ATAR Notes: Forum
HSC Stuff => HSC Science Stuff => HSC Subjects + Help => HSC Chemistry => Topic started by: Droolv on July 23, 2016, 05:26:26 pm
-
Hey guys, I'm doing some revision for my Chem assessment and I'm having difficulties with questions revolving around ionic concentrations. I've posted a photo with the question and possible answers. I'd love some help, thanks in advance.
The question reads: a solution is made by dissolving 0.1mol of sodium chloride, and 0.1mol of calcium chloride in water to make a volume of 200ml of solution. What are the ionic concentrations, in molL^-1, of this solution?
(http://uploads.tapatalk-cdn.com/20160723/c7cb36faa96fdd84c473b84635baa82e.jpg)
-
Hey guys, I'm doing some revision for my Chem assessment and I'm having difficulties with questions revolving around ionic concentrations. I've posted a photo with the question and possible answers. I'd love some help, thanks in advance.
The question reads: a solution is made by dissolving 0.1mol of sodium chloride, and 0.1mol of calcium chloride in water to make a volume of 200ml of solution. What are the ionic concentrations, in molL^-1, of this solution?
(http://uploads.tapatalk-cdn.com/20160723/c7cb36faa96fdd84c473b84635baa82e.jpg)
In 0.1 mol of NaCl there is exactly 0.1 mol of Na+, and 0.1 mol of Cl-
Using the formula C=n/V we therefore have
[Na+] = nNa+/V = 0.1/0.2 = 0.5 mol L-1
In 0,1 mol of CaCl2 there is exactly 0.1 mol of Ca2+, and 0.2 mol of Cl-
So we have [Ca2+] = nCa2+/V = 0.1/0.2 = 0.5 mol L-1
Our total moles of the chloride ion, however, is
nCl- = 0.1 + 0.2 = 0.3 mol
Hence [Cl-] = 0.3/0.2 = 1.5 mol L-1
-
Thanks so much!