Term
| What is the pH of .0056 M KOH? |
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Definition
1. KOH->K+ +OH- (use ICE table and Kb value to find OH-). pOH=-log[OH-]
2.pOH+pH=14
3. pOH=2.2
4. pH=11.75 |
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Term
| What is the pH of 2.7x10^-4M Ba(OH)2? |
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Definition
1. Ba(OH)2->Ba2+ + 2OH-
2. Ba ionizes (100%)
3. need to do stoichometry to account for the 2 mol of OH= 5.4x10 ^-4M
4. take -log(5.4x10^-4)=pOH=3.27
5. pH=10.73-> basic solution |
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Term
What volume of a 15.0% by mass KOH solution is
required to make 25.0 L of a solution whose
pH=11.55? The density of the KOH solution is 1.14
g/mL. |
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Definition
1. use M1V1=M2V2
2. find molarity
3. 87.72mL soln
4. in 100g of soln u have 15g KOH
5. .267 mol KOH..use these mol to find M of KOH (L=.08772L)
6. Now plug everything into M1V1=M2V2
7. V=0.029 |
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Term
*** How much NaOH is needed to prepare 546
ml of soln with pH = 10.00? (exam question need to be able to work backwards) |
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Definition
1. given pH. convert to pOH
2. pOh=4 pOH=-log(OH-)=1x10^-4M=NaOH
3.Stoich= 1x10^-4M/L x 0.546L x 40gNaOh/ 1mol NaOh=2.18x10^-3g NaOH. |
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Term
How much NaOH is needed to prepare 546
ml of soln with pH = 10.00? Already solved
• What if had asked about Ba(OH)
2? |
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Definition
Ba(OH)2->Ba2+ + 2OH-
Stoichiometry:
1x10^-4 OH-x1mol (Ba(OH)2/2molOH-=5.10^-5M Ba(OH)2 |
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Term
WEak Base Problems
Calc. pH .10M weak base whose Kb= 4.1x10^-4 |
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Definition
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Term
• What is the original molarity of a solution of
CH
3NH2whose pH is 10.32? |
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Definition
B+H20->BH+ + OH-
1. Ice table
2. Kb= [BH+][OH-]/[B]
3. (2.09x10^-4)/(4.4x10^-4)=A-2.09x10^-4
4. A=3.08x10^-4M |
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