Title: Laws of Thermodynamics Open your journal to the next blank page (it should be facing page 27) and set up as below: Page: 28 Date: 1-18-17 Title: Laws of Thermodynamics Essential Question: What are the laws of thermodynamics? No, it does not have to be Cornell notes.

First, let’s review your foldable… You do NOT have to write anything from this section unless you want to add information to yesterday’s notes.

21.1 Temperature There is more internal (total) energy in a bucket of warm water than in the small cup of hot water, because there are more total water molecules in the bucket. The water molecules in the cup of hot water are moving faster, however, so the average kinetic energy (TEMPERATURE) is higher.

If you touch ice, energy passes from your hand into the colder ice. 21.2 Heat If you touch a hot stove, energy enters your hand from the stove because the stove is warmer than your hand. If you touch ice, energy passes from your hand into the colder ice. Humans cannot actually feel TEMPERATURE…what you feel is HEAT TRANSFER.

21.2 Heat There is more total internal energy in a large bowl of warm water than in a red-hot thumbtack. However, if the tack is immersed in the water heat flows from the hot tack to the cooler water. Heat flows according to temperature – always from hot (higher temperature) to cold (lower temperature). Heat never flows on its own from a cooler substance into a hotter substance. + = Final temperature somewhere between 60°C and 90°C 90°C 60°C

21.2 Heat Just as water will not flow uphill by itself, regardless of the relative amounts of water in the reservoirs, heat will not flow from a cooler substance into a hotter substance by itself.

21.6 Specific Heat Capacity You can touch the aluminum pan of the frozen dinner soon after it has been taken from the hot oven, but you’ll burn your fingers if you touch the food it contains. This is because most foods have a higher specific heat than aluminum. That is, they can hold and retain more heat for longer periods of time.

21.6 Specific Heat Capacity Different substances have different capacities for storing internal energy, or heat. A pot of water on a stove might require 15 minutes to be heated from room temperature to its boiling temperature. An equal mass of iron on the same flame would rise through the same temperature range in only about 2 minutes. For silver, the time would be less than a minute.

15 g of gold at 80°C cools to 20°C. If the specific heat of gold is 0 15 g of gold at 80°C cools to 20°C. If the specific heat of gold is 0.129 J/g°C, how much heat is given off?

Now, today’s notes…

Laws of Thermodynamics 0th Law: Objects at thermal equilibrium are at the same temperature. So…if TA = TB and TB = TC then TA = TC 1st Law: The internal energy of a system can be increased by adding heat or doing work. ∆U = Qheat + Won system  positive ∆T 2nd Law: Heat will travel from hot to cold on its own, and NEVER from cold to hot; entropy increases. ENTROPY: the amount of disorder in a system. More organized = less entropy. Entropy naturally increases.

Before we move on, let’s set up for tomorrow’s lab.

Let’s see a more complicated problem…

A 75 g block of copper at 140°C is dropped into a bucket containing 250 g of water at 30°C.