اريد المساعده في هذه المسائل و شكرراا ...

[Wasan R. AL-Qurashi]

السلام عليكم و رحمة الله و بركاته ...
a solution is prepared by dissolving 516.5 mg of oxalic acid (C2H3O4) to make 100 ml of solution . a 159 ml portion is then diluted to 250 ml > whatis the mo;arity of the final solution ??




what mass of Li3PO4 is needed to prepare 107ml of a solution having a lithium concentration of 0.175 M ?
HE SAID THAT THE ANSWER IS : 0.72 g





a 0.580 g sample of compound containing only carbpn and hydrogen contains 0.480 g of carbon and 0.100 g of hydrogen .at stp , 33.6 ml of the gas has a mass of 0.087 g what is the molecular formula for the copound ?



thanks alote ....