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Announcements. EXAM #1 ANSWER KEY POSTED OWL: CHAPTER 4 PART 1 HOMEWORK EXAM GRADES POSTED (LEFT SIDE “COURSE GRADES” LINK). Solution Concentration. Solution Solute Solvent Concentration Qualitative Dilute Concentrated Quantitative Molarity=# moles of solute per 1L of solution. - PowerPoint PPT Presentation
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•EXAM #1 ANSWER KEY POSTED
•OWL:
•CHAPTER 4 PART 1 HOMEWORK
•EXAM GRADES POSTED (LEFT SIDE “COURSE GRADES” LINK)
Announcements
Solution Concentration
Solution Solute Solvent
Concentration Qualitative
Dilute Concentrated
Quantitative Molarity=# moles of solute per 1L of solution
What do goldfish have to do with concentration?
goldfishcupfoodbaby
goldfishxcupsfoodbaby 2010
2
Solution Concentration Examples
How many moles of NH3 are in 575mL of 0.12mol/L solution?
A 0.56M solution of NH3 contains 22 mol NH3. How many Liters of solution are there?
What you “have”Conversion
factor
What volume of a 0.23M solution of K2SO4 contains 0.50 moles?
1. 0.115L2. 0.115mL3. 2.174L4. 2.174mL
How would you make 250mL of 1.00M NH3 from 15M NH3?
1. Take 16.7mL of 15M NH3 and dilute it to 250mL with water
2. Take 60mL of 15M NH3 and dilute it to 250mL with water
3. Take 0.0167mL of 15M NH3 and dilute it to 250mL with water
4. Take 3.75mL of 15M NH3 and dilute it to 250mL with water
Stoichiometry in Solution
Grams or mL reactant A
Grams or mL reactant B
Moles reactant BMoles reactant A
Molar massor
Solution concentration
Molar massor
Solution concentration
Balanced equation
andStoichiometry
Titration Example- Part 1
GOAL: To determine the molar mass of an unknown acid (H2A)
H2A + 2NaOH Na2A + 2H2O
1. Standardizing an NaOH solution using a “primary standard”A solution of sodium hydroxide is “standardized” by titration using solid oxalic acid, H2C2O4, as the acid. It is found that 24.5 mL of the NaOH solution is needed to react completely with 2.05 g of oxalic acid. What is the concentration of the NaOH solution?H2C2O4(aq) + 2 NaOH 2 H2O(l) + Na2C2O4(aq)
Titration Example- Part 2
2. Determining the molar mass of an unknown diprotic acid
The NaOH solution above was used to titrate an acid of unknown formula, but known to be diprotic: H2A, where we don’t know what “A” is. A 1.046 gram sample of the unknown acid is titrated using 31.4 mL of the NaOH solution. What is the molar mass of H2A?
H2A(aq) + 2 NaOH 2 H2O(l) + Na2A(aq)