Biology study set 4
What is covalent bond?
A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Why don't lakes freeze solid?
At some point, ice becomes insulator.
What is cohesion?
Cohesion is an attraction between molecules of different substances.
Why do some things float and some things sink?
Floating or sinking of an object does not depend on its weight, it depends upon its density and the one it flows on. Things denser than water sink in water whereas things having less mass than water float over it
Why do so many substances dissolve in water?
Molecules that have partially charged positive and negative areas are polar. Because water molecules are polar, water can dissolve many other polar substances. Water can also dissolve ionic compounds such as table salt.
What does polarity mean? Explain Polarity of water.
Polarity is the property of having poles or being polar.
What is surface tension? explain.
Surface tension is the attractive force exerted upon the surface molecules of a liquid by the molecules beneath that tends to draw the surface molecules into the bulk of the liquid and makes the liquid assume the shape having the least surface area. The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension.
Is water's surface tension strong enough to support a paperclip? Explain how this might be possible on a molecular level.
Yes because Water is a polar chemical. That means each water particle, called a molecule, has a positive and negative charge. The water molecules are attracted to each other and "stick" together. The positive end of one molecule sits next to the negative end of another molecule. The water particles at the surface "stick" only to particles next to and below them. this makes the surface act as if it had a thin "skin". This is called surface tension. The surface tension of water is strong enough to support a paperclip! The fork helps you lower the paperclip gently into the water without breaking the surface tension. When you put soap into the water, it disrupts the order of the water molecules. The water molecules are no longer lined up from positive to negative, so the surface tension is no longer strong enough to support the weight of the paperclip. The paperclip falls into the water. Now go try the floating paperclip experiment yourself with some friends.
What is osmosis?
a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane
Why is water cohesive? explain.
because of polarity. The opposite of molecules attract.
Why volume of ice increase? by how much? Explain how pot holes form.
because there is more space between molecules. idk how much. puddles freeze expanding causing potholes.
Describe the surface of water and why it is formed that way.
graduated cylinder dips in the center because adhesion between water molecules and glass molecules in stronger than cohesion between water molecules.
Why does it adhere to different substances?
it is an adhesive bond because it is between different molecules.
