The effect of temperature on salinity and pH of seawater
- The materials required for this science project:10 beakers of the same size
- 1 pail of seawater
- 1 ruler
- 10 hotplates
- 10 thermometers
- pH paper
- A hygrometer
1. For this experiment, the independent variable is the temperature of the seawater – 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C and 65 °C. The dependent variable is the pH and specific gravity of the seawater. This is determined by using the pH paper and the hygrometer. The constants (control variables) are the size of the beaker, the amount of seawater used and the exposed surface area of the water.
2. Ten beakers are filled with seawater up to 10cm in height. The viscosity and pH levels of the seawater in all 10 beakers is tested using the hygrometer and pH paper. The readings in all 10 beakers should be the same. If different readings are obtained, repeat the test using a fresh pail of seawater.
3. A thermometer is placed inside each of the beakers. Each beaker is then placed on a hot plate. The hot plate is then regulated so that the seawater in each beaker will reach a temperature of 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C and 65 °C respectively. The temperature of the chosen beaker is written outside the beaker. The temperatures are kept constant for 24 hours.
4. The height, pH level and specific gravity of the seawater in the beakers is measured after 24 hours and the results are recorded in the table given below.
Handle hot plates carefully