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.
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EXAM #1 ANSWER KEY POSTED
CHAPTER 4 PART 1 HOMEWORK
EXAM GRADES POSTED (LEFT SIDE “COURSE GRADES” LINK)
What you “have”
Grams or mL reactant A
Grams or mL reactant B
Moles reactant A
Moles reactant B
GOAL: To determine the molar mass of an unknown acid (H2A)
H2A + 2NaOH Na2A + 2H2O
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)
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)