Topic 1.1 Water and Hydrogen Bonding

Topic 1.1 Water and Hydrogen Bonding

Multiple Choice

The Hydrogen atoms in the molecule shown have this charge:

• Positive

• Partial Positive

• Negative

• Partial Negative

Multiple Choice

The Oxygen atoms in the molecule shown have this charge:

• Positive

• Partial Positive

• Negative

• Partial Negative

Multiple Choice

Because water has a positive and a negative end, and is attracted to other molecules it is called a ______ molecule.

• mickey mouse
• polar (tiny magnet)
• special
• miracle

Multiple Choice

Why does ice float?

• As water freezes, it expands and its density decreases.
• As water freezes, it takes up more hydrogen from the atmosphere, causing it to have a greater buoyancy.
• As water freezes, air becomes trapped between the hydrogen bonds of water molecules.
• As water freezes, it takes up more oxygen from the atmosphere, causing it to have a greater buoyancy.

Multiple Choice

Why is it important that ice is less dense than liquid water?

• It lowers the pH of lakes and ponds

• It disrupts hydrogen bonds.

• It allows nonpolar substances to dissolve in water.

• It creates an ice layer on the surface of lakes and ponds, and prevents them from completely freezing.

Hydrogen Bonds Cause:

• Cohesion - water sticks to water

• Adhesion - water sticks to other molecules

Multiple Choice

What word describes when water is attracted to other substances?

• cohesion
• adhesion
• capillary action
• surface tension

Multiple Choice

When we added red food coloring to the water, what did that prove?

• That the celery leaves caught the evaporating red water.

• That the celery was absorbing all the red water.

• That the water was passing through the celery all the way up to the leaves.

Multiple Choice

Why can some insects walk on water?

• The water sticks to the insect.
• The insect is too light to break the surface tension.
• The insect has hydrophobic oils on its legs.
• Insects can't walk on water.

Multiple Choice

Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together

• The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet

• The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface

• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

Multiple Choice

Letter A is?

• evaporation
• transpiration
• condensation
• accumulation 

Multiple Choice

Why does water move from the roots to the leaves of plants through the plants' tiny tubes?

• specific heat 
• capillary action

• atoms

• density

Multiple Choice

Large bodies of water, such as lakes and oceans, do not quickly fluctuate in temperature. What is the reason for this phenomenon?

• Water is an acid.
• Water is a versatile solvent.
• Water has a high heat capacity.
•  Water acts as a buffer.

Multiple Choice

Water has an unusually high boiling point for a molecular compound because it has

• hydrogen bonding

• ion-ion attractions

• a high density

• a large gram formula mass

Multiple Choice

Water is a universal solvent because it...

• It can be found anywhere
• It freezes when it gets cold
• floats when frozen
• Dissolves most substances

Multiple Choice

What kind of molecule is water?

• Ionic

• Polar Covalent

• Nonpolar Covalent

• Metallic

Multiple Choice

Which of the following is LEAST likely to dissolve in water?

• nonpolar fats and oils
• polar sugar molecules
• salt made of a positive sodium ion and a negative chloride ion
• all of the substances will dissolve easily in water

pH and [H⁺] Concentration

• pH = - log [H⁺]

• Inverse relationship between pH and [H⁺]

• Low pH has a higher concentration of [H⁺] ions.

• Changes by a factor of 10 as you move down the scale

Buffers & Homeostasis

• Buffers are a weak conjugate acid-base pair.

• They resist changes in pH by adding or removing H⁺ ions from solution.

• Buffers in the body maintain physiological pH (6.5-8.0)

Multiple Choice

What does pH measure?

• the amount of hydrogen (H⁺) ions

• the amount of hydroxide (OH^-) ions

• amount of water

• all of the above

Multiple Choice

Which of the following pH measurements has the highest [H⁺] concentration?

• 1

• 4

• 8

• 14

Multiple Choice

The pH scale is a range from:

• 1-7
• 0-14
• 1-5
• 1-20

Multiple Choice

A(n) _______ is a substance with a pH greater than 7.

• Base
• Acid
• Buffer
• Water

Multiple Choice

A(n) ______ is a substance with a pH less than 7

• Acid
• Alkaline
• Base
• Buffer

Multiple Choice

What is the only substance with a neutral pH of 7?

• Milk
• Orange Juice
• Water
• Blood

Multiple Choice

What is a mixture of chemicals that react with a base/acid to keep pH in a particular range?

• catalyst

• enzyme

• water

• buffer

Multiple Choice

Water has a neutral pH because

• it has more H+ ions than OH-

• it has more OH- ions than H+

• it does not produce any ions

• it has an equal amount of H+ and OH- in solution