By the end of this lab, you will see how some
materials diffuse through a semipermeable
membrane but others do not. the materials that
you examine will differ in molecule size. some will
be larger and some smaller. formulate an
investigative question for this situation.

Calculate the number of molecules present in 0.750 mol of mgo.

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.

The scheme below is from a series of reactions that are part of a synthesis of vitamin a. answer the following questions with reference to this scheme. (i) what is "reagent a"? (ii) draw a step-by-step mechanism which explains the formation of compound c from compound b (iii) which reagents would you use to form compound e from compounds c and d (reagents b and c)? for each reagent suggested above in (ii) explain the role of the reagent in the reaction to (iv) form compound e. you may wish to do this by drawing a mechanism. 1. addition of reagent a но reagent a 2. н,о" thо oh нон-с compound a. compound b. compound c .ch-оh 1. reagent b "сно 2. reagent c сh oh compound e. compound d.