Bell Ringer Which of the following aqueous solutions will cause litmus paper to turn red? A NaOH B NaCl C HCl D H 2 O pH 1-6 7 8-14 Soluti on Added Litmus paper changes from Acid Neutra l Base Blue to Red Does not Change Red to Blue Source: 2003 VA EOC Exam
20
Embed
Bell Ringer Which of the following aqueous solutions will cause litmus paper to turn red? A NaOH B NaCl C HCl D H 2 O pH1-678-14 Solution Added Litmus.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Bell Ringer
Which of the following aqueous solutions will cause litmus paper to turn red?
A NaOH
B NaCl
C HCl
D H2O
pH 1-6 7 8-14
Solution Added
Litmus paper changes from
Acid Neutral Base
Blue to Red
Does not Change
Red to Blue
Source: 2003 VA EOC Exam
pHAcids and
Bases
A Quick Reminder…• Reactions can stop at an EQUILIBRIUM
Practice ProblemsUsing the knowledge that Kw = 1.00 x 10-14, solve for the missing piece of information:
1. Calculate the hydroxide ion concentration in a solution whose hydronium ion concentration is 1 x 10-5 M
Kw = [H3O+] [OH-]
1.00 x 10-14 = [1 x 10-5 M] [OH-]
[OH-] = 1.00 x 10-14
1 x 10-5 M= 1 x 10-9 M
Practice Problems2. Calculate the hydronium concentration for a solution whose hydroxide concentration is 0.0010 M.
Kw = [H3O+] [OH-]
1.00 x 10-14 = [H3O+] [0.0010 M]
[H3O+] = 1.00 x 10-14
0.0010 M= 1 x 10-11 M
Practice Problems3. What is the hydroxide concentration of a solution if 0.080 grams of NaOH are dissolved in 2.0 L of solution?
What is the hydronium ion concentration of this solution?
0.080 g NaOH x 1 mol NaOH
40.00 g NaOHx 1 mol OH-
1 mol NaOH= 0.0020 mol OH-
[OH-] = 0.0020 mol OH-
2.0 L
= 0.0010 M OH-
0.0010 M OH-
Kw = [H3O+] [OH-]
1.00 x 10-14 = [H3O+] [0.0010 M]
[H3O+] = 1.00 x 10-14
0.0010 M= 1.0 x 10-11 M H3O+
1.0 x 10-11 M H3O+
Practice Problems4. What is the hydroxide ion concentration of a solution if 0.080 grams of Ca(OH)2 are dissolved in 2.0 L of solution?
What is the hydronium ion concentration of this solution?
0.080 g Ca(OH)2 x 1 mol Ca(OH)2
74.10 g Ca(OH)2
x 2 mol OH-
1 mol Ca(OH)2
= 0.00216 mol OH-
[OH-] = 0.00216 mol OH-
2.0 L
= 0.00108 M OH-
Kw = [H3O+] [OH-]
1.00 x 10-14 = [H3O+] [0.00108 M]
[H3O+] = 1.00 x 10-14
0.00108 M= 9.3 x 10-12 M H3O+
0.0020 M OH-
9.3 x 10-12 M H3O+
pH – the POWER of H+!
These numbers represent the POWER of H+
pH = the negative logarithm of [H3O+]Image source: http://www.lowimpactdevelopment.org
Log-o-rhythms
= =
pH = the negative logarithm of [H3O+]POWERpH – the POWER of H+!
Answer the following questions without using a calculator:• What is the pH of a solution with [H3O+] = 1.0 x 10-4 M?
pH = 4.00 ACID
• What is the pH of a solution with [H3O+] = 1.0 x 10-12 M?
pH = 12.00 BASE
pH = - log [H3O+]
My Kingdom for a Calculator!
On TI-83:
• push “(-)” key
• push “log” key
• type in number
On Scientific Calculators:
• type in number
• push “log” key
• push +/- key
To solve for pH, given hydronium molarity
Practice Problems1. What is the pH of a solution if the concentration of hydronium ions is 1.0 x 10-2 M? Is the solution acidic or basic?
pH = - log [H3O+]
pH = - log (1.0 x 10-2)
pH = 2.00 ACIDIC
SIG FIG RULES: Put the correct number of Sig Figs BEHIND the decimal point.
Practice Problems2. What is the pH of a solution if the concentration of hydroxide ions is 1.0 x 10-4 M? Is the solution acidic or basic?
pH = - log [H3O+]
pH = - log (1.0 x 10-10)
pH = 10.00 BASIC
Kw = [H3O+] [OH-]
1.00 x 10-14 = [H3O+] [1.0 x 10-4 M]
[H3O+] = 1.00 x 10-14
1.0 x 10-4 M= 1 x 10-10 M
My Kingdom for a Calculator (again)!
On TI-83:
• push “10x” key
• push “(-)” key
• type in pH
On Scientific Calculators:
• type in number
• push +/- key
• push “2nd” key
• push “log” key
To solve for hydronium molarity, given pH
Practice Problems3. What is the concentration of hydronium ions in a solution whose pH is 8.00?
pH = 8.00 = - log [H3O+]
-8.00 = log [H3O+]
10–8.00 M = [H3O+]
[H3O+] = 1.00 x 10-8 M
Practice Problems4. For Question #3, what is the concentration of hydroxide ions?
Kw = [H3O+] [OH-]
1.00 x 10-14 = [1.0 x 10-8 M] [OH-]
[OH-] = 1.00 x 10-14
1.0 x 10-8 M= 1 x 10-6 M
Practice Problems5. What is the concentration of hydronium ions in a solution that has a volume of 2.50 L and 5.33 g of HCl? What is the pH of this solution?
5.33 g HCl x 1 mol HCl
36.46 g HClx 1 mol H+
1 mol HCl= 0.146 mol H+
[H+] = 0.146 mol H+
2.50 L
= 0.0584 M H+
pH = - log [H3O+]
pH = - log (0.0584)
pH = 1.234
Homework
• Complete the practice problems on the worksheet. Due next class