posted by Carrie on .
I was just wanting to make sure I did these right.
How many grams of solute are in each of the following solutions?
a.) 2.5 L of 3.0 M Al(NO3)3 solution.
for this one I get 1600 g of Al(NO3)3
b.) 75 ml of 0.5 M C6H12O6 solution.
and for this one I get 6.8g of C6 H12 O6
How many milliliters of a 12% (v/v) propyl alcohol solution would you need to obtain 4.5 ml of propyl alcohol.
I get 38 ml of solution
A student prepared a solution by dissolving 5 g of KI in enough water to give a final volume of 250 ml. what is the mass/volume percent (m/v) of KI solution.
I got 2% (m/v)KI
For #1 I obtained 1597 g and I understand why you rounded to 1600 g (because you are allowed only two significant figures); however, the 1600, leaves the reader (or instructor) in a quandary. He/she doesn't know if the last two zeros are significant or not. Technically it means they are not and if that is what you meant, (and your instructor knows that, too) great. A better way to write the answer is 1.6E2 and that leaves no doubt how many s.f. there are.
The others look ok.