Solution Chemistry Solutions, Problems, Solutions, Problems. Does it ever end?

How can you express concentration?

1)Mass % composition 2)Molarity 3)Molality 4)Mole fraction 5)Density

Mass % problems: Find mass % Find amount of solute Find total mass of solution

Mass % problems: Find mass % Mass % = mass of solute x 100 % total mass of solution Don’t forget to add the masses of the solute and solvent for the total mass

Mass % problems: Find amount of solute Mass % = mass of solute x 100 % total mass of solution Multiply by total mass and divide by 100% to solve for mass of solute

Mass % problems: Find total mass of solution Mass % = mass of solute x 100 % total mass of solution Multiply both sides by the mass of solution first to get it out of the denominator.

Molarity problems: Find molarity Find amount of solute Find volume of solution

Molarity problems: Find molarity M= moles solute Volume of solution (L)

Molarity problems: Find amount of solute M= moles solute Volume of solution (L) Molarity x volume= moles!

Molarity problems: Find volume of solution M= moles solute Volume of solution (L) Multiply both sides by the volume of solution first to get it out of the denominator. OR!

Molarity problems: Find volume of solution Use the molarity as a conversion factor! moles solute x 1 L = Volume of solution! M

Dilution Problems M x V = Moles Moles of solute in new solution = moles in the stock solution. Molarity goes down, volume goes up

Dilution Problems Example: What is the concentration of a solution made by diluting 25 ml of a.50 M HCl solution to a new volume of 150 ml?

Dilution Problems Example: What is the concentration of a solution made by diluting 25 ml of a.50 M HCl solution to a new volume of 150 ml? M x V = moles..50 M x.025 L=.0125 moles HCl M = mol/vol=.0125 mol /.150 L =.083 M

Dilution Problems 1)What is the concentration of a solution made by diluting 125 ml of a 2.5 M NH 3 solution to a new volume of 350 ml? 2)What is the concentration of a solution made by diluting 2.5 ml of a 6.0 M NaCl solution to a new volume of 80. ml? 3)What is the concentration of a solution made by diluting 30. ml of a 1.0 M Fe(NO 3 ) 3 solution with 20. ml of water? (The final volume should be = 50. ml)

Dilution Problems Example: What volume of a 2.0 M NaOH stock solution is required to mix 1.50 L of a.150 M NaOH solution?

Dilution Problems Example: What volume of a 2.0 M NaOH stock solution is required to mix 1.50 L of a.150 M NaOH solution? M x V = moles..150 M x 1.50 L =.225 moles NaOH.225 moles NaOH x 1 L/ 2.0 moles=.113 L

Dilution Problems 1)What volume of a 6.0 M NaOH stock solution is required to mix 1.50 L of a.150 M NaOH solution? 2)What volume of a 2.0 M MgCl 2 stock solution is required to mix L of a.10 M MgCl 2 solution? 3)What volume of a 1.0 M HCl stock solution is required to mix 100. ml of a.10 M HCl solution?

Volume Stoichiometry If you mix 10. ml of.10 M HCl with.10 M NaOH, …it should take 10. ml of the NaOH to react completely.

Volume Stoichiometry If you mix 10. ml of.10 M HCl with.20 M NaOH, …it should take only 5.0 ml of the NaOH to react completely.

Volume Problems 1)If you react 10.0 ml of.10 M HCl with.050 M NaOH, what volume of NaOH solution will be needed? 2)If you react 10.0 ml of.10 M H 2 SO 4 with.050 M NaOH, what volume of NaOH solution will be needed? 3)If you react 50.0 ml of 1.0 M CaCl 2 with 1.9 M Na 2 CO 3, what volume of Na 2 CO 3 solution will be needed?

Volume Stoichiometry If 10. ml of.10 M HCl reacts completely with 10. ml NaOH, …the concentration of the NaOH must be the same,.10 M

Volume Stoichiometry If 10. ml of.10 M HCl reacts completely with 20. ml NaOH, …the concentration of the NaOH must be half of that,.050 M.

Volume problems If 25.0 ml of.30 M HCl reacts completely with 25. ml NaOH, what is the concentration of the NaOH? If 10.0 ml of.10 M HCl reacts completely with 20. ml NaOH, what is the concentration of the NaOH? If 15.0 ml of.10 M HCl reacts completely with 50. ml Pb(NO 3 ) 2, what is the concentration of the Pb(NO 3 ) 2 ?

Acids and Bases

Examples? Acids Bases

Properties of Acids and Bases Acids Bases

Properties of Acids and Bases Acids Are electrolyte solutions Make ions in solution Affect indicators Have low pH Taste sour Neutralize bases Can cause serious burns Corrode reactive metals Have more H + than OH - (in solution) Bases Are electrolyte solutions Make ions in solution Affect indicators Have high pH Taste bitter Neutralize acids Can cause serious burns Corrode aluminum only Have more OH - than H + (in solution)

Properties of Both Acids Are electrolyte solutions Make ions in solution Affect indicators Have low pH Taste sour Neutralize bases Can cause serious burns Corrode reactive metals Have more H + than OH - (in solution) Bases Are electrolyte solutions Make ions in solution Affect indicators Have high pH Taste bitter Neutralize acids Can cause serious burns Corrode aluminum only Have more OH - than H + (in solution)

Br Ø nsted-Lowry Definition Substances that donate a proton (H + ion) in a reaction are acids. Substances that accept a proton (H + ion) are bases. Arrhenius acids and bases make H + and OH - ions in solution. Br Ø nsted-Lowry bases are also Arrhenius bases.

Conjugates After an acid has donated a proton, the rest of the species is the conjugate base. HA  A - + H + After a base has accepted a proton, the resulting species is the conjugate acid. B - + H +  HB

What is the conjugate base of… HCl CH 3 COOH H 2 SO 4 HSO 4 - H 2 O NH 4 + NH 3

What is the conjugate base of… ACID (loses H + to form its) Conjugate base HCl CH 3 COOH H 2 SO 4 HSO 4 - H 2 O NH 4 + NH 3

What is the conjugate base of… ACID (loses H + to form its) Conjugate base HCl (  H + and) Cl - CH 3 COOH H 2 SO 4 HSO 4 - H 2 O NH 4 + NH 3

What is the conjugate base of… ACID (loses H + to form its) Conjugate base HCl (  H + and) Cl - CH 3 COOH(  H + and) CH 3 COO - H 2 SO 4 (  H + and) HSO 4 - HSO 4 - (  H + and) SO 4 -2 H 2 O (  H + and) OH - NH 4 + (  H + and) NH 3 NH 3 (  H + and) NH 2 -

What is the conjugate acid of… NO 3 - C 2 O 4 -2 HPO 4 -2 HSO 4 - H 2 O F -

What is the conjugate acid of… Base (gains H + to form its) Conjugate acid NO 3 - C 2 O 4 -2 HPO 4 -2 HSO 4 - H 2 O F -

What is the conjugate acid of… Base (gains H + to form its) Conjugate acid NO 3 - (+H +  ) HNO 3 C 2 O 4 -2 HPO 4 -2 HSO 4 - H 2 O F -

What is the conjugate acid of… Base (gains H + to form its) Conjugate acid NO 3 - (+H +  ) HNO 3 C 2 O 4 -2 (+H +  ) HC 2 O 4 - HPO 4 -2 (+H +  ) H 2 PO 4 - HSO 4 - (+H +  ) H 2 SO 4 H 2 O (+H +  ) H 3 O + F - (+H +  ) HF

Nomenclature If the anion name then the acid name ends in…. is…

Fill in the blanks HCl is _____________acid HClO 4 is _____________acid HClO 3 is _____________acid HClO 2 is _____________acid HClO is _____________acid

Fill in the blanks HCl is _____________acid HClO 4 is _____________acid HClO 3 is _____________acid HClO 2 is _____________acid HClO is _____________acid Hydrogen chloride Hydrogen chlorate Hydrogen perchlorate Hydrogen hypochlorite Hydrogen chlorite

Nomenclature If the anion name then the acid name ends in…. is… --ideHydro___ic acid (hypo--) --iteHypo___ous acid --ite___ous acid --ate___ic acid (per--) –atePer___ic acid

Fill in the blanks HNO 3 is _____________acid HIO 4 is _____________acid H 2 CO 3 is _____________acid H 3 PO 3 is _____________acid HBrO is _____________acid

Fill in the blanks _____________is hydrocyanic acid _____________ is perbromic acid _____________ is phosphoric acid _____________ is sulfurous acid _____________ is hypoiodous acid

Show the conjugate acid/base pairs in the following reactions. C 2 O H 3 O +  HC 2 O H 2 O CH 3 COOH + NH 2 -  NH 3 + CH 3 COO -

Show the conjugate acid/base pairs in the following reactions. C 2 O H 3 O +  HC 2 O H 2 O CH 3 COOH + NH 2 -  NH 3 + CH 3 COO - Acid Base Conjugate Base Conjugate Acid

Show the conjugate acid/base pairs in the following reactions. C 2 O H 3 O +  HC 2 O H 2 O CH 3 COOH + NH 2 -  NH 3 + CH 3 COO - Acid Base Conjugate Base Conjugate Acid Conjugate Base Conjugate Acid

[H + ] is inversely related to [OH - ] When [H + ] increases, [OH - ] decreases in a water solution, and vice versa.

[H + ] is inversely related to [OH - ] When [H + ] decreases, [OH - ] increases in a water solution, and vice versa. (Why?)

pH The basic (and acidic) definitions are: pH= -log [H + ] [H + ]= 10 -pH pOH= -log [OH - ] [OH - ]=10 -pOH Kw=[H + ][OH - ]=1 x (at 25 o C) pH + pOH = 14 (at 25 o C)

pH practice If pH is 3.38…. 1)What is the pOH?

pH practice If pH is 3.38…. 1)What is the pOH? 14-pH= 10.62

pH practice If pH is 3.38…. 1)What is the pOH? 14-pH= )What is [H + ]?

pH practice If pH is 3.38…. 1)What is the pOH? 14-pH= )What is [H + ]? = 4.17 x M

pH practice If pH is 3.38…. 1)What is the pOH? 14-pH= )What is [H + ]? = 4.17 x M 3)What is [OH - ]?

pH practice If pH is 3.38…. 1)What is the pOH? 14-pH= )What is [H + ]? = 4.17 x M 3)What is [OH - ]? =2.40x M and K w /4.17x10 -4 M=2.40x M!

pH practice If [OH - ]= 4.8 x M…

pH practice If [OH - ]= 4.8 x M… 1)What is pOH?

pH practice If [OH - ]= 4.8 x M… 1)What is pOH? -log (4.8 x )= 5.32

pH practice If [OH - ]= 4.8 x M… 1)What is pOH? -log (4.8 x )= )What is pH?

pH practice If [OH - ]= 4.8 x M… 1)What is pOH? -log (4.8 x )= )What is pH? = 8.68

pH practice If [OH - ]= 4.8 x M… 1)What is pOH? -log (4.8 x )= )What is pH? = )What is [H + ]?

pH practice If [OH - ]= 4.8 x M… 1)What is pOH? -log (4.8 x )= )What is pH? = )What is [H + ]? = 2.08 x M and Kw/ 4.8 x = 2.08 x M !

Please recall: Strong acids and bases dissociate completely in water. Weak acids/bases do not. Strong acids= nitric, hydrochloric, sulfuric, hydrobromic, hydroiodic, perchloric Strong bases-Group 1 & 2 hydroxides—(group 2’s don’t dissolve much)

Please recall: 1.What is the concentration (M) of NaOH if.35 mole NaOH is dissolved in.120 L solution? 2.What is the molarity of HCl if 12 g HCl is dissolved in.85 L of solution? 3.What is [OH - ] if.35 g Ba(OH) 2 is dissolved in.250 L solution? 4.What mass of H 2 SO 4 is in 55 ml of.38 M H 2 SO 4 ?

Please recall: 1.What is the concentration (M) of NaOH if.35 mole NaOH is dissolved in.120 L solution? 2.What is the molarity of HCl if 12 g HCl is dissolved in.85 L of solution? 3.What is [OH - ] if.35 g Ba(OH) 2 is dissolved in.250 L solution? 4.What mass of H 2 SO 4 is in 55 ml of.38 M H 2 SO 4 ? Did you notice?

Analyze these solutions ContentspH[H + ] (M)[OH - ] (M)pOHAcidic or Basic mol HCl /L 21.5g NaOH /L 3? mol LiOH / L ? mol KOH/L ? gHClO 4 /L.020 6? mol Ba(OH) 2 /L.0070

Right! ContentspH[H + ] (M)[OH - ] (M)pOHAcidic or Basic mol HCl /L x Acidic 21.5g NaOH /L x Basic 33.2 x10 -6 mol LiOH / L x x basic 43.1 x10 -4 mol KOH/L x x basic 52.0 gHClO 4 /L x acidic mol Ba(OH) 2 /L x basic

Review question: 125 ml of a KOH solution is mixed so that the pH is ) What is the pOH, [OH - ] and [H + ]? 2) What is the [KOH] ? 3) How many moles KOH was used? 4) What mass of KOH was used? (FM KOH = 56.1 g/mol)

Review question: 125 ml of a KOH solution is mixed so that the pH is )pOH=1.77;[OH - ]=.0170M;[H + ]=5.88x M 2) [KOH]=[OH - ]=.0170M (it’s a strong base!) 3)moles=MxV=.0170Mx.125L=.00213mol 4) mass KOH =moles KOH x FM KOH =.00213mol x 56.1 g/mol =.119 g

Strength of acids and bases. HCl H 2 CO 3

Strength of acids and bases. HCl -- strong acid H 2 CO 3 -- weak acid Strength is determined by amount of dissociation

Strength of acids and bases. HCl -- strong acid, it dissociates completely H 2 CO 3 -- weak acid, dissociates partly What about their conjugates?

Strength of acids and bases. Cl - HCO 3 -

Strength of acids and bases. Cl - -- not a base HCO weak base Strength is determined by amount of association

Strength of acids and bases. Cl - -- not a base, it does not associate with water. HCO weak base, it associates partly What about their conjugates?

Strength of acids and bases. The conjugate of a strong acid is not a base The conjugate of a weak acid is a weak base The conjugate of a strong base is not an acid

Strength of acids and bases. The conjugate of a strong acid is not a base The conjugate of a weak acid is a weak base  the stronger the acid, the weaker the base and vice versa The conjugate of a strong base is not an acid