Ka, Kb Ka, Kb Comparing the pH of two acids Comparing the pH of two acids 1. Predict the pH of HCl and HF (below) 2. Calibrate a pH meter 3. Measure the pH of HCl(aq) and HF(aq) 4. Complete the chart below Actual [H + ] pH measured Predicted [H + ] Predicted pH Lower / weaker Higher / stronger Conductivity (demo) Net ionic equation [ ] in mol/L (on label) HF (aq) HCl (aq) Questions Questions Read15.3. (pg. 607+) 1. Based on your results, which acid ionizes (forms ions) to a greater degree? 2. Which two measurements taken in the lab support your answer to 1? 3. What is another name for Ka? 4. Solve PE 5, 6 5. Write the Ka equation for HCl (aq) and HF (aq) from today’s lab 6. Solve for PE 8, 9 (use this equilibrium for butyric acid: HBu ↔ H + + Bu – ) 7. For HF(aq) set up a RICE chart, then solve for Ka. How does your value for Ka compare to the accepted value (pg. 608)? 8. Try PE 10 (follow example 15.7 on pg. 610) Ka summary Ka summary • Ka follows the pattern of other “K” equations
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