Chemistry PLEASE GET OUT YOUR PHET ONLINE SIMULATOR HOMEWORK HW SHEET HAVE ONE PERSON IN YOUR GROUP TURN IN “BOYLE’S LAB” ON GOOGLE CLASSROOM Make sure you include everyone’s name! ASK YOUR PARTNER… “WOULD YOU RATHER… TAKE AP CHEMISTRY NEXT YEAR, OR A DIFFERENT SCIENCE CLASS?”

Warm-up- Boyle’s Law should be turned in by now!  What causes pressure? How did volume effect pressure?  What does this look like on a macroscopic level?  What does this look like on the particle level?  What does this look like on a mathematical level?

Learning Targets

Pressure vs. Volume – Boyle’s Law: Looking for Constants(k) Volume (in mL) Pressur e ( in kPa) P/VP∙V = k

Explaining the Graph

Boyle’s Law  P/V or P ∙ V?  If pressure increases, what happens to volume?  Mathematical Relationship?  Which gas law variables are being held constant?  How did you keep them constant in the lab?  P ∙ V  If pressure increases, volume decreases  Indirect Relationship (variables change in different direction)  Same Temp + Same Moles  The air in the syringe had the same # of moles (they were just squished more) and it was at the same temp

Scientific Explanations  Claim  A simple statement that clearly identifies the outcome (often the relationship between variables)  Evidence  Data that is appropriate and sufficient to support the claim  Reasoning  Justification that links the claim and evidence  Shows why by using scientific concepts (like definitions, models, theories, or laws) and background knowledge  Often refers to resources such as lab books, articles, textbooks, and/or the Internet

On a blank piece of paper… Given a closed system in which the temperature stays the same, explain the relationship between pressure and volume of a gas. (Your claim should include a mathematical equation that demonstrates this relationship).

Practice with Boyle’s Law

Boyle’s Law—Think Questions  If in the first scenario you had your pressure/volume equaled that constant P 1 V 1 =K  And in the second scenario you had your pressure/volume equal to that same constant P 2 V 2 = K  Couldn’t we simplify this? P 1 V 1 =K=P 2 V 2 P 1 V 1 =P 2 V 2

Calculations: Solving for Unknowns Since PV = constant (k), then… P 1 V 1 = k = P 2 V 2 P 1 V 1 = P 2 V 2 Sample: a balloon is inflated to a volume of 3.5 L at 1.25 atm. What is the volume of the balloon if it rises up to 0.50 atm? P 1 = 1.25 atm V 1 = 3.5 L P 2 = 0.50 atm V 2 = ??? (1.25 ∙ 3.5) = (0.50 ∙ V 2 ) = 0.50 V 2 V 2 = 8.75 L sig figs  8.8 L

Consider this scenario… A balloon with a set amount of air has a volume of 6 L at sea level (1 atm). The balloon is brought underwater where the pressure is now 3 atm.  Will the balloon’s volume decrease or increase? Explain why this makes sense.  What will be the new volume of the balloon?

Ans: Consider this scenario… A balloon with a set amount of air has a volume of 6 L at sea level (1 atm). The balloon is brought underwater where the pressure is now 3 atm.  Will the balloon’s volume decrease or increase? Explain why this makes sense. Pressure increased, therefore volume would decrease  What will be the new volume of the balloon? P 1 V 1 = P 2 V 2  1 atm ∙ 6 L = 3 atm ∙ V 2 V 2 = 2 L

HW Review  Compare responses to the Gas Properties Simulator W.S  I will be calling popsicle sticks for answers and examples!

Gas Laws! Pressure TemperatureVolume Last Time!Today/ Next Class Next (& next) Time!!

Kelvin vs. Celsius  To Avoid Negative Numbers: Absolute Temperature is measured in Kelvin.  0 K = -273°C  K = °C  °C = K °C 0°C25°C 50°C 0 K 273 K298 K 323 K 25 K 50 K

Gay-Lussac Lab In the next 5 minutes…  Please have (at least) two computer’s per lab station  Have one person log on to Google Classroom and download “Gay-Lussac’s Lab” and share with the rest of the group.  Read the procedure (on google docs or paper)  Fill up your beaker with tap water to ~350 mL

Gay Lussac’s Lab (P vs. T) 1. Use the Pressure + Temperature sensors to determine the relationship between P and T 2. Get the following data. (do half, and have a neighbor lab group do half and swap data) 3. Use this data, come up with a formula for the relationship Pressure (kPa) Temp ( ₒ C) Temp (K= C + 273) (P / T )(PT) ~0 ~20 ~50 ~85

Are you already done?  Double check and swap data on the Gay-Lussac Lab  Do you have:  Data table filled in, with units and sig figs?  2 Graphs of temp vs. volume (in C, in K)?  Answers to processing questions 1-4 in complete sentences?  Shared the Google Doc all your lab groups? Homework:  Finish GL Lab  #1-6 of BGC W.S

Pressure vs. Temperature – Gay Lussac’s Law Pressure (kPa) Temperat ure (K) Constant k (P / T ) (PT)

Absolute Zero on a Celsius Graph

Temperature & Absolute Zero  Heat something = Add Energy to Atoms  Atoms move ____________!  Cool something = Removing Energy to atoms  Atoms move _____________!  You can keep adding Energy, but there is only so much you can take away!!! Cold  Limit to how “ Cold ” something can be. ABSOLUTE ZERO  -273°C or 0 K FASTER SLOWER

Exit Task Draw a simple line graph showing the relationship between pressure and volume  Label the axes Homework: Finish GL Law Lab on Google Docs

Exit Task A 2.0 liter tank of oxygen gas is at a pressure of 3.5 atm. What volume of oxygen will be available if the oxygen is used at a pressure of 752 mm Hg? Draw and Explain How I did this?

ANS on ETD 51A A. A 2.0 liter tank of oxygen gas is at a pressure of 3.5 atm. What volume of oxygen will be available if the oxygen is used at a pressure of 752 mm Hg?