There are a lot of things we could have done to improve the accuracy of our coursework. For example, we could have used different beakers for each concentration to avoid cross-contamination. We could have pre-mixed the different dilutions in the lab, to ensure we did it correctly, rather than diluting as we went.The temperature is another factor that may have changed during the experiment - how could we have prevented this happening?
There are a few pieces of equipment we could have used instead:
Volumetric flask (
Pictures available here) - this piece of equipment is used to dilute solutions, and the long neck allows us to be very accurate about the amount of liquid that we add. It would have allowed us to dilute the acid with much greater accuracy
Colorimeter (
Pictures available here) - a colorimeter is a fancy machine that shoots lasers at a solution and calculates how much of the laser is able to pass through the liquid. From this you can work out how much of the light is blocked, or how cloudy the liquid is. We could have performed a much more rigorous experiment in which we took a colorimeter reading of the different reactions every 10 or 30 seconds.
As this equipment is expensive, we could instead have used a simple colorimeter, which consists of a light dependent resistor attached to a multimeter and power pack. We could have placed the resistor under the beaker and noted the current through the resistor at different times in the experiment, or stopped our stopwatch whenever the current reached a certain value.
Electric Stirrer (there are a lot of different variations of this - type magnetic stirrer or laboratory shaker into Google Images) - if you stirred your solution, there is a chance that you stirred different ones with a different amount of force. To prevent this happening, you could have used one of these specialised pieces of equipment. It would be a little bit of overkill in our experiment, but there's no harm in mentioning it, just to show that you're aware of how to improve.
