How many grams are there in 6.21 moles of cacl2? #1 i am not sure if it's right and explain .

Rearrange the equation n=M÷Mr. Where n = the number of moles. M= the mass in grams. And Mr = the molecular mass of the substance.
Since you are working out mass use the equation M= n x Mr. So you have
6.21 × 111 (molecular mass of CaCl2).
This will give you the answer 689.31 grams which would be your final answer.

Self-ionizes to form an equilibruium system in which [ h_{3} o^{+} ]=[ oh^{-} ]=10^{-7} m