Mass approximately 3 g of impure acetanilide, transfer to a 250 ml round bottom flask, and add 2-3 boiling chips. add 75 ml of tap water to the flask, place on an electric heating mantle (ask instructor if you do not understand this) attached to a voltage regulator (do not connect the heating mantle directly to the electric outlet). you can slowly start heating the water and if it is too slow increase the voltage in the regulator. try not to spill any water as you are dealing with heating mantle. you need to bring the solution to boiling and while you are waiting for the solution to boil, arrange a gravity filtration set up (see book chapter 4) using a stemless funnel, fluted filter, and 125 ml erlenmeyer flask. when mixture has boiled for 3 mins, pour the dark suspension over the filter paper at a rate so that filter paper remains about half full. be careful the solution is hot. time to time while you are filtering, you can put the flask in the mantle to avoid cooling and crashing out of the product beforehand. after all solution is filtered, the fluted filter paper containing black precipitate (due to presence of charcoal) may be discarded (goes to solid waste). the solution in the erlenmeyer flask is allowed to cool undisturbed to room temperature (this may take a long time). the crystals that formed in the erlenmeyer flask are filtered using a buchner funnel/suction flask which is clamped to a ring stand (ask instructor if you do not understand and see book for details). do not forget to put a filter paper in the buchner funnel before filtration (not the flutted filter paper). use a little bit of the filtrate already in the funnel and rinse your erlenmeyer to collect all the precipitate. do not use just tap water to rinse your crystals. filter the crystal under suction for 5 mins. carefully remove all the crystals in a watch glass and air dry for 5 to 10 mins. measure and record the mass of the crystals you have obtained and calculate percent recovery (remember you have started with 3 g, you’ll get less than that for sure). record the melting points of the impure acetanilide and pure acetanilide.

Stage in which a typical star has completely stopped fusion

Experiment: effect of solution concentration on reaction rate you have learned that as the concentration of reactants increases, there will most likely be a greater number of collisions, and hence increase the rate of a reaction. in this experiment, you will see a demonstration of this, with a twist. there will be three reactions going on in this experiment. objectives determine how solution concentration can affect the rate of a reaction. the first reaction will be a reaction of the iodide ion (i-1) with hydrogen peroxide (h2o2) in an acidic solution. this reaction produces a slightly orange solution. in our experiment, we will add some orange food coloring to make this solution more orange. 2 h+ (aq) + 2 i- (aq) + h2o2 (aq) ⟶ i2 (aq) + 2 h2o (l) the next reaction will be between the iodine and starch i2 + starch ⟶ i2-starch complex (blue-black) so, when starch is added to the iodine solution made from the first reaction, the solution will turn black immediately, so it is difficult to find the rate of reaction. in order to be able to time this reaction, you will slow it down with another reaction. adding ascorbic acid will react with the iodine, reducing the concentration of the iodine available to react with the starch. c6h8o6 (aq) + i2 (aq) ⟶ 2i- (aq) + c6h6o6 (aq) + 2 h+ (aq) when the ascorbic acid is used up, the remaining iodine molecules can react with the starch and form the black color. the more ascorbic acid you add, the slower the reaction to form the iodine-starch complex will be. use your data and observations to complete the assignment. analysis and conclusions submit your data and the answers to these questions in the essay box below. what was your hypothesis? plot your data as drops of ascorbic acid vs. time. as the concentration of ascorbic acid was increased, did the rate of the formation of the iodine-starch complex increase or decrease? explain your answer in terms of the chemical reactions involved. was your hypothesis correct? make a general rule about the effects of concentration of reactants on reaction rates. for practice, the molecular formula for ascorbic acid is c6h8o6, and you used 6 g in this experiment, calculate the molarity of the ascorbic acid. now calculate the concentration in moles per drop (assume 1 ml = 20 drops).

The graph shows one consequence of urban sprawl. how did urban sprawl contribute to the change in biodiversity