Monthly Archives: October 2016

Acids, Bases, and pH

Part A

What is the arrow pointing to?

Correct

The arrow is indicating a single proton, a hydrogen ion (H⁺).

Part B

What is the arrow pointing to?

Correct

The arrow is indicating a hydroxide ion (OH^–).

Part C

In a neutral solution the concentration of _____.

	water molecules is less than the concentration of hydrogen ions
	hydrogen ions is less than the concentration of hydroxide ions
	hydrogen ions is greater than the concentration of hydroxide ions
	hydrogen ions is equal to the concentration of hydroxide ions
	water molecules is less than the concentration of hydroxide ions

Correct

This is the definition of a neutral solution.

Part D

How does the pH of the solution on the right compare with that of the solution on the left?

	Both of these solutions are equally basic.
	Both of these solutions are equally acidic.
	The solution on the right is basic relative to the solution on the left.
	The solution on the right is neutral relative to the solution on the left.
	The solution on the right is acidic relative to the solution on the left.

Correct

The solution on the right has a lower concentration of hydrogen ions relative to hydroxide ions than does the solution on the left.

Cohesion of Water

Part A

What process is illustrated by this animation?

To view the animation, click here. Then click on the image to start the animation.

What process is illustrated by this animation?

Correct

Water is moving up the tree as it evaporates from the leaf surface.

The Polarity of Water

Part A

Each water molecule is joined to _____ other water molecules by ____ bonds.

Correct

As can be seen in the illustration on page 1 of the activity titled “The Polarity of Water” a water molecule is joined to four other water molecules by hydrogen bonds.

Part B

The unequal sharing of electrons within a water molecule makes the water molecule _____.

Correct

The electrons spend more time with the oxygen of the water molecule than with the hydrogens of water. Thus, the oxygen has a net negative charge and the hydrogens have a net positive charge.

Part C

The tendency of an atom to pull electrons toward itself is referred to as its _____.

Correct

The question defines electronegativity.

Part D

In this molecule, what type of bond is found between the oxygen and hydrogens?

Correct

While oxygen shares electrons with hydrogen, the electrons spend more time with the oxygen than with the hydrogens.

Part E

Which of these bonds is weakest?

Correct

Hydrogen Bonds are weaker than covalent bonds because they do not involve sharing of electrons, and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges.

Part F

Why isn’t this insect drowning?

	It is difficult to change the temperature of water.
	The insect is very light.
	Surface tension.
	The insect is swimming.
	The insect is flying just above the water surface.

Correct

The high surface tension of water allows the insect to remain on the surface.

Nonpolar and Polar Molecules

Part A

Which of these figures correctly illustrates the nature of the bonding of H2O?

Correct

Oxygen is more electronegative than hydrogen.

Part B

What type of bond joins the carbon atom to each of the hydrogen atoms?

Correct

Each carbon-hydrogen bond involves a single pair of equally shared electrons.

Ionic Bonds

Ionic Bonds

Part A

Atoms with the same number of protons but with different electrical charges _____.

	have different numbers of neutrons
	have different atomic masses
	are different isotopes
	are different ions
	have different atomic numbers

Correct

Ions are charged atoms.

Part B

In salt, what is the nature of the bond between sodium and chlorine?

Correct

Sodium and chlorine ions are attracted to each other.

Part C

What is the result of the animated process?

To view the animation, click here. Then click on the image to start the animation.

	covalent bond formation
	a positively charged sodium ion and a positively charged chlorine ion
	a negatively charged sodium ion and a negatively charged chlorine ion
	a positively charged sodium ion and a negatively charged chlorine ion
	a negatively charged sodium ion and a positively charged chlorine ion

Correct

Sodium loses an electron and thus becomes positively charged; chlorine gains an electron and thus becomes negatively charged.

Part D

An ionic bond involves _____.

	an attraction between ions of opposite charge
	water avoidance
	the sharing of a single pair of electrons
	no atoms other than sodium and chlorine
	the unequal sharing of an electron pair

Correct

This is the definition of an ionic bond.

Hydrogen Bonds

Hydrogen Bonds

Part A

The brackets are indicating a(n) _____ bond.

Correct

A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge.

Part B

What name is given to the bond between water molecules?

Correct

A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge.

Covalent Bonds

Part A

What type of bond is joining the two hydrogen atoms?

Correct

A covalent bond is one in which electron pairs are shared.

Part B

A(n) _____ refers to two or more atoms held together by covalent bonds.

Correct

A molecule is defined as two or more atoms held together by covalent bonds.

Part C

This atom can form up to _____ single covalent bond(s).

Correct

There are four electrons in the outermost electron shell.

Part D

A(n) _____ bond joins these two oxygen atoms.

Correct

The oxygen atoms are sharing two pairs of electrons.

	push
	precipitation
	evaporation
	gravity
	antigravity

	two … hydrogen
	two … polar covalent
	four … hydrogen
	four … polar covalent
	three … ionic

	polar
	have a low surface tension
	hydrophobic
	ionic
	change easily from a liquid to gaseous form

	polarity
	electronegativity
	covalency
	tonicity
	ionic potential

	nonpolar covalent
	hydrophobic
	hydrophilic
	ionic
	polar covalent

Monthly Archives: October 2016

Acids, Bases, and pH

Acids, Bases, and pH

Cohesion of Water

Cohesion of Water

The Polarity of Water

The Polarity of Water

Nonpolar and Polar Molecules

Nonpolar and Polar Molecules

Ionic Bonds

Ionic Bonds

Hydrogen Bonds

Hydrogen Bonds

Covalent Bonds

Covalent Bonds

Introduction to Experimental Design

Introduction to Experimental Design

	electron
	water molecule
	hydroxide ion
	hydrogen ion
	hydronium ion

	hydrogen
	double (nonpolar) covalent
	ionic
	polar covalent
	single (nonpolar) covalent

	hydrogen
	single (nonpolar) covalent
	polar covalent
	ionic
	hydrophobic

	double covalent
	quadruple covalent
	single covalent
	hydrogen
	ionic

	They must be well documented.
	They yield useful results regardless of whether the hypothesis is supported or rejected.
	They must occur under carefully controlled conditions found in a laboratory.

	To enable investigators to repeat the test
	To eliminate alternative explanations for the results of an experiment
	To create a control group

	College students think football is more fun to watch than baseball.
	Grass is green because it contains chlorophyll.
	The first living cell on Earth came from outer space

	A hypothesis can be proved.
	A hypothesis can be supported or rejected through experimentation.

	The length of time that the flasks were allowed to sit before being sampled for organisms
	The shape of the flask
	The length of time that the broth was boiled
	The broth used in each flask

	To provide nutrients to stimulate the growth of microorganisms
	To expose the broth to a source of organisms
	To attract dust particles to each flask
	To kill any existing organisms in the broth


	Answer

	community
	isotope
	molecule
	ion
	shell

	Zonosemata flies with their own wings cut and reglued are attacked less frequently.
	Houseflies with Zonosemata wings are attacked less frequently.
	Zonosemata flies with housefly wings are attacked less frequently.
	Untreated Zonosemata flies are attacked less frequently.

	All results for the experimental groups involving wing surgery would be invalid.
	All results for the experimental groups using houseflies would be invalid.
	All results for the experimental groups using Zonosemata flies would be invalid.
	The reliability of the experimental results would not change.

Acids, Bases, and pH

Cohesion of Water

The Polarity of Water

Nonpolar and Polar Molecules

Ionic Bonds

Hydrogen Bonds

Covalent Bonds

Introduction to Experimental Design

Think!