What is the concentration of the base (koh) in the following titration, given the data below?
0.75 m hbr unknown koh
initial burette reading
0.0 ml
0.5 ml
final burette reading
22.6 ml
37.5 ml

Amass of 100.0 g of solute is dissolved in water so that 850. ml of a 0.7500 m solution has been prepared. what is the molar mass of the solute?

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.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.