Chem chapter 8 review
Why doesn't the temperature of melting ice rise as the ice is heated?
Because of the heat absorbed by the ice during melting at the melting point is used for phase transformation. temp wont go up until everything is melted.
Imagine that you dip a paper clip into water and then slowly pull it upward toward to the point where it is nearly free from the surface. You'll find that for a short distance, the water is brought up with the metal. Are these adhesive or cohesive forces at work?
Both adhesion because its sticking to the paper clip and cohesion because its allowing the water on the paper clip to stay connected to the water in the cup
Which should have a lower freezing point: a 1 M solution of sodium chloride, NaCl, or a 1 M solution solution of calcium chloride, CaCl2? Why?
Calcium Chloride because it has more ions, more ions more disruption of structure which makes it harder to freeze
What is the difference between cohesive forces and adhesive forces?
Cohesive forces is how well it stick to itself and adhesive is how well it sticks to other things .
What is released when a hydrogen bond forms between two molecules of water?
Heat or energy. form bonds -release break bonds-absorb
What accounts for the fact that ice is less dense as compared to water?
Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density. More organized in the solid forms verse the liquid form.
Why do we feel uncomfortably warm on a hot, humid day?
In humid places condensation outpaces evaporation, and you feel the warming effect as water vapor in the air condenses on your skin.
Does a substance that heats up quickly have a high or a low specific heat?
Low, because this means it doesn't take long to reach the specific heat
Does liquid water rise higher in a narrow tube or a wide tube? Why?
Narrow, because there is more adhesion which means they stick to other things which pull the molecules up the side.
Which should have a lower freezing point: a 1 M solution of sodium chloride, NaCl, or a 1 M solution of sucrose, C12H22O11? Why?
Sodium Chloride because the sugars won't break apart
Rank the following in order of increasing amount of energy required to change 1 g of water from:Liquid to gas, Solid to liquid, Solid to gas.
Solid to liquid 3- least amount of energy Liquid to gas 2- medium because molecules are already moving Solid to gas 1- highest amount of energy because of their structure
What within liquid water is most responsible for its unusual specific heat?
The hydrogen bonding
Why is it important to protect water pipes so that they don't freeze?
The pipes could burst open with the amount of energy the ice has it pushes out depending on the room it has.
What does it mean when water boils?
The water at the bottom is being heated which is breaking and reforming hydrogen bonds, actual boiling is when the bubbles have enough pressure to make their way to the top. the pressure of the bubbles has to be equal to the atmospheric pressure.
Why does wetting a cloth in a bucket of cold water and then wrapping the cloth around a bottle produce colder water than placing the bottle directly in the bucket of cold water?
The water on the cloth is breaking bonds and its pulling the energy from the water bottle
How does the specific heat of liquid water compare with the specific heats of other common materials?
Water has an abnormally high heat capacity compared to most other substances. Because of the hydrogen bonds.
When liquid water freezes, is heat released to the surroundings or absorbed from the surroundings?
When water freezes it releases heat into the environment. It's forming a bond.
Rank the following in order of increasing boiling point: Tampa Bay, Florida(elevation 2ft) Winfield Kansas(elevation 1129ft) Death Valley, California(elevation-282 ft)
Winfield, Kansas (elevation 1129 ft) 1 Tampa Bay, Florida (elevation 2 ft) 2 Death Valley, California (elevation -282 ft)3
What condition permits liquid water to boil at a temperature below 100oC?
lower atmospheric pressure, if your at high altitude it will boil at a lower temperature.
What happens to ice when great pressure is applied to it?
the open space collapses, and the result is the formation of liquid water. The ice is melting due to pressure which makes it more dense.
