 Acids and Bases Unit

What is an Acid? A solution with an excess of H +1 ions

How do we know that a chemical is an acid? Most Acids start with an ‘H’ in their chemical formula

What are the properties of an Acid?  Tastes sour  Turns blue litmus paper red  Reacts strongly with metals  Very Corrosive

Examples of Acids

What is a Base? A solution with an excess of (OH) -1 ions

What is another name for a Base? Alkali

What are the properties of a Base?  Tastes bitter  Feels slippery  Turns red litmus paper blue  Corrosive

Examples of Bases Soap Drano Bleach Chalk

More Examples of Bases Blood Ammonia

 Stop and Think?!?! Why do you think blood is Basic and not Acidic?

Warm Up 1. Name three properties of Acids. 2. Name one property that both Acids and Bases have in common.

So, how do you know if a substance is a Base or an Acid? We use a pH scale

What does the pH scale measure? This is a measure of the concentration of hydrogen ions

What is used to indicate the type of substance (Acid or Base) ? Acid-Base Indicators 1. There is blue litmus paper and red litmus paper 2. The Universal indicator 3. Phenolphthalein 4. Cabbage juice

What happens to litmus paper in the presence of an Acid? Blue litmus paper turns RED in the presence of an acid

What happens to litmus paper in the presence of a Base?  Red litmus paper turns BLUE in the presence of a Base

 On the blank pH scale, label Acids, Bases and Neutral locations!

Where can Acids be found on the pH scale?  pH is less than 7  The lower the number the stronger the acid!!

Where can Bases be found on the pH scale?  pH is more than 7  The higher the number the stronger the base!!

Where can Neutral substances be found on the pH scale? pH is equal to 7

Warm Up 1.What element do all acids start with? 2.Where can you find the strongest acids on the pH scale? 3.What color do acids turn litmus paper?

 Let’s go back to Acids!

What is a Monoprotic acid?  There is only ONE hydrogen [H] +1 ion or proton Example: HCl

What is a Diprotic acid?  There are TWO hydrogen [H] +1 ions or protons Example: H 2 SO 4

What is a Triprotic acid?  There are THREE hydrogen [H] +1 ions or protons Ex. H 3 PO 4

Steps to name acids:  Identify the non-metal group first  Look at ‘green’ sheet for group name ***If it is not on the ‘green’ sheet it ends in ‘ide’.  Drop the non-metal ending and add new acid name

What are the acid names? No Oxygen  w/Oxygen

Easy way to remember!  No “O” use hydro…  I ate something icky  And ite got nauseous

HBrHBr H 2 CO 3H 2 CO 3 H 2 SO 3H 2 SO 3    Let’s try together: Examples

On your own

So, how do we write the formula for an acid? 1. Identify the cation (for an acid it is always H +1 ) 2. Use the acid name to find the corresponding anion 3. Swap n’ Drop

Example  Hydrochloric acid CationAnionSwap n’ Drop H +1 Cl -1 HCl

Let’s practice

Warm Up 05/10/16  For the following, name the acid and identify its type (monoprotic, diprotic or triprotic). Acid FormulaAcid NameType of Acid H 2 Te H 2 CrO 4 HBrO 2

How do you name bases? 1. Name the metal first, the same name as on the Periodic Table 2. Name the hydroxide (OH) group. 3. If the metal is a transition metal, the charge must be placed in parentheses ( ) in roman numeral (reverse swap n’ drop)

Example  Mg(OH) 2 is magnesium hydroxide

Example with a Transition Metal  Cu(OH) 2  To find the charge we reverse Swap n’ Drop! Cu 1 (OH) 2 Cu +2 (OH) -1  Cu(OH) 2 is copper (II) hydroxide  Because the Cu has a +2 charge

How do you write the formula for bases?  Treat the Base Name as a First and Last name.  Find the charge for each. Always (OH) -1 for the Last name for a Base.  Swap n’ Drop

Example

How to calculate pH? You must first know the concentration of hydrogen ions (H +1 )

How is concentration represented? With empty square brackets, such as [ ].

So, How to calculate pH? pH= -log[H+]

Let’s practice 1. Find the pH when the hydrogen ion concentration is M in solution. Ans= Find the pH when the hydrogen ion concentration is 3.5x10 -5 M in solution. Ans= 4.46

Other important formulas? Use these to help calculate pH when [H +1 ] is not given: pOH= -log[OH-] pH + pOH=14

Let’s practice using pOH= -log[OH - ] pH + pOH=14 1. What is the pOH, in a solution that has a hydroxide concentration of 4.82x10 -5 M? Ans= 4.32 Will this solution be Acidic or Basic?

Do you have an Acidic or Basic solution? Can only be determined by calculating the pH NOT pOH. Be Careful!

Example 1 continued Will this solution be Acidic or Basic? pH + pOH=14 pH =14 pH= 9.68 This solution is Basic!!!

On your own! 2. What is the pOH, in a solution that has a hydroxide concentration of 2.00x10 -4 M? Will this solution be Basic or Acidic?

 Acids/Bases definitions

What is an Arrhenius Acid? This type of Acid produces hydrogen ions [H +1 ] in solution.

What is an Arrhenius Base? This type of Base produces hydroxide ions [OH -1 ] in solution.

What is the problem with the Arrhenius definition? Not all Bases produces hydroxide ions [OH -1 ] Example: NH 3

What is a Bronsted-Lowry acid? This type of acid donates hydrogen ions [H +1 ] to another compound.

What is a Bronsted-Lowry base? This type of base accepts hydrogen ions [H +1 ] from another compound.

Did Bronsted-Lowry fix the problem? Yes. This definition shows that substances can be bases even though they do not release OH -.

Example  NH 3 is a BASE in water. NH 3 accepts H + to make NH 4  Water is itself an ACID. Water donates H + to make OH -

What is a conjugate acid-base pair? These are the two compounds involved in the transfer of a hydrogen in a reaction.

Conjugate Pairs

How to identify the conjugate pairs? Each pair is made up of the same elements ***The only difference is a hydrogen (H + ).

Learning Check! Label the acid, base, conjugate acid (CA), and conjugate base (CB) in each reaction: HCl + OH -  Cl - + H 2 O H 2 O + H 2 SO 4  HSO H 3 O +

What happens when an Acid and Base react? Neutralization

What is neutralization? [H + ]=[OH - ] pH=7

What is produced in a neutralization reaction? Salt and water

What is a ‘salt’ made up of?  It is an ionic compound  It contains the metal from the base  And the non-metal from the acid.