PLS:i want to ask about form 5 physics chapter 4 ~~~~wht is the characteristics of cathode ray??
i juz know move in the straight line,negatively charge....then another i dnt know le
sejarah is not difficult.if u want to pass only,u need to memorise 8 "special" topics only without loss memory.i guarantee u can pass very good,but not A!
A fisher man is rowing a boat to cross the river with a force of 50N. The river is flowing downstream with a force of 30N at the right-angle of the boat. What is the resultant force
请问 chemistry的chapter 3的B The mole and the munber of particles 这课。。
什么6.02 X 10^23 的 ...
×寂寞°心 发表于 21-2-2011 05:35 PM
mole华语也可以把它当作是"倍",例如1mole of copper=6.02 x 10^23 copper atoms (1倍的copper里有6.02 x 10^23的atom)
6.02x10^23 atoms = number of particle in on mole of substance = Avogadro Constant (AV or NA)
molecular substances的话算出来的就是molecules,例如1mole of water=6.02 x 10^23 H2O molecules
ionic substances就分成formula units和或者把它们拆开来算咯~formula units算出来就写后面就写formula units,例如1mole of sodium oxide=6.02 x 10^23 formula units。可是sodium oxide(Na2O)是由sodium ion(Na+)和oxide ion(O2-)组成的,应此它的total ion是=3 x formula unit of sodium oxide