Spontaneous reactions, Entropy and Gibb

Hey everyone~

Sorry about not posting yesterday :(

But otherwise, i'll be explaining yesterday and today's day in Chemistry.

On Tuesday, Mr. Liebs explained Spontaneous Reactions and Entropy (\DeltaS).

Although it's all in our notes, I'll just summarize the basic points:

Spontaneous Reactions: a process that takes place on their own, without outside forces

Some examples are...

- ice cubes melting when added to water at room temperature

- mixing hydrogen and oxygen to form water when a spark is applied

- iron rusting because it's exposed to moist air

(These reactions will happen no matter what, in these given conditions)

Entropy

Nature tends to move spontaneously from an orderly state to a random/disorderly state (a process known as the randomness factor).

And connecting with this "randomness" idea is entropy: an increase in disorder or randomness shown as \Delta S

Entropy is highest in this order of states: solid <>

When using entropy in reactions, the equation is \Delta S =\Sigma \Delta S (products) - \Sigma \Delta S (reactions)

Note: when calculating entropy, the coefficients should be a part of the equation (multiplied to each term, accordingly)

On Wednesday, Mr. Liebs continued on with another explanation of notes on Gibb's Free Energy: the energy in the system that is available to do useful work.

A reaction can do useful work if it's spontaneous; and whether or not it's spontaneous can be found through this equation: \Delta G = \Delta H - T \Delta S (as long as temperature and pressure are constant)

Note: In the latter equation, 'T' or temperature has to be in Kelvin)

We will know if the reaction is spontaneous by knowing if \Delta G is a positive or negative value.

If \Delta G is negative, the equation is spontaneous

If \Delta G is positive, the reverse equation is spontaneous

[Look at Table 17.2 in the textbook for more information]

Homework:

Tuesday's homework: Hess' Law Lab

Hess' Law Worksheet

Wednesday's homework: Gibb's Free Energy Worksheet

WebAssign

AND THURSDAY'S TEST WILL BE MOVED TO FRIDAY BECAUSE OF THE SNOW DAY!

So have a fun snow day tomorrow! :)

And the next scribe will be....... Paige H.

Specific Heat of Metal Lab

Hey everyone~

So we started class by looking over two of the problems from the worksheet: 8 and 9.

Mr. Liebs explained that problem 8 can be done by setting the amount of energy for copper equal to the amount of energy for water. Knowing that, you can use the law of thermodynamics to solve for the mass of water:

q Copper = q Water

(110)(0.2)(57.5)=(4.18)(2.6)(m)

m= ______

In problem 9, you find the specific heat capacity using the law of thermodynamics again. Once you have calculated the specific heat capacity, you convert moles (because the question asks for you to solve for the molar heat capacity of mercury). You can easily convert it by knowing that the unit for specific heat capacity is J/g C and that the grams of mercury is over 1 mole:

585J=(125.6g)(53.5-20.0) c

c= 0.14 J/gC

0.14J/gC x 200.51g/1 mole = ______

Check the answers on moodle!

After the worksheet, we moved onto our lab: The Specific Heat of Metals Lab

We were assigned to work with our partners and follow the procedures from the lab, which was basically just to...

1. collect a dry test tube and measure the mass

2. mass the test tube with a given metal

http://www.flickr.com/photos/hc1011/5324135903/

3. heat up a beaker full of water until it is boiling

4. Put the test tube inside the boiling water for 10 minutes

http://www.flickr.com/photos/hc1011/5324740964/

5. Fill a calorimeter with about 50 mL of water and measure its volume

6. Then measure the initial temperature

http://www.flickr.com/photos/hc1011/5324740468/

7. After the 10 minutes are up, place the test tube inside the calorimeter and measure its final temperature.

http://www.flickr.com/photos/hc1011/5324136951/

After recording each of these measurements, complete the rest of the lab for homework.

The next scribe is... Paige H.

Periodic Table of Aliens

Hey everyone!

Today, we started a “Periodic Table of Aliens” with our partners.

Basically, we arranged Aliens in an 8 x 5 chart by organizing the groups (columns) and periods (rows) with similar features.

Since there is only one way for the chart to work, you should have ended up with something like this:

(If you didn't, you probably want to fix that by tomorrow...)

Here's how it was done:

The Periods (rows)~

The periods were simply grouped together by the shape of their bodies: The first row is triangle, second row is circle, third row is rectangle, fourth row is oval, and the fifth row is upside down triangle)

And it would specifically be in that order because of the number of stripes/squiggly lines/cones/lines/etc. on their bodies: all the triangular-bodied aliens, which is the first row, had only one (let's say, cone) on their head.

The Groups (columns)~

Organizing the groups were pretty simple once you've figured out that there were similar features for each column.

1. Number of cones on their head

2. Number of sticks on their head

3. Start with short legs, then start getting longer

4. Number of stripes across their body

5. Number of stripes on top of their head. (Side Note: You should notice that one seems to be missing in the last row; the directions state that there are two missing from the whole chart, so it's okay)

6. Number of squiggles on their head

7. Number of rectangles on their head

8. Number of legs (starting with 2 legs and one is missing from this column too)

The aliens are specifically charted in this order by the number of fingers they're holding up. (If they were holding 1 finger, they'd be in the first column; 3 fingers, the third column, etc.)

After you get this chart done, there are other questions in the packet, so make sure to get that done. In addition to this Period Table of Aliens, you also have the Oleic Acid Lab due tomorrow and a WebAssign coming up on Oct. 8 (Friday).

And that's all for today!

The next scribe is.... Faith S.