Rates of reaction
Method overview
Use either gas collection/mass loss for acid–carbonate or disappearance of a cross for thiosulfate. Change one factor, start timing on mixing, record at fixed intervals or a defined endpoint, repeat and compare rates.
Apparatus set-up
Diagramconical flask; gas syringe; balance; stopwatch; acid; marble chips; sodium thiosulfate; cross; measuring cylinders
Independent variable
concentration or surface area
Dependent variable
gas volume/mass loss/turbidity time and rate
Control variables
temperature; reactant amounts; apparatus; total volume; endpoint
Apparatus
conical flask; gas syringe; balance; stopwatch; acid; marble chips; sodium thiosulfate; cross; measuring cylinders
Safety
Wear eye protection; acids irritate; sulfur dioxide from thiosulfate should be produced on small scale in ventilation.
Scientific rationale
Higher concentration or surface area increases collision frequency; higher temperature increases collision frequency and fraction above activation energy.