Ocean Presentation

Properties of Water Lab

By: Zainab Attar

Summary

Water is essential for life on Earth, making up 50-95% of living cells. Its unique properties, such as dissolving abilities and high heat capacity, are due to its polarity and hydrogen bonds. Water's polarity, resulting from its unequal sharing of electrons, allows it to dissolve many substances and form hydrogen bonds, making it sticky (adhesive and cohesive). This leads to four key properties: cohesion and adhesion (sticks together and to other surfaces), surface tension (acts like an elastic sheet), capillary action (moves through small spaces), and high specific heat (regulates temperature changes). While water's dissolving ability is crucial, it's not a universal solvent, unable to dissolve nonpolar molecules like lipids and some proteins. These properties help form cell membranes and regulate life processes, making water vital for life on Earth.

Stations

01

1a

02

1b

03

2a

04

2b

05

2c

06

3a

07

3b

08

4a

09

4b

10

5a

11

5b

12

6a

13

6b

1a

Hydrogen Bonding

Water molecules form hydrogen bonds with up to four molecules, creating cohesion that holds them together. Hydrogen bonding cohesion allows living organisms to transport water and nutrients. For example, in plants, cohesion helps water move up the xylem from roots to leaves through capillary action, producing photosynthesis.

1b

Hydrogen Bonding

Water cannot form hydrogen bonds with nonpolar ethane molecules, causing them to separate and illustrating the concept of nonpolar molecules being insoluble in water. Insolubility helps maintain cell membrane structure, keeping certain substances out of cells. Cell membranes use insolubility to regulate what enters and leaves the cell, protecting it from harmful substances.

Table

2a

Cohesion

Water's surface tension, due to hydrogen bonding and cohesion, enables it to maintain its shape against gravity, demonstrated by counting drops on a penny. Significance: Surface tension keeps cell membranes strong and controls what goes in and out of cells. Example: Cells use surface tension to maintain their shape and function properly.

Cohesion Surface Tension

2b

Food coloring droplets maintain their shape and merge due to cohesion and surface tension, illustrating how these forces show liquid behavior. Significance: Cohesion and surface tension help maintain cell membrane structure and regulate substance transport. Example: Blood vessels rely on cohesion and surface tension to maintain blood flow and pressure.

2c

Surface Tension Hydrophobicity

Soap molecules break hydrogen bonds between water molecules, reducing surface tension. Hydrophobic pepper particles are repelled by water, moving away from the disrupted surface. Significance: Surface tension and hydrophobicity help maintain cell membrane structure and regulate substance transport. Example: Surface tension and hydrophobicity help maintain cell membrane structure and regulate substance transport.

3a

Adhesion, Cohesion, Capillary Action

Celery absorbs colored water through tiny tubes, showing adhesion, cohesion, and capillary action. Significance: These forces help plants transport water and nutrients. Example: Plants use capillary action to move water from roots to leaves.

3b

Adhesion, Cohesion, Capillary Action

The paper towel "sucks up" water because: - Water sticks to it - Water molecules stick together - Water moves through tiny spaces Significance: Helps plants and animals move fluids. Example: Plants move water from roots to leaves.

4a

Solvent Properties

Water is a polar solvent which dissolves salt (solute), an ionic compound, by breaking its strong ionic bonds and forming hydrogen bonds. Significance: Water helps dissolve essential minerals for our bodies. Example: Our kidneys use water to filter waste from the blood.

4b

Solvent Properties

Sucrose dissolves faster than [4A's substance] in water, breaking covalent bonds and forming hydrogen bonds with water molecules, showcasing water's strong solvent properties. Significance: Water's solvent properties allow it to dissolve nutrients and oxygen, supplying cells with important resources. Example: Blood cells use water as a solvent to transport oxygen and nutrients to body tissues.

5a

Polarity

The Oil stays still on top of water. Oil floats on water due to its hydrophobic nature, resulting from nonpolar bonds, which cannot form hydrogen bonds with water molecules. Significance: Hydrophobicity helps cells keep their shape by keeping water out of certain areas. Example: Cell membranes have hydrophobic tails that repel water, keeping cells stable and controlling what goes in and out.

5b

Surface tension

Paper clip floats on water when placed horizontally due to surface tension Significance: It is essential for aquatic life, surface tension helps insects breathe and float. Example: Water striders use surface tension to walk on water and gather oxygen.

6a

Evaporative cooling

Alcohol evaporates faster than water because its molecules have weaker bonds, allowing quicker escape. Significance: Evaporative cooling helps maintain thermal balance in living organisms and machines. Example: Air conditioners and refrigerators utilize evaporative cooling principles to cool air and liquids.

Data

6b

Thermal Properties

Here's the information condensed into one paragraph: Design an experiment to demonstrate water's thermal properties by filling three identical cups with hot water (~90°C), cold water (~10°C), and ice, and measuring temperature changes every minute for 10 minutes using thermometers. Diagrams illustrate the setup and temperature vs. time graphs. Expected results show hot water cooling slowly due to high heat capacity (4.184 J/g°C), cold water remaining stable, and ice absorbing heat slowly. Water's unique thermal properties are due to hydrogen bonds absorbing and releasing energy slowly, regulating Earth's climate, maintaining stable ocean temperatures, and supporting life. This experiment highlights water's ability to absorb and release heat energy slowly, demonstrating its essential role on Earth. The results can be visualized in a graph tracking temperature changes over time for each cup, illustrating water's remarkable thermal resilience.

Soapy Water

Water

Thermal Properties of Water Experiment