Task 1: Working out calculations
Step 1: We need to work out the required concentration of the unknown HCl (Hydrochloric Acid). The values given to us are that we need 100ml of 0.05mol HCl.
Step 2: Convert ml to dm^3 100ml = 0.1dm^3
Step 3: Using the fomula c = n/v c=0.05/0.1
∴ c = 0.5mol/dm^3 of HCl
Task 2: Writing out the equation and balancing
Hydrochloric acid + Sodium Hydroxide —> Sodium Chloride + Water
HCl + NaOH —> NaCl + H2O
This is a neutralisation reaction. The equation is already balanced so there is no need to do so. This also suggests that the mol ratios are all going to be the same at 1.
Task 3: Making a standard solution
To make the standard solution, the sodium hydroxide pellets should be put into a beaker.
When it comes to titrations, we need to titrate an alkali of a certain concentration (from the burette into a beaker which holds the unknown acid). To do so, we must put the alkali in the burette.
Method:
1. Pour acid into the burette until the meniscus of the fluid is at exactly 50cm^3 to a degree of ±0.1cm^3.
2. Pour the alkali of unknown concentration and 3 drops of phenolphthalein to the conical flask.
3. Slowly turn the tap to drip the hydrochloric acid into the conical flask whilst stirring the flask every drip to ensure the neutralisation occurs properly.
4. Continue until the solution is at a point where it is not a full pink colour but clear to an extent.
Equipment List:
Burette (50cm^3)
Sodium Hydroxide Pellets
Hydrochloric Acid
Phenolphthalein (Indicator)
Beaker x3
Conical Flask
Plastic Pipette
Pipette
Pipette Filler
Boss
Clamp
White Tile
Funnel
Risk Assessment:
1. Ensure that the tap is always closed when you are not using the burette as it may spill out and increase the overall uncertainty of the experiment.
2. Move any obstacles that may be hazards out of the way such as chairs so that if any chemicals spill, it is easy to manoeuvre.
3. Keep chemicals away from the edge of tables to prevent then from spilling.
4. Wear safety goggles to protect the eyes
5. Adding water to sodium hydroxide pellets is an exothermic reaction. Due to this, a lot of thermal energy is released so once the water is poured in to the beaker, everyone must be a safe distance away in case the beaker spills as it may cause severe burns.
http://www.creative-chemistry.org.uk/alevel/module1/documents/N-ch1-49.pdf
React!