pH

Today We will go over how to calculate pH Titration calculations Titrations lab Get out ipad and something to take notes

Tomorrow You will have a sub and tutorials is cancelled although I might be here at lunch but will have 2 babies with me so… if you need help stop by and I will try Go to Unit 5 and everything highlighted in red is what you will be responsible for: – Look over acid/base notes powerpoint – Do the acid/base vocab practice online “game” – 5 titration practice problems – This should take you minutes to do if you focus and get it done at the beginning of the period – Quiz Monday over indicators, pH calculations, and titration calculations – Another titration lab competition on Monday

Today Titrations lab redo… Due today for a grade!!!! Tuesday- review and quiz Wednesday- test review/snowflakes and snow globe lab Thursday- TEST units 4 and 5 Friday – polar bear movie :0)

REMEMBER Bring a baby food jar and a 1 inch figurine to class!!!

Review Formula for molarity? Formula for dilutions?

pH Stands for “potential hydrogen” or “hydrogen power” Measured on a scale of 0-14

equation pH = -log[H+] Brackets [ ] refer to Molarity

Why this equation? Because expressing pH in terms of concentrated hydrogen ions tends to be cumbersome and the values are very small so we use the log base 10 function to make the numbers easier to work with Remember the common logarithm of a number is the power to which 10 must be raised to equal that number. So the log of 1x10 -7 is -7.

Calculate the pH of the following solutions [H+] = 1x [H+] = 5 x [H+] = 2 x

pOH Hydroxide potential – (when you have a base like NaOH) pOH = -log[OH] 14 – pOH = pH

Solve the following pOH of a solution that has a hydroxide concentration of 4x10 -5 What is the pH?

ON COURSE WEBSITE UNIT 5 Acids and Bases introduction ph and poh practice (word Version) Acids and Bases introduction ph and poh practice (word Version) CLICK ON THE WORD VERSION AND COMPLETE PRACTICE

Neutralization Basically a neutralization reaction is when you add an acid to base to get salt and water. Example: HCl + NaOH 

Example: HCl + NaOH  NaCl + H 2 O

Titration A titration is a technique used in the lab to find an unknown concentration of an acid or a base Formula: (M acid )(V acid ) = (M base )(V base )

In today’s lab, you know that HCl has a concentration of 0.1M and that you are using 50mL to titrate a base (NaOH) with an unknown concentration. You perform your titration and get a perfect light pink color. Your initial volume in the buret was 25mL. After titration your buret had 10mL left. What is M acid What is M base What is V acid What is V base

In today’s lab, you know that HCl has a concentration of 0.1M and that you are using 50mL to titrate a base (NaOH) with an unknown concentration. You perform your titration and get a perfect light pink color. Your initial volume in the buret was 25mL. After titration your buret had 10mL left. What is M acid 0.1M What is M base unknown What is V acid 50mL What is V base 15mL Plug into the formula and solve for the unknown molarity of the base. Formula: (M acid )(V acid ) = (M base )(V base )

Lab You know the concentration and volume of your acid. You are pouring a base from the buret into the acid until the indicator stays pink to indicate the pH has shifted to above 7. Your goal is to get a VERY LIGHT pink color so that your pH is JUST ABOVE neutral and then you can calculate the molarity of the base 20 test points given to individuals (divided up) who get the right color and calculate the right concentration

Procedure Pour 50 mL of hydrochloric acid 0.1M into flask Add 5 drops of phenolphthalein to flask Fill buret halfway with NaOH (unknown concentration) RECORD BEGINNING VOLUME OF BASE IN BURET Slowly pour base into acid shaking flask often until you get a light pink color (NOT HOT PINK!) Record final volume of NaOH in buret Calculate the unknown concentration using the titration formula

Today Snowflake Lab Nuclear Vocabulary Test grades will go in tonight Those that need to take the test come Wednesday after school or Thursday after school

Snowflake Lab Cut your pipe cleaner into 4 pieces and twist together to make snoflake shape Dissolve 6 spoonfuls of Borax into 300mL of water while heating and stirring Pour solution into a styrofoam cup Suspend your snowflake into the solution using a hook and stick Clean up, go back to your desk, and begin looking up vocab words