As the lab was taking place, is it possible that the atmospheric (air) pressure may have changed? If it did change, how could the results have been affected? What other variables may not have been accounted for in this lab? (Hint: Air pressure changes if a weather front is moving through the area, such as might be the case when rainstorms occur.)

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

An unknown insoluble substance displaced the water shown. it's mass is indicated on the triple beam balance. mass = a. 694 b. 693.5 c. 693.0 d.693.8

Ahelium balloon contains 16.9 l of helium at stp. how many atoms of helium are in the balloon