Scientific Design, Statistics & Water Properties Flashcards

Vocabulary flashcards covering key terms in scientific design, statistical analysis, and the physical and chemical properties of water based on Unit 1 lecture notes.

Independent variable

The factor in an experiment that the scientist changes.

Dependent variable

The factor in an experiment that the scientist measures.

Controlled variables

Factors kept the same for all groups in an experiment.

Control group

The group that does not receive the experimental treatment and provides a baseline for comparison.

Experimental group

The group that receives the treatment being tested in an experiment.

Null hypothesis

A hypothesis that predicts no significant effect or difference.

Alternative hypothesis

A hypothesis that predicts a significant effect or difference.

Replication

Repeating an experiment to make results more reliable by showing they can be reproduced.

Sample size

The number of observations or subjects in a sample; larger sizes reduce the effect of random variation and increase precision.

Water polarity

The property of water where oxygen attracts shared electrons more strongly than hydrogen, creating a partial negative charge near oxygen and partial positive charges near hydrogen.

Polar covalent bonds

Bonds that hold the hydrogen and oxygen atoms together within a single water molecule.

Hydrogen bonds

Weak attractions between separate water molecules.

Cohesion

Attraction between molecules of the same substance, such as water sticking to water.

Adhesion

Attraction between different substances, such as water sticking to glass or plant tissues.

High specific heat

The requirement of a lot of energy to change water's temperature, helping organisms and environments resist rapid temperature changes.

High heat of vaporization

The requirement of a lot of energy for water to evaporate, enabling evaporative cooling.

Evaporative cooling

A cooling process where the highest-energy water molecules escape as vapor, leaving behind lower-energy molecules and lowering the temperature of the remaining liquid.

Density of ice

Ice is less dense than liquid water because hydrogen bonds arrange water molecules into an open structure when frozen, allowing ice to float.

Solvent

A substance capable of dissolving other polar or charged substances; water's polarity makes it an excellent solvent.

Hydrophilic

"Water-loving"; describes substances that interact with or dissolve in water, usually because they are polar or charged.

Hydrophobic

"Water-fearing"; describes substances that do not mix well with water, usually because they are nonpolar.

Standard Error (SE)

A measure showing how precisely a sample mean estimates the population mean, calculated as $\text{SE} = \text{SD} \times \frac{1}{\text{n}}$ or $\text{SE} = \text{SD} \frac{1}{\sqrt{n}}$.

$$\pm 2\text{ SE}$$

Represents the mean plus and minus two standard errors, showing the range around the mean to indicate the precision or variation of the estimate.