Structure of Water 1
What is the chemical structure of water?
H2O (or drawing of H2O)
What characteristic of water allows it to dissolve many things?
Because it's a polar compound
What is a solvent?
A substance that dissolves another substance (e.g. water)
This property of water is responsible for surface tension.
Cohesion
If water will not dissolve a particular substance, what is it?
How many hydrogen atoms are in a water molecule?
There are 2 hydrogen atoms.
Why is water considered polar?
It has uneven charges (positive hydrogens, negative oxygens).
What is a solute?
Something that gets dissolved in a solvent (solution).
This property of water allows ice to float.
Expansion upon freezing
What property of water is responsible for water flowing up a plants' xylem?
Cohesion
How many oxygen atoms does a water molecule have?
It has one oxygen molecule.
What bonds hold together the oxygen and hydrogens inside the water molecule?
Covalent bonds
Moderate (or moderating)
Keeping in the middle
This property of water allows water to dissolve many substances.
Universal/versatile solvent
What property of water allows aquatic habitats to survive in the winter?
Expansion upon freezing
What is the charge on the oxygen in a water molecule?
What is the charge on the hydrogens in a water molecule?
Negative charge (oxygen)
Positive charge (hydrogen)
What bonds are made between water molecules?
Hydrogen bonds
What is the mixture that is formed when one substance dissolves another?
Solution
This property of water makes it hard to heat water up.
High specific heat capacity
What property of water allows nutrients to be dissolved into our blood and transported around our body?
Versatility as a solvent (universal solvent)
Scientific _______ are logical conclusions that are drawn from scientific observations.
A. phenomena
B. inferences
C. hypotheses
D. data
B. inferences
Spontaneous generation is the hypothesis that nonliving material can spontaneously change into a living organism. Hundreds of years ago, many scientists accepted this hypothesis. The following is one experiment that was performed to test the hypothesis of spontaneous generation: Meat was placed in three identical glass jars. One jar was left open, one jar was tightly sealed, and one jar was covered with a fine mesh that allowed air into the jar but kept flies out. Maggots (fly larvae) only appeared in the open jar. Was a control used in this experiment?
A. No, this experiment did not include a control group.
B. Yes, the open jar acted as a control.
C. No, this experiment included two variables instead of one.
D. Yes, both the sealed jar and the jar with mesh were controls for the open jar.
B. Yes, the open jar acted as a control.
Bill likes to go to horse races. At the races, he notices that a certain breed of horse usually comes in first place, while a different breed of horse usually comes in last place. Which of the following is a testable scientific question that Bill could ask about his observations?
A. Do faster breeds of horses have longer legs?
B. Do some horses want to win the race more than others?
C. Do slower breeds of horses lack determination?
D. Are some breeds of horses prettier than others?
A. Do faster breeds of horses have longer legs?
A scientist discovered a new antibiotic and wanted to know if it would be effective against group A Streptococcus bacteria. He designed a test experiment in a lab with ten different cultures of the bacteria. He introduced the antibiotic into five of the cultures, leaving the other five to grow without it. He recorded observations every three hours for a week. What is the independent variable in this experiment?
A. the presence of the new antibiotic
B. the total number of bacteria cultures
C. the reaction of the bacteria to the antibiotic
D. the presence of the Streptococcus bacteria
A. the presence of the new antibiotic
Annie wants to find out if having a substance dissolved in water changes the temperature at which the liquid boils. She prepares two samples of water with equal volumes. She dissolves 3.0 grams of salt in the first sample, and uses the second sample of pure water for a control group. She then heats each sample until it boils and records the temperature while it is boiling. Which of the following is the dependent variable in this experiment?
A. the boiling point of pure water
B. the volume of the water samples
C. the type substance dissolved in the water
D. the temperature at which the liquid boils
D. the temperature at which the liquid boils