. Measure 10 cm3 of sodium thiosulfate solution and put it into a conical flask and measure out 40 cm3 of water and add it to the conical flask
2. Put the conical flask on the black cross and measure out 10 cm3 of hydrochloric acid
3. Put it into the conical flask and start the stopwatch and swirl the flask
4. Look through the top of the flask while wearing goggles and stop the stopwatch when you can no longer see the cross
5. Repeat the steps changing the conc of sodium thiosulfate by 10 cm3 each time until cm3 and decrease the water each time until you reach 0

Question 7

Chem: in the temperature changes required practical why is a polystyrene cup used

Answer 7

Because it is a better insulator than the glass of the beaker