Question

Where did I mess up? 90.0 mL 0.439 M NaCl and 100.0 mL 0.0516 M MgCl2 and 235.0 mL water--what is the resulting molarity of Cl in the solution that results?

Answer 1

I said 0.0439 mol Cl from NaCl and 0.00929 mol Cl from MgCl2 together makes 0.05319 mol Cl, divided by 0.425 L of total solution, and got 1.252. Note that my teacher prefers finding sig figs for every step of the process, not just the answer.

Answer 2

1) You have 0.0439 mol Cl (from NaCl) per 1 L. You calculated last time correctly the mol per 90 ml

2) Your mol for Cl from MgCl2 is not 0.00929 mol. Please post your calculation for mol Cl from MgCl2.

Answer 3

Oh, ok. Sorry for responding late, trying to make sense of these other problems at the same time.

Answer 4

My calculation for Cl from MgCl2 was:
90 x (1/1000) x (0.0576/1) x (2/1) = 0.00929

Answer 5

You're using 90 mL. The 90 mL is from NaCl. MgCl2 has a different value for volume.

Answer 6

Now that you mention it, I used 100 for the NaCl one, too. Let me fix that and see if it's correct then.

Answer 7

Yep, now I got it. Thanks.