Physical chemistry practicals Flashcards
1
Q
Steps to make a solution of a known concentration
A
- Weigh out a precise amount of the solid
- Add a small volume of water and pre-dissolve the solid, stirring with a glass rod
3.Transfer to a volumetric flask with a funnel - Rinse the beaker with distilled water and add the rinsings to the flask
- Make up to the scratch mark with water. Add the stopper and gently shake to mix.
2
Q
Steps for a titration
A
- Measure a known volume of one of the solutions and put it into a conical flask.
- Fill the burette with the other solution
- Add a few drops of indicator to the conical flask.
- Open the tap on the burette carefully and add the solution to the conical flask until the solution starts to change colour.
- As you get near the end point, slow the flow from the burette until it is dropwise.
- stop adding once the solution changes colour and the find the titre by subtracting the initial burette reading from the final reading.
3
Q
Method for measuring enthalpy change
A
- Using a measuring cylinder place 25 decimetres cubed of 1 mol per decimeter cubed copper sulfate solution into a polystyrene cup
- Weigh about 6g of zinc powder- there is no need to be accurate as it is added in excess
3.Put a thermometer into the cup and stir, record the temperature every minute for 2.5 mins - At 3 mins, add the zinc powder to the cup- dont record the temp
- Continue stirring and record the temperature for an additional 6 mins.
Find the enthalpy change using q=mcdeltat
4
Q
Rate of reaction required practical
A
Disappearing cross experiment-
1. Measure a set amount of sodium thiosulfate and put into a conical flask.
2. Put onto a cross
3. Add HCl and start timing. Time the amount of time taken for the cross to disappear from sight, looking through the top of the conical flask.
4. Change the concentration of HCl to see effect of concentration on rate, put into a water bath and change the temp for effect of temperature on rate.
