Answers

Station #1 – All Charged Up Explanation: Water is a polar molecule oxygen end of the molecule slightly negatively charged – thus attracted to +vely charged glass rod hydrogen end of the molecule is slightly positively charged – thus attracted to –vely charged ebonite rod

Station #2 – Defying Gravity Explanation: Water is a polar molecule and clings to the paper towel (adhesion) Also, water clings to other water molecules due to H- bonding (cohesion) This draws the water upwards and faster than the oil which is non-polar

Trees, as an example, move water by capillary action which is the result of both cohesion and adhesion.

Station # 3 – Drop in Currency Explanation: Water molecules are clinging to themselves (cohesion), allowing the drops of water to pile on top of each other without spillage. The effect is high surface tension Both H2SO4 and alcohol have lower surface tension

Station #4 – Pepper Magic Explanation: Pepper floating on water means there is a high surface tension before the detergent was added Detergent reduces the surface tension by interfering with the H-bonding between water molecules

The reason many ultra-light insects can walk on water is due to the surface tension created by cohesive water molecules. If detergent gets introduces it will get in between the water molecules and prevent the insect from landing on the water and staying

Question #1 Water possesses a high specific heat of vaporization. How is that different from specific heat capacity? Specific heat of vaporization is the amount of energy required for water to change into a gas, while… …specific heat capacity involves the amount of energy required to heat 1g of substance 1°C.

Question #2 Explain the importance of water having a high specific heat capacity. Give an example. H-bonding allows water to absorb or lose high amounts of heat before its temp. changes. Example: Maintaining constant body temperature

Question #3 Why is water considered the universal solvent? Water can dissolve both polar substances and ionic substances Dissolves more substances than any other substance

Question #4 How is polarity determined, and what is the difference between a polar and a non-polar molecule? Polarity is determined by bond polarity AND molecular shape. Create a Lewis Dot Structure for the molecule and then use the VESPR theory to determine the shape.