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Biology (2nd Period) / Chemistry (4th Period) / Forensics (5th Period)

"Good morning, everyone. First thing we have today is a quiz. Please don't ~~forget to tell me how you did~~ forget to turn it in."

Once the quiz is complete, Ms. Sidle lectures extensively on DNA.

"Good morning."

The concentration of a solution is the "strength" of a solution. A solution typically refers to the dissolving of some solid substance in a liquid, such as dissolving salt in water. It is also often necessary to figure out how much water to add to a solution to change it to a specific concentration.

The concentration of a solution is typically given in molarity. Molarity is defined as the number of moles of solute (what is actually dissolved in the solution) divided by the liters of solution (the total volume of what is dissolved and what it has been dissolved in).

Molarity is probably the most commonly used term because measuring a volume of liquid is a fairly easy thing to do.

Example: If 5.00 grams of NaOH are dissolved in 5000 mL of water, what is the molarity of the solution?
One of our first steps is to convert the amount of NaOH given in grams into moles:

Now we simply use the definition of molarity: moles/liters to get the answer

So the molarity (M) of the solution is 0.025 mol/L.

Molality is another common measurement of concentration. Molality is defined as moles of solute divided by kilograms of solvent (the substance in which it is dissolved, like water).

Molality is sometimes used in place of molarity at extreme temperatures because the volume can contract or expand.

Example: If the molality of a solution of C2H5OH dissolved in water is 1.5 and the weight of the water is 11.7 kg, figure out how much C2H5OH must have been added in grams to the solution?
Our first step is to substitute what we know into the equation. Then we try to solve for what we don't know: moles of solute. Once we know the moles of solute we can look at the periodic table and figure out the conversion from moles to grams.

It is possible to convert between molarity and molality. The only information needed is density.

Example: If the molarity of a solution is 0.30 M, calculate the molality of the solution knowing that the density is 3.25 g/mL.
To do this problem we can assume one (1) liter of solution to make the numbers easier. We need to get from the molarity units of mols/Liter to the molality units of mols/kg. We work the problem as follows, remembering that there are 1000 mL in a Liter and 1000 grams in a kg. This conversion will only be accurate at small molarities and molalities.

It is also possible to calculate colligative properties, such as boiling point depression, using molality. The equation for temperature depression or expansion is

Change in T= K * m

Where: T is temperature depression (for freezing point) or temperature expansion (for boiling point) (°C)
K is the freezing point constant (kg °C/moles)
m is molality in moles/kg

Example: If the freezing point of the salt water put on roads is -5.2 C, what is the molality of the solution? (The Kf for water is 1.86 C/m.)
This is a simple problem where we just plug in numbers into the equation. One piece of information we do have to know is that water usually freezes at 00C.

T=K * m
T/K= m
m = 5.2/1.86
m = 2.8 mols/kg

In forensics, they continue discussing elements of arsonists.

"I'm dismissing you guys early today. I want you to find a newspaper article relating to arson by Friday and summarize it."

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"Come in!" she calls, peeling the lid off of her bowl.

"Hi, sweetheart." Yes, she's addressing both of them.

Honey yaps before Grissom can say anything, and he turns to give the dog a funny, sour look before closing the door behind him, so he can let the puppy off her leash.

He then walks over and kisses Sara on the cheek as Honey whines, scampering after his feet before moving her attentions directly to her mommy, omgcute.

"Hi."

"Hi," she says back, returning the kiss before picking up Honey.

"Has this little rascal been causing trouble again?"

"No, she's actually been pretty well-behaved today," he says mildly.

"She used the newspaper when she was by herself for almost an hour during my second period class, and we went for a walk before coming to visit you, and she didn't try to attack any innocent wildlife. All together, a successful outing," he says with a little bit of pride, and not just because he legitimately exercised.

"How's your day been?" he asks as he heads to wash his hands before eating.

"Quiet so far. I don't think anyone in my biology class is getting out of there with anything higher than a B." She shrugs, freeing one hand to spear a piece of lettuce. "Not much I can do if they aren't doing the work."

Honey decides to investigate this strange green stuff her mommy is eating. She nips a piece when Sara goes for another forkful.

If dogs could look disgusted, Honey most assuredly does. Which cracks Sara up.

Grissom laughs as well, sitting down and unwrapping his sandwich.

"Well, that confirms it. She obviously gets her intelligence from me."

"That means you cheated on me with a breeding bitch," she says dryly, waiting until he'd begun swallowing his drink.

And... his drink comes out of his nose a little bit as he jokes and turns red.

"Sara..." he admonishes, still composing himself.

"I'm going to refrain from ending up in a pun battle with you over this, because... I'm eating. And even I occasionally can be," he waves a hand around, "grossed out."

She hands him napkins without comment, smirking.

Honey cocks her head to the side, wriggling in Sara's lap.

"Oh, I forgot to tell you last night ~~because, in my continued un-breaking of you, let's say they had too much awesome sex all night to discuss anything properly~~," he says, the red not fading away from his cheeks as quickly as it normally would, "but Lorelai and Luke are having a boy. She just went for her sonogram. So if you have any name suggestions, she could use them."

He takes a small bite of his sandwich, smiling at his girls being so adorable, and chews quickly, adding -

"Before she names the baby Juan Valdez."

"What's wrong with that name? It sounds nice to me," she says innocently. ~~Hot sexx0rs makes everything better omg~~

"Seriously, I'll talk to Lorelai and give her my congratulations."

Her biological clock isn't ticking. Shut it.

"I'm sure she'd like that," he says with a smile, but then puts on a mock frown.

"But seriously, don't encourage her, because I think she may not be kidding when it comes to naming the poor, innocent child Folger Maxwell."

She winces. "Okay, that is a name that would doom that kid to immediate ass-kickings upon entering school. Good point."

He's still smiling, and laughs a little as Honey sits upright in Sara's lap and starts straining over to try and sniff Grissom's sandwich from several feet away.

"It's almost as bad as Gilbert."

"Gilbert's a name you can grow into--Honey, no!" She catches her by the scruff before she can fully leap off Sara's lap.

"I swear I fed her before we left. There's no way she could even fit any more food in that stomach of hers."

He pulls his food closer to himself.

"And it only really matters when you're a child what your name is, unless you're cursed with something truly horrible."

"Brat," Sara tells her affectionately. Honey turns wounded brown eyes back up at her before turning to groom herself.

"True enough, I suppose. I happen to like your name though."

"Well, thank you, but alas, I have a signed contract with myself, in an old composition notebook from the third grade that's probably sitting in my mother's attic, that states that I would never advocate the naming of any other person or thing Gilbert. I'm afraid it still stands," he says with a slight twinkle in his eye.

"And you have a beautiful name, so due to experience, my opinion has more weight than yours."

"The only thing I dislike about my name is people insisting on adding the h to the end. Irritates the hell out of me."

"The difference between Standard Hebrew and Tiberian Hebrew," he nods.

"Although, originally she was known as Sarai or Saray, my princess, and only later was she known as Sara, princess to all."

"Look unto Abraham your father, and unto Sara that bare you."

"Only you could make Biblical references seem beautiful."

She glances at the time. "I'll finish my salad and take her on another walk before class."

He nods, beginning to clean up his own mess.

"Do you want to take her for the afternoon? I can manage, either is fine."

"I just have Forensics and office hours left. I'll take her."

She's amused--it sounds almost like a custody battle.

"Okay," he agrees quickly, taking Honey's things out of his bag and leaving them for Sara.

Because he did so bring a few of her toys with him, just in case.

He puts his things back together, and walks over to Sara, giving Honey a soft scratch under her chin as she is still curled up in Sara's lap.

"I had low-fat mayonnaise on my sandwich today," he says with a little bit of a smirk, leaning over. "Does that earn me a kiss before I go?"

Honey's tail thumps against Sara's lap. She lurves her daddy.

"It does, if only so you're not in a bad mood later with your students." Her own little smirk and she gives him a quick kiss. "Have a good afternoon, babe."

He steals another quick peck, and a giant smile spreads across his face.

"You too," he says, moving to sign the affectionate nickname he uses for her.

He signs his love as well, and heads out for class prep.

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Biology (2nd Period) / Chemistry (4th Period) / Forensics (5th Period)

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