Please help! History of the Periodic Table When did people first start really looking for patterns in the elements? Why then?

Phosphorous acid, h3po3(aq) , is a diprotic oxyacid that is an important compound in industry and agriculture. the values of phosphorous acid are 1.30 6.70 calculate the ph for each of the given points in the titration of 50.0 ml of 1.5 m h3po3(aq) with 1.5 m koh(aq) .

How many moles of gas are present if p=11 atm, v=12l, t=185k?

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.