Gases in water
Dissolved oxygen keeps water life alive.
Fish in water
A fish lives in water but breathes oxygen.
Where does it get oxygen from?
What this lesson covers
The idea
Many gases, including oxygen, dissolve evenly in water to form a uniform mixture; oxygen dissolves only to a small extent, yet this dissolved oxygen sustains all aquatic life.
Fish in water
A fish lives in water but breathes oxygen.
Where does it get oxygen from?
- From the oxygen dissolved in water
- From the water molecules
- From the mud
Oxygen in water
Open both tabs.
A small amount matters
Gases dissolve evenly in water, so a gas in water is a uniform mixture. Even a minute amount of dissolved oxygen sustains all aquatic life.
Many gases, including oxygen, dissolve in water and form a uniform mixture. A small amount of dissolved oxygen sustains all aquatic life.
Notes
Gases such as oxygen dissolve evenly in water; the dissolved oxygen sustains aquatic life.
Check yourself
A gas dissolved in water forms …
Which gas dissolved in water sustains aquatic life?
Oxygen dissolves in water …
Aquatic life includes …
- a non-uniform mixture. Gases dissolve evenly in water, so it is uniform.
- a uniform mixture — correct. Yes!
- a pure substance. It is a mixture of gas and water.
- Sand. Sand is not a gas. The gas is oxygen.
- Salt. Salt is not a gas. The gas is oxygen.
- Oxygen — correct. Yes!
- only to a small extent — correct. Yes!
- completely, like sugar. Oxygen dissolves only to a small extent.
- not at all. Oxygen dissolves a little, enough to sustain aquatic life.
- only fishes. It includes plants and other organisms as well.
- plants, fishes and other organisms — correct. Yes!
- only plants. Fishes and other organisms are included too.