Name. Academic Chemistry. Acid Base. Notes. Unit #14 Test Date: cincochem.pbworks.com

Transcription

1 Periodic Table Name Academic Chemistry Acids & Bases Notes Unit #14 Test Date: 20 cincochem.pbworks.com Acid Base cincochem.pbworks.com

2 Notes Find ph To go from [H 3 O + ] to ph EXAMPLE: [H 3 O + ] = 3.23 x 10 5 Using the TI Calculator for ph Take the log of the [H 3 O + ] concentration Key in -l3.23`,-5). This yields a ph of Brackets, [ ], mean concentration or MOLARITY (M) So, [H + ] = 1M means The concentration of hydrogen ions is 1 M. Find concentration To go from ph to [H + ] EXAMPLE: ph = Set 10 to the power of the ph. Key in ` l-9.51) This yields [H + ] of 3.09 x ph to poh To go from ph to poh (and vice versa) EXAMPLE: ph = 4.49 Subtract ph from 14. This yields a poh of cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 19

3 Titration Titration a process in which a reaction is used to determine the of a solution. *concentration is molarity (M) = Acid a compound that produces ions when dissolved in water. Ex. Vinegar Lemon juice Sour candy Properties of Acids acid acid acid Acids To solve: 1) write the chemical equation 2) use acid/base coefficients for mol ACID and mol BASE values Example How many ml of 0.45 M HCl must be added to 25.0 ml of 1.00 M KOH to make a neutral solution? taste Reacts with (corrodes) to form gas turns blue litmus paper solutions of acids are (must be mixed with water!) react with BASES to form and Practice What is the molarity of nitric acid (HNO 3 ) if 15.0 ml of the solution is completely neutralized by 38.5 ml of M NaOH?. Naming Acids Binary acids H bonded to one nonmetal (HF) Begin with, use the of the element name, add the suffix 1. HCl acid A 25.0 ml solution of sulfuric acid (H 2 SO 4 ) is completely neutralized by 18 ml of 1.0 M LiOH. What is the concentration of the H 2 SO 4 solution? 2. HBr acid Ternary Acids H bonded to a polyatomic ion (H 2 SO 4 ) Begin with ion without the. 18 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 3

4 Acids Neutralization Add suffix if there was an Add suffix if there was an. 1. HNO 3 2. HClO 2 Q: What happens with you mix an acid with a base? A: A reaction! HCl + NaOH + Strength of Acids STRONG acids completely, or dissociate, in water. All the acid breaks into ions. HCl + H 2 O H 3 O + + Cl 1 way arrow ALL IONS AFTER MIXING WEAK acids d ionize completely in solution. Some acid stays intact instead of ionizing. H 2 SO 3 + H 2 O H 3 O + + SO 3 2 SOME ACID 2 head arrow SOME IONS Binary Acid Strength There are 3 STRONG Binary acids ALL other Binary acids are weak: H 2 S, H 2 Se, HF Ternary Acid Strength There are 4 STRONG Ternary acids (that we will use!) Products are ALWAYS a salt and water (H 2 O) Salt: ( + ) also known as an compound This is called a reaction. When writing the products, write first, then criss-cross the charges of the metal and nonmetal to find the formula of the. Practice: Write the balanced chemical equation for the neutralization reaction between: 1) nitric acid (HNO 3 ) and potassium hydroxide (KOH) 2) sulfuric acid (H 2 SO 4 ) and magnesium hydroxide (Mg(OH) 2 ) All other Ternary acids are weak: H 3 PO 4, H 2 SO 3, HNO 2 etc A quick way to determine if a ternary acid is strong: SUBTRACT #H from #O s in the acid. If the difference is 2, the acid is strong. Less than 2, the acid is weak. Neutralization reaction: 4 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 17

5 ph and [H + ] Bases ph = [H + ] = ph + poh = Determine the ph of a 0.01 M HCl solution Base a compound that produces ( ) ions when dissolved in water. Examples: Milk of Magnesia hydroxide Drain cleaner hydroxide Window cleaner Determine the ph of a M H 2 SO 4 solution Red litmus paper with a drop of base here Find [H 3 O + ] for a solution that has a ph of 3.1 Find [H 3 O + ] for a solution that has a ph of 9.5 Blue litmus paper with a drop of acid here Properties of Bases Find [H + ] for a solution that has a ph of 8.2 Find [H 3 O + ] for a solution that has a ph of taste Feels to the touch Does react with metal turns red litmus paper solutions of bases are (must be mixed with water!) reacts with ACIDS to form and 16 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 5

6 Bases Naming Bases Use the same rules as for ions (name the cation, then name the anion) 1. NaOH 2. Ca(OH) 2 3. KOH 4. Mg(OH) 2 Strength of Bases STRONG bases completely in [H + ] Finding [H 3 O + ] or [H + ] Given ph, we can determine by using the inverse of the log of ph! To find [H + ], set 10 to the power of the ph. To convert FROM ph to [H + ] using a TI calculator Example: ph = [H 3 O + ]= Key in ` l-9.51) This yields a [H + ] of 3.09 x Practice: If the ph of a solution is 4.4, what is the [H 3 O + ]? If the ph of a solution is 9.8, what is the [H + ]? water. All base breaks into ions. All hydroxides with groups and metals (except ) are STRONG bases. LiOH, NaOH, KOH, RbOH, CsOH Mg(OH) 2, Ca(OH) 2, Sr(OH) 2, Ba(OH) 2, Ra(OH) 2 ph poh [H 3 O + ] Acid/Base Neutral WEAK bases - only. Some of the base stays intact instead of ionizing. All bases NOT LISTED ABOVE AS STRONG. 6 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 15

7 poh Arrhenius Theory like H + ions, OH ions exist in very concentrations in aqueous solutions. However, we can find to make the numbers easier to work with. poh range is also from t_. An Arrhenius acid must contain a and dissociates (ionizes) in water to produce. An Arrhenius base must contain a and dissociates (ionizes) in water to produce. poh is the OPPOSITE of ph, so if.. poh is Practice: Classify each of the following as an Arrhenius acid or Arrhenius base. Ca(OH) 2 poh is poh is HBr H 2 SO 4 ph and poh are ALSO related, so ph + poh = LiOH Disadvantages of Arrhenius Theory Only compounds with can be classified as a base. What about ammonia,? Can only be applied to reactions that occur in Would classify some compounds as acids, such as 14 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 7

8 Bronsted Lowry Theory of Acids and Bases Brønsted Lowry Theory of Acids and Bases In an acid-base reaction, substances are defined by their ACTIONS in Brønsted Lowry theory! The Brønsted Lowry acid is the reactant that To find ph using a TI calculator Example [H 3 O + ] = 3.23 x 10-5 find the log[3.23 x 10-5 ] key in: _l3.23`,_5) then e This yields a ph of ph a. The Brønsted Lowry base is the reactant that a. The Brønsted Lowry Conjugate acid is the product that forms after a B-L accepts an H +. The Brønsted Lowry Conjugate base is the product that forms after a B-L has donated an H +. To identify the B-L acid, base, and conjugates in an acid base reaction, we will use the following process and build 2 conjugate pairs between reactants and products 1. Ask yourself Which reactant loses an H +? This is the. Its partner in the products (missing an H + ) Remember, in a aqueous solution, ph is ph is ph is [H + ] = [OH ] = 1 x 10-7 M So ph = Practice: If [H 3 O + ] = 1.0 x 10 5 M, what is the ph? Is the solution BASIC, NEUTRAL, or ACIDIC? If [H 3 O + ] = 1.0 x M, what is the ph? Is the solution BASIC, NEUTRAL, or ACIDIC? is the conjugate. Connect with an arrow. 2. Ask yourself, Which reactant gains an H +? This is the. Its partner in the products (with its new H + ) If [H 3 O + ] = 1.0 x 10 7 M, what is the ph? Is the solution BASIC, NEUTRAL, or ACIDIC? is the conjugate. Connect with an arrow. 8 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 13

9 ph Brønsted-Lowry Theory of Acids and Bases ph Scale 3. Remember: Conjugates are always! [ ] [ ] HCl + H 2 O H 3 O + + Cl Practice: Identify the B-L acid, B-L base, conjugate acid, and conjugate base. HNO 3 + H 2 O H 3 O + + NO 3 - Concentration of Ions in Solutions [H + ] [OH - ] [H + ] [OH - ] [H + ] [OH - ] ph Scale [H + ] are in very concentration, so the ph scale is easier to use to represent acidity and basicity. ph range is from t_. Using a calculator, we use the key to generate a value for ph we can easily work with. Remember, [H 3 O + ] = [H + ] Given an acid or base, to predict the conjugate acid and conjugate base we will use the following rules. 1. Given a B-L acid, to find its conjugate base, take away one and lower (subtract ) the charge by 2. Given a B-L base, to find its conjugate acid, add one and raise (add to +) the charge by. Practice: Give the formula of the conjugate base of the following B-L acids. HI HBr ph = HCO 3-1 H 2 PO cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 9

10 Bronsted Lowry, Hydronium, Protons Self-Ionization of water Practice: Give the formula of the conjugate acid of the following B-L bases. H 2 PO 4-1 F -1 Self-Ionization of Water Water can act as a B-L or a B-L. In any sample of water, a very small amount of H + and OH - ClO 3-1 CO 3-2 ions will form. Thus, equal amounts of hydronium and The Hydronium ion, H 3 O + Hydrogen ions are not always free in an acidic solution. The ion forms when an acid is dissolved in H 2 O. H 2 O and H + can combine to form H 3 O +. The hydronium ion functions the same as an H + ion. HCl + H 2 O H 3 O + + Cl A hydrogen ion (H + ) is a PROTON! A hydrogen atom contains a single proton and an electron, so after it loses an electron all that remains is a PROTON. SO, hydrogen ions (H + ) are often referred to as PROTONS. Acids can be defined by how many H + they can donate. Type # of H + to give Example hydroxide ions form, creating conjugate pairs. This is called the self- of water: H 2 O + H 2 O H 3 O + + OH In water, equal concentrations of [H + ] and [OH ] are present at 1 x 10-7 M ( M). NEUTRAL is where [H + ] = [OH ] with at molarity of 1 x 10-7 M Therefore, for any aqueous solution, [H + ] x [OH ] = 1 x M AND As [H + ], [OH ] must As [OH ], [H + ] must This is an relationship between hydrogen and hydroxide ions. With greater [H + ] you have and acid, with greater [OH ], a base. 10 cincochem.pbworks.com Acid Base Acid Base cincochem.pbworks.com 11