April 19, 2015

Posts by Chemistry

Total # Posts: 209

A combustion bomb containing 5.417 g of aluminum metal and 15.974 g of iron III oxide is placed in an ice calorimeter that initially contained 7.746 kg of ice (at o degrees C) and 7.894 kg of liquid water (at o degrees C). The reaction, once ignited by remote control, forms ...
October 16, 2007

If 142.38 g of l water at 21.7 degrees C is placed into a syrofoam cup with 174.36 g of ice at -27.5 degrees C what would be the final temperature of the entire contents at equilibrium? If it is partially frozen, how many g of the ice has melted? given values cp water = 4.184 ...
October 16, 2007

Thank you DrBob222! I got it now!
September 27, 2007

what does an atom of lead look like? what are the parts that compose of the atom? help me pls
September 3, 2007

A certain mine produces 2.5 108 kg of copper from chalcopyrite (CuFeS2) each year. The ore contains only 0.80% Cu by mass. (a) If the density of the ore is 2.0 g/cm3, calculate the volume of ore removed each year. (b) Calculate the mass of SO2 produced by roasting (assume ...
April 13, 2007

I asked this question yesterday and it was answered, but I still have a question on it. Standard entropies for substances are defined at a pressure of exactly 1 bar in some books or exactly 1 atm(760 torr) in different books. For gases, this correction factor would be..... in ...
April 4, 2007

I need some help with calculating percent yield and percent purity of aspirin. Here's my data (questions follow): SYNTHESIS Mass of salicylic acid.., 2.0 g Volume of acetic anhydride.., 5 mL Mass of watch glass.., 22.10 g Mass of aspirin and watch glass.., 28.01 g Mass of ...
March 24, 2007

Which of the following does form a Group II cation? lead iron cobalt nickel How do you figure this one out? You must know what is in group II. Fe, Co, and Ni are in group III. Pb is in both group I and group II. Pb ppts as the chloride in group I and as the sulfide in group II.
February 20, 2007

Al3+ and Pb2+ act as acids or bases in acidic or alkaline environment. True or False? I think this is true because they are amphoteric, but I am not sure. yes. They are amphoteric.
February 20, 2007

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