Earth and Environmental Science 11–12 · Year 11
Properties of water that shape the Earth: heat capacity, density of ice, surface tension and solvent action
Module 3: Energy Transformations
School laboratory, not for home
In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
The idea
Water’s high heat capacity, expansion on freezing, surface tension and solvent power each follow from hydrogen bonding and each governs a large-scale Earth process.
Safety card
Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
Hazards
- hot lamp
- boiling water and steam
- hotplate
Controls
- teacher runs the boiling station
- lamp on a stand away from hands
- safety glasses
Note
Heat or hot water is used: follow the NSW Department of Education Chemical Safety in Schools (CSIS) package, Section 1, and record a RiskAssess risk assessment before the lesson.
What you need
- station 1: two identical beakers, 100 g water and 100 g vegetable oil (or dry sand), a 100 W lamp at a fixed distance, two thermometers
- station 2: ice cubes, cold water, measuring cylinder, balance, a thin wire or pin to hold the cube under
- station 3: 20 cent coin, dropper, detergent
- station 4: salt, sugar, sand, oil, four test tubes of water
- station 5: 250 mL beaker of water, thermometer, hotplate (teacher-run) for the boiling point
How to do it
- Station 1: record both temperatures every minute for 10 minutes under the lamp and plot the two curves.
- Station 2: weigh an ice cube, push it fully under the cold water in the measuring cylinder with the wire or pin, read the rise in level as its volume and calculate its density (a cube left floating displaces only its own mass of water and gives 1.00 g/cm³); note the fraction of a floating cube below the surface.
- Station 3: count drops of water on the coin before it overflows; repeat with a drop of detergent added.
- Station 4: shake each solute with water and record which dissolve.
- Station 5: heat the water and record the temperature at which boiling holds steady; compare with the sea-level value 100 °C.
What you should see
Water has a specific heat capacity of 4.18 kJ/(kg·K) at 20 °C (NIST WebBook), higher than that of oil or dry sand, so the learner expects the water to warm more slowly than the same mass of oil or sand under the same lamp and tests it. Ice is about 9 % less dense than liquid water (USGS Water Science School), so about nine tenths of a floating cube sits below the surface. The coin holds a dome of many drops until detergent, which lowers surface tension, cuts the count sharply; salt and sugar dissolve, sand and oil do not; water boils near 100 °C at sea-level pressure and at a lower temperature where the pressure is lower, as at altitude. Each result is linked to an Earth process: oceans buffer climate, ice floats and insulates the water beneath, capillary rise moves water through soils, rivers carry dissolved load.
What changes
This activity lists no variables to change, measure and keep the same.
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Ice sinks in very cold water.
- Water boils at 100 °C everywhere.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-10EES11/12-5EES11/12-6EES11/12-7
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-11-03
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.