Titration

Do Now 1. Calculate the molarity of a 3.00-L solution that contains 4.5 moles of NaBr. 2. Calculate the pH of a 0.125M HI solution. 3. Predict the products of the following neutralization reaction: NaOH + HCl 

Agenda ItemTime Do Now10 min. Neutralization Example10 min. Titration25 min. Titration Investigation20 min. pH Balance in Humans15 min. Exit ticket and closure10 min.

Universal Indicator

Neutralization What is the pH of each solution? What do you think will happen when they are mixed? What will the products of this reaction be? NaOH + HCl 

New Challenge A 10mL sample of ammonia, NH 3, is in the lab. The concentration and pH of the ammonia are unknown. However, there is a supply of 1M HCl and universal indicator that can be used to help identify the concentration and pH of the solution. How can you identify the pH and concentration of the ammonia?

Sample Experimental Design Read the experiment designed by a student to investigate the pH and concentration of the ammonia. Look for elements of the experimental design: aim, methods, procedure, variables, tools, etc.

Agenda ItemTime Do Now10 min. Neutralization Example10 min. Titration25 min. Titration Investigation20 min. pH Balance in Humans15 min. Exit ticket and closure10 min.

Titration Titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution. A known solution (called a titrant) is added to the unknown solution until the reaction has reached the equivalence point. An equivalence point is when the exact number of H+ ions and OH- ions are in the solution so that the acid and base have neutralized each other.

The first example: 10mL of 0.1M HCl neutralizes 10mL of 0.1M NaOH Neutralization means: moles of H+ = moles of OH- So… how do we use this information?

The first example: Use the same formula as dilutions: M 1 V 1 = M 2 V 2 M 1 = 0.1 M V 1 = 10mL M 2 = ? V 2 = 10mL

Here’s another… A 10mL sample of ammonia of an unknown concentration is in a beaker. A student performs a titration with 1.0M HCl to discover the concentration of the ammonia. The data are shown to the right. Calculate the molarity and pH of the ammonia. Volume of HCl AddedColor of the Solution 1 mLDark blue 2 mLDark blue 3 mLDark blue 4 mLLight blue 5 mLDark green 6 mLLight green 7 mLYellow 8 mLOrange

One more… A 30mL sample of sulfuric acid is in a beaker, but the concentration is unknown. A student uses 6M NaOH in a titration. The data are shown to the right. Calculate the pH and concentration of the sulfuric acid. Volume of HCl AddedColor of the Solution 10 mLRed 20 mLRed 25 mLRed 30 mLOrange 33 mLYellow 35mLYellow 36 mLLight green 37 mLDark green

Agenda ItemTime Do Now10 min. Neutralization Example10 min. Titration25 min. Titration Investigation20 min. pH Balance in Humans15 min. Exit ticket and closure10 min.

Titration Example For 7 minutes, answer the questions by your self. Spend 4 minutes checking your answers with your partner.

Agenda ItemTime Do Now10 min. Neutralization Example10 min. Titration25 min. Titration Investigation20 min. pH Balance in Humans15 min. Exit ticket and closure10 min.

Jaime developed acne in the past year. After his acne breakouts became more and more intense, Jaime began using a face wash which he thought might prevent the breakouts. Unfortunately, the breakouts actually became worse as a result of his usage of facial scrubs. Jaime went to the dermatologist and found out that acne is not actually caused by dirty skin, but that oil and dead skin cells clog pores and hair follicles and create the breakouts. The dermatologist told Jaime that the reason the facial washes he was using were making his breakouts worse is because they were changing the natural pH of his skin. Humans’ faces usually have a pH of roughly 5.5, but facial washes can raise or lower that pH, which causes irritation and inflammation. Jaime’s facial wash is a silvery, white cream which is soluble in water. Jaime is interested to know whether this facial wash is raising or lowering his skin’s pH so that he can look for a different treatment which will not cause more breakouts. Develop a procedure for an investigation which could help Jaime discover the pH of his facial wash.

Agenda ItemTime Do Now10 min. Neutralization Example10 min. Titration25 min. Titration Investigation20 min. pH Balance in Humans15 min. Exit ticket and closure10 min.