All we know is that it is the ration of the distance travelled by the pigment and the distance travelled by the solvent, but why do we need to know it? What is the point of calculating it? What does it tell us?
Answer: There is a very good reason for calculating the Rf factor for each spot on your TLC plate. It can help with identification of an unknown material. A substance will have a characteristic Rf value in a specific solvent system. If you have several different solvent systems then you have good data for identifying an unknown (or at least eliminating a lot of substances that it is not). Another good reason is ease in data collection and recording. Writing down the Rf and solvent system in your lab notebook is easy whereas drawing or preserving a TLC plate is not. You can also publish Rf and solvent data in a scientific paper so another scientist can monitor his (or her) reaction if they are trying to repeat the experiment.
Category: Chemistry; 2010-03-09 19:48:08
2. When you order a fish online, how is it shipped?
I found out that you can order fish online that aren't available in local stores. I can't grasp the concept of how they are shipped though? Someone told me they are shipped in bags, but if so, how did they travel a couple states in a bag when you're not even supposed to keep them in one for more than 45 minutes? Does UPS deliver them to your door, or are fish only shipped as eggs?
Answer: There are two questions here, How are the fish packed?, and How are the fish shipped? Both vary according to the seller, and you should ask any prospective seller how he or she ships the fish. But in general: The fish are packed in plastic bags containing water and air or pure oxygen. Most shipper use pure oxygen to fill the bags after putting the fish in a bag about 1/3 full of water. Some also use "hypno" drugs to calm the fish, and/or small amounts of chemicals (such as hydrogen peroxide) that gradually release more oxygen. These bags are then packed into styrofoam boxes that both insulate and pad the bags of fish. The styro box should be surrounded by a strong corrugated carboard box. During very cold or very hot weather, many shippers also put heat packs or ice packs into the box (not in the bags themselves). An alternative is to use the newer "breathable bags." These bags are made of a gas-permeable plastic bag, so that it is not necessary to put air in the bag, because oxygen and carbon dioxide can pass through the wall of the bag so the fish won't suffocate. However, it is therefore necessary to pack the breathable bags in such a way that air will get to all of them. You can't just stick them all together in the box. Also, breathable bags have had some problems with leakage, from what I hear. My experience is that they tend to slowly ooze water, which can be a problem. Different sellers use different shippers, but in general they are shipped by air, using the fastest service available, so that the package will arrive in less than 24 hours. This might be the air freight service of a passenger airline, Express Mail, FedEx next day delivery, UPS overnight, etc. If all goes well, the fish will arrive in good shape. Many sellers guarantee that they will arrive alive. If the fish are packed as described above, they can usually stay in a shipping bag for up to three days without serious harm. But they shouldn't have to. One more thing: The fish shipped as eggs are most often the annual killifishes. These fish lay eggs in ponds that are drying up. The eggs stay dormant until the rainy season, when they finish developing and hatch. This dormancy is called a "diapause." During the dormant period, they eggs can be sent through the regular mail, packed in damp peat moss, and usually arrive alive.
Category: Fish; 2010-03-09 18:18:10
3. Is my rewards in Heaven gonna be much better?
Is my rewards in Heaven gonna be much better than constantly winning millions of $ from the lottery? Also is my rewards in Heaven gonna be much better than constantly getting to travel all around the world? Is Heaven gonna be far bigger than Earth?
Answer: In both cases, riches and travel, you have the problem of maybe losing your health, or losing a loved one, etc, etc. As a human you will have many things that can ruin your day. That is what makes Heaven different then anything we can have here. It is at least one of the problems of earth.
Category: Religion & Spirituality; 2010-03-09 17:54:36
4. i plan on traveling to quebec/montreal next week for spring break, what should i know?
do i need to convert to canadian money? i plan on going to alot of bars/clubs/casinos, do i need to convert my money? is there any place i should check out? or stay away?
Answer: Yep, you'll need to convert your cash to Canadian Dollars. It's better to get the cash from a currency exchanger before you come, because if you have to withdraw cash or use credit cards after you arrive, the exchange fees can be outrageous! The only limitation is that you can't carry more than $10,000 cash over the Canadian border without making special arrangements. Keep in mind that the legal drinking age in Quebec is 18. Some exclusive nightclubs, however, will turn away the younger crowds (i.e. under 21, 23, or 25). As long as you stick to the more touristy areas, you shouldn't have any language difficulties, but if you venture outside the traditional tourist areas, you might want to learn some french. Even if you speak almost no French, a simple Bonjour (hello), S'il-Vous-Plait (Please), Merci (thank-you), or Au Revoir (Goodbye) will be appreciated. The best casino is the Casino de Montréal. Very trendy place. Save some money for that.
Category: Montreal; 2010-03-09 15:36:43
5. A clock and the distance it will travel?
A clock has a minute hand with a length of 5.75 inches. How far does the tip of the minute hand travel in 15 minutes? Please help me!
Answer: In 1 hour, the minute hand conpletes one revolution of the clockface, meaning in 1 hour, it travels the circumference of a circle with radius 5.75 inches. The circumference of a circle with radius r = 2Ï€r. In this case r = 5.75. So the circumference of the circle is 2*5.75*Ï€ = 11.5Ï€ = 36.12 inches. Now 15 minutes is quarter of an hour, so in 15 minutes the time of the minute hand will travel a quarter of this distance, or 9.03 inches.
Category: Mathematics; 2010-03-09 15:13:58
6. "Does Anyone Have Cricket Cell Phone Service VS Straight Talk..Cricket is 20.00 Cheaper?>>"?
I was wondering how good.. clear.. or bad.. the signals are.. and how far they reach ... I was told.. Verizon trac phones... use Verizon towers which go everywhere.. even if you travel far out of range or another state.. But.. I save 20.00 by using Crickets Unlimited.. where as.. Verizon Straight Talk Unlmited is 45.00.. I got rid of my home phone.. I just will be using the headset with the Cell.. Can you all please compare.. and let me know.. IF your using the two? I am on a limited income rt now.. so.. 25.00 a month is better.. BUT>> on the other hand .. if I lose the signals or.. can't get out in range or travel and its dead.. I will be in trouble.. Let Me Know.. Thank You All I am not sure if Cricket occasionally offers new plans for new customers .. but.. it says on line 25.00 for unlimited plan .. any more and I can go with Verizon.. but.. Not sure of how far their coverage expands.
Answer: I have Cricket and love it. I used to have ATT land line and cell. Cricket let me keep my home phone number to use on the Cricket cell. It is my only phone. I get totally clear reception and no dropped calls. My unlimited plan comes to about $40 including all taxes. It allows me to make unlimited calls local and long distance with no time blackouts. There are no contracts so you can drop it any time if you don't like it, although I've had it over a year now with no complaints. You do need to look at their maps to be sure you have coverage. Also, mine is 3G.
Category: Cell Phones & Plans; 2010-03-09 13:53:08