Presentation on theme: "Activity 48 Follow-up Discuss in your groups the difference in results for each neutralization between pairs. Lack of consistency in drop size Error in."— Presentation transcript:
1Activity 48 Follow-upDiscuss in your groups the difference in results for each neutralization between pairs.Lack of consistency in drop sizeError in countingDifficultly deciding which number of drops gave a neutral solution if you overshot the neutral colorContamination of equipment
3What happens as you add an acid to a basic solution or add a base to an acidic solution? first becomes closer to neutraleventually when you add too much, you overshoot the neutral point
42. Which solution seems more powerful in this investigation, the acidic or the basic? Explain your answer.acid seems more powerfultakes more drops of base than acid to produce a neutral solution
5Based on what you know so far, which do you think is a better way of neutralizing an acid: distilling it with water, or adding a base?dilution is better because you only need waterwhen you add the base you are creating another productneutralization is better, because dilution requires a huge volume of waterdilution because the change is more gradual and there is less chance to overshoot neutral.
6Given two solutions, how might you determine: Whether these solutions are acidic or basic?test them with universal indicator solution or pH paperblue = base, red = acidWhich is more acidic or basic?mix equal amounts together and test with universal indicatorthe more powerful solution will show up with the indicator
7Background Information Both the HCl and the KOH are 1% solutions by mass.There are different numbers of reacting particles in the two solutions of the same volume.The more powerful the solution, the more capable it is of changing the pH of the mixed solution.
8Activity 48 Major Concepts When they react in the appropriate ratio, an acidic solution and a basic solution will neutralize each other.Substances react chemically with other substances to form new substances. For example, an acid reacts with a base to form a neutral product.A change in pH is a chemical change.
9Title: A Model for Acid-Base Neutralization Activity 49Title: A Model for Acid-Base NeutralizationRead pg. C-94Problem: How can acid-base neutralization be described in a model?Hypothesis/Initial Thoughts:
10The model you will be using today: The 3 red As represent three acid particles (in one drop of acidic solution).The 2 blue Bs represent two base particles (in one drop of basic solution).These numbers represent the ratio of acid and base particles, not the actual number, which is many billions in a drop.
11The whole class represents the solution—that is, all the drops that collectively make up a sample of solution.For procedure step 1 your challenge is to determine if the solution (the class) is neutral.---Suggestion: form several small neutral groups (groups w/ equal number of acid/base particles)Begin
12Raise your hand if you are not part of a neutral solution. Is the overall solution neutral?What chemical, acidic or basic, would make this a neutral solution?How many drops of it must be added to make this a neutral solution?
13How would we prepare cards to represent a neutralization in which a drop of basic solution and a drop of acidic solution have equal numbers of acid and base particles?Did the acid and base solutions in the neutralization we performed earlier have equal concentrations of particles per drop?AB
14Data/Observation: Procedure steps 3 & 4: Read the instructions in your book and draw the indicated diagrams in your lab notebook. Label each drawing according to the step number (3a, 3b, 4a, and 4b).
17Analysis QuestionsFor the example in Procedure Step 1, how many drops of base would be needed to neutralize:2 drops of acid? Explain, or draw to show your reasoning.3 drops of base because the acid droplethas 3 particles in it and the base droplethas 2.
1810 drops of acid? 4 liters of acid? 15 drops The acid droplet has 3 particles in it and the base droplet has 24 liters of acid?6 liters of baseThe acid droplet has 3 particles in it and the base droplet has 2 (even though the parts are in liters)10 x 3 = 30 and 15 x 2 = 304 x 3 = 12 and 6 x 2 = 12
19Given that the HCl and KOH solutions used in Activity 48 were 1% (each of them contains one gram of solute per 100 grams of solution), how could you explain that the ratio of particles per drop of the neutral solution is not 1:1?HCl has more acid particles than KOH has base particles per gramgrams of each of the solutes don’t behave the sameIt takes more KOH to neutralize HCl