[danny411]

30.0 g of potassium chloride , kcl, dissolves in 175 ml of water

calculate the kcl In M

i got 2.30 M

and for the ions the same

the other one was 50.0 ml solution Ca(No3)2 has a [No3] of 4.0 x10^-1. how many grams of ca(no3)2 has been dissolved?

i think i can divide 4.0 x 10^-1 /2 since the mole rations is 2

then ca(no3)2 is .200

do i divide this by 1.00 or 50.0 ?

maybe im lost can someone show me the way to do it ? step by step ?

[sameeralord]

30.0 g of potassium chloride , kcl, dissolves in 175 ml of water

Concentration is= n/v

n=moles
v= volumes in litres

So first find the moles.

n=m/mr 

m=mass
mr=molar mass you find in the periodic table

After that divide the moles you found by 0.175

the other one was 50.0 ml solution Ca(No3)2 has a [No3] of 4.0 x10^-1. how many grams of ca(no3)2 has been dissolved?

I'm assuming 4.0 x10^-1 is M. Make a another equation like this.

Ca²⁺ + 2NO₃^- =Ca(NO₃)₂

First find the moles of  [No3]

n=cxv
   4.0 x10^-1 x 0.050

Now use mole ratios to find the moles of Ca(NO₃)₂
Times the moles you found by 1/2.

Now find the mass m=nxmr