Ch 202 Problem 3.34

3.34 calculate the following quantities:

(a) mass, in grams, of 5.76x10-3 mol CdS.

the conversion factor from grams -> moles or moles -> grams is the molar mass; calculate it

for cadmium sulfide...

now set the problem up as a simple unit conversion:

(b)number of moles of NH4Cl in 112.6 g of this substance

again, use the molar mass....

(c) number of molecules in 1.305 x 10-2 mol of C6H6

whenever we calculate a number of atoms or molecules, we will use Avogadro's number, since this number gives us the number of things (atoms, molecules, ions, gnus) in 1 mol of those things. Here we're given a mol quantity and asked to convert it to individual molecules:

dummy unit

(d) number of O atoms in 4.88x10-3 mol Al(NO3)3

again, we're given a molar quantity and asked to convert to a numerical quantitiy, The trick here is

to notice that for each aluminum nitrate unit, we have nine O atoms.....

fake unit

DAC 7/2/08