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How is freezing point affected by different ratios of solute to solvent?

How is freezing point affected by different ratios of solute to solvent?. Experiment 1. Do Now:. Obtain a pair of goggles from the front lab table. Put on your apron (or help your neighbor) Sit in your regular seats for now. Get your shoes on and hair tied back.

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How is freezing point affected by different ratios of solute to solvent?

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  1. How is freezing point affected by different ratios of solute to solvent? Experiment 1

  2. Do Now: • Obtain a pair of goggles from the front lab table. • Put on your apron (or help your neighbor) • Sit in your regular seats for now. • Get your shoes on and hair tied back

  3. Collect Lab Safety Contracts and HW

  4. Goals • Main Goals: • Answer the question on the first slide • Calculate the molar mass of benzoic acid (we’re going to do this first…) • Secondary Goals • Use Excel to get a line of best fit and correlation constant • Learn the components of a lab write-up

  5. Safety • Hot glassware looks the same as cold glassware! • Goggles, gloves and apron at all times • Never point a test tube at a neighbor • Don’t stick your face in the test tube (don’t inhale vapors)

  6. Materials Safety Data Sheets • https://www.google.com/search?q=Lauric+Acid+MSDS&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a • https://www.google.com/search?q=Lauric+Acid+MSDS&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#fp=e16816eed2dd2a1e&q=Benzoic+Acid+MSDS&rls=org.mozilla:en-US%3Aofficial

  7. Helpful Hints • Make detailed observations about what “freezing” looks like! It goes quickly, so pay attention. • Use 2.0 grams of benzoic acid or less for your mixture. • Be efficient! Get a game plan for who is going to do what BEFORE you start. • Replace the water bath between trials (it gets warm)

  8. Class Data (on board)

  9. Calculation Framework for benzoic acid molar mass • What’s your goal? (Find the molecular weight of benzoic acid) • Work Backwards – What’s the formula for molecular weight? (Units) • What data did we collect? • Take it from there To the lab notebooks!

  10. Excel to graph Ratio vs. Freezing Point • Crash Course • How is freezing point affected by different ratios of solute to solvent? • Clearly see a trend • Can we go deeper than that? (Hooke’s Law spring lab F=kx)

  11. Accuracy vs. Precision • Accuracy – How close are we to actual value? • Precision – How consistent are our data points?

  12. Error Analysis • You accidentally stop stirring your impure sample and your solution “freezes” too soon. How will this error affect ΔT? Molar mass of benzoic acid? • You accidentally stop stirring your pure sample and your solution “freezes” too soon. How will this error affect ΔT? Molar mass of benzoic acid? • You are clumsy and you accidentally spill some benzoic acid after massing it, but before getting it into the test tube. How will this affect ΔT? The calculated molar mass of benzoic acid? • Your test tube had some dirt in it before starting your pure sample. How would this affect your freezing point? ΔT? The calculated molar mass of benzoic acid? • Instead of using a digital thermometer (reading to the hundreths place), we used a thermometer that reads to the ones place. How would this affect your data?

  13. Conclusion • Paragraph 1 – What were the purposes of this lab? What new equipment or techniques did we use? (melt to freeze) • Paragraph 2 – Claims and evidence (answer the questions) • Paragraph 3 – Answer error analysis questions. • Paragraph 4 - Nanoscale Reflection (what was happening at the particulate level to explain what happened) • Paragraph 5 - Real-life Reflection (from reading or research) How have your ideas changed throughout the experimental process?

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