Solutions
Water is such a great solvent because of its...
polarity.
An acid/base is strong or weak based on....
How completely it dissociates/ionizes
Choose an answer in parentheses: If considered "strong" the acid/base will ionize/dissocaite (partially OR 100%).
100%
Solute =, Solvent =
Solute= That which is dissolved; dissolved substance(s).
Solvent=Substance that is doing the dissolving; the dissolving medium
Explain what makes an acid or base strong versus weak.
Strength is dependent upon the degree to which an acid or base forms ions in water; strong acids/bases fully dissociate/ionize.
If a 1.75L solution has a concentration of 12.0 M , what volume of water must be added to it for its concentration to become 3.75 M?
1.75 L x 12 M = 3.75 M x V2
V2 = (1.75 L x 12.0 M)/3.75 M
V2 = 5.60 L of water.
Choose one answer from each set in parentheses: If a particle diagram still has some of the original acid or base present, the acid/base is (strong/weak) and its dissociation would be described as (partial/100%).
Weak, partial
As hydroxide concentration goes up, does the solution become more acidic or basic?
It becomes more basic
Molarity (M) =
= the concentration of solution expressed in number of moles of solute per liter of solution.
Describe a real-world example of how “like dissolves like”.
Polar molecules, like water, can dissolve other polar molecules, like salt.
Nonpolar molecules, like soap, can dissolve other nonpolar molecules, like oil stains.
If you have 25.0 g of NaCl dissolved into 200. mL of water, what is the concentration of NaCl in the solution?
25 g x (1 mol/58.44 g (MMNaCl)) = 0.428 mol
200 mL x (1L/1,000mL) = 0.20 L
0.428 mol/0.20 L = 2.14 M
Define an acid in any way that we have in this unit.
Low pH
Adds H+ ions to a solution when dissolved in water
Increases [Hydronium] (hydronium ion concentration)
DONATES protons (H+)
Describe a neutral solution in terms of pH, pOH, and concentration of hydroxide and hydronium ions.
pH & pOH = 7
Concentrations of hydroxide and hydronium are EQUAL
pH =
pOH =
pH = A mathematical scale representing the concentration of H3O+ ions on a scale of 0-14.
pOH = A mathematical scale representing the concentration of OH- ions on a scale of 0-14.
Compare and contrast how ionic substances dissolve vs. how covalent substances dissolve.
Similarities: both separate out and become hydrated by being surrounded by water molecules
Differences:
Ionic dissociate into ions, covalent separate but remain as molecules
Ionic create electrolyte solutions that can conduct electricity, covalent create nonelectrolyte solutions that cannot
What mass of KOH is needed to prepare 1,500. mL of a 1.250 M solution?
105.2 g KOH
n/1.5 L = 1.25M
n = 1.875 moles KOH x (56.11g/1 mol KOH) = 105.2g KOH
pH<7
pOH>7
more hydronium ions than hydroxide
If hydronium ion concentration goes DOWN, what happens to pH?
pH goes UP.
Note, hydronium is H3O+ or H+
Arrhenius Acid =
Arrhenius Base =
Arrh. Acid = A chemical compound that increases the concentration of hydrogen ions in an aqueous solution.
Arrh. Base = A chemical compound that increases the concentration of hydroxide ions in an aqueous solution.
Summarize the relationship between pH and pOH.
As pH goes up, pOH goes down.
pH + pOH = 14.0
If you have 250 g of HNO3 and 555 mL of solution, what is its concentration?
7.15M
250 g x 1 mol/63.02g = 3.97 mol HNO3
555mL x (1L/1,000mL) = 0.555L
3.97 mol/0.555L = 7.15M
What will happen to the pH of a solution if RbOH is added to it?
pH will increase (because it is a base; recognizable by "OH" on the end.
What will happen to the pH of a solution if HCl is added to it?
pH will decrease
(Because HCl is an acid; recognizable by the "H" on the front of the formula)
Bronsted Lowrey Acid =
Bronsted Lowrey Base =
Bronsted-Lowry acid = A proton donor (in the form of a hydrogen ion)
Bronsted-Lowry base = A proton acceptor (in the form of a hydrogen ion)
Write a chemical equation to represent what happens when H2SO4 is placed in water. Then identify it as an acid or base using both the Arrhenius and Bronsted-Lowry definitions.
H2SO4 + H2O 🡪 HSO4- + H3O+
H2SO4 is an Arrhenius acid because it adds H+ to the solution, making H3O+ and it is also a Bronsted-Lowry acid because it donates a proton, in the form of a H+, to H2O.