Water and Polarity

What property of water molecules causes surface tension and cohesion?

• Covalent bonds
• Bent shape
• All non-metal atoms
• Polarity

What is another word for "stick together"?

• Cohesion
• Covalent
• Cooperation
• Surface tension

What factor below will NOT affect the rate of dissolution?

• Temperature of the solvent

• Time of day

• Amount of agitation when solvent and solute are mixed

• Surface area of the solute

A substance that is dissolved in a liquid is called the

• solvent
• solution
• solute
• polar

When the temperature of a solvent is increased, the time it takes for the solute to dissolve is decreased because

• water molecules have more energy and strike the surface of solute more frequently.
• solute molecules transfer their energy to the solvent which causes the solute to dissolve more quickly.
• the ions in the solute strike the water molecules as they vibrate
• the water molecules lose energy to the solute

Why does dissolution occur faster when the crystal size is smaller?

• When crystal size is smaller, the temperature drops

• When crystal size is smaller, more surfaces are exposed to the solvent.

• When crystal size is smaller, there is a lower mass of solute available.

• When crystal size is smaller, it absorbs the solvent.

Which of the following statements is justified by the surface collision model?

• Increased temperature causes water molecules to strike the surface of solute more frequently.
• The greater the surface area, the more surfaces exposed to water molecules, which strike the surface to cause dissolution
• The more agitation when solvent or solute are mixed, the more water molecules move and strike the solute.
• All of the above.

Why would a large crystal of an ionic solute dissolve in water even if there is no heat or agitation added?

• The Kinetic Molecular theory explains that all molecules are in constant motion so molecules will strike the solute.
• The large crystal would dissolve because it is so big and takes up so much space in the solvent.
• The large crystal would not dissolve without adding heat or agitation.
• The crystal would only dissolve if you crush it up.

Which statement describes the polarity of a water molecule?

• The oxygen end has slight positive charge and the hydrogen end has a slight negative charge
• The oxygen end has a slight negative charge and the hydrogen end has a slight positive charge
• Electrons are shared evenly between the hydrogens and the oxygen.
• The charge on each end of the molecule is balanced.

A teaspoon of dry coffee crystals dissolves when mixed in a cup of hot water. This process produces a coffee solution. The orginal crystals are classified as a

• solute

• solvent

• reactant

• product