Question

How many ions are present in 9.4g of pottasium oxide K2O? (K=39 ,O=16) (Avogadros constant=6.0*10^23/mol)

Answer 1

each unit of K2O is made up of 3 ions: 2-K ions and 1-O ion. In each mole of K2O there are 6.022x10^23 formula units of K2O. Find the moles of K2O using the MM of K2O, then find the ## of formula units using avogadro's ##. Finally, find the ## of ions by taking that ## and multiplying by 3. I get about 1.8x10^23 ions

Answer 2

Well I dont understand why we are saying that each unit of K2O is made up of 3 ions.

Answer 3

each K ion has a +1 charge. each O ion has a -2 charge. In order to make an electrically neutral combination, you need to have 2 K's and 1 O. That's why there are 3 ions per formula unit of K2O

Answer 4

ok

Answer 5

wats an electrical neutral combination?

Answer 6

the sum of the charges have to add up to zero. You can't change the charges that each ion has, but you can have more than one copy of an ion to act like a multiplier

Answer 7

but -2+-1=-3

Answer 8

is negative two and negative 1 not the charges?

Answer 9

positive 1 and negative 2 are the charges.\[2(+1) + 1(-2) = 0\]

Answer 10

sorry um puzzled isnt the sum of the charges( =1+-2)

Answer 11

if all you had was one of each ion, then the charge would be -1. The compound MUST have a charge of zero, so that means you need 2 positive ions for every one negative 2 piece.

Answer 12

please give me an example of if i had one of each ion?

Answer 13

oh my i get it now boss thanks a lot and it matches the marking scheme