Title: The Chemistry of Acids and Bases Read pg. C-98 Problem: What chemical reaction takes place when you neutralize an acid or base? Hypothesis/Initial Thoughts: Activity 50

Do you think that the ability of an acid and a base to neutralize each other is a chemical or a physical property? A chemical property requires interaction of chemicals which produces new substances with different properties There is pH change You may infer this provides evidence that a new substance is produced

Electrical conductivity is the ability of a solution to conduct electrical current In a solution, the concentration of free ions determines how well the liquid conducts electricity Create a table and record the results of the conductivity of 7 different solutions Make a prediction before the demo begins Electrical Conductivity Demo

SolutionpHPredictionConductive? 1. Distilled Water 2. Tap Water 3. Distilled water + sugar 4. Distilled water + table salt (NaCl) 5. Acid (HCl) 6. Base (KOH) 7. Neutralization acid-base Data/Observation: Table 1: Testing Electrical Conductivity of Solutions 7 Around No Yes No Yes

Results Table salt, sodium chloride (NaCl) conducts electricity when dissolved, but has a balanced, neutral pH This is the same for the neutralized acid- and-base solution Using pH and conductivity, you cannot distinguish the difference between neutralized solutions and saltwater

Do you have any ideas about why the HCl plus KOH still conduct electricity, even though it is neutral? The product of neutralization is salt HCl provides chloride ions and KOH provides potassium ions K (potassium) is in the same family as Na (sodium)

How could we test the idea that there is salt in the mixture of HCl and KOH? Evaporate the water out of the mixture to see if a solid resembling salt remains We will do this and look at it next class period

Before you begin reading: A three-level reading guide will be the second part of your data/observation for this activity Review the statements in the reading guide before you begin As you finish each section or after you finish reading, check off the statements you agree with