Reaction:
Sodium thiosulfate + hydrochloric acid → sulfur + sulfur dioxide + water
RQ: How does the temperature of sodium thiosulfate solution affect the rate of reaction with hydrochloric acid?
Hypothesis: Increasing temperature will increase the rate of reaction (time for X to disappear will decrease) because particles have greater kinetic energy so more collisions exceed Ea.
Variables:
IV: Temperature of sodium thiosulfate solution (e.g., 15, 25, 35, 45 °C)
DV: Time (s) for cross to disappear (or Rate = 1/time)
CVs: Concentration of reagents, volumes used, total reaction vessel size, same observer, same black X, ambient light, stirring (none)
Apparatus
| Equipment | Size/Specification | Quantity |
|---|---|---|
| Conical flask | 100 cm³ | 1 |
| Measuring cylinder | 50cm³ | 1 |
| Measuring cylinder | 10cm³ | 1 |
| Thermometer | - | 1 |
| Stopwatch | - | 1 |
| Water bath / beakers | 250 cm³ | 1 |
| Sodium thiosulfate solution | 0.10 mol | 25 cm³ per trial |
| Hydrochloric acid | 1.0 mol | 5 cm³ per trial |
| White card with black “X” | - | 1 |
Risk Assessment:
| Hazard | Risk | Precaution |
|---|---|---|
| Hydrochloric acid | Corrosive and causes irritation | Wear goggles, gloves and lab coat |
| Hot water in bath | Causes burns | Wear goggles, gloves and lab coat |
| Sulfur dioxide (from reaction) | Causes respiratory irritation | Use in well-ventilated area or fume cupboard |
| Glassware | Causes cuts and scrapes | Wear goggles, gloves and lab coat |
Method: