Thursday, May 26, 2011

Lab 10.2: Solubility vs. Temperature

Our graph was similar to table G in our reference tables but because we only had four points our graph it showed some differences and created some room for error. Only using ten grams of solvent instead of one-hundred on our graph created less accurate results as compared to the one on table G.
In our experiment the temperature of water impacted on how quickly solvent dissolved. The more KLO3 (greater concentration) the more time it takes to dissolve. To dissolve more quickly we put the test tube into a hot water bath to increasing the temperature of the solution. When the solution is liquifyied the particles make more collisions, and they are also more efficient(effective). At the liquid stage the particles are less attracted to each other than at a solid. bB crushing the KLO3 you could increase its surface area and help to speed up the rate of reaction. In our experiment the solution was unsaturated when the KLO3 was undissolved at the bottom of the test tube. It was saturated when the KLO3 had completely dissolved into the solution.

Enrichment:
Rock candy is a saturated solution. Yo saturate the water you add as much sugar as it can take, but then heating the water you create more space for sugar creating a supersaturated solution. You would then add the string into the water on which the rock candy would form as the water cools the sugar to come out of the solution forming a precipitate which we know as the crystals of the rock candy. This is because the super saturated solution has more sugar in it than it can possibly hold.

Lab 11.1: Corrosion of metals

1.
a) The penny wrapped in steel wool was less corroded then the unwrapped penny.
b) This is sacrificing metal technique because you did not coat the penny with a metal so only the outside only corrodes you merely wrapped it leaving some parts of the penny showing and corroding. The iron was "sacrificed" so most of the penny was protected(steel wool was corroded in place for the copper in the penny).
c) This works because iron is more active on table j than copper so the copper won't react with the rain. The active iron bands react with the rain and become erroded but leaves the copper unharmed. Hence them being checked and replaced regularly.
2.The corrosion is occuring because the aluminum is more active than the iron that was surrounding it; yhe Al ion and the iron are reacting because the metal is higher on table j.

3. The caulk would've created a barrier between the Al and Fe. So there would have been a coating and less corrosion would have had taken place.

4.
a) Corrosion is when a metal and an ion reacting cause the metal to errode.
b) Chemists have created different ways to outsmart it by putting the iron is the copper made statue of liberty or using caulk between the metals and ions. This coats the metal they want to protect with another metal so that metal will corrode instead of the one you need.
Enrichment:
Al+O2---> Al+3 and Fe +Al+3 ---->Al +Fe +3.
Aluminum is represented by A and iron would represented B.

Monday, May 16, 2011

Lab 11.2: Table J and Metal Reactivity

1.    a) The nitrate ion known as a “spectator ion” is an appropriet title because as examined in the reaction equation nitrate stays the same befor and after the reaction. 

     b) In the reaction between magnesium and silver solution, silver was oxidized and magnesium is reduced. 

2. Metal X and metal ion Y+2 will react, when X is higher then Y based on Table J.


3.  1. An activity series is a list of substances ranked in order of decreasing relative reactivity. The most metallic elements of group 1 have the most relitive reactivity nonmetalic elements at the bottom of table J are the least reactive(left side of table s moving towards the right go from most metallic elements to non metallic).
     2.   Which ever metal is higher on table J is more reactive then the metal below it.

4. Gold, silver, and copper are on the bottom of table j suggesting the are the least reactive metals. This made it easier for humans to discover these metals because they havent reacted with there surrondings. Other metals (lead, tin, iron, mercury) that are more reactive were dicovered much later because you must go deeper into the surface to find these metals nonreactive to the surrondings.5. 
  • Copper was smelted from its ores Malachite and Azurite in anctient times. In a pottery kiln with charcoal these elements were fired and reduced to metallic copper.
  • Bronze is made of copper and tin melted together at high temperatures.
Enrichment:
The light sensitivity of the silver halides exposed to a light, a chemical reaction darkens the film to produce an image. AgCl used in photography, consists tightly packed ions of silver and chlorine, when film containing Ag+ and Cl- is exposed to light energy, the chlorine ion's extra electron captured by a silver ion. When silver metal is produced as a result of the electron capture, it forms a dark image on film.  Ag+ has been reduced to Ag (metal), and Cl- has been oxidised.

Wednesday, May 4, 2011

Lab 10.3: Titration+ Colligative Properties

  • When measuring the concentration of base (NaOH) there was not much difference in the readings of each sample. This wasnt surprising since we were doing the same procedure with the same material three times.Some possible errors that may have caused differences in the values are not reading the graduated cilinder to an exact decimal amount or not reading the value at the exact time of post-neutralization (8 pH). To fix this you can have more then one person observe at the same time as you to catch the right value right at nuetralization and also have a graduated cylinder with more measurement marks for a more precise measure rather then geuss the value between two lines.
  • Antifreeze is an important for your engine in different climates. When the temperature gets cold we need something that has a lower freezing points to still finction in cold weather. Antifreeze has chemicals that will remove the access metal and other substances from your car engine, without freezing in the pipes of the engine. By having molecules that can be dissolved into ions and are soluble in water in the antifreeze, the freezing point is lowered because of the energy transfers. In order for water to freeze, a set ratio of water molecules needs to form a specific crystal  If extra ions are in the water, the polar ends of water molecules will attract to these ions more so than they will with other water molecules. Therefor the antifreeze will not freeze the pipes within your car while in use. The opposite happens when it is really hot out. When the temp may be above the boiling point of water the extra ions increase the boiling point because the attractions are stronger than standerd hydrogen bonds between water molecules. So with stronger bonds between molecules, the more energy will be need to break them apart meaning a higher boiling point. Antifreeze is needed in order to raise the boiling point of the water above the temperature surronding it so that the water solution created stays a liquid and allows your car to function.
  • Enrichment: Ice cream.
    The dissolved sugar, by getting in the way of the molecules that bond together to form ice crystals lowering the freezing point of the cream. This is why the cream solution will not freeze at the same temperature that water freezes. When the temperature of the cream gets low enough the water molecules have slowed down enough thso now their attraction becomes stronger than the disruptive influence of the sugar. For the temperature of the cream to get low enough  they crystallize, the water molecules are removed from the solution which means the remaining solution gets more concentrated with sugar so its freezing point is even lowered further.