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Flashcards in Solutions Deck (63)
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1
Define and give an example of:

a solution

A solution is a homogeneous mixture of two or more substances in a single phase.

Ex: NaCl dissolved into water creates a solution of Na+ ions, Cl- ions, and H2O all in one phase (liquid).

2
Define:

a solvent

A solvent is the substance whose phase remains after solvation (or the substance in excess).

Ex: dissolving a small amount of solid NaCl into liquid water produces a liquid solution. Water was the solvent.

3
Define:

a solute

A solute is the substance whose phase is lost after solvation (or the substance in scarcity).

Ex: dissolving a small amount of solid NaCl into liquid water produces a liquid solution. NaCl was the solute.

4

Ionic compounds dissolve readily in polar solvents; what ion form do metals usually take? 

Metals typically become cations in solution.

Metals, which are found on the left side of the periodic table, mostly form cations by losing electrons to a nonmetal so that both can form stable octets. 

5

Ionic compounds dissolve readily in polar solvents; what ion form do nonmetals usually take? 

Nonmetals typically become anions in solution.

Nonmetals, which are found on the right side of the periodic table, mostly form anions by gaining electrons from a metal so that both can form stable octets. 

6

What charge do the elements below usually take when forming ions in solution?

  • Li
  • Na
  • K

The alkali metals form cations with a single positive charge, +1.

Li, Na, and K are all alkali metals from column 1 of the periodic table.

7

What charge do the elements below usually take when forming ions in solution?

  • Br
  • Cl
  • F

The halides form anions with a single negative charge, -1.

Br, Cl, and F are all halides from column 7 of the periodic table.

8

Give the molecular form and charge for these common ions:

  1. ammonium
  2. chloride
  3. dichromate
  4. mercury(II) mercuric
  5. silver

  1. ammonium, NH4+, +1 charge
  2. chloride, Cl-, -1 charge
  3. dichromate, Cr2O7--, -2 charge
  4. mercury(II) mercuric, Hg++, +2 charge
  5. silver, Ag+, +1 charge

9

Give the molecular form and charge for these common ions:

  1. hydroxide
  2. barium
  3. sodium
  4. permanganate
  5. sulfite

  1. hydroxide, OH-, -1 charge
  2. barium, Ba++, +2 charge
  3. sodium, Na+, +1 charge
  4. permanganate, MnO4-, -1 charge
  5. sulfite, SO3--, -2 charge

10

Give the molecular form and charge for these common ions:

  1. hydrogen phosphate
  2. magnesium
  3. calcium
  4. bromide
  5. copper(I) cuprous

  1. hydrogen phosphate, HPO4--, -2 charge
  2. magnesium, Mg++, +2 charge
  3. calcium, Ca++, +2 charge
  4. bromide, Br-, -1 charge
  5. copper(I) cuprous, Cu+, +1 charge

11

Give the molecular form and charge for these common ions:

  1. sulfate
  2. nitrate
  3. peroxide
  4. hydronium
  5. iron (II) ferrous

  1. sulfate, SO4--, -2 charge
  2. nitrate, NO3-, -1 charge
  3. peroxide, O2--, -2 charge
  4. hydronium, H3O+, +1 charge
  5. iron (II) ferrous, Fe++, +2 charge

12
Define:

solvation

Solvation occurs when oppositely charged ends of polar solvent molecules surround solute ions.

Ex: water solvates the Na+ ion in the image below, creating a "solvation shell" around it.

13
Define:

hydration for solutions

Hydration is the process of solvation, where water is specifically used as the solvent. 

Ex: because water is being used as the solvent in the image below, this can also be called a "hydration shell" of water molecules surrounding the Na+ ion.

14

Explain the "like dissolves like" rule.

Polar solvents readily dissolve polar solutes, while nonpolar solvents readily dissolve nonpolar solutes.

Ex: a non-polar solute such as naphthalene is insoluble in water, slightly soluble in methanol, and highly soluble in non-polar benzene.

15

Explain why exams like the AP Chemistry exam will rarely refer to an ion of H+ in aqueous solution? What ion will be used instead?

Because H+ is simply a proton in solution, it represents a very strong positive ion that water will form a hydration shell around. 

Most commonly the ion H3O+ is used to represent the fact that a water molecule has bound to the free proton.

Rarely seen, but also possible, is H5O2+ (two water molecules sharing the proton) and H7O3+ (three water molecules). 

16
Define:

solubility

Solubility is a measure of how much solute can be dissolved in the given solvent at a specific temperature and pressure.

17

In general, are the following soluble or insoluble in water?

  1. Nitrates (NO3-)
  2. Sulfites (SO3--)
  3. Acetates (CH3COO-)
  4. Chlorides (Cl-)
  5. Bromides (Br-)

  1. Nitrates, always soluble
  2. Sulfites, insoluble (except in group I and ammonium compounds)
  3. Acetates, soluble (except in silver compounds)
  4. Chlorides, always soluble
  5. Bromides, soluble (except in Silver, Lead, Copper, or Mercury compounds)

18

How soluble are the salts of alkali metal cations such as Li+, Na+, K+, etc.?

All salts of alkali metals are highly soluble.

19

How soluble are the salts of the ammonium cation, NH4+?

All ammonium salts are highly soluble.

20

What determines solubilities of the salts of alkaline earth and transition metal cations such as Ca+2, Mg+2, Fe+3, etc.?

Salts of alkaline earth metals and transition metals have solubilities that vary based on the anion that the cation is paired with in the salt.

Highly soluble anions like chloride (Cl-) will make soluble salts with alkaline earth and transition metals. Insoluble anions like phosphate (PO4-3) will make insoluble salts with these cations.

21

Which anions make salts that are always fully soluble?

The following anions make salts that are always soluble:

  • Nitrate (NO3-)
  • Chlorate (ClO3-)
  • Perchlorate (ClO4-)
  • Acetate (CH3COO-)

22

What is the solubility of salts made with the halogen anions Cl-, Br-, and I-?

Halogen anion salts are soluble unless the cation is Ag+, Pb2+, or Hg22+.

23

What is the solubility of salts made with the sulfate anion, SO42-?

Sulfate anion salts are soluble unless the cation is Ag+, Pb2+, Hg22+, Ca2+, Sr2+, or Ba2+.

24

Which anions make salts that are generally insoluble?

The following anions make salts that are generally insoluble:

  • Hydroxide (OH-)
  • Carbonate (CO3-2)
  • Phosphate (PO4-3)
  • Sulfite (SO3-2)
  • Chromate (CrO42-)
  • Sulfide (S2-)

Exception: salts with these anions paired with alkali metals (such as NaOH) or ammonium cations (such as (NH4)2CO3) will be soluble.

25

Describe what is meant by a saturated solution.

A saturated solution contains the maximum amount of solute that can be dissolved into the solvent at a particular temperature and pressure.

The solution is at equilibrium when fully saturated, so if more solute is added it will not dissolve (or there will be a precipitate formed). 

26

A solute is being added to a solvent, and the solute is readily dissolving. During that time, what do we call the solution?

unsaturated

A solution containing less solute than needed for saturation is said to be unsaturated, and not yet at saturation equilibrium.

27

A solution is somehow formed that contains more solute particles per solvent than should be possible at that temperature and pressure. What is that solution termed?

supersaturated

A solution containing more solute than needed for saturation is said to be supersaturated; it has exceeded the saturation equilibrium.

28
Define:

precipitation

Precipitation is the reverse reaction of dissolution. Previously dissolved (solvated) salt ions bond together to form the original salt (solid).

Precipitation indicates that saturation has been exceeded at that temperature and pressure.

29
Define and give the equation for:

molarity (M)

Molarity is a measure of the concentration of a solution, given in units of moles of solute dissolved per liter of solvent.

30

How many moles of sodium chloride would 2 liters of a 5.0 M solution contain?

10 mol NaCl

Molarity = mol/L
5M = x?mol / 2L
x? = 10 moles