Water and buffer

Question 1

Atomic structure determines element behavior.

Answer 1

true

Question 2

Atoms combine by chemical bonding to form compounds.

Answer 2

false. to form molecules

Question 3

list some organic compounds.

Answer 3

carbohydrates, fats, proteins, nucleic acids, urea, carbon tetrachloride

Question 4

list some inorganic compounds.

Answer 4

sodium chloride, brass, glass, carbonates, cyanides, cyanates, carbides, thyocyanates, carbon monoxide, carbon dioxide, water

Question 5

what is covalent bonds?

Answer 5

Covalent bonds consist of shared pairs of electrons

Question 6

If one atom is much more electronegative than the other, a complete transfer of one or more electrons can occur

Answer 6

ionic bonds

Question 7

what is the effects of Water’s Polarity?

Answer 7

polarity results in hydrogen bonding and this gives water its unusual properties

Question 8

why water has nearly tetrahedral shape?

Answer 8

due to electron pairs repelling each other

Question 9

Pick the right statement for hydrogen bonds.

1. Occurs between a covalently bonded hydrogen and an electronegative atom, usually O or N
2. Hydrogen bonds are strong
3. hydrogen bonding is not involved in the important properties of water and in macromolecule structure and function (DNA and Proteins)
4. Hydrogen bonds form between small molecules or different portions of large molecules

Answer 9

1 and 4. 2. hydrogen are weak. 3. they involved

Question 10

why does ice floats?

Answer 10

Solid state is usually denser than liquid state. Because molecules are more densely packed. Solid->Melt->molecules move apart -> liquid. But water behaves in an opposite manner

Question 11

what caused cohesion?

Answer 11

due to the hydrogen bonds that can form between water molecules.

Question 12

what is adhesion?

Answer 12

Adhesion is the clinging of one substance to another.

- Allows water to move up plants from the roots.

Question 13

surface tension of water is greater than many liquids.

Answer 13

true. we can see how easy to stretch or break the surface of liquids.

Question 14

explain why water has high heat capacity.

Answer 14

Water moderates temperatures on Earth. Energy changes required for state change are
significant. Water has a high heat capacity compared to
other liquids. Takes a lot more energy to change the
temperature of water than other liquids.

Question 15

hydrophilic is water ___ (polar) and hydrophobic is water __ (non-polar).

Answer 15

1. loving 2. fearing

Question 16

Svante Arrhenius defined acids as substances that

dissociate in water to provide hydrogen ions and bases as substances that dissociate in water to provide hydroxide ions

Answer 16

true

Question 17

what Bronsted-Lowry Theory said about acid and bases?

Answer 17

acids are defined as any hydrogen contain substances capable of donating protons to other substances.

Bases are substances that accept and form covalent bonds with protons.

When a substance behaves as a Bronsted acid by donating a proton the substance becomes a conjugate base and vice versa

Question 18

why water is considered as an important solvent?

Answer 18

• universal solvent
• biological solvent
• small size
• density of water is greater than ice
• very polar
• hydrogen bonding

Question 19

Water, a hydrogen-containing material, is able to behave as both a Bronsted acid and a Bronsted base.

Answer 19

true

Question 20

what do we called when water can behave like an acid or base?

Answer 20

amphiprotic substances

Question 21

what is autoionization?

Answer 21

when water molecules react with one another to form ions.

Question 22

list common acids used.

Answer 22

nitric(HNO3), hydrocloric(HCl), sulfuric(H2SO4), acetic(HC2H302)

Question 23

list common bases used.

Answer 23

ammonium hydroxide(NH4OH), sodium hydroxide(NaOH)

Question 24

what is the properties of acids?

Answer 24

sour taste, a reaction with water to produce hydronium ions, reacts with solid metallic oxides, hydroxides,
carbonates, and bicarbonates, reacts with certain metals to give hydrogen gas, produce H30+ when dissolved in water

Question 25

what is the properties of bases?

Answer 25

Basic solutions feel soapy or slippery and change the color of litmus from red to blue.
Neutralization reaction with acids to produce water and a salt.

Question 26

at what temperature does salts are solid crystalline

substances that contain the cation of a base and the anion of an acid.

Answer 26

at room temperature

Question 27

how to prepare salts?

Answer 27

by reacting an appropriate acid with one of a number of other materials. KOH + HNO3 -> KNO3 (salt) + H20

Question 28

what are some strong acids that dissolved completely in water?

Answer 28

HCl, HBr, HI, HClO3, HNO3, HClO4, H2SO4

Question 29

what are strong bases that dissolved completely in wotah?

Answer 29

NaOH, LiOH, KOH

Question 30

which statement is true for Ka and Kb?

1. Ka and Kb always have values that smaller than one.
2. Acid with larger Ka are stronger than those with smaller Ka.
3. Bases with larger Kb are stronger than those with smaller Kb.
4. most bases and acids are considered weaks.

Answer 30

all true

Question 31

what comes in mind?
pH =
pOH=
pH+ pOH=

Answer 31

ph= -log[H+]
pOH= -log[OH-]
pH + pOH= 14

Question 32

which is correct?

1. pH of 1 M HCl is 0.0
2. pH of lemon juice is2.3
3. pH of blood is 7.3
4. pH of 1 M of NaOH is14.0

Answer 32

all true oh yeahh

Question 33

what is neutralization and what do we used in neutralization?

Answer 33

the reaction of an acid with a base to produce salt and water. we use antacids

Question 34

in titrations, what do we use as the indicator?

Answer 34

phenolphtalein

Question 35

how do we know when the endpoint of titration has reached?

Answer 35

the color changed from colourless to pink

Question 36

what is buffer?

Answer 36

solutions which has the ability to maintain essentially constant pH values when acid (H+) or base (OH-) are added