8 Summary 3 Which of the following are strong acids? H2SO4, HSO3, HClO2, HBr, HNO3, HNO2
9 Standard 5c: continued Weak acids = weak electrolytes Weak electrolyte = Partial dissociation(= equilibrium)e.x HCN + H2O H3O+ + CN-In solutionAll other acids are weak acidsExamples: acetic acid HC2H3O2, carbonic acid H2CO3, HCN, H3PO4~97%~3%
10 Summary 4At equilibrium does a weak acid solution contain mostly products or mostly reactants?At equilibrium does a strong acid solution contain mostly products or mostly reactants?
11 Conjugate acids & bases: Standard 5c: continuedConjugate acids & bases:e.x. HF + H2O H3O+ + F-acidDonates hydrogen ionConjugate baseDifferent from acid by a protonBaseAccepts hydrogen ionConjugate acidDifferent from base by a protonCBABCA
12 Summary 5 HNO3 + H2O H3O+ + NO3- Label the acid (A), base (B), conjugate acid (ca), and conjugate base (cb) in the following reaction:HNO3 + H2O H3O+ + NO3-
13 Conjugate acids & base pairs: e.x. HF + H2O H3O+ + F-Acid and Conjugate base pair = HF & F-A strong acid has a weak conjugate baseA weak acid has a strong conjugate baseBase and conjugate acid pair = H2O & H3O+A strong base has a weak conjugate acidA weak base has a strong conjugate acid
14 Summary 6HF + H2O H3O+ + F-Identify the acid and conjugate base. Label each as ‘weak’ or ‘strong’Identify the base and conjugate acid. Label each as ‘weak’ or ‘strong’
15 pH measures the concentration (amount) of H3O+ ions in solution Standard 5d: pH scaleDefinition:pH = -log[H3O+]pH measures the concentration (amount) of H3O+ ions in solution
16 Summary 7Write the equation for HCl reacting with water to make a hydronium ion and a chloride ionIs the concentration of hydronium ions in this solution high or low?
29 Summary 14Complete the following table:[H3O+][OH-]pHpOH10-5M1
30 5e: acid/base definitions Arrhenius:acids are hydrogen containing compounds that ionize to yield H+ ions in aqueous solution.e.x. HCl(aq) H+(aq) + Cl-(aq)Bases ionize to yield OH- ions in aqueous solutions.e.x. NaOH(aq) Na+(aq) + OH-(aq)Problems: NH3 is not a base according to Arrhenius
31 Summary 15Explain why NH3 is not a base according to the Arrhenius definition of a base.
33 An acid accepts a pair of electrons (accepts a negative charge) Lewis:An acid accepts a pair of electrons (accepts a negative charge)Acid = proton donor = electron acceptorA base donates a pair of electronsBase = proton acceptor = electron donore.x. HCl + H2O H3O+ + Cl-
36 Summary 16Explain the difference between the Bronsted-Lowry definition and the Lewis definition of acids and bases
37 5g: buffersBuffer = a solution whose pH does not change (much) when acid or base are added.A buffer is a solution made from an acid and its conjugate base
38 There are 2 buffer systems in human blood: H2PO4-/HPO42- & H2CO3/HCO3- Example: human blood must have a pH between 7.35 – 7.45 (or we will die)There are 2 buffer systems in human blood: H2PO4-/HPO42- & H2CO3/HCO3-B- + H2PO4- HPO42- + HBB- + H2CO3 HCO3- + HBHB = acid (H+ donor)B- = base (H+ acceptor)
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