# Acid base speed dating | Chem 13 News Magazine | University of Waterloo

# Acid base speed dating

Editor’s Note This dating acid-base rate was first published in Chemed Education Xchange (Chemed X)!It is a community of chemistry educators empowered by providing learning resources and forums for discussion and collaboration on an interactive platform.

The Acids and Bases unit is difficult for most students in advanced chemistry. You will be overwhelmed by the number of different calculations. I thought it was time to make pH-acid-base calculations more fun. speed dating!

I posted a speed -Provide a PowerPoint to the board to guide students through this activit y-Show sample slides and provide upon request. Please email [email protected] ca for this slide.

After completing notes and examples for each solution type throughout the unit, my chemistry students were given handouts to organize their calculations. Students completed an idea organizer (see next page) in their own words as a Do-Now and discussed their answers. After this quick review, each one offered a concrete solution. Repeat for the number of people in your class and come up with 10 answers. There were 32 students, 8 strong acids, 8 weak acids, 8 strong bases, 8 weak bases, so their future dates all matched.

List of solutions used | ||
---|---|---|

10 mL | 1, 0 m Ha | K_{a}= 2. 0 x 1 0-7 |

10 mL | 1, 0mHCl | |

10 mL | 1. 0 m NH_{3} |
K_{b}= 1, 8 x 1 0-5 |

10 mL | 1, 0m. NaOH | |

20 mL | 1, 0 m Ha | K_{a}= 2. 0 x 1 0-7 |

20 mL | 1, 0mHCl | |

20 mL | 1. 0 m NH_{3} |
K_{b}= 1, 8 x 1 0-5 |

20 mL | 1, 0m. NaOH | |

40 mL | 1, 0 m Ha | K_{a}= 2. 0 x 1 0-7 |

40 mL | 1. 0 m NH_{3} |
K_{b}= 1, 8 x 1 0-5 |

This activity becomes easier when there are many students with the same answer. Because there are multiple people you can match, you can find a “date partner” faster. I made the quantities quick and easy to compare because the purpose of the class was to quickly remind her how to calculate pH, not to hit the students. Students were asked to determine their individual pH and complete a “solution biography” to use throughout the activity.

Then it was time to speed date!For each date, students had to find a specific match and determine the combined pH value.

Through the slides, the students indicated what kind of matching they wanted. The students were able to stand up, talk to each other, look for partners, and travel. If you find a partner, sit down with him and he will start the pH complex calculation. If you can’t find your opponent, wait near the center of the room until there are only a few people left. I moved while Match sat. to check and were sent to the middle of the class if their race matching was inaccurate. In the end, everyone found a match (with the exception of odd numbers of students, he has to match three).

On day 1, they were asked to find matching solutions of the same strength and class, such as weak acid to weak acid and strong base to strong base. I was told to calculate the binding pH value by calculating the binding moles, the binding volume, the binding moles and finally the binding pH. it was easy to check The students change the volume as needed to have the students with exactly the same kind of answer, but the students do not seem to have difficulty matching. The pH does not change when two of the same concentration are mixed, and the pH changes when two different concentrations change.

For example, a weakly acidic student looks for a strong acidic student. The pH was determined by the solution of a strong acid, which had to be recognized that it was after diluted the solution of the weak acid. However, I asked the matching pair to tell which strong acid or weak bases had, and confirmed that the matching was correct. Students did not have a hard time matching. If you write down the procedure for calculating pH, you will dilute a strong substance to the additional value and take the negative logarithm. the new diluted molarity.

Date 3 was difficult because I had to find a partner to make a buffer solution together. Some students did not have a schedule, so after the schedule was decided first, we grouped in the center of the room. Just as everyone could find something that matched, I checked with the answer that the actual matching species are strong and strong alternative species, and the weaker is more moles than the stronger. The longest ran was that students understood that the weak solution must be combined in order to obtain a solution that contains more moles than a strong solution. After calculating the pH combined to the student, the reaction of the two solution was written out, the amount of the generated salt was calculated, and the calculation was taken with the formula of Henderson-Hasselch. the new PH. This combination took the longest time to install, but I think it was well thought that it was easy to understand the solution of cushioning material.

On the last date (date 4), it was required to find a match to make salt. It was necessary to estimate the final pH and indicate which solution is neutral salt, acidic salt, or basic salt. The students noticed that they had to find something that matched the molar amount. Unless the solution was the same, there was rarely needed intervention. The most difficult thing was when both solutions contained a weak electrolytic (in this case, the K value must be compared).

### Quick hint

- It is possible to make corrections to this activity, but be aware that the more difficult the number, the more difficult it is for students to find out what they match.
- Make sure that everyone is actually matching on each schedule. If the number of people is biased, we have two weak students as one answer.
- It is also possible to differentiate students, such as a weak answer for students with good grades, and assigning a strong answer to students who are not good at it.
- If you want to experience a different answer, you can change the answer for each date.
- The activity ended in 50 minutes.

At that time, I witnessed the smiles and excitement of the students seeking matching. After the class, I asked several students about their activities. Every student said, “It was more fun than the usual questions” and “I want to do it again.”In addition, some students said, “I can understand dilution and power more.”And today’s favorite words were “I can’t let go of the struggle! I made a perfect cushioning material and resisted!”

## Student acid/base organizer

### How do you calculate the pH?

PH process | Type of acid | Base type |
---|---|---|

Solution of. | Strong acid | Strong base |

A solution. | Mild acidity | Weak bass |

With securitization. | Remaining strong acid | A strong bass remained |

With securitization. | Weakly acidic remaining | Weak bass remains |

With securitization. | 1 basic salt remaining | One acidic salt remains |

With securitization. | 1 neutral salt remaining |

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